A new neural framework for visuospatial processing

PubMed Central

Kravitz, Dwight J.; Saleem, Kadharbatcha S.; Baker, Chris I.; Mishkin, Mortimer

2012-01-01

The division of cortical visual processing into distinct dorsal and ventral streams is a key framework that has guided visual neuroscience. The characterization of the ventral stream as a ‘What’ pathway is relatively uncontroversial, but the nature of dorsal stream processing is less clear. Originally proposed as mediating spatial perception (‘Where’), more recent accounts suggest it primarily serves non-conscious visually guided action (‘How’). Here, we identify three pathways emerging from the dorsal stream that consist of projections to the prefrontal and premotor cortices, and a major projection to the medial temporal lobe that courses both directly and indirectly through the posterior cingulate and retrosplenial cortices. These three pathways support both conscious and non-conscious visuospatial processing, including spatial working memory, visually guided action and navigation, respectively. PMID:21415848

Inter-area correlations in the ventral visual pathway reflect feature integration

PubMed Central

Freeman, Jeremy; Donner, Tobias H.; Heeger, David J.

2011-01-01

During object perception, the brain integrates simple features into representations of complex objects. A perceptual phenomenon known as visual crowding selectively interferes with this process. Here, we use crowding to characterize a neural correlate of feature integration. Cortical activity was measured with functional magnetic resonance imaging, simultaneously in multiple areas of the ventral visual pathway (V1–V4 and the visual word form area, VWFA, which responds preferentially to familiar letters), while human subjects viewed crowded and uncrowded letters. Temporal correlations between cortical areas were lower for crowded letters than for uncrowded letters, especially between V1 and VWFA. These differences in correlation were retinotopically specific, and persisted when attention was diverted from the letters. But correlation differences were not evident when we substituted the letters with grating patches that were not crowded under our stimulus conditions. We conclude that inter-area correlations reflect feature integration and are disrupted by crowding. We propose that crowding may perturb the transformations between neural representations along the ventral pathway that underlie the integration of features into objects. PMID:21521832

Neural pathways for visual speech perception

PubMed Central

Bernstein, Lynne E.; Liebenthal, Einat

2014-01-01

This paper examines the questions, what levels of speech can be perceived visually, and how is visual speech represented by the brain? Review of the literature leads to the conclusions that every level of psycholinguistic speech structure (i.e., phonetic features, phonemes, syllables, words, and prosody) can be perceived visually, although individuals differ in their abilities to do so; and that there are visual modality-specific representations of speech qua speech in higher-level vision brain areas. That is, the visual system represents the modal patterns of visual speech. The suggestion that the auditory speech pathway receives and represents visual speech is examined in light of neuroimaging evidence on the auditory speech pathways. We outline the generally agreed-upon organization of the visual ventral and dorsal pathways and examine several types of visual processing that might be related to speech through those pathways, specifically, face and body, orthography, and sign language processing. In this context, we examine the visual speech processing literature, which reveals widespread diverse patterns of activity in posterior temporal cortices in response to visual speech stimuli. We outline a model of the visual and auditory speech pathways and make several suggestions: (1) The visual perception of speech relies on visual pathway representations of speech qua speech. (2) A proposed site of these representations, the temporal visual speech area (TVSA) has been demonstrated in posterior temporal cortex, ventral and posterior to multisensory posterior superior temporal sulcus (pSTS). (3) Given that visual speech has dynamic and configural features, its representations in feedforward visual pathways are expected to integrate these features, possibly in TVSA. PMID:25520611

Functionally defined white matter reveals segregated pathways in human ventral temporal cortex associated with category-specific processing

PubMed Central

Gomez, Jesse; Pestilli, Franco; Witthoft, Nathan; Golarai, Golijeh; Liberman, Alina; Poltoratski, Sonia; Yoon, Jennifer; Grill-Spector, Kalanit

2014-01-01

Summary It is unknown if the white matter properties associated with specific visual networks selectively affect category-specific processing. In a novel protocol we combined measurements of white matter structure, functional selectivity, and behavior in the same subjects. We find two parallel white matter pathways along the ventral temporal lobe connecting to either face-selective or place-selective regions. Diffusion properties of portions of these tracts adjacent to face- and place-selective regions of ventral temporal cortex correlate with behavioral performance for face or place processing, respectively. Strikingly, adults with developmental prosopagnosia (face blindness) express an atypical structure-behavior relationship near face-selective cortex, suggesting that white matter atypicalities in this region may have behavioral consequences. These data suggest that examining the interplay between cortical function, anatomical connectivity, and visual behavior is integral to understanding functional networks and their role in producing visual abilities and deficits. PMID:25569351

Ventral Lateral Geniculate Input to the Medial Pons Is Necessary for Visual Eyeblink Conditioning in Rats

ERIC Educational Resources Information Center

Halverson, Hunter E.; Freeman, John H.

2010-01-01

The conditioned stimulus (CS) pathway that is necessary for visual delay eyeblink conditioning was investigated in the current study. Rats were initially given eyeblink conditioning with stimulation of the ventral nucleus of the lateral geniculate (LGNv) as the CS followed by conditioning with light and tone CSs in separate training phases.…

Spontaneous in-flight accommodation of hand orientation to unseen grasp targets: A case of action blindsight.

PubMed

Prentiss, Emily K; Schneider, Colleen L; Williams, Zoë R; Sahin, Bogachan; Mahon, Bradford Z

2018-03-15

The division of labour between the dorsal and ventral visual pathways is well established. The ventral stream supports object identification, while the dorsal stream supports online processing of visual information in the service of visually guided actions. Here, we report a case of an individual with a right inferior quadrantanopia who exhibited accurate spontaneous rotation of his wrist when grasping a target object in his blind visual field. His accurate wrist orientation was observed despite the fact that he exhibited no sensitivity to the orientation of the handle in a perceptual matching task. These findings indicate that non-geniculostriate visual pathways process basic volumetric information relevant to grasping, and reinforce the observation that phenomenal awareness is not necessary for an object's volumetric properties to influence visuomotor performance.

Representation of Gravity-Aligned Scene Structure in Ventral Pathway Visual Cortex.

PubMed

Vaziri, Siavash; Connor, Charles E

2016-03-21

The ventral visual pathway in humans and non-human primates is known to represent object information, including shape and identity [1]. Here, we show the ventral pathway also represents scene structure aligned with the gravitational reference frame in which objects move and interact. We analyzed shape tuning of recently described macaque monkey ventral pathway neurons that prefer scene-like stimuli to objects [2]. Individual neurons did not respond to a single shape class, but to a variety of scene elements that are typically aligned with gravity: large planes in the orientation range of ground surfaces under natural viewing conditions, planes in the orientation range of ceilings, and extended convex and concave edges in the orientation range of wall/floor/ceiling junctions. For a given neuron, these elements tended to share a common alignment in eye-centered coordinates. Thus, each neuron integrated information about multiple gravity-aligned structures as they would be seen from a specific eye and head orientation. This eclectic coding strategy provides only ambiguous information about individual structures but explicit information about the environmental reference frame and the orientation of gravity in egocentric coordinates. In the ventral pathway, this could support perceiving and/or predicting physical events involving objects subject to gravity, recognizing object attributes like animacy based on movement not caused by gravity, and/or stabilizing perception of the world against changes in head orientation [3-5]. Our results, like the recent discovery of object weight representation [6], imply that the ventral pathway is involved not just in recognition, but also in physical understanding of objects and scenes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Binocular depth processing in the ventral visual pathway

PubMed Central

Vogels, Rufin

2016-01-01

One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The brain employs these disparities to facilitate various computations, including sensori-motor transformations (reaching, grasping), scene segmentation and object recognition. In accordance with these different functions, disparity activates a large number of regions in the brain of both humans and monkeys. Here, we review how disparity processing evolves along different regions of the ventral visual pathway of macaques, emphasizing research based on both correlational and causal techniques. We will discuss the progression in the ventral pathway from a basic absolute disparity representation to a more complex three-dimensional shape code. We will show that, in the course of this evolution, the underlying neuronal activity becomes progressively more bound to the global perceptual experience. We argue that these observations most probably extend beyond disparity processing per se, and pertain to object processing in the ventral pathway in general. We conclude by posing some important unresolved questions whose answers may significantly advance the field, and broaden its scope. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269602

Binocular depth processing in the ventral visual pathway.

PubMed

Verhoef, Bram-Ernst; Vogels, Rufin; Janssen, Peter

2016-06-19

One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The brain employs these disparities to facilitate various computations, including sensori-motor transformations (reaching, grasping), scene segmentation and object recognition. In accordance with these different functions, disparity activates a large number of regions in the brain of both humans and monkeys. Here, we review how disparity processing evolves along different regions of the ventral visual pathway of macaques, emphasizing research based on both correlational and causal techniques. We will discuss the progression in the ventral pathway from a basic absolute disparity representation to a more complex three-dimensional shape code. We will show that, in the course of this evolution, the underlying neuronal activity becomes progressively more bound to the global perceptual experience. We argue that these observations most probably extend beyond disparity processing per se, and pertain to object processing in the ventral pathway in general. We conclude by posing some important unresolved questions whose answers may significantly advance the field, and broaden its scope.This article is part of the themed issue 'Vision in our three-dimensional world'. © 2016 The Author(s).

Dissociation and Convergence of the Dorsal and Ventral Visual Streams in the Human Prefrontal Cortex

PubMed Central

Takahashi, Emi; Ohki, Kenichi; Kim, Dae-Shik

2012-01-01

Visual information is largely processed through two pathways in the primate brain: an object pathway from the primary visual cortex to the temporal cortex (ventral stream) and a spatial pathway to the parietal cortex (dorsal stream). Whether and to what extent dissociation exists in the human prefrontal cortex (PFC) has long been debated. We examined anatomical connections from functionally defined areas in the temporal and parietal cortices to the PFC, using noninvasive functional and diffusion-weighted magnetic resonance imaging. The right inferior frontal gyrus (IFG) received converging input from both streams, while the right superior frontal gyrus received input only from the dorsal stream. Interstream functional connectivity to the IFG was dynamically recruited only when both object and spatial information were processed. These results suggest that the human PFC receives dissociated and converging visual pathways, and that the right IFG region serves as an integrator of the two types of information. PMID:23063444

Ventral and Dorsal Pathways Relate Differently to Visual Awareness of Body Postures under Continuous Flash Suppression

PubMed Central

Goebel, Rainer

2018-01-01

Abstract Visual perception includes ventral and dorsal stream processes. However, it is still unclear whether the former is predominantly related to conscious and the latter to nonconscious visual perception as argued in the literature. In this study upright and inverted body postures were rendered either visible or invisible under continuous flash suppression (CFS), while brain activity of human participants was measured with functional MRI (fMRI). Activity in the ventral body-sensitive areas was higher during visible conditions. In comparison, activity in the posterior part of the bilateral intraparietal sulcus (IPS) showed a significant interaction of stimulus orientation and visibility. Our results provide evidence that dorsal stream areas are less associated with visual awareness. PMID:29445766

The dorsal "action" pathway.

PubMed

Gallivan, Jason P; Goodale, Melvyn A

2018-01-01

In 1992, Goodale and Milner proposed a division of labor in the visual pathways of the primate cerebral cortex. According to their account, the ventral pathway, which projects to occipitotemporal cortex, constructs our visual percepts, while the dorsal pathway, which projects to posterior parietal cortex, mediates the visual control of action. Although the framing of the two-visual-system hypothesis has not been without controversy, it is clear that vision for action and vision for perception have distinct computational requirements, and significant support for the proposed neuroanatomic division has continued to emerge over the last two decades from human neuropsychology, neuroimaging, behavioral psychophysics, and monkey neurophysiology. In this chapter, we review much of this evidence, with a particular focus on recent findings from human neuroimaging and monkey neurophysiology, demonstrating a specialized role for parietal cortex in visually guided behavior. But even though the available evidence suggests that dedicated circuits mediate action and perception, in order to produce adaptive goal-directed behavior there must be a close coupling and seamless integration of information processing across these two systems. We discuss such ventral-dorsal-stream interactions and argue that the two pathways play different, yet complementary, roles in the production of skilled behavior. Copyright © 2018 Elsevier B.V. All rights reserved.

Two speed factors of visual recognition independently correlated with fluid intelligence.

PubMed

Tachibana, Ryosuke; Namba, Yuri; Noguchi, Yasuki

2014-01-01

Growing evidence indicates a moderate but significant relationship between processing speed in visuo-cognitive tasks and general intelligence. On the other hand, findings from neuroscience proposed that the primate visual system consists of two major pathways, the ventral pathway for objects recognition and the dorsal pathway for spatial processing and attentive analysis. Previous studies seeking for visuo-cognitive factors of human intelligence indicated a significant correlation between fluid intelligence and the inspection time (IT), an index for a speed of object recognition performed in the ventral pathway. We thus presently examined a possibility that neural processing speed in the dorsal pathway also represented a factor of intelligence. Specifically, we used the mental rotation (MR) task, a popular psychometric measure for mental speed of spatial processing in the dorsal pathway. We found that the speed of MR was significantly correlated with intelligence scores, while it had no correlation with one's IT (recognition speed of visual objects). Our results support the new possibility that intelligence could be explained by two types of mental speed, one related to object recognition (IT) and another for manipulation of mental images (MR).

Dorsal and ventral stream contributions to form-from-motion perception in a patient with form-from motion deficit: a case report.

PubMed

Mercier, Manuel R; Schwartz, Sophie; Spinelli, Laurent; Michel, Christoph M; Blanke, Olaf

2017-03-01

The main model of visual processing in primates proposes an anatomo-functional distinction between the dorsal stream, specialized in spatio-temporal information, and the ventral stream, processing essentially form information. However, these two pathways also communicate to share much visual information. These dorso-ventral interactions have been studied using form-from-motion (FfM) stimuli, revealing that FfM perception first activates dorsal regions (e.g., MT+/V5), followed by successive activations of ventral regions (e.g., LOC). However, relatively little is known about the implications of focal brain damage of visual areas on these dorso-ventral interactions. In the present case report, we investigated the dynamics of dorsal and ventral activations related to FfM perception (using topographical ERP analysis and electrical source imaging) in a patient suffering from a deficit in FfM perception due to right extrastriate brain damage in the ventral stream. Despite the patient's FfM impairment, both successful (observed for the highest level of FfM signal) and absent/failed FfM perception evoked the same temporal sequence of three processing states observed previously in healthy subjects. During the first period, brain source localization revealed cortical activations along the dorsal stream, currently associated with preserved elementary motion processing. During the latter two periods, the patterns of activity differed from normal subjects: activations were observed in the ventral stream (as reported for normal subjects), but also in the dorsal pathway, with the strongest and most sustained activity localized in the parieto-occipital regions. On the other hand, absent/failed FfM perception was characterized by weaker brain activity, restricted to the more lateral regions. This study shows that in the present case report, successful FfM perception, while following the same temporal sequence of processing steps as in normal subjects, evoked different patterns of brain activity. By revealing a brain circuit involving the most rostral part of the dorsal pathway, this study provides further support for neuro-imaging studies and brain lesion investigations that have suggested the existence of different brain circuits associated with different profiles of interaction between the dorsal and the ventral streams.

Two Visual Pathways in Primates Based on Sampling of Space: Exploitation and Exploration of Visual Information

PubMed Central

Sheth, Bhavin R.; Young, Ryan

2016-01-01

Evidence is strong that the visual pathway is segregated into two distinct streams—ventral and dorsal. Two proposals theorize that the pathways are segregated in function: The ventral stream processes information about object identity, whereas the dorsal stream, according to one model, processes information about either object location, and according to another, is responsible in executing movements under visual control. The models are influential; however recent experimental evidence challenges them, e.g., the ventral stream is not solely responsible for object recognition; conversely, its function is not strictly limited to object vision; the dorsal stream is not responsible by itself for spatial vision or visuomotor control; conversely, its function extends beyond vision or visuomotor control. In their place, we suggest a robust dichotomy consisting of a ventral stream selectively sampling high-resolution/focal spaces, and a dorsal stream sampling nearly all of space with reduced foveal bias. The proposal hews closely to the theme of embodied cognition: Function arises as a consequence of an extant sensory underpinning. A continuous, not sharp, segregation based on function emerges, and carries with it an undercurrent of an exploitation-exploration dichotomy. Under this interpretation, cells of the ventral stream, which individually have more punctate receptive fields that generally include the fovea or parafovea, provide detailed information about object shapes and features and lead to the systematic exploitation of said information; cells of the dorsal stream, which individually have large receptive fields, contribute to visuospatial perception, provide information about the presence/absence of salient objects and their locations for novel exploration and subsequent exploitation by the ventral stream or, under certain conditions, the dorsal stream. We leverage the dichotomy to unify neuropsychological cases under a common umbrella, account for the increased prevalence of multisensory integration in the dorsal stream under a Bayesian framework, predict conditions under which object recognition utilizes the ventral or dorsal stream, and explain why cells of the dorsal stream drive sensorimotor control and motion processing and have poorer feature selectivity. Finally, the model speculates on a dynamic interaction between the two streams that underscores a unified, seamless perception. Existing theories are subsumed under our proposal. PMID:27920670

Two Visual Pathways in Primates Based on Sampling of Space: Exploitation and Exploration of Visual Information.

PubMed

Sheth, Bhavin R; Young, Ryan

2016-01-01

Evidence is strong that the visual pathway is segregated into two distinct streams-ventral and dorsal. Two proposals theorize that the pathways are segregated in function: The ventral stream processes information about object identity, whereas the dorsal stream, according to one model, processes information about either object location, and according to another, is responsible in executing movements under visual control. The models are influential; however recent experimental evidence challenges them, e.g., the ventral stream is not solely responsible for object recognition; conversely, its function is not strictly limited to object vision; the dorsal stream is not responsible by itself for spatial vision or visuomotor control; conversely, its function extends beyond vision or visuomotor control. In their place, we suggest a robust dichotomy consisting of a ventral stream selectively sampling high-resolution/ focal spaces, and a dorsal stream sampling nearly all of space with reduced foveal bias. The proposal hews closely to the theme of embodied cognition: Function arises as a consequence of an extant sensory underpinning. A continuous, not sharp, segregation based on function emerges, and carries with it an undercurrent of an exploitation-exploration dichotomy. Under this interpretation, cells of the ventral stream, which individually have more punctate receptive fields that generally include the fovea or parafovea, provide detailed information about object shapes and features and lead to the systematic exploitation of said information; cells of the dorsal stream, which individually have large receptive fields, contribute to visuospatial perception, provide information about the presence/absence of salient objects and their locations for novel exploration and subsequent exploitation by the ventral stream or, under certain conditions, the dorsal stream. We leverage the dichotomy to unify neuropsychological cases under a common umbrella, account for the increased prevalence of multisensory integration in the dorsal stream under a Bayesian framework, predict conditions under which object recognition utilizes the ventral or dorsal stream, and explain why cells of the dorsal stream drive sensorimotor control and motion processing and have poorer feature selectivity. Finally, the model speculates on a dynamic interaction between the two streams that underscores a unified, seamless perception. Existing theories are subsumed under our proposal.

Attention reduces spatial uncertainty in human ventral temporal cortex.

PubMed

Kay, Kendrick N; Weiner, Kevin S; Grill-Spector, Kalanit

2015-03-02

Ventral temporal cortex (VTC) is the latest stage of the ventral "what" visual pathway, which is thought to code the identity of a stimulus regardless of its position or size [1, 2]. Surprisingly, recent studies show that position information can be decoded from VTC [3-5]. However, the computational mechanisms by which spatial information is encoded in VTC are unknown. Furthermore, how attention influences spatial representations in human VTC is also unknown because the effect of attention on spatial representations has only been examined in the dorsal "where" visual pathway [6-10]. Here, we fill these significant gaps in knowledge using an approach that combines functional magnetic resonance imaging and sophisticated computational methods. We first develop a population receptive field (pRF) model [11, 12] of spatial responses in human VTC. Consisting of spatial summation followed by a compressive nonlinearity, this model accurately predicts responses of individual voxels to stimuli at any position and size, explains how spatial information is encoded, and reveals a functional hierarchy in VTC. We then manipulate attention and use our model to decipher the effects of attention. We find that attention to the stimulus systematically and selectively modulates responses in VTC, but not early visual areas. Locally, attention increases eccentricity, size, and gain of individual pRFs, thereby increasing position tolerance. However, globally, these effects reduce uncertainty regarding stimulus location and actually increase position sensitivity of distributed responses across VTC. These results demonstrate that attention actively shapes and enhances spatial representations in the ventral visual pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

Attention reduces spatial uncertainty in human ventral temporal cortex

PubMed Central

Kay, Kendrick N.; Weiner, Kevin S.; Grill-Spector, Kalanit

2014-01-01

SUMMARY Ventral temporal cortex (VTC) is the latest stage of the ventral ‘what’ visual pathway, which is thought to code the identity of a stimulus regardless of its position or size [1, 2]. Surprisingly, recent studies show that position information can be decoded from VTC [3–5]. However, the computational mechanisms by which spatial information is encoded in VTC are unknown. Furthermore, how attention influences spatial representations in human VTC is also unknown because the effect of attention on spatial representations has only been examined in the dorsal ‘where’ visual pathway [6–10]. Here we fill these significant gaps in knowledge using an approach that combines functional magnetic resonance imaging and sophisticated computational methods. We first develop a population receptive field (pRF) model [11, 12] of spatial responses in human VTC. Consisting of spatial summation followed by a compressive nonlinearity, this model accurately predicts responses of individual voxels to stimuli at any position and size, explains how spatial information is encoded, and reveals a functional hierarchy in VTC. We then manipulate attention and use our model to decipher the effects of attention. We find that attention to the stimulus systematically and selectively modulates responses in VTC, but not early visual areas. Locally, attention increases eccentricity, size, and gain of individual pRFs, thereby increasing position tolerance. However, globally, these effects reduce uncertainty regarding stimulus location and actually increase position sensitivity of distributed responses across VTC. These results demonstrate that attention actively shapes and enhances spatial representations in the ventral visual pathway. PMID:25702580

Two Speed Factors of Visual Recognition Independently Correlated with Fluid Intelligence

PubMed Central

Tachibana, Ryosuke; Namba, Yuri; Noguchi, Yasuki

2014-01-01

Growing evidence indicates a moderate but significant relationship between processing speed in visuo-cognitive tasks and general intelligence. On the other hand, findings from neuroscience proposed that the primate visual system consists of two major pathways, the ventral pathway for objects recognition and the dorsal pathway for spatial processing and attentive analysis. Previous studies seeking for visuo-cognitive factors of human intelligence indicated a significant correlation between fluid intelligence and the inspection time (IT), an index for a speed of object recognition performed in the ventral pathway. We thus presently examined a possibility that neural processing speed in the dorsal pathway also represented a factor of intelligence. Specifically, we used the mental rotation (MR) task, a popular psychometric measure for mental speed of spatial processing in the dorsal pathway. We found that the speed of MR was significantly correlated with intelligence scores, while it had no correlation with one’s IT (recognition speed of visual objects). Our results support the new possibility that intelligence could be explained by two types of mental speed, one related to object recognition (IT) and another for manipulation of mental images (MR). PMID:24825574

Opposing dorsal/ventral stream dynamics during figure-ground segregation.

PubMed

Wokke, Martijn E; Scholte, H Steven; Lamme, Victor A F

2014-02-01

The visual system has been commonly subdivided into two segregated visual processing streams: The dorsal pathway processes mainly spatial information, and the ventral pathway specializes in object perception. Recent findings, however, indicate that different forms of interaction (cross-talk) exist between the dorsal and the ventral stream. Here, we used TMS and concurrent EEG recordings to explore these interactions between the dorsal and ventral stream during figure-ground segregation. In two separate experiments, we used repetitive TMS and single-pulse TMS to disrupt processing in the dorsal (V5/HMT⁺) and the ventral (lateral occipital area) stream during a motion-defined figure discrimination task. We presented stimuli that made it possible to differentiate between relatively low-level (figure boundary detection) from higher-level (surface segregation) processing steps during figure-ground segregation. Results show that disruption of V5/HMT⁺ impaired performance related to surface segregation; this effect was mainly found when V5/HMT⁺ was perturbed in an early time window (100 msec) after stimulus presentation. Surprisingly, disruption of the lateral occipital area resulted in increased performance scores and enhanced neural correlates of surface segregation. This facilitatory effect was also mainly found in an early time window (100 msec) after stimulus presentation. These results suggest a "push-pull" interaction in which dorsal and ventral extrastriate areas are being recruited or inhibited depending on stimulus category and task demands.

Parallel processing of general and specific threat during early stages of perception

PubMed Central

2016-01-01

Differential processing of threat can consummate as early as 100 ms post-stimulus. Moreover, early perception not only differentiates threat from non-threat stimuli but also distinguishes among discrete threat subtypes (e.g. fear, disgust and anger). Combining spatial-frequency-filtered images of fear, disgust and neutral scenes with high-density event-related potentials and intracranial source estimation, we investigated the neural underpinnings of general and specific threat processing in early stages of perception. Conveyed in low spatial frequencies, fear and disgust images evoked convergent visual responses with similarly enhanced N1 potentials and dorsal visual (middle temporal gyrus) cortical activity (relative to neutral cues; peaking at 156 ms). Nevertheless, conveyed in high spatial frequencies, fear and disgust elicited divergent visual responses, with fear enhancing and disgust suppressing P1 potentials and ventral visual (occipital fusiform) cortical activity (peaking at 121 ms). Therefore, general and specific threat processing operates in parallel in early perception, with the ventral visual pathway engaged in specific processing of discrete threats and the dorsal visual pathway in general threat processing. Furthermore, selectively tuned to distinctive spatial-frequency channels and visual pathways, these parallel processes underpin dimensional and categorical threat characterization, promoting efficient threat response. These findings thus lend support to hybrid models of emotion. PMID:26412811

The neural representation of objects formed through the spatiotemporal integration of visual transients

PubMed Central

Erlikhman, Gennady; Gurariy, Gennadiy; Mruczek, Ryan E.B.; Caplovitz, Gideon P.

2016-01-01

Oftentimes, objects are only partially and transiently visible as parts of them become occluded during observer or object motion. The visual system can integrate such object fragments across space and time into perceptual wholes or spatiotemporal objects. This integrative and dynamic process may involve both ventral and dorsal visual processing pathways, along which shape and spatial representations are thought to arise. We measured fMRI BOLD response to spatiotemporal objects and used multi-voxel pattern analysis (MVPA) to decode shape information across 20 topographic regions of visual cortex. Object identity could be decoded throughout visual cortex, including intermediate (V3A, V3B, hV4, LO1-2,) and dorsal (TO1-2, and IPS0-1) visual areas. Shape-specific information, therefore, may not be limited to early and ventral visual areas, particularly when it is dynamic and must be integrated. Contrary to the classic view that the representation of objects is the purview of the ventral stream, intermediate and dorsal areas may play a distinct and critical role in the construction of object representations across space and time. PMID:27033688

Selective involvement of superior frontal cortex during working memory for shapes.

PubMed

Yee, Lydia T S; Roe, Katherine; Courtney, Susan M

2010-01-01

A spatial/nonspatial functional dissociation between the dorsal and ventral visual pathways is well established and has formed the basis of domain-specific theories of prefrontal cortex (PFC). Inconsistencies in the literature regarding prefrontal organization, however, have led to questions regarding whether the nature of the dissociations observed in PFC during working memory are equivalent to those observed in the visual pathways for perception. In particular, the dissociation between dorsal and ventral PFC during working memory for locations versus object identities has been clearly present in some studies but not in others, seemingly in part due to the type of objects used. The current study compared functional MRI activation during delayed-recognition tasks for shape or color, two object features considered to be processed by the ventral pathway for perceptual recognition. Activation for the shape-delayed recognition task was greater than that for the color task in the lateral occipital cortex, in agreement with studies of visual perception. Greater memory-delay activity was also observed, however, in the parietal and superior frontal cortices for the shape than for the color task. Activity in superior frontal cortex was associated with better performance on the shape task. Conversely, greater delay activity for color than for shape was observed in the left anterior insula and this activity was associated with better performance on the color task. These results suggest that superior frontal cortex contributes to performance on tasks requiring working memory for object identities, but it represents different information about those objects than does the ventral frontal cortex.

A Dual-Route Perspective on Brain Activation in Response to Visual Words: Evidence for a Length by Lexicality Interaction in the Visual Word Form Area (VWFA)

PubMed Central

Schurz, Matthias; Sturm, Denise; Richlan, Fabio; Kronbichler, Martin; Ladurner, Gunther; Wimmer, Heinz

2010-01-01

Based on our previous work, we expected the Visual Word Form Area (VWFA) in the left ventral visual pathway to be engaged by both whole-word recognition and by serial sublexical coding of letter strings. To examine this double function, a phonological lexical decision task (i.e., “Does xxx sound like an existing word?”) presented short and long letter strings of words, pseudohomophones, and pseudowords (e.g., Taxi, Taksi and Tazi). Main findings were that the length effect for words was limited to occipital regions and absent in the VWFA. In contrast, a marked length effect for pseudowords was found throughout the ventral visual pathway including the VWFA, as well as in regions presumably engaged by visual attention and silent-articulatory processes. The length by lexicality interaction on brain activation corresponds to well-established behavioral findings of a length by lexicality interaction on naming latencies and speaks for the engagement of the VWFA by both lexical and sublexical processes. PMID:19896538

A dual-route perspective on brain activation in response to visual words: evidence for a length by lexicality interaction in the visual word form area (VWFA).

PubMed

Schurz, Matthias; Sturm, Denise; Richlan, Fabio; Kronbichler, Martin; Ladurner, Gunther; Wimmer, Heinz

2010-02-01

Based on our previous work, we expected the Visual Word Form Area (VWFA) in the left ventral visual pathway to be engaged by both whole-word recognition and by serial sublexical coding of letter strings. To examine this double function, a phonological lexical decision task (i.e., "Does xxx sound like an existing word?") presented short and long letter strings of words, pseudohomophones, and pseudowords (e.g., Taxi, Taksi and Tazi). Main findings were that the length effect for words was limited to occipital regions and absent in the VWFA. In contrast, a marked length effect for pseudowords was found throughout the ventral visual pathway including the VWFA, as well as in regions presumably engaged by visual attention and silent-articulatory processes. The length by lexicality interaction on brain activation corresponds to well-established behavioral findings of a length by lexicality interaction on naming latencies and speaks for the engagement of the VWFA by both lexical and sublexical processes. Copyright (c) 2009 Elsevier Inc. All rights reserved.

First-Pass Processing of Value Cues in the Ventral Visual Pathway.

PubMed

Sasikumar, Dennis; Emeric, Erik; Stuphorn, Veit; Connor, Charles E

2018-02-19

Real-world value often depends on subtle, continuously variable visual cues specific to particular object categories, like the tailoring of a suit, the condition of an automobile, or the construction of a house. Here, we used microelectrode recording in behaving monkeys to test two possible mechanisms for category-specific value-cue processing: (1) previous findings suggest that prefrontal cortex (PFC) identifies object categories, and based on category identity, PFC could use top-down attentional modulation to enhance visual processing of category-specific value cues, providing signals to PFC for calculating value, and (2) a faster mechanism would be first-pass visual processing of category-specific value cues, immediately providing the necessary visual information to PFC. This, however, would require learned mechanisms for processing the appropriate cues in a given object category. To test these hypotheses, we trained monkeys to discriminate value in four letter-like stimulus categories. Each category had a different, continuously variable shape cue that signified value (liquid reward amount) as well as other cues that were irrelevant. Monkeys chose between stimuli of different reward values. Consistent with the first-pass hypothesis, we found early signals for category-specific value cues in area TE (the final stage in monkey ventral visual pathway) beginning 81 ms after stimulus onset-essentially at the start of TE responses. Task-related activity emerged in lateral PFC approximately 40 ms later and consisted mainly of category-invariant value tuning. Our results show that, for familiar, behaviorally relevant object categories, high-level ventral pathway cortex can implement rapid, first-pass processing of category-specific value cues. Copyright © 2018 Elsevier Ltd. All rights reserved.

Population Coding of Visual Space: Comparison of Spatial Representations in Dorsal and Ventral Pathways

PubMed Central

Sereno, Anne B.; Lehky, Sidney R.

2011-01-01

Although the representation of space is as fundamental to visual processing as the representation of shape, it has received relatively little attention from neurophysiological investigations. In this study we characterize representations of space within visual cortex, and examine how they differ in a first direct comparison between dorsal and ventral subdivisions of the visual pathways. Neural activities were recorded in anterior inferotemporal cortex (AIT) and lateral intraparietal cortex (LIP) of awake behaving monkeys, structures associated with the ventral and dorsal visual pathways respectively, as a stimulus was presented at different locations within the visual field. In spatially selective cells, we find greater modulation of cell responses in LIP with changes in stimulus position. Further, using a novel population-based statistical approach (namely, multidimensional scaling), we recover the spatial map implicit within activities of neural populations, allowing us to quantitatively compare the geometry of neural space with physical space. We show that a population of spatially selective LIP neurons, despite having large receptive fields, is able to almost perfectly reconstruct stimulus locations within a low-dimensional representation. In contrast, a population of AIT neurons, despite each cell being spatially selective, provide less accurate low-dimensional reconstructions of stimulus locations. They produce instead only a topologically (categorically) correct rendition of space, which nevertheless might be critical for object and scene recognition. Furthermore, we found that the spatial representation recovered from population activity shows greater translation invariance in LIP than in AIT. We suggest that LIP spatial representations may be dimensionally isomorphic with 3D physical space, while in AIT spatial representations may reflect a more categorical representation of space (e.g., “next to” or “above”). PMID:21344010

A computational exploration of complementary learning mechanisms in the primate ventral visual pathway.

PubMed

Spoerer, Courtney J; Eguchi, Akihiro; Stringer, Simon M

2016-02-01

In order to develop transformation invariant representations of objects, the visual system must make use of constraints placed upon object transformation by the environment. For example, objects transform continuously from one point to another in both space and time. These two constraints have been exploited separately in order to develop translation and view invariance in a hierarchical multilayer model of the primate ventral visual pathway in the form of continuous transformation learning and temporal trace learning. We show for the first time that these two learning rules can work cooperatively in the model. Using these two learning rules together can support the development of invariance in cells and help maintain object selectivity when stimuli are presented over a large number of locations or when trained separately over a large number of viewing angles. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Awareness Becomes Necessary Between Adaptive Pattern Coding of Open and Closed Curvatures

PubMed Central

Sweeny, Timothy D.; Grabowecky, Marcia; Suzuki, Satoru

2012-01-01

Visual pattern processing becomes increasingly complex along the ventral pathway, from the low-level coding of local orientation in the primary visual cortex to the high-level coding of face identity in temporal visual areas. Previous research using pattern aftereffects as a psychophysical tool to measure activation of adaptive feature coding has suggested that awareness is relatively unimportant for the coding of orientation, but awareness is crucial for the coding of face identity. We investigated where along the ventral visual pathway awareness becomes crucial for pattern coding. Monoptic masking, which interferes with neural spiking activity in low-level processing while preserving awareness of the adaptor, eliminated open-curvature aftereffects but preserved closed-curvature aftereffects. In contrast, dichoptic masking, which spares spiking activity in low-level processing while wiping out awareness, preserved open-curvature aftereffects but eliminated closed-curvature aftereffects. This double dissociation suggests that adaptive coding of open and closed curvatures straddles the divide between weakly and strongly awareness-dependent pattern coding. PMID:21690314

Deep Neural Networks Reveal a Gradient in the Complexity of Neural Representations across the Ventral Stream.

PubMed

Güçlü, Umut; van Gerven, Marcel A J

2015-07-08

Converging evidence suggests that the primate ventral visual pathway encodes increasingly complex stimulus features in downstream areas. We quantitatively show that there indeed exists an explicit gradient for feature complexity in the ventral pathway of the human brain. This was achieved by mapping thousands of stimulus features of increasing complexity across the cortical sheet using a deep neural network. Our approach also revealed a fine-grained functional specialization of downstream areas of the ventral stream. Furthermore, it allowed decoding of representations from human brain activity at an unsurpassed degree of accuracy, confirming the quality of the developed approach. Stimulus features that successfully explained neural responses indicate that population receptive fields were explicitly tuned for object categorization. This provides strong support for the hypothesis that object categorization is a guiding principle in the functional organization of the primate ventral stream. Copyright © 2015 the authors 0270-6474/15/3510005-10$15.00/0.

Encodings of implied motion for animate and inanimate object categories in the two visual pathways.

PubMed

Lu, Zhengang; Li, Xueting; Meng, Ming

2016-01-15

Previous research has proposed two separate pathways for visual processing: the dorsal pathway for "where" information vs. the ventral pathway for "what" information. Interestingly, the middle temporal cortex (MT) in the dorsal pathway is involved in representing implied motion from still pictures, suggesting an interaction between motion and object related processing. However, the relationship between how the brain encodes implied motion and how the brain encodes object/scene categories is unclear. To address this question, fMRI was used to measure activity along the two pathways corresponding to different animate and inanimate categories of still pictures with different levels of implied motion speed. In the visual areas of both pathways, activity induced by pictures of humans and animals was hardly modulated by the implied motion speed. By contrast, activity in these areas correlated with the implied motion speed for pictures of inanimate objects and scenes. The interaction between implied motion speed and stimuli category was significant, suggesting different encoding mechanisms of implied motion for animate-inanimate distinction. Further multivariate pattern analysis of activity in the dorsal pathway revealed significant effects of stimulus category that are comparable to the ventral pathway. Moreover, still pictures of inanimate objects/scenes with higher implied motion speed evoked activation patterns that were difficult to differentiate from those evoked by pictures of humans and animals, indicating a functional role of implied motion in the representation of object categories. These results provide novel evidence to support integrated encoding of motion and object categories, suggesting a rethink of the relationship between the two visual pathways. Copyright © 2015 Elsevier Inc. All rights reserved.

Normal form from biological motion despite impaired ventral stream function.

PubMed

Gilaie-Dotan, S; Bentin, S; Harel, M; Rees, G; Saygin, A P

2011-04-01

We explored the extent to which biological motion perception depends on ventral stream integration by studying LG, an unusual case of developmental visual agnosia. LG has significant ventral stream processing deficits but no discernable structural cortical abnormality. LG's intermediate visual areas and object-sensitive regions exhibit abnormal activation during visual object perception, in contrast to area V5/MT+ which responds normally to visual motion (Gilaie-Dotan, Perry, Bonneh, Malach, & Bentin, 2009). Here, in three studies we used point light displays, which require visual integration, in adaptive threshold experiments to examine LG's ability to detect form from biological and non-biological motion cues. LG's ability to detect and discriminate form from biological motion was similar to healthy controls. In contrast, he was significantly deficient in processing form from non-biological motion. Thus, LG can rely on biological motion cues to perceive human forms, but is considerably impaired in extracting form from non-biological motion. Finally, we found that while LG viewed biological motion, activity in a network of brain regions associated with processing biological motion was functionally correlated with his V5/MT+ activity, indicating that normal inputs from V5/MT+ might suffice to activate his action perception system. These results indicate that processing of biologically moving form can dissociate from other form processing in the ventral pathway. Furthermore, the present results indicate that integrative ventral stream processing is necessary for uncompromised processing of non-biological form from motion. Copyright © 2011 Elsevier Ltd. All rights reserved.

Age, Sex, and Verbal Abilities Affect Location of Linguistic Connectivity in Ventral Visual Pathway

ERIC Educational Resources Information Center

Burman, Douglas D.; Minas, Taylor; Bolger, Donald J.; Booth, James R.

2013-01-01

Previous studies have shown that the "strength" of connectivity between regions can vary depending upon the cognitive demands of a task. In this study, the "location" of task-dependent connectivity from the primary visual cortex (V1) was examined in 43 children (ages 9-15) performing visual tasks; connectivity maxima were identified for a visual…

The sequence of cortical activity inferred by response latency variability in the human ventral pathway of face processing.

PubMed

Lin, Jo-Fu Lotus; Silva-Pereyra, Juan; Chou, Chih-Che; Lin, Fa-Hsuan

2018-04-11

Variability in neuronal response latency has been typically considered caused by random noise. Previous studies of single cells and large neuronal populations have shown that the temporal variability tends to increase along the visual pathway. Inspired by these previous studies, we hypothesized that functional areas at later stages in the visual pathway of face processing would have larger variability in the response latency. To test this hypothesis, we used magnetoencephalographic data collected when subjects were presented with images of human faces. Faces are known to elicit a sequence of activity from the primary visual cortex to the fusiform gyrus. Our results revealed that the fusiform gyrus showed larger variability in the response latency compared to the calcarine fissure. Dynamic and spectral analyses of the latency variability indicated that the response latency in the fusiform gyrus was more variable than in the calcarine fissure between 70 ms and 200 ms after the stimulus onset and between 4 Hz and 40 Hz, respectively. The sequential processing of face information from the calcarine sulcus to the fusiform sulcus was more reliably detected based on sizes of the response variability than instants of the maximal response peaks. With two areas in the ventral visual pathway, we show that the variability in response latency across brain areas can be used to infer the sequence of cortical activity.

Integration of color, orientation, and size functional domains in the ventral pathway

PubMed Central

Ghose, Geoffrey M.; Ts’o, Daniel Y.

2017-01-01

Abstract. Functional specialization within the extrastriate areas of the ventral pathway associated with visual form analysis is poorly understood. Studies comparing the functional selectivities of neurons within the early visual areas have found that there are more similar than different between the areas. We simultaneously imaged visually evoked activation over regions of V2 and V4 and parametrically varied three visual attributes for which selectivity exists in both areas: color, orientation, and size. We found that color selective regions were observed in both areas and were of similar size and spatial distribution. However, two major areal distinctions were observed: V4 contained a greater number and diversity of color-specific regions than V2 and exhibited a higher degree of overlap between domains for different functional attributes. In V2, size and color regions were largely segregated from orientation domains, whereas in V4 both color and size regions overlapped considerably with orientation regions. Our results suggest that higher-order composite selectivities in the extrastriate cortex may arise organically from the interactions afforded by an overlap of functional domains for lower order selectivities. PMID:28573155

Computational modeling of the neural representation of object shape in the primate ventral visual system

PubMed Central

Eguchi, Akihiro; Mender, Bedeho M. W.; Evans, Benjamin D.; Humphreys, Glyn W.; Stringer, Simon M.

2015-01-01

Neurons in successive stages of the primate ventral visual pathway encode the spatial structure of visual objects. In this paper, we investigate through computer simulation how these cell firing properties may develop through unsupervised visually-guided learning. Individual neurons in the model are shown to exploit statistical regularity and temporal continuity of the visual inputs during training to learn firing properties that are similar to neurons in V4 and TEO. Neurons in V4 encode the conformation of boundary contour elements at a particular position within an object regardless of the location of the object on the retina, while neurons in TEO integrate information from multiple boundary contour elements. This representation goes beyond mere object recognition, in which neurons simply respond to the presence of a whole object, but provides an essential foundation from which the brain is subsequently able to recognize the whole object. PMID:26300766

'What' and 'where' in the human brain.

PubMed

Ungerleider, L G; Haxby, J V

1994-04-01

Multiple visual areas in the cortex of nonhuman primates are organized into two hierarchically organized and functionally specialized processing pathways, a 'ventral stream' for object vision and a 'dorsal stream' for spatial vision. Recent findings from positron emission tomography activation studies have localized these pathways within the human brain, yielding insights into cortical hierarchies, specialization of function, and attentional mechanisms.

Defining the cortical visual systems: "what", "where", and "how"

NASA Technical Reports Server (NTRS)

Creem, S. H.; Proffitt, D. R.; Kaiser, M. K. (Principal Investigator)

2001-01-01

The visual system historically has been defined as consisting of at least two broad subsystems subserving object and spatial vision. These visual processing streams have been organized both structurally as two distinct pathways in the brain, and functionally for the types of tasks that they mediate. The classic definition by Ungerleider and Mishkin labeled a ventral "what" stream to process object information and a dorsal "where" stream to process spatial information. More recently, Goodale and Milner redefined the two visual systems with a focus on the different ways in which visual information is transformed for different goals. They relabeled the dorsal stream as a "how" system for transforming visual information using an egocentric frame of reference in preparation for direct action. This paper reviews recent research from psychophysics, neurophysiology, neuropsychology and neuroimaging to define the roles of the ventral and dorsal visual processing streams. We discuss a possible solution that allows for both "where" and "how" systems that are functionally and structurally organized within the posterior parietal lobe.

On the usefulness of 'what' and 'where' pathways in vision.

PubMed

de Haan, Edward H F; Cowey, Alan

2011-10-01

The primate visual brain is classically portrayed as a large number of separate 'maps', each dedicated to the processing of specific visual cues, such as colour, motion or faces and their many features. In order to understand this fractionated architecture, the concept of cortical 'pathways' or 'streams' was introduced. In the currently prevailing view, the different maps are organised hierarchically into two major pathways, one involved in recognition and memory (the ventral stream or 'what' pathway) and the other in the programming of action (the dorsal stream or 'where' pathway). In this review, we question this heuristically influential but potentially misleading linear hierarchical pathway model and argue instead for a 'patchwork' or network model. Copyright © 2011 Elsevier Ltd. All rights reserved.

Disturbed default mode network connectivity patterns in Alzheimer's disease associated with visual processing.

PubMed

Krajcovicova, Lenka; Mikl, Michal; Marecek, Radek; Rektorova, Irena

2014-01-01

Changes in connectivity of the posterior node of the default mode network (DMN) were studied when switching from baseline to a cognitive task using functional magnetic resonance imaging. In all, 15 patients with mild to moderate Alzheimer's disease (AD) and 18 age-, gender-, and education-matched healthy controls (HC) participated in the study. Psychophysiological interactions analysis was used to assess the specific alterations in the DMN connectivity (deactivation-based) due to psychological effects from the complex visual scene encoding task. In HC, we observed task-induced connectivity decreases between the posterior cingulate and middle temporal and occipital visual cortices. These findings imply successful involvement of the ventral visual pathway during the visual processing in our HC cohort. In AD, involvement of the areas engaged in the ventral visual pathway was observed only in a small volume of the right middle temporal gyrus. Additional connectivity changes (decreases) in AD were present between the posterior cingulate and superior temporal gyrus when switching from baseline to task condition. These changes are probably related to both disturbed visual processing and the DMN connectivity in AD and reflect deficits and compensatory mechanisms within the large scale brain networks in this patient population. Studying the DMN connectivity using psychophysiological interactions analysis may provide a sensitive tool for exploring early changes in AD and their dynamics during the disease progression.

Smelling directions: Olfaction modulates ambiguous visual motion perception

PubMed Central

Kuang, Shenbing; Zhang, Tao

2014-01-01

Senses of smells are often accompanied by simultaneous visual sensations. Previous studies have documented enhanced olfactory performance with concurrent presence of congruent color- or shape- related visual cues, and facilitated visual object perception when congruent smells are simultaneously present. These visual object-olfaction interactions suggest the existences of couplings between the olfactory pathway and the visual ventral processing stream. However, it is not known if olfaction can modulate visual motion perception, a function that is related to the visual dorsal stream. We tested this possibility by examining the influence of olfactory cues on the perceptions of ambiguous visual motion signals. We showed that, after introducing an association between motion directions and olfactory cues, olfaction could indeed bias ambiguous visual motion perceptions. Our result that olfaction modulates visual motion processing adds to the current knowledge of cross-modal interactions and implies a possible functional linkage between the olfactory system and the visual dorsal pathway. PMID:25052162

Curvature-processing network in macaque visual cortex

PubMed Central

Yue, Xiaomin; Pourladian, Irene S.; Tootell, Roger B. H.; Ungerleider, Leslie G.

2014-01-01

Our visual environment abounds with curved features. Thus, the goal of understanding visual processing should include the processing of curved features. Using functional magnetic resonance imaging in behaving monkeys, we demonstrated a network of cortical areas selective for the processing of curved features. This network includes three distinct hierarchically organized regions within the ventral visual pathway: a posterior curvature-biased patch (PCP) located in the near-foveal representation of dorsal V4, a middle curvature-biased patch (MCP) located on the ventral lip of the posterior superior temporal sulcus (STS) in area TEO, and an anterior curvature-biased patch (ACP) located just below the STS in anterior area TE. Our results further indicate that the processing of curvature becomes increasingly complex from PCP to ACP. The proximity of the curvature-processing network to the well-known face-processing network suggests a possible functional link between them. PMID:25092328

Neural correlates of consciousness: a definition of the dorsal and ventral streams and their relation to phenomenology.

PubMed

Vakalopoulos, Costa

2005-01-01

The paper presents a hypothesis for a neural correlate of consciousness. A proposal is made that both the dorsal and ventral streams must be concurrently active to generate conscious awareness and that V1 (striate cortex) provides a serial link between them. An argument is presented against a true extrastriate communication between the dorsal and ventral streams. Secondly, a detailed theory is developed for the structure of the visual hierarchy. Premotor theory states that each organism-object interaction can be described by the two quantitative measures of torque and change in joint position served by the basal ganglia and cerebellum, respectively. This leads to a component theory of motor efference copy providing a fundamental tool for categorizing dorsal and ventral stream networks. The rationale for this is that the dorsal stream specifies spatial coordinates of the external world, which can be coded by the reafference of changes in joint position. The ventral stream is concerned with object recognition and is coded for by forces exerted on the world during a developmental exploratory phase of the organism. The proposed pathways for a component motor efference copy from both the cerebellum and basal ganglia converge on the thalamus and modulate thalamocortical projections via the thalamic reticular nucleus. The origin of the corticopontine projections, which are a massive pathway for cortical information to reach the cerebellum, coincides with the area typically considered as part of the dorsal stream, whereas the entire cortex projects to the striatum. This adds empirical support for a new conceptualization of the visual streams. The model also presents a solution to the binding problem of a neural correlate of consciousness, that is, how a distributed neural network synchronizes its activity during a cognitive event. It represents a reinterpretation of the current status of the visual hierarchy.

A PDP model of the simultaneous perception of multiple objects

NASA Astrophysics Data System (ADS)

Henderson, Cynthia M.; McClelland, James L.

2011-06-01

Illusory conjunctions in normal and simultanagnosic subjects are two instances where the visual features of multiple objects are incorrectly 'bound' together. A connectionist model explores how multiple objects could be perceived correctly in normal subjects given sufficient time, but could give rise to illusory conjunctions with damage or time pressure. In this model, perception of two objects benefits from lateral connections between hidden layers modelling aspects of the ventral and dorsal visual pathways. As with simultanagnosia, simulations of dorsal lesions impair multi-object recognition. In contrast, a large ventral lesion has minimal effect on dorsal functioning, akin to dissociations between simple object manipulation (retained in visual form agnosia and semantic dementia) and object discrimination (impaired in these disorders) [Hodges, J.R., Bozeat, S., Lambon Ralph, M.A., Patterson, K., and Spatt, J. (2000), 'The Role of Conceptual Knowledge: Evidence from Semantic Dementia', Brain, 123, 1913-1925; Milner, A.D., and Goodale, M.A. (2006), The Visual Brain in Action (2nd ed.), New York: Oxford]. It is hoped that the functioning of this model might suggest potential processes underlying dorsal and ventral contributions to the correct perception of multiple objects.

A spatiotemporal profile of visual system activation revealed by current source density analysis in the awake macaque.

PubMed

Schroeder, C E; Mehta, A D; Givre, S J

1998-01-01

We investigated the spatiotemporal activation pattern, produced by one visual stimulus, across cerebral cortical regions in awake monkeys. Laminar profiles of postsynaptic potentials and action potentials were indexed with current source density (CSD) and multiunit activity profiles respectively. Locally, we found contrasting activation profiles in dorsal and ventral stream areas. The former, like V1 and V2, exhibit a 'feedforward' profile, with excitation beginning at the depth of Lamina 4, followed by activation of the extragranular laminae. The latter often displayed a multilaminar/columnar profile, with initial responses distributed across the laminae and reflecting modulation rather than excitation; CSD components were accompanied by either no changes or by suppression of action potentials. System-wide, response latencies indicated a large dorsal/ventral stream latency advantage, which generalizes across a wide range of methods. This predicts a specific temporal ordering of dorsal and ventral stream components of visual analysis, as well as specific patterns of dorsal-ventral stream interaction. Our findings support a hierarchical model of cortical organization that combines serial and parallel elements. Critical in such a model is the recognition that processing within a location typically entails multiple temporal components or 'waves' of activity, driven by input conveyed over heterogeneous pathways from the retina.

Changes in brain morphology in albinism reflect reduced visual acuity.

PubMed

Bridge, Holly; von dem Hagen, Elisabeth A H; Davies, George; Chambers, Claire; Gouws, Andre; Hoffmann, Michael; Morland, Antony B

2014-07-01

Albinism, in humans and many animal species, has a major impact on the visual system, leading to reduced acuity, lack of binocular function and nystagmus. In addition to the lack of a foveal pit, there is a disruption to the routing of the nerve fibers crossing at the optic chiasm, resulting in excessive crossing of fibers to the contralateral hemisphere. However, very little is known about the effect of this misrouting on the structure of the post-chiasmatic visual pathway, and the occipital lobes in particular. Whole-brain analyses of cortical thickness in a large cohort of subjects with albinism showed an increase in cortical thickness, relative to control subjects, particularly in posterior V1, corresponding to the foveal representation. Furthermore, mean cortical thickness across entire V1 was significantly greater in these subjects compared to controls and negatively correlated with visual acuity in albinism. Additionally, the group with albinism showed decreased gyrification in the left ventral occipital lobe. While the increase in cortical thickness in V1, also found in congenitally blind subjects, has been interpreted to reflect a lack of pruning, the decreased gyrification in the ventral extrastriate cortex may reflect the reduced input to the foveal regions of the ventral visual stream. Copyright © 2012 Elsevier Ltd. All rights reserved.

Posterior Inferotemporal Cortex Cells Use Multiple Input Pathways for Shape Encoding.

PubMed

Ponce, Carlos R; Lomber, Stephen G; Livingstone, Margaret S

2017-05-10

In the macaque monkey brain, posterior inferior temporal (PIT) cortex cells contribute to visual object recognition. They receive concurrent inputs from visual areas V4, V3, and V2. We asked how these different anatomical pathways shape PIT response properties by deactivating them while monitoring PIT activity in two male macaques. We found that cooling of V4 or V2|3 did not lead to consistent changes in population excitatory drive; however, population pattern analyses showed that V4-based pathways were more important than V2|3-based pathways. We did not find any image features that predicted decoding accuracy differences between both interventions. Using the HMAX hierarchical model of visual recognition, we found that different groups of simulated "PIT" units with different input histories (lacking "V2|3" or "V4" input) allowed for comparable levels of object-decoding performance and that removing a large fraction of "PIT" activity resulted in similar drops in performance as in the cooling experiments. We conclude that distinct input pathways to PIT relay similar types of shape information, with V1-dependent V4 cells providing more quantitatively useful information for overall encoding than cells in V2 projecting directly to PIT. SIGNIFICANCE STATEMENT Convolutional neural networks are the best models of the visual system, but most emphasize input transformations across a serial hierarchy akin to the primary "ventral stream" (V1 → V2 → V4 → IT). However, the ventral stream also comprises parallel "bypass" pathways: V1 also connects to V4, and V2 to IT. To explore the advantages of mixing long and short pathways in the macaque brain, we used cortical cooling to silence inputs to posterior IT and compared the findings with an HMAX model with parallel pathways. Copyright © 2017 the authors 0270-6474/17/375019-16$15.00/0.

Posterior Inferotemporal Cortex Cells Use Multiple Input Pathways for Shape Encoding

PubMed Central

2017-01-01

In the macaque monkey brain, posterior inferior temporal (PIT) cortex cells contribute to visual object recognition. They receive concurrent inputs from visual areas V4, V3, and V2. We asked how these different anatomical pathways shape PIT response properties by deactivating them while monitoring PIT activity in two male macaques. We found that cooling of V4 or V2|3 did not lead to consistent changes in population excitatory drive; however, population pattern analyses showed that V4-based pathways were more important than V2|3-based pathways. We did not find any image features that predicted decoding accuracy differences between both interventions. Using the HMAX hierarchical model of visual recognition, we found that different groups of simulated “PIT” units with different input histories (lacking “V2|3” or “V4” input) allowed for comparable levels of object-decoding performance and that removing a large fraction of “PIT” activity resulted in similar drops in performance as in the cooling experiments. We conclude that distinct input pathways to PIT relay similar types of shape information, with V1-dependent V4 cells providing more quantitatively useful information for overall encoding than cells in V2 projecting directly to PIT. SIGNIFICANCE STATEMENT Convolutional neural networks are the best models of the visual system, but most emphasize input transformations across a serial hierarchy akin to the primary “ventral stream” (V1 → V2 → V4 → IT). However, the ventral stream also comprises parallel “bypass” pathways: V1 also connects to V4, and V2 to IT. To explore the advantages of mixing long and short pathways in the macaque brain, we used cortical cooling to silence inputs to posterior IT and compared the findings with an HMAX model with parallel pathways. PMID:28416597

Visual agnosia and focal brain injury.

PubMed

Martinaud, O

Visual agnosia encompasses all disorders of visual recognition within a selective visual modality not due to an impairment of elementary visual processing or other cognitive deficit. Based on a sequential dichotomy between the perceptual and memory systems, two different categories of visual object agnosia are usually considered: 'apperceptive agnosia' and 'associative agnosia'. Impaired visual recognition within a single category of stimuli is also reported in: (i) visual object agnosia of the ventral pathway, such as prosopagnosia (for faces), pure alexia (for words), or topographagnosia (for landmarks); (ii) visual spatial agnosia of the dorsal pathway, such as cerebral akinetopsia (for movement), or orientation agnosia (for the placement of objects in space). Focal brain injuries provide a unique opportunity to better understand regional brain function, particularly with the use of effective statistical approaches such as voxel-based lesion-symptom mapping (VLSM). The aim of the present work was twofold: (i) to review the various agnosia categories according to the traditional visual dual-pathway model; and (ii) to better assess the anatomical network underlying visual recognition through lesion-mapping studies correlating neuroanatomical and clinical outcomes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Interaction between dorsal and ventral processing streams: where, when and how?

PubMed

Cloutman, Lauren L

2013-11-01

The execution of complex visual, auditory, and linguistic behaviors requires a dynamic interplay between spatial ('where/how') and non-spatial ('what') information processed along the dorsal and ventral processing streams. However, while it is acknowledged that there must be some degree of interaction between the two processing networks, how they interact, both anatomically and functionally, is a question which remains little explored. The current review examines the anatomical, temporal, and behavioral evidence regarding three potential models of dual stream interaction: (1) computations along the two pathways proceed independently and in parallel, reintegrating within shared target brain regions; (2) processing along the separate pathways is modulated by the existence of recurrent feedback loops; and (3) information is transferred directly between the two pathways at multiple stages and locations along their trajectories. Copyright © 2012 Elsevier Inc. All rights reserved.

Goal-directed reaching: the allocentric coding of target location renders an offline mode of control.

PubMed

Manzone, Joseph; Heath, Matthew

2018-04-01

Reaching to a veridical target permits an egocentric spatial code (i.e., absolute limb and target position) to effect fast and effective online trajectory corrections supported via the visuomotor networks of the dorsal visual pathway. In contrast, a response entailing decoupled spatial relations between stimulus and response is thought to be primarily mediated via an allocentric code (i.e., the position of a target relative to another external cue) laid down by the visuoperceptual networks of the ventral visual pathway. Because the ventral stream renders a temporally durable percept, it is thought that an allocentric code does not support a primarily online mode of control, but instead supports a mode wherein a response is evoked largely in advance of movement onset via central planning mechanisms (i.e., offline control). Here, we examined whether reaches defined via ego- and allocentric visual coordinates are supported via distinct control modes (i.e., online versus offline). Participants performed target-directed and allocentric reaches in limb visible and limb-occluded conditions. Notably, in the allocentric task, participants reached to a location that matched the position of a target stimulus relative to a reference stimulus, and to examine online trajectory amendments, we computed the proportion of variance explained (i.e., R 2 values) by the spatial position of the limb at 75% of movement time relative to a response's ultimate movement endpoint. Target-directed trials performed with limb vision showed more online corrections and greater endpoint precision than their limb-occluded counterparts, which in turn were associated with performance metrics comparable to allocentric trials performed with and without limb vision. Accordingly, we propose that the absence of ego-motion cues (i.e., limb vision) and/or the specification of a response via an allocentric code renders motor output served via the 'slow' visuoperceptual networks of the ventral visual pathway.

Deconstructing Visual Scenes in Cortex: Gradients of Object and Spatial Layout Information

PubMed Central

Kravitz, Dwight J.; Baker, Chris I.

2013-01-01

Real-world visual scenes are complex cluttered, and heterogeneous stimuli engaging scene- and object-selective cortical regions including parahippocampal place area (PPA), retrosplenial complex (RSC), and lateral occipital complex (LOC). To understand the unique contribution of each region to distributed scene representations, we generated predictions based on a neuroanatomical framework adapted from monkey and tested them using minimal scenes in which we independently manipulated both spatial layout (open, closed, and gradient) and object content (furniture, e.g., bed, dresser). Commensurate with its strong connectivity with posterior parietal cortex, RSC evidenced strong spatial layout information but no object information, and its response was not even modulated by object presence. In contrast, LOC, which lies within the ventral visual pathway, contained strong object information but no background information. Finally, PPA, which is connected with both the dorsal and the ventral visual pathway, showed information about both objects and spatial backgrounds and was sensitive to the presence or absence of either. These results suggest that 1) LOC, PPA, and RSC have distinct representations, emphasizing different aspects of scenes, 2) the specific representations in each region are predictable from their patterns of connectivity, and 3) PPA combines both spatial layout and object information as predicted by connectivity. PMID:22473894

Comparative Study on Interaction of Form and Motion Processing Streams by Applying Two Different Classifiers in Mechanism for Recognition of Biological Movement

PubMed Central

2014-01-01

Research on psychophysics, neurophysiology, and functional imaging shows particular representation of biological movements which contains two pathways. The visual perception of biological movements formed through the visual system called dorsal and ventral processing streams. Ventral processing stream is associated with the form information extraction; on the other hand, dorsal processing stream provides motion information. Active basic model (ABM) as hierarchical representation of the human object had revealed novelty in form pathway due to applying Gabor based supervised object recognition method. It creates more biological plausibility along with similarity with original model. Fuzzy inference system is used for motion pattern information in motion pathway creating more robustness in recognition process. Besides, interaction of these paths is intriguing and many studies in various fields considered it. Here, the interaction of the pathways to get more appropriated results has been investigated. Extreme learning machine (ELM) has been implied for classification unit of this model, due to having the main properties of artificial neural networks, but crosses from the difficulty of training time substantially diminished in it. Here, there will be a comparison between two different configurations, interactions using synergetic neural network and ELM, in terms of accuracy and compatibility. PMID:25276860

A cross-validated cytoarchitectonic atlas of the human ventral visual stream.

PubMed

Rosenke, Mona; Weiner, Kevin S; Barnett, Michael A; Zilles, Karl; Amunts, Katrin; Goebel, Rainer; Grill-Spector, Kalanit

2018-04-15

The human ventral visual stream consists of several areas that are considered processing stages essential for perception and recognition. A fundamental microanatomical feature differentiating areas is cytoarchitecture, which refers to the distribution, size, and density of cells across cortical layers. Because cytoarchitectonic structure is measured in 20-micron-thick histological slices of postmortem tissue, it is difficult to assess (a) how anatomically consistent these areas are across brains and (b) how they relate to brain parcellations obtained with prevalent neuroimaging methods, acquired at the millimeter and centimeter scale. Therefore, the goal of this study was to (a) generate a cross-validated cytoarchitectonic atlas of the human ventral visual stream on a whole brain template that is commonly used in neuroimaging studies and (b) to compare this atlas to a recently published retinotopic parcellation of visual cortex (Wang et al., 2014). To achieve this goal, we generated an atlas of eight cytoarchitectonic areas: four areas in the occipital lobe (hOc1-hOc4v) and four in the fusiform gyrus (FG1-FG4), then we tested how the different alignment techniques affect the accuracy of the resulting atlas. Results show that both cortex-based alignment (CBA) and nonlinear volumetric alignment (NVA) generate an atlas with better cross-validation performance than affine volumetric alignment (AVA). Additionally, CBA outperformed NVA in 6/8 of the cytoarchitectonic areas. Finally, the comparison of the cytoarchitectonic atlas to a retinotopic atlas shows a clear correspondence between cytoarchitectonic and retinotopic areas in the ventral visual stream. The successful performance of CBA suggests a coupling between cytoarchitectonic areas and macroanatomical landmarks in the human ventral visual stream, and furthermore, that this coupling can be utilized for generating an accurate group atlas. In addition, the coupling between cytoarchitecture and retinotopy highlights the potential use of this atlas in understanding how anatomical features contribute to brain function. We make this cytoarchitectonic atlas freely available in both BrainVoyager and FreeSurfer formats (http://vpnl.stanford.edu/vcAtlas). The availability of this atlas will enable future studies to link cytoarchitectonic organization to other parcellations of the human ventral visual stream with potential to advance the understanding of this pathway in typical and atypical populations. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparing visual representations across human fMRI and computational vision

PubMed Central

Leeds, Daniel D.; Seibert, Darren A.; Pyles, John A.; Tarr, Michael J.

2013-01-01

Feedforward visual object perception recruits a cortical network that is assumed to be hierarchical, progressing from basic visual features to complete object representations. However, the nature of the intermediate features related to this transformation remains poorly understood. Here, we explore how well different computer vision recognition models account for neural object encoding across the human cortical visual pathway as measured using fMRI. These neural data, collected during the viewing of 60 images of real-world objects, were analyzed with a searchlight procedure as in Kriegeskorte, Goebel, and Bandettini (2006): Within each searchlight sphere, the obtained patterns of neural activity for all 60 objects were compared to model responses for each computer recognition algorithm using representational dissimilarity analysis (Kriegeskorte et al., 2008). Although each of the computer vision methods significantly accounted for some of the neural data, among the different models, the scale invariant feature transform (Lowe, 2004), encoding local visual properties gathered from “interest points,” was best able to accurately and consistently account for stimulus representations within the ventral pathway. More generally, when present, significance was observed in regions of the ventral-temporal cortex associated with intermediate-level object perception. Differences in model effectiveness and the neural location of significant matches may be attributable to the fact that each model implements a different featural basis for representing objects (e.g., more holistic or more parts-based). Overall, we conclude that well-known computer vision recognition systems may serve as viable proxies for theories of intermediate visual object representation. PMID:24273227

The neurobiological basis of seeing words

PubMed Central

Wandell, Brian A.

2011-01-01

This review summarizes recent ideas about the cortical circuits for seeing words, an important part of the brain system for reading. Historically, the link between the visual cortex and reading has been contentious. One influential position is that the visual cortex plays a minimal role, limited to identifying contours, and that information about these contours is delivered to cortical regions specialized for reading and language. An alternative position is that specializations for seeing words develop within the visual cortex itself. Modern neuroimaging measurements—including both functional magnetic resonance imaging (fMRI) and diffusion weighted imaging with tractography data—support the position that circuitry for seeing the statistical regularities of word forms develops within the ventral occipitotemporal cortex, which also contains important circuitry for seeing faces, colors, and forms. The review explains new findings about the visual pathways, including visual field maps, as well as new findings about how we see words. The measurements from the two fields are in close cortical proximity, and there are good opportunities for coordinating theoretical ideas about function in the ventral occipitotemporal cortex. PMID:21486296

The neurobiological basis of seeing words.

PubMed

Wandell, Brian A

2011-04-01

This review summarizes recent ideas about the cortical circuits for seeing words, an important part of the brain system for reading. Historically, the link between the visual cortex and reading has been contentious. One influential position is that the visual cortex plays a minimal role, limited to identifying contours, and that information about these contours is delivered to cortical regions specialized for reading and language. An alternative position is that specializations for seeing words develop within the visual cortex itself. Modern neuroimaging measurements-including both functional magnetic resonance imaging (fMRI) and diffusion weighted imaging with tractography (DTI) data-support the position that circuitry for seeing the statistical regularities of word forms develops within the ventral occipitotemporal cortex, which also contains important circuitry for seeing faces, colors, and forms. This review explains new findings about the visual pathways, including visual field maps, as well as new findings about how we see words. The measurements from the two fields are in close cortical proximity, and there are good opportunities for coordinating theoretical ideas about function in the ventral occipitotemporal cortex. © 2011 New York Academy of Sciences.

Visual-Cerebellar Pathways and Their Roles in the Control of Avian Flight.

PubMed

Wylie, Douglas R; Gutiérrez-Ibáñez, Cristián; Gaede, Andrea H; Altshuler, Douglas L; Iwaniuk, Andrew N

2018-01-01

In this paper, we review the connections and physiology of visual pathways to the cerebellum in birds and consider their role in flight. We emphasize that there are two visual pathways to the cerebellum. One is to the vestibulocerebellum (folia IXcd and X) that originates from two retinal-recipient nuclei that process optic flow: the nucleus of the basal optic root (nBOR) and the pretectal nucleus lentiformis mesencephali (LM). The second is to the oculomotor cerebellum (folia VI-VIII), which receives optic flow information, mainly from LM, but also local visual motion information from the optic tectum, and other visual information from the ventral lateral geniculate nucleus (Glv). The tectum, LM and Glv are all intimately connected with the pontine nuclei, which also project to the oculomotor cerebellum. We believe this rich integration of visual information in the cerebellum is important for analyzing motion parallax that occurs during flight. Finally, we extend upon a suggestion by Ibbotson (2017) that the hypertrophy that is observed in LM in hummingbirds might be due to an increase in the processing demands associated with the pathway to the oculomotor cerebellum as they fly through a cluttered environment while feeding.

Neural networks for Braille reading by the blind.

PubMed

Sadato, N; Pascual-Leone, A; Grafman, J; Deiber, M P; Ibañez, V; Hallett, M

1998-07-01

To explore the neural networks used for Braille reading, we measured regional cerebral blood flow with PET during tactile tasks performed both by Braille readers blinded early in life and by sighted subjects. Eight proficient Braille readers were studied during Braille reading with both right and left index fingers. Eight-character, non-contracted Braille-letter strings were used, and subjects were asked to discriminate between words and non-words. To compare the behaviour of the brain of the blind and the sighted directly, non-Braille tactile tasks were performed by six different blind subjects and 10 sighted control subjects using the right index finger. The tasks included a non-discrimination task and three discrimination tasks (angle, width and character). Irrespective of reading finger (right or left), Braille reading by the blind activated the inferior parietal lobule, primary visual cortex, superior occipital gyri, fusiform gyri, ventral premotor area, superior parietal lobule, cerebellum and primary sensorimotor area bilaterally, also the right dorsal premotor cortex, right middle occipital gyrus and right prefrontal area. During non-Braille discrimination tasks, in blind subjects, the ventral occipital regions, including the primary visual cortex and fusiform gyri bilaterally were activated while the secondary somatosensory area was deactivated. The reverse pattern was found in sighted subjects where the secondary somatosensory area was activated while the ventral occipital regions were suppressed. These findings suggest that the tactile processing pathways usually linked in the secondary somatosensory area are rerouted in blind subjects to the ventral occipital cortical regions originally reserved for visual shape discrimination.

Visual search for feature conjunctions: an fMRI study comparing alcohol-related neurodevelopmental disorder (ARND) to ADHD.

PubMed

O'Conaill, Carrie R; Malisza, Krisztina L; Buss, Joan L; Bolster, R Bruce; Clancy, Christine; de Gervai, Patricia Dreessen; Chudley, Albert E; Longstaffe, Sally

2015-01-01

Alcohol-related neurodevelopmental disorder (ARND) falls under the umbrella of fetal alcohol spectrum disorder (FASD). Diagnosis of ARND is difficult because individuals do not demonstrate the characteristic facial features associated with fetal alcohol syndrome (FAS). While attentional problems in ARND are similar to those found in attention-deficit/hyperactivity disorder (ADHD), the underlying impairment in attention pathways may be different. Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) was conducted at 3 T. Sixty-three children aged 10 to 14 years diagnosed with ARND, ADHD, and typically developing (TD) controls performed a single-feature and a feature-conjunction visual search task. Dorsal and ventral attention pathways were activated during both attention tasks in all groups. Significantly greater activation was observed in ARND subjects during a single-feature search as compared to TD and ADHD groups, suggesting ARND subjects require greater neural recruitment to perform this simple task. ARND subjects appear unable to effectively use the very efficient automatic perceptual 'pop-out' mechanism employed by TD and ADHD groups during presentation of the disjunction array. By comparison, activation was lower in ARND compared to TD and ADHD subjects during the more difficult conjunction search task as compared to the single-feature search. Analysis of DTI data using tract-based spatial statistics (TBSS) showed areas of significantly lower fractional anisotropy (FA) and higher mean diffusivity (MD) in the right inferior longitudinal fasciculus (ILF) in ARND compared to TD subjects. Damage to the white matter of the ILF may compromise the ventral attention pathway and may require subjects to use the dorsal attention pathway, which is associated with effortful top-down processing, for tasks that should be automatic. Decreased functional activity in the right temporoparietal junction (TPJ) of ARND subjects may be due to a reduction in the white matter tract's ability to efficiently convey information critical to performance of the attention tasks. Limited activation patterns in ARND suggest problems in information processing along the ventral frontoparietal attention pathway. Poor integrity of the ILF, which connects the functional components of the ventral attention network, in ARND subjects may contribute to the attention deficits characteristic of the disorder.

Contributions of local speech encoding and functional connectivity to audio-visual speech perception

PubMed Central

Giordano, Bruno L; Ince, Robin A A; Gross, Joachim; Schyns, Philippe G; Panzeri, Stefano; Kayser, Christoph

2017-01-01

Seeing a speaker’s face enhances speech intelligibility in adverse environments. We investigated the underlying network mechanisms by quantifying local speech representations and directed connectivity in MEG data obtained while human participants listened to speech of varying acoustic SNR and visual context. During high acoustic SNR speech encoding by temporally entrained brain activity was strong in temporal and inferior frontal cortex, while during low SNR strong entrainment emerged in premotor and superior frontal cortex. These changes in local encoding were accompanied by changes in directed connectivity along the ventral stream and the auditory-premotor axis. Importantly, the behavioral benefit arising from seeing the speaker’s face was not predicted by changes in local encoding but rather by enhanced functional connectivity between temporal and inferior frontal cortex. Our results demonstrate a role of auditory-frontal interactions in visual speech representations and suggest that functional connectivity along the ventral pathway facilitates speech comprehension in multisensory environments. DOI: http://dx.doi.org/10.7554/eLife.24763.001 PMID:28590903

Dynamic Integration of Task-Relevant Visual Features in Posterior Parietal Cortex

PubMed Central

Freedman, David J.

2014-01-01

Summary The primate visual system consists of multiple hierarchically organized cortical areas, each specialized for processing distinct aspects of the visual scene. For example, color and form are encoded in ventral pathway areas such as V4 and inferior temporal cortex, while motion is preferentially processed in dorsal pathway areas such as the middle temporal area. Such representations often need to be integrated perceptually to solve tasks which depend on multiple features. We tested the hypothesis that the lateral intraparietal area (LIP) integrates disparate task-relevant visual features by recording from LIP neurons in monkeys trained to identify target stimuli composed of conjunctions of color and motion features. We show that LIP neurons exhibit integrative representations of both color and motion features when they are task relevant, and task-dependent shifts of both direction and color tuning. This suggests that LIP plays a role in flexibly integrating task-relevant sensory signals. PMID:25199703

Cerebrospinal and Interstitial Fluid Transport via the Glymphatic Pathway Modeled by Optimal Mass Transport

PubMed Central

Ratner, Vadim; Gao, Yi; Lee, Hedok; Elkin, Rena; Nedergaard, Maiken; Benveniste, Helene; Tannenbaum, Allen

2017-01-01

The glymphatic pathway is a system which facilitates continuous cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange and plays a key role in removing waste products from the rodent brain. Dysfunction of the glymphatic pathway may be implicated in the pathophysiology of Alzheimer's disease. Intriguingly, the glymphatic system is most active during deep wave sleep general anesthesia. By using paramagnetic tracers administered into CSF of rodents, we previously showed the utility of MRI in characterizing a macroscopic whole brain view of glymphatic transport but we have yet to define and visualize the specific flow patterns. Here we have applied an alternative mathematical analysis approach to a dynamic time series of MRI images acquired every 4 min over ∼3 hrs in anesthetized rats, following administration of a small molecular weight paramagnetic tracer into the CSF reservoir of the cisterna magna. We use Optimal Mass Transport (OMT) to model the glymphatic flow vector field, and then analyze the flow to find the network of CSF-ISF flow channels. We use 3D visualization computational tools to visualize the OMT defined network of CSF-ISF flow channels in relation to anatomical and vascular key landmarks from the live rodent brain. The resulting OMT model of the glymphatic transport network agrees largely with the current understanding of the glymphatic transport patterns defined by dynamic contrast-enhanced MRI revealing key CSF transport pathways along the ventral surface of the brain with a trajectory towards the pineal gland, cerebellum, hypothalamus and olfactory bulb. In addition, the OMT analysis also revealed some interesting previously unnoticed behaviors regarding CSF transport involving parenchymal streamlines moving from ventral reservoirs towards the surface of the brain, olfactory bulb and large central veins. PMID:28323163

Cerebrospinal and interstitial fluid transport via the glymphatic pathway modeled by optimal mass transport.

PubMed

Ratner, Vadim; Gao, Yi; Lee, Hedok; Elkin, Rena; Nedergaard, Maiken; Benveniste, Helene; Tannenbaum, Allen

2017-05-15

The glymphatic pathway is a system which facilitates continuous cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange and plays a key role in removing waste products from the rodent brain. Dysfunction of the glymphatic pathway may be implicated in the pathophysiology of Alzheimer's disease. Intriguingly, the glymphatic system is most active during deep wave sleep general anesthesia. By using paramagnetic tracers administered into CSF of rodents, we previously showed the utility of MRI in characterizing a macroscopic whole brain view of glymphatic transport but we have yet to define and visualize the specific flow patterns. Here we have applied an alternative mathematical analysis approach to a dynamic time series of MRI images acquired every 4min over ∼3h in anesthetized rats, following administration of a small molecular weight paramagnetic tracer into the CSF reservoir of the cisterna magna. We use Optimal Mass Transport (OMT) to model the glymphatic flow vector field, and then analyze the flow to find the network of CSF-ISF flow channels. We use 3D visualization computational tools to visualize the OMT defined network of CSF-ISF flow channels in relation to anatomical and vascular key landmarks from the live rodent brain. The resulting OMT model of the glymphatic transport network agrees largely with the current understanding of the glymphatic transport patterns defined by dynamic contrast-enhanced MRI revealing key CSF transport pathways along the ventral surface of the brain with a trajectory towards the pineal gland, cerebellum, hypothalamus and olfactory bulb. In addition, the OMT analysis also revealed some interesting previously unnoticed behaviors regarding CSF transport involving parenchymal streamlines moving from ventral reservoirs towards the surface of the brain, olfactory bulb and large central veins. Copyright © 2017. Published by Elsevier Inc.

Stabilizing bidirectional associative memory with Principles in Independent Component Analysis and Null Space (PICANS)

NASA Astrophysics Data System (ADS)

LaRue, James P.; Luzanov, Yuriy

2013-05-01

A new extension to the way in which the Bidirectional Associative Memory (BAM) algorithms are implemented is presented here. We will show that by utilizing the singular value decomposition (SVD) and integrating principles of independent component analysis (ICA) into the nullspace (NS) we have created a novel approach to mitigating spurious attractors. We demonstrate this with two applications. The first application utilizes a one-layer association while the second application is modeled after the several hierarchal associations of ventral pathways. The first application will detail the way in which we manage the associations in terms of matrices. The second application will take what we have learned from the first example and apply it to a cascade of a convolutional neural network (CNN) and perceptron this being our signal processing model of the ventral pathways, i.e., visual systems.

Non-accidental properties, metric invariance, and encoding by neurons in a model of ventral stream visual object recognition, VisNet.

PubMed

Rolls, Edmund T; Mills, W Patrick C

2018-05-01

When objects transform into different views, some properties are maintained, such as whether the edges are convex or concave, and these non-accidental properties are likely to be important in view-invariant object recognition. The metric properties, such as the degree of curvature, may change with different views, and are less likely to be useful in object recognition. It is shown that in a model of invariant visual object recognition in the ventral visual stream, VisNet, non-accidental properties are encoded much more than metric properties by neurons. Moreover, it is shown how with the temporal trace rule training in VisNet, non-accidental properties of objects become encoded by neurons, and how metric properties are treated invariantly. We also show how VisNet can generalize between different objects if they have the same non-accidental property, because the metric properties are likely to overlap. VisNet is a 4-layer unsupervised model of visual object recognition trained by competitive learning that utilizes a temporal trace learning rule to implement the learning of invariance using views that occur close together in time. A second crucial property of this model of object recognition is, when neurons in the level corresponding to the inferior temporal visual cortex respond selectively to objects, whether neurons in the intermediate layers can respond to combinations of features that may be parts of two or more objects. In an investigation using the four sides of a square presented in every possible combination, it was shown that even though different layer 4 neurons are tuned to encode each feature or feature combination orthogonally, neurons in the intermediate layers can respond to features or feature combinations present is several objects. This property is an important part of the way in which high capacity can be achieved in the four-layer ventral visual cortical pathway. These findings concerning non-accidental properties and the use of neurons in intermediate layers of the hierarchy help to emphasise fundamental underlying principles of the computations that may be implemented in the ventral cortical visual stream used in object recognition. Copyright © 2018 Elsevier Inc. All rights reserved.

Action Control: Independent Effects of Memory and Monocular Viewing on Reaching Accuracy

ERIC Educational Resources Information Center

Westwood, D.A.; Robertson, C.; Heath, M.

2005-01-01

Evidence suggests that perceptual networks in the ventral visual pathway are necessary for action control when targets are viewed with only one eye, or when the target must be stored in memory. We tested whether memory-linked (i.e., open-loop versus memory-guided actions) and monocular-linked effects (i.e., binocular versus monocular actions) on…

Development of Tool Representations in the Dorsal and Ventral Visual Object Processing Pathways

PubMed Central

Kersey, Alyssa J.; Clark, Tyia S.; Lussier, Courtney A.; Mahon, Bradford Z.; Cantlon, Jessica F.

2016-01-01

Tools represent a special class of objects, because they are processed across both the dorsal and ventral visual object processing pathways. Three core regions are known to be involved in tool processing: the left posterior middle temporal gyrus, the medial fusiform gyrus (bilaterally), and the left inferior parietal lobule. A critical and relatively unexplored issue concerns whether, in development, tool preferences emerge at the same time and to a similar degree across all regions of the tool-processing network. To test this issue, we used functional magnetic resonance imaging to measure the neural amplitude, peak location, and the dispersion of tool-related neural responses in the youngest sample of children tested to date in this domain (ages 4–8 years). We show that children recruit overlapping regions of the adult tool-processing network and also exhibit similar patterns of co-activation across the network to adults. The amplitude and co-activation data show that the core components of the tool-processing network are established by age 4. Our findings on the distributions of peak location and dispersion of activation indicate that the tool network undergoes refinement between ages 4 and 8 years. PMID:26108614

Progressive posterior cortical dysfunction

PubMed Central

Porto, Fábio Henrique de Gobbi; Machado, Gislaine Cristina Lopes; Morillo, Lilian Schafirovits; Brucki, Sonia Maria Dozzi

2010-01-01

Progressive posterior cortical dysfunction (PPCD) is an insidious syndrome characterized by prominent disorders of higher visual processing. It affects both dorsal (occipito-parietal) and ventral (occipito-temporal) pathways, disturbing visuospatial processing and visual recognition, respectively. We report a case of a 67-year-old woman presenting with progressive impairment of visual functions. Neurologic examination showed agraphia, alexia, hemispatial neglect (left side visual extinction), complete Balint’s syndrome and visual agnosia. Magnetic resonance imaging showed circumscribed atrophy involving the bilateral parieto-occipital regions, slightly more predominant to the right. Our aim was to describe a case of this syndrome, to present a video showing the main abnormalities, and to discuss this unusual presentation of dementia. We believe this article can contribute by improving the recognition of PPCD. PMID:29213665

Here, there and everywhere: higher visual function and the dorsal visual stream.

PubMed

Cooper, Sarah Anne; O'Sullivan, Michael

2016-06-01

The dorsal visual stream, often referred to as the 'where' stream, represents the pathway taken by visual information from the primary visual cortex to the posterior parietal lobe and onwards. It partners the ventral or 'what' stream, the subject of a previous review and largely a temporal-based system. Here, we consider the dorsal stream disorders of perception (simultanagnosia, akinetopsia) along with their consequences on action (eg, optic ataxia and oculomotor apraxia, along with Balint's syndrome). The role of the dorsal stream in blindsight and hemispatial neglect is also considered. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Stream-related preferences of inputs to the superior colliculus from areas of dorsal and ventral streams of mouse visual cortex.

PubMed

Wang, Quanxin; Burkhalter, Andreas

2013-01-23

Previous studies of intracortical connections in mouse visual cortex have revealed two subnetworks that resemble the dorsal and ventral streams in primates. Although calcium imaging studies have shown that many areas of the ventral stream have high spatial acuity whereas areas of the dorsal stream are highly sensitive for transient visual stimuli, there are some functional inconsistencies that challenge a simple grouping into "what/perception" and "where/action" streams known in primates. The superior colliculus (SC) is a major center for processing of multimodal sensory information and the motor control of orienting the eyes, head, and body. Visual processing is performed in superficial layers, whereas premotor activity is generated in deep layers of the SC. Because the SC is known to receive input from visual cortex, we asked whether the projections from 10 visual areas of the dorsal and ventral streams terminate in differential depth profiles within the SC. We found that inputs from primary visual cortex are by far the strongest. Projections from the ventral stream were substantially weaker, whereas the sparsest input originated from areas of the dorsal stream. Importantly, we found that ventral stream inputs terminated in superficial layers, whereas dorsal stream inputs tended to be patchy and either projected equally to superficial and deep layers or strongly preferred deep layers. The results suggest that the anatomically defined ventral and dorsal streams contain areas that belong to distinct functional systems, specialized for the processing of visual information and visually guided action, respectively.

Toward a Unified Theory of Visual Area V4

PubMed Central

Roe, Anna W.; Chelazzi, Leonardo; Connor, Charles E.; Conway, Bevil R.; Fujita, Ichiro; Gallant, Jack L.; Lu, Haidong; Vanduffel, Wim

2016-01-01

Visual area V4 is a midtier cortical area in the ventral visual pathway. It is crucial for visual object recognition and has been a focus of many studies on visual attention. However, there is no unifying view of V4’s role in visual processing. Neither is there an understanding of how its role in feature processing interfaces with its role in visual attention. This review captures our current knowledge of V4, largely derived from electrophysiological and imaging studies in the macaque monkey. Based on recent discovery of functionally specific domains in V4, we propose that the unifying function of V4 circuitry is to enable selective extraction of specific functional domain-based networks, whether it be by bottom-up specification of object features or by top-down attentionally driven selection. PMID:22500626

The Role of the Ventral and Dorsal Pathways in Reading Chinese Characters and English Words

ERIC Educational Resources Information Center

Sun, Yafeng; Yang, Yanhui; Desroches, Amy S.; Liu, Li; Peng, Danling

2011-01-01

Previous literature in alphabetic languages suggests that the occipital-temporal region (the ventral pathway) is specialized for automatic parallel word recognition, whereas the parietal region (the dorsal pathway) is specialized for serial letter-by-letter reading (and). However, few studies have directly examined the role of the ventral and…

Differential modulation of visual object processing in dorsal and ventral stream by stimulus visibility.

PubMed

Ludwig, Karin; Sterzer, Philipp; Kathmann, Norbert; Hesselmann, Guido

2016-10-01

As a functional organization principle in cortical visual information processing, the influential 'two visual systems' hypothesis proposes a division of labor between a dorsal "vision-for-action" and a ventral "vision-for-perception" stream. A core assumption of this model is that the two visual streams are differentially involved in visual awareness: ventral stream processing is closely linked to awareness while dorsal stream processing is not. In this functional magnetic resonance imaging (fMRI) study with human observers, we directly probed the stimulus-related information encoded in fMRI response patterns in both visual streams as a function of stimulus visibility. We parametrically modulated the visibility of face and tool stimuli by varying the contrasts of the masks in a continuous flash suppression (CFS) paradigm. We found that visibility - operationalized by objective and subjective measures - decreased proportionally with increasing log CFS mask contrast. Neuronally, this relationship was closely matched by ventral visual areas, showing a linear decrease of stimulus-related information with increasing mask contrast. Stimulus-related information in dorsal areas also showed a dependency on mask contrast, but the decrease rather followed a step function instead of a linear function. Together, our results suggest that both the ventral and the dorsal visual stream are linked to visual awareness, but neural activity in ventral areas more closely reflects graded differences in awareness compared to dorsal areas. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of deep neural networks to spatio-temporal cortical dynamics of human visual object recognition reveals hierarchical correspondence

PubMed Central

Cichy, Radoslaw Martin; Khosla, Aditya; Pantazis, Dimitrios; Torralba, Antonio; Oliva, Aude

2016-01-01

The complex multi-stage architecture of cortical visual pathways provides the neural basis for efficient visual object recognition in humans. However, the stage-wise computations therein remain poorly understood. Here, we compared temporal (magnetoencephalography) and spatial (functional MRI) visual brain representations with representations in an artificial deep neural network (DNN) tuned to the statistics of real-world visual recognition. We showed that the DNN captured the stages of human visual processing in both time and space from early visual areas towards the dorsal and ventral streams. Further investigation of crucial DNN parameters revealed that while model architecture was important, training on real-world categorization was necessary to enforce spatio-temporal hierarchical relationships with the brain. Together our results provide an algorithmically informed view on the spatio-temporal dynamics of visual object recognition in the human visual brain. PMID:27282108

Comparison of deep neural networks to spatio-temporal cortical dynamics of human visual object recognition reveals hierarchical correspondence.

PubMed

Cichy, Radoslaw Martin; Khosla, Aditya; Pantazis, Dimitrios; Torralba, Antonio; Oliva, Aude

2016-06-10

The complex multi-stage architecture of cortical visual pathways provides the neural basis for efficient visual object recognition in humans. However, the stage-wise computations therein remain poorly understood. Here, we compared temporal (magnetoencephalography) and spatial (functional MRI) visual brain representations with representations in an artificial deep neural network (DNN) tuned to the statistics of real-world visual recognition. We showed that the DNN captured the stages of human visual processing in both time and space from early visual areas towards the dorsal and ventral streams. Further investigation of crucial DNN parameters revealed that while model architecture was important, training on real-world categorization was necessary to enforce spatio-temporal hierarchical relationships with the brain. Together our results provide an algorithmically informed view on the spatio-temporal dynamics of visual object recognition in the human visual brain.

Development of Tool Representations in the Dorsal and Ventral Visual Object Processing Pathways.

PubMed

Kersey, Alyssa J; Clark, Tyia S; Lussier, Courtney A; Mahon, Bradford Z; Cantlon, Jessica F

2016-07-01

Tools represent a special class of objects, because they are processed across both the dorsal and ventral visual object processing pathways. Three core regions are known to be involved in tool processing: the left posterior middle temporal gyrus, the medial fusiform gyrus (bilaterally), and the left inferior parietal lobule. A critical and relatively unexplored issue concerns whether, in development, tool preferences emerge at the same time and to a similar degree across all regions of the tool-processing network. To test this issue, we used functional magnetic resonance imaging to measure the neural amplitude, peak location, and the dispersion of tool-related neural responses in the youngest sample of children tested to date in this domain (ages 4-8 years). We show that children recruit overlapping regions of the adult tool-processing network and also exhibit similar patterns of co-activation across the network to adults. The amplitude and co-activation data show that the core components of the tool-processing network are established by age 4. Our findings on the distributions of peak location and dispersion of activation indicate that the tool network undergoes refinement between ages 4 and 8 years. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Tactile spatial working memory activates the dorsal extrastriate cortical pathway in congenitally blind individuals.

PubMed

Bonino, D; Ricciardi, E; Sani, L; Gentili, C; Vanello, N; Guazzelli, M; Vecchi, T; Pietrini, P

2008-09-01

In sighted individuals, both the visual and tactile version of the same spatial working memory task elicited neural responses in the dorsal "where" cortical pathway (Ricciardi et al., 2006). Whether the neural response during the tactile working memory task is due to visually-based spatial imagery or rather reflects a more abstract, supramodal organization of the dorsal cortical pathway remains to be determined. To understand the role of visual experience on the functional organization of the dorsal cortical stream, using functional magnetic resonance imaging (fMRI) here we examined brain response in four individuals with congenital or early blindness and no visual recollection, while they performed the same tactile spatial working memory task, a one-back recognition of 2D and 3D matrices. The blind subjects showed a significant activation in bilateral posterior parietal cortex, dorsolateral and inferior prefrontal areas, precuneus, lateral occipital cortex, and cerebellum. Thus, dorsal occipito-parietal areas are involved in mental imagery dealing with spatial components in subjects without prior visual experience and in response to a non-visual task. These data indicate that recruitment of the dorsal cortical pathway in response to the tactile spatial working memory task is not mediated by visually-based imagery and that visual experience is not a prerequisite for the development of a more abstract functional organization of the dorsal stream. These findings, along with previous data indicating a similar supramodal functional organization within the ventral cortical pathway and the motion processing brain regions, may contribute to explain how individuals who are born deprived of sight are able to interact effectively with the surrounding world.

Direct neural pathways convey distinct visual information to Drosophila mushroom bodies

PubMed Central

Vogt, Katrin; Aso, Yoshinori; Hige, Toshihide; Knapek, Stephan; Ichinose, Toshiharu; Friedrich, Anja B; Turner, Glenn C; Rubin, Gerald M; Tanimoto, Hiromu

2016-01-01

Previously, we demonstrated that visual and olfactory associative memories of Drosophila share mushroom body (MB) circuits (Vogt et al., 2014). Unlike for odor representation, the MB circuit for visual information has not been characterized. Here, we show that a small subset of MB Kenyon cells (KCs) selectively responds to visual but not olfactory stimulation. The dendrites of these atypical KCs form a ventral accessory calyx (vAC), distinct from the main calyx that receives olfactory input. We identified two types of visual projection neurons (VPNs) directly connecting the optic lobes and the vAC. Strikingly, these VPNs are differentially required for visual memories of color and brightness. The segregation of visual and olfactory domains in the MB allows independent processing of distinct sensory memories and may be a conserved form of sensory representations among insects. DOI: http://dx.doi.org/10.7554/eLife.14009.001 PMID:27083044

Serial functional imaging poststroke reveals visual cortex reorganization.

PubMed

Brodtmann, Amy; Puce, Aina; Darby, David; Donnan, Geoffrey

2009-02-01

Visual cortical reorganization following injury remains poorly understood. The authors performed serial functional magnetic resonance imaging (fMRI) on patients with visual cortex infarction to evaluate early and late striate, ventral, and dorsal extrastriate cortical activation. Patients were studied with fMRI within 10 days and at 6 months. The authors used a high-level visual activation task designed to activate the ventral extrastriate cortex. These data were compared to those of age-appropriate healthy control participants. The results from 24 healthy control individuals (mean age 65.7 +/- SE 3.6 years, range 32-89) were compared to those from 5 stroke patients (mean age 73.8 +/- SE 7 years, range 49-86). Patients had infarcts involving the striate and ventral extrastriate cortex. Patient activation patterns were markedly different to controls. Bilateral striate and ventral extrastriate activation was reduced at both sessions, but dorsal extrastriate activated voxel counts remained comparable to controls. Conversely, mean percent magnetic resonance signal change increased in dorsal sites. These data provide strong evidence of bilateral poststroke functional depression of striate and ventral extrastriate cortices. Possible utilization or surrogacy of the dorsal visual system was demonstrated following stroke. This activity could provide a target for novel visual rehabilitation therapies.

A Spiking Neural Network Based Cortex-Like Mechanism and Application to Facial Expression Recognition

PubMed Central

Fu, Si-Yao; Yang, Guo-Sheng; Kuai, Xin-Kai

2012-01-01

In this paper, we present a quantitative, highly structured cortex-simulated model, which can be simply described as feedforward, hierarchical simulation of ventral stream of visual cortex using biologically plausible, computationally convenient spiking neural network system. The motivation comes directly from recent pioneering works on detailed functional decomposition analysis of the feedforward pathway of the ventral stream of visual cortex and developments on artificial spiking neural networks (SNNs). By combining the logical structure of the cortical hierarchy and computing power of the spiking neuron model, a practical framework has been presented. As a proof of principle, we demonstrate our system on several facial expression recognition tasks. The proposed cortical-like feedforward hierarchy framework has the merit of capability of dealing with complicated pattern recognition problems, suggesting that, by combining the cognitive models with modern neurocomputational approaches, the neurosystematic approach to the study of cortex-like mechanism has the potential to extend our knowledge of brain mechanisms underlying the cognitive analysis and to advance theoretical models of how we recognize face or, more specifically, perceive other people's facial expression in a rich, dynamic, and complex environment, providing a new starting point for improved models of visual cortex-like mechanism. PMID:23193391

A spiking neural network based cortex-like mechanism and application to facial expression recognition.

PubMed

Fu, Si-Yao; Yang, Guo-Sheng; Kuai, Xin-Kai

2012-01-01

In this paper, we present a quantitative, highly structured cortex-simulated model, which can be simply described as feedforward, hierarchical simulation of ventral stream of visual cortex using biologically plausible, computationally convenient spiking neural network system. The motivation comes directly from recent pioneering works on detailed functional decomposition analysis of the feedforward pathway of the ventral stream of visual cortex and developments on artificial spiking neural networks (SNNs). By combining the logical structure of the cortical hierarchy and computing power of the spiking neuron model, a practical framework has been presented. As a proof of principle, we demonstrate our system on several facial expression recognition tasks. The proposed cortical-like feedforward hierarchy framework has the merit of capability of dealing with complicated pattern recognition problems, suggesting that, by combining the cognitive models with modern neurocomputational approaches, the neurosystematic approach to the study of cortex-like mechanism has the potential to extend our knowledge of brain mechanisms underlying the cognitive analysis and to advance theoretical models of how we recognize face or, more specifically, perceive other people's facial expression in a rich, dynamic, and complex environment, providing a new starting point for improved models of visual cortex-like mechanism.

Tracking Training-Related Plasticity by Combining fMRI and DTI: The Right Hemisphere Ventral Stream Mediates Musical Syntax Processing.

PubMed

Oechslin, Mathias S; Gschwind, Markus; James, Clara E

2018-04-01

As a functional homolog for left-hemispheric syntax processing in language, neuroimaging studies evidenced involvement of right prefrontal regions in musical syntax processing, of which underlying white matter connectivity remains unexplored so far. In the current experiment, we investigated the underlying pathway architecture in subjects with 3 levels of musical expertise. Employing diffusion tensor imaging tractography, departing from seeds from our previous functional magnetic resonance imaging study on music syntax processing in the same participants, we identified a pathway in the right ventral stream that connects the middle temporal lobe with the inferior frontal cortex via the extreme capsule, and corresponds to the left hemisphere ventral stream, classically attributed to syntax processing in language comprehension. Additional morphometric consistency analyses allowed dissociating tract core from more dispersed fiber portions. Musical expertise related to higher tract consistency of the right ventral stream pathway. Specifically, tract consistency in this pathway predicted the sensitivity for musical syntax violations. We conclude that enduring musical practice sculpts ventral stream architecture. Our results suggest that training-related pathway plasticity facilitates the right hemisphere ventral stream information transfer, supporting an improved sound-to-meaning mapping in music.

Differential Expression Patterns of occ1-Related Genes in Adult Monkey Visual Cortex

PubMed Central

Takahata, Toru; Komatsu, Yusuke; Watakabe, Akiya; Hashikawa, Tsutomu; Tochitani, Shiro

2009-01-01

We have previously revealed that occ1 is preferentially expressed in the primary visual area (V1) of the monkey neocortex. In our attempt to identify more area-selective genes in the macaque neocortex, we found that testican-1, an occ1-related gene, and its family members also exhibit characteristic expression patterns along the visual pathway. The expression levels of testican-1 and testican-2 mRNAs as well as that of occ1 mRNA start of high in V1, progressively decrease along the ventral visual pathway, and end of low in the temporal areas. Complementary to them, the neuronal expression of SPARC mRNA is abundant in the association areas and scarce in V1. Whereas occ1, testican-1, and testican-2 mRNAs are preferentially distributed in thalamorecipient layers including “blobs,” SPARC mRNA expression avoids these layers. Neither SC1 nor testican-3 mRNA expression is selective to particular areas, but SC1 mRNA is abundantly observed in blobs. The expressions of occ1, testican-1, testican-2, and SC1 mRNA were downregulated after monocular tetrodotoxin injection. These results resonate with previous works on chemical and functional gradients along the primate occipitotemporal visual pathway and raise the possibility that these gradients and functional architecture may be related to the visual activity–dependent expression of these extracellular matrix glycoproteins. PMID:19073625

Decreased activation along the dorsal visual pathway after a 3-month treatment with galantamine in mild Alzheimer disease: a functional magnetic resonance imaging study.

PubMed

Bokde, Arun L W; Karmann, Michaela; Teipel, Stefan J; Born, Christine; Lieb, Martin; Reiser, Maximilian F; Möller, Hans-Jürgen; Hampel, Harald

2009-04-01

Visual perception has been shown to be altered in Alzheimer disease (AD) patients, and it is associated with decreased cognitive function. Galantamine is an active cholinergic agent, which has been shown to lead to improved cognition in mild to moderate AD patients. This study examined brain activation in a group of mild AD patients after a 3-month open-label treatment with galantamine. The objective was to examine the changes in brain activation due to treatment. There were 2 tasks to visual perception. The first task was a face-matching task to test the activation along the ventral visual pathway, and the second task was a location-matching task to test neuronal function along the dorsal pathway. Brain activation was measured using functional magnetic resonance imaging. There were 5 mild AD patients in the study. There were no differences in the task performance and in the cognitive scores of the Consortium to Establish a Registry for Alzheimer's Disease battery before and after treatment. In the location-matching task, we found a statistically significant decrease in activation along the dorsal visual pathway after galantamine treatment. A previous study found that AD patients had higher activation in the location-matching task compared with healthy controls. There were no differences in activation for the face-matching task after treatment. Our data indicate that treatment with galantamine leads to more efficient visual processing of stimuli or changes the compensatory mechanism in the AD patients. A visual perception task recruiting the dorsal visual system may be useful as a biomarker of treatment effects.

Posterior Parietal Cortex Drives Inferotemporal Activations During Three-Dimensional Object Vision.

PubMed

Van Dromme, Ilse C; Premereur, Elsie; Verhoef, Bram-Ernst; Vanduffel, Wim; Janssen, Peter

2016-04-01

The primate visual system consists of a ventral stream, specialized for object recognition, and a dorsal visual stream, which is crucial for spatial vision and actions. However, little is known about the interactions and information flow between these two streams. We investigated these interactions within the network processing three-dimensional (3D) object information, comprising both the dorsal and ventral stream. Reversible inactivation of the macaque caudal intraparietal area (CIP) during functional magnetic resonance imaging (fMRI) reduced fMRI activations in posterior parietal cortex in the dorsal stream and, surprisingly, also in the inferotemporal cortex (ITC) in the ventral visual stream. Moreover, CIP inactivation caused a perceptual deficit in a depth-structure categorization task. CIP-microstimulation during fMRI further suggests that CIP projects via posterior parietal areas to the ITC in the ventral stream. To our knowledge, these results provide the first causal evidence for the flow of visual 3D information from the dorsal stream to the ventral stream, and identify CIP as a key area for depth-structure processing. Thus, combining reversible inactivation and electrical microstimulation during fMRI provides a detailed view of the functional interactions between the two visual processing streams.

Posterior Parietal Cortex Drives Inferotemporal Activations During Three-Dimensional Object Vision

PubMed Central

Van Dromme, Ilse C.; Premereur, Elsie; Verhoef, Bram-Ernst; Vanduffel, Wim; Janssen, Peter

2016-01-01

The primate visual system consists of a ventral stream, specialized for object recognition, and a dorsal visual stream, which is crucial for spatial vision and actions. However, little is known about the interactions and information flow between these two streams. We investigated these interactions within the network processing three-dimensional (3D) object information, comprising both the dorsal and ventral stream. Reversible inactivation of the macaque caudal intraparietal area (CIP) during functional magnetic resonance imaging (fMRI) reduced fMRI activations in posterior parietal cortex in the dorsal stream and, surprisingly, also in the inferotemporal cortex (ITC) in the ventral visual stream. Moreover, CIP inactivation caused a perceptual deficit in a depth-structure categorization task. CIP-microstimulation during fMRI further suggests that CIP projects via posterior parietal areas to the ITC in the ventral stream. To our knowledge, these results provide the first causal evidence for the flow of visual 3D information from the dorsal stream to the ventral stream, and identify CIP as a key area for depth-structure processing. Thus, combining reversible inactivation and electrical microstimulation during fMRI provides a detailed view of the functional interactions between the two visual processing streams. PMID:27082854

The ventralizing activity of Radar, a maternally expressed bone morphogenetic protein, reveals complex bone morphogenetic protein interactions controlling dorso-ventral patterning in zebrafish.

PubMed

Goutel, C; Kishimoto, Y; Schulte-Merker, S; Rosa, F

2000-12-01

In Xenopus and zebrafish, BMP2, 4 and 7 have been implicated, after the onset of zygotic expression, in inducing and maintaining ventro-lateral cell fate during early development. We provide evidence here that a maternally expressed bone morphogenetic protein (BMP), Radar, may control early ventral specification in zebrafish. We show that Radar ventralizes zebrafish embryos and induces the early expression of bmp2b and bmp4. The analysis of Radar overexpression in both swirl/bmp2b mutants and embryos expressing truncated BMP receptors shows that Radar-induced ventralization is dependent on functional BMP2/4 pathways, and may initially rely on an Alk6-related signaling pathway. Finally, we show that while radar-injected swirl embryos still exhibit a strongly dorsalized phenotype, the overexpression of Radar into swirl/bmp2b mutant embryos restores ventral marker expression, including bmp4 expression. Our results suggest that a complex regulation of different BMP pathways controls dorso-ventral (DV) patterning from early cleavage stages until somitogenesis.

Reframing the action and perception dissociation in DF: haptics matters, but how?

PubMed

Whitwell, Robert L; Buckingham, Gavin

2013-02-01

Goodale and Milner's (1992) "vision-for-action" and "vision-for-perception" account of the division of labor between the dorsal and ventral "streams" has come to dominate contemporary views of the functional roles of these two pathways. Nevertheless, some lines of evidence for the model remain controversial. Recently, Thomas Schenk reexamined visual form agnosic patient DF's spared anticipatory grip scaling to object size, one of the principal empirical pillars of the model. Based on this new evidence, Schenk rejects the original interpretation of DF's spared ability that was based on segregated processing of object size and argues that DF's spared grip scaling relies on haptic feedback to calibrate visual egocentric cues that relate the posture of the hand to the visible edges of the goal-object. However, a careful consideration of the tasks that Schenk employed reveals some problems with his claim. We suspect that the core issues of this controversy will require a closer examination of the role that cognition plays in the operation of the dorsal and ventral streams in healthy controls and in patient DF.

The Anatomical and Functional Organization of the Human Visual Pulvinar

PubMed Central

Pinsk, Mark A.; Kastner, Sabine

2015-01-01

The pulvinar is the largest nucleus in the primate thalamus and contains extensive, reciprocal connections with visual cortex. Although the anatomical and functional organization of the pulvinar has been extensively studied in old and new world monkeys, little is known about the organization of the human pulvinar. Using high-resolution functional magnetic resonance imaging at 3 T, we identified two visual field maps within the ventral pulvinar, referred to as vPul1 and vPul2. Both maps contain an inversion of contralateral visual space with the upper visual field represented ventrally and the lower visual field represented dorsally. vPul1 and vPul2 border each other at the vertical meridian and share a representation of foveal space with iso-eccentricity lines extending across areal borders. Additional, coarse representations of contralateral visual space were identified within ventral medial and dorsal lateral portions of the pulvinar. Connectivity analyses on functional and diffusion imaging data revealed a strong distinction in thalamocortical connectivity between the dorsal and ventral pulvinar. The two maps in the ventral pulvinar were most strongly connected with early and extrastriate visual areas. Given the shared eccentricity representation and similarity in cortical connectivity, we propose that these two maps form a distinct visual field map cluster and perform related functions. The dorsal pulvinar was most strongly connected with parietal and frontal areas. The functional and anatomical organization observed within the human pulvinar was similar to the organization of the pulvinar in other primate species. SIGNIFICANCE STATEMENT The anatomical organization and basic response properties of the visual pulvinar have been extensively studied in nonhuman primates. Yet, relatively little is known about the functional and anatomical organization of the human pulvinar. Using neuroimaging, we found multiple representations of visual space within the ventral human pulvinar and extensive topographically organized connectivity with visual cortex. This organization is similar to other nonhuman primates and provides additional support that the general organization of the pulvinar is consistent across the primate phylogenetic tree. These results suggest that the human pulvinar, like other primates, is well positioned to regulate corticocortical communication. PMID:26156987

Resting state functional connectivity of the ventral auditory pathway in musicians with absolute pitch.

PubMed

Kim, Seung-Goo; Knösche, Thomas R

2017-08-01

Absolute pitch (AP) is the ability to recognize pitch chroma of tonal sound without external references, providing a unique model of the human auditory system (Zatorre: Nat Neurosci 6 () 692-695). In a previous study (Kim and Knösche: Hum Brain Mapp () 3486-3501), we identified enhanced intracortical myelination in the right planum polare (PP) in musicians with AP, which could be a potential site for perceptional processing of pitch chroma information. We speculated that this area, which initiates the ventral auditory pathway, might be crucially involved in the perceptual stage of the AP process in the context of the "dual pathway hypothesis" that suggests the role of the ventral pathway in processing nonspatial information related to the identity of an auditory object (Rauschecker: Eur J Neurosci 41 () 579-585). To test our conjecture on the ventral pathway, we investigated resting state functional connectivity (RSFC) using functional magnetic resonance imaging (fMRI) from musicians with varying degrees of AP. Should our hypothesis be correct, RSFC via the ventral pathway is expected to be stronger in musicians with AP, whereas such group effect is not predicted in the RSFC via the dorsal pathway. In the current data, we found greater RSFC between the right PP and bilateral anteroventral auditory cortices in musicians with AP. In contrast, we did not find any group difference in the RSFC of the planum temporale (PT) between musicians with and without AP. We believe that these findings support our conjecture on the critical role of the ventral pathway in AP recognition. Hum Brain Mapp 38:3899-3916, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

More than blindsight: Case report of a child with extraordinary visual capacity following perinatal bilateral occipital lobe injury.

PubMed

Mundinano, Inaki-Carril; Chen, Juan; de Souza, Mitchell; Sarossy, Marc G; Joanisse, Marc F; Goodale, Melvyn A; Bourne, James A

2017-11-13

Injury to the primary visual cortex (V1, striate cortex) and the geniculostriate pathway in adults results in cortical blindness, abolishing conscious visual perception. Early studies by Larry Weiskrantz and colleagues demonstrated that some patients with an occipital-lobe injury exhibited a degree of unconscious vision and visually-guided behaviour within the blind field. A more recent focus has been the observed phenomenon whereby early-life injury to V1 often results in the preservation of visual perception in both monkeys and humans. These findings initiated a concerted effort on multiple fronts, including nonhuman primate studies, to uncover the neural substrate/s of the spared conscious vision. In both adult and early-life cases of V1 injury, evidence suggests the involvement of the Middle Temporal area (MT) of the extrastriate visual cortex, which is an integral component area of the dorsal stream and is also associated with visually-guided behaviors. Because of the limited number of early-life V1 injury cases for humans, the outstanding question in the field is what secondary visual pathways are responsible for this extraordinary capacity? Here we report for the first time a case of a child (B.I.) who suffered a bilateral occipital-lobe injury in the first two weeks postnatally due to medium-chain acyl-Co-A dehydrogenase deficiency. At 6 years of age, B.I. underwent a battery of neurophysiological tests, as well as structural and diffusion MRI and ophthalmic examination at 7 years. Despite the extensive bilateral occipital cortical damage, B.I. has extensive conscious visual abilities, is not blind, and can use vision to navigate his environment. Furthermore, unlike blindsight patients, he can readily and consciously identify happy and neutral faces and colors, tasks associated with ventral stream processing. These findings suggest significant re-routing of visual information. To identify the putative visual pathway/s responsible for this ability, MRI tractography of secondary visual pathways connecting MT with the lateral geniculate nucleus (LGN) and the inferior pulvinar (PI) were analysed. Results revealed an increased PI-MT pathway in the left hemisphere, suggesting that this pulvinar relay could be the neural pathway affording the preserved visual capacity following an early-life lesion of V1. These findings corroborate anatomical evidence from monkeys showing an enhanced PI-MT pathway following an early-life lesion of V1, compared to adults. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sensitivity to timing and order in human visual cortex

PubMed Central

Singer, Jedediah M.; Madsen, Joseph R.; Anderson, William S.

2014-01-01

Visual recognition takes a small fraction of a second and relies on the cascade of signals along the ventral visual stream. Given the rapid path through multiple processing steps between photoreceptors and higher visual areas, information must progress from stage to stage very quickly. This rapid progression of information suggests that fine temporal details of the neural response may be important to the brain's encoding of visual signals. We investigated how changes in the relative timing of incoming visual stimulation affect the representation of object information by recording intracranial field potentials along the human ventral visual stream while subjects recognized objects whose parts were presented with varying asynchrony. Visual responses along the ventral stream were sensitive to timing differences as small as 17 ms between parts. In particular, there was a strong dependency on the temporal order of stimulus presentation, even at short asynchronies. From these observations we infer that the neural representation of complex information in visual cortex can be modulated by rapid dynamics on scales of tens of milliseconds. PMID:25429116

Electrophysiological Evidence for Ventral Stream Deficits in Schizophrenia Patients

PubMed Central

Plomp, Gijs; Roinishvili, Maya; Chkonia, Eka; Kapanadze, George; Kereselidze, Maia; Brand, Andreas; Herzog, Michael H.

2013-01-01

Schizophrenic patients suffer from many deficits including visual, attentional, and cognitive ones. Visual deficits are of particular interest because they are at the fore-end of information processing and can provide clear examples of interactions between sensory, perceptual, and higher cognitive functions. Visual deficits in schizophrenic patients are often attributed to impairments in the dorsal (where) rather than the ventral (what) stream of visual processing. We used a visual-masking paradigm in which patients and matched controls discriminated small vernier offsets. We analyzed the evoked electroencephalography (EEG) responses and applied distributed electrical source imaging techniques to estimate activity differences between conditions and groups throughout the brain. Compared with controls, patients showed strongly reduced discrimination accuracy, confirming previous work. The behavioral deficits corresponded to pronounced decreases in the evoked EEG response at around 200 ms after stimulus onset. At this latency, patients showed decreased activity for targets in left parietal cortex (dorsal stream), but the decrease was most pronounced in lateral occipital cortex (in the ventral stream). These deficiencies occurred at latencies that reflect object processing and fine shape discriminations. We relate the reduced ventral stream activity to deficient top-down processing of target stimuli and provide a framework for relating the commonly observed dorsal stream deficiencies with the currently observed ventral stream deficiencies. PMID:22258884

Electrophysiological evidence for ventral stream deficits in schizophrenia patients.

PubMed

Plomp, Gijs; Roinishvili, Maya; Chkonia, Eka; Kapanadze, George; Kereselidze, Maia; Brand, Andreas; Herzog, Michael H

2013-05-01

Schizophrenic patients suffer from many deficits including visual, attentional, and cognitive ones. Visual deficits are of particular interest because they are at the fore-end of information processing and can provide clear examples of interactions between sensory, perceptual, and higher cognitive functions. Visual deficits in schizophrenic patients are often attributed to impairments in the dorsal (where) rather than the ventral (what) stream of visual processing. We used a visual-masking paradigm in which patients and matched controls discriminated small vernier offsets. We analyzed the evoked electroencephalography (EEG) responses and applied distributed electrical source imaging techniques to estimate activity differences between conditions and groups throughout the brain. Compared with controls, patients showed strongly reduced discrimination accuracy, confirming previous work. The behavioral deficits corresponded to pronounced decreases in the evoked EEG response at around 200 ms after stimulus onset. At this latency, patients showed decreased activity for targets in left parietal cortex (dorsal stream), but the decrease was most pronounced in lateral occipital cortex (in the ventral stream). These deficiencies occurred at latencies that reflect object processing and fine shape discriminations. We relate the reduced ventral stream activity to deficient top-down processing of target stimuli and provide a framework for relating the commonly observed dorsal stream deficiencies with the currently observed ventral stream deficiencies.

Identification of a pathway for intelligible speech in the left temporal lobe

PubMed Central

Scott, Sophie K.; Blank, C. Catrin; Rosen, Stuart; Wise, Richard J. S.

2017-01-01

Summary It has been proposed that the identification of sounds, including species-specific vocalizations, by primates depends on anterior projections from the primary auditory cortex, an auditory pathway analogous to the ventral route proposed for the visual identification of objects. We have identified a similar route in the human for understanding intelligible speech. Using PET imaging to identify separable neural subsystems within the human auditory cortex, we used a variety of speech and speech-like stimuli with equivalent acoustic complexity but varying intelligibility. We have demonstrated that the left superior temporal sulcus responds to the presence of phonetic information, but its anterior part only responds if the stimulus is also intelligible. This novel observation demonstrates a left anterior temporal pathway for speech comprehension. PMID:11099443

Ultra-Rapid serial visual presentation reveals dynamics of feedforward and feedback processes in the ventral visual pathway.

PubMed

Mohsenzadeh, Yalda; Qin, Sheng; Cichy, Radoslaw M; Pantazis, Dimitrios

2018-06-21

Human visual recognition activates a dense network of overlapping feedforward and recurrent neuronal processes, making it hard to disentangle processing in the feedforward from the feedback direction. Here, we used ultra-rapid serial visual presentation to suppress sustained activity that blurs the boundaries of processing steps, enabling us to resolve two distinct stages of processing with MEG multivariate pattern classification. The first processing stage was the rapid activation cascade of the bottom-up sweep, which terminated early as visual stimuli were presented at progressively faster rates. The second stage was the emergence of categorical information with peak latency that shifted later in time with progressively faster stimulus presentations, indexing time-consuming recurrent processing. Using MEG-fMRI fusion with representational similarity, we localized recurrent signals in early visual cortex. Together, our findings segregated an initial bottom-up sweep from subsequent feedback processing, and revealed the neural signature of increased recurrent processing demands for challenging viewing conditions. © 2018, Mohsenzadeh et al.

Deep Residual Network Predicts Cortical Representation and Organization of Visual Features for Rapid Categorization.

PubMed

Wen, Haiguang; Shi, Junxing; Chen, Wei; Liu, Zhongming

2018-02-28

The brain represents visual objects with topographic cortical patterns. To address how distributed visual representations enable object categorization, we established predictive encoding models based on a deep residual network, and trained them to predict cortical responses to natural movies. Using this predictive model, we mapped human cortical representations to 64,000 visual objects from 80 categories with high throughput and accuracy. Such representations covered both the ventral and dorsal pathways, reflected multiple levels of object features, and preserved semantic relationships between categories. In the entire visual cortex, object representations were organized into three clusters of categories: biological objects, non-biological objects, and background scenes. In a finer scale specific to each cluster, object representations revealed sub-clusters for further categorization. Such hierarchical clustering of category representations was mostly contributed by cortical representations of object features from middle to high levels. In summary, this study demonstrates a useful computational strategy to characterize the cortical organization and representations of visual features for rapid categorization.

The TINS Lecture. The parietal association cortex in depth perception and visual control of hand action.

PubMed

Sakata, H; Taira, M; Kusunoki, M; Murata, A; Tanaka, Y

1997-08-01

Recent neurophysiological studies in alert monkeys have revealed that the parietal association cortex plays a crucial role in depth perception and visually guided hand movement. The following five classes of parietal neurons covering various aspects of these functions have been identified: (1) depth-selective visual-fixation (VF) neurons of the inferior parietal lobule (IPL), representing egocentric distance; (2) depth-movement sensitive (DMS) neurons of V5A and the ventral intraparietal (VIP) area representing direction of linear movement in 3-D space; (3) depth-rotation-sensitive (RS) neurons of V5A and the posterior parietal (PP) area representing direction of rotary movement in space; (4) visually responsive manipulation-related neurons (visual-dominant or visual-and-motor type) of the anterior intraparietal (AIP) area, representing 3-D shape or orientation (or both) of objects for manipulation; and (5) axis-orientation-selective (AOS) and surface-orientation-selective (SOS) neurons in the caudal intraparietal sulcus (cIPS) sensitive to binocular disparity and representing the 3-D orientation of the longitudinal axes and flat surfaces, respectively. Some AOS and SOS neurons are selective in both orientation and shape. Thus the dorsal visual pathway is divided into at least two subsystems, V5A, PP and VIP areas for motion vision and V6, LIP and cIPS areas for coding position and 3-D features. The cIPS sends the signals of 3-D features of objects to the AIP area, which is reciprocally connected to the ventral premotor (F5) area and plays an essential role in matching hand orientation and shaping with 3-D objects for manipulation.

Finding and recognizing objects in natural scenes: complementary computations in the dorsal and ventral visual systems

PubMed Central

Rolls, Edmund T.; Webb, Tristan J.

2014-01-01

Searching for and recognizing objects in complex natural scenes is implemented by multiple saccades until the eyes reach within the reduced receptive field sizes of inferior temporal cortex (IT) neurons. We analyze and model how the dorsal and ventral visual streams both contribute to this. Saliency detection in the dorsal visual system including area LIP is modeled by graph-based visual saliency, and allows the eyes to fixate potential objects within several degrees. Visual information at the fixated location subtending approximately 9° corresponding to the receptive fields of IT neurons is then passed through a four layer hierarchical model of the ventral cortical visual system, VisNet. We show that VisNet can be trained using a synaptic modification rule with a short-term memory trace of recent neuronal activity to capture both the required view and translation invariances to allow in the model approximately 90% correct object recognition for 4 objects shown in any view across a range of 135° anywhere in a scene. The model was able to generalize correctly within the four trained views and the 25 trained translations. This approach analyses the principles by which complementary computations in the dorsal and ventral visual cortical streams enable objects to be located and recognized in complex natural scenes. PMID:25161619

Reading without the left ventral occipito-temporal cortex

PubMed Central

Seghier, Mohamed L.; Neufeld, Nicholas H.; Zeidman, Peter; Leff, Alex P.; Mechelli, Andrea; Nagendran, Arjuna; Riddoch, Jane M.; Humphreys, Glyn W.; Price, Cathy J.

2012-01-01

The left ventral occipito-temporal cortex (LvOT) is thought to be essential for the rapid parallel letter processing that is required for skilled reading. Here we investigate whether rapid written word identification in skilled readers can be supported by neural pathways that do not involve LvOT. Hypotheses were derived from a stroke patient who acquired dyslexia following extensive LvOT damage. The patient followed a reading trajectory typical of that associated with pure alexia, re-gaining the ability to read aloud many words with declining performance as the length of words increased. Using functional MRI and dynamic causal modelling (DCM), we found that, when short (three to five letter) familiar words were read successfully, visual inputs to the patient’s occipital cortex were connected to left motor and premotor regions via activity in a central part of the left superior temporal sulcus (STS). The patient analysis therefore implied a left hemisphere “reading-without-LvOT” pathway that involved STS. We then investigated whether the same reading-without-LvOT pathway could be identified in 29 skilled readers and whether there was inter-subject variability in the degree to which skilled reading engaged LvOT. We found that functional connectivity in the reading-without-LvOT pathway was strongest in individuals who had the weakest functional connectivity in the LvOT pathway. This observation validates the findings of our patient’s case study. Our findings highlight the contribution of a left hemisphere reading pathway that is activated during the rapid identification of short familiar written words, particularly when LvOT is not involved. Preservation and use of this pathway may explain how patients are still able to read short words accurately when LvOT has been damaged. PMID:23017598

Spatial Attention Reduces Burstiness in Macaque Visual Cortical Area MST.

PubMed

Xue, Cheng; Kaping, Daniel; Ray, Sonia Baloni; Krishna, B Suresh; Treue, Stefan

2017-01-01

Visual attention modulates the firing rate of neurons in many primate cortical areas. In V4, a cortical area in the ventral visual pathway, spatial attention has also been shown to reduce the tendency of neurons to fire closely separated spikes (burstiness). A recent model proposes that a single mechanism accounts for both the firing rate enhancement and the burstiness reduction in V4, but this has not been empirically tested. It is also unclear if the burstiness reduction by spatial attention is found in other visual areas and for other attentional types. We therefore recorded from single neurons in the medial superior temporal area (MST), a key motion-processing area along the dorsal visual pathway, of two rhesus monkeys while they performed a task engaging both spatial and feature-based attention. We show that in MST, spatial attention is associated with a clear reduction in burstiness that is independent of the concurrent enhancement of firing rate. In contrast, feature-based attention enhances firing rate but is not associated with a significant reduction in burstiness. These results establish burstiness reduction as a widespread effect of spatial attention. They also suggest that in contrast to the recently proposed model, the effects of spatial attention on burstiness and firing rate emerge from different mechanisms. © The Author 2016. Published by Oxford University Press.

Spatial Attention Reduces Burstiness in Macaque Visual Cortical Area MST

PubMed Central

Xue, Cheng; Kaping, Daniel; Ray, Sonia Baloni; Krishna, B. Suresh; Treue, Stefan

2017-01-01

Abstract Visual attention modulates the firing rate of neurons in many primate cortical areas. In V4, a cortical area in the ventral visual pathway, spatial attention has also been shown to reduce the tendency of neurons to fire closely separated spikes (burstiness). A recent model proposes that a single mechanism accounts for both the firing rate enhancement and the burstiness reduction in V4, but this has not been empirically tested. It is also unclear if the burstiness reduction by spatial attention is found in other visual areas and for other attentional types. We therefore recorded from single neurons in the medial superior temporal area (MST), a key motion-processing area along the dorsal visual pathway, of two rhesus monkeys while they performed a task engaging both spatial and feature-based attention. We show that in MST, spatial attention is associated with a clear reduction in burstiness that is independent of the concurrent enhancement of firing rate. In contrast, feature-based attention enhances firing rate but is not associated with a significant reduction in burstiness. These results establish burstiness reduction as a widespread effect of spatial attention. They also suggest that in contrast to the recently proposed model, the effects of spatial attention on burstiness and firing rate emerge from different mechanisms. PMID:28365773

The role of temporo-parietal junction (TPJ) in global Gestalt perception.

PubMed

Huberle, Elisabeth; Karnath, Hans-Otto

2012-07-01

Grouping processes enable the coherent perception of our environment. A number of brain areas has been suggested to be involved in the integration of elements into objects including early and higher visual areas along the ventral visual pathway as well as motion-processing areas of the dorsal visual pathway. However, integration not only is required for the cortical representation of individual objects, but is also essential for the perception of more complex visual scenes consisting of several different objects and/or shapes. The present fMRI experiments aimed to address such integration processes. We investigated the neural correlates underlying the global Gestalt perception of hierarchically organized stimuli that allowed parametrical degrading of the object at the global level. The comparison of intact versus disturbed perception of the global Gestalt revealed a network of cortical areas including the temporo-parietal junction (TPJ), anterior cingulate cortex and the precuneus. The TPJ location corresponds well with the areas known to be typically lesioned in stroke patients with simultanagnosia following bilateral brain damage. These patients typically show a deficit in identifying the global Gestalt of a visual scene. Further, we found the closest relation between behavioral performance and fMRI activation for the TPJ. Our data thus argue for a significant role of the TPJ in human global Gestalt perception.

Language Learning Variability within the Dorsal and Ventral Streams as a Cue for Compensatory Mechanisms in Aphasia Recovery

PubMed Central

López-Barroso, Diana; de Diego-Balaguer, Ruth

2017-01-01

Dorsal and ventral pathways connecting perisylvian language areas have been shown to be functionally and anatomically segregated. Whereas the dorsal pathway integrates the sensory-motor information required for verbal repetition, the ventral pathway has classically been associated with semantic processes. The great individual differences characterizing language learning through life partly correlate with brain structure and function within these dorsal and ventral language networks. Variability and plasticity within these networks also underlie inter-individual differences in the recovery of linguistic abilities in aphasia. Despite the division of labor of the dorsal and ventral streams, studies in healthy individuals have shown how the interaction of them and the redundancy in the areas they connect allow for compensatory strategies in functions that are usually segregated. In this mini-review we highlight the need to examine compensatory mechanisms between streams in healthy individuals as a helpful guide to choosing the most appropriate rehabilitation strategies, using spared functions and targeting preserved compensatory networks for brain plasticity. PMID:29021751

Sensitivity to timing and order in human visual cortex.

PubMed

Singer, Jedediah M; Madsen, Joseph R; Anderson, William S; Kreiman, Gabriel

2015-03-01

Visual recognition takes a small fraction of a second and relies on the cascade of signals along the ventral visual stream. Given the rapid path through multiple processing steps between photoreceptors and higher visual areas, information must progress from stage to stage very quickly. This rapid progression of information suggests that fine temporal details of the neural response may be important to the brain's encoding of visual signals. We investigated how changes in the relative timing of incoming visual stimulation affect the representation of object information by recording intracranial field potentials along the human ventral visual stream while subjects recognized objects whose parts were presented with varying asynchrony. Visual responses along the ventral stream were sensitive to timing differences as small as 17 ms between parts. In particular, there was a strong dependency on the temporal order of stimulus presentation, even at short asynchronies. From these observations we infer that the neural representation of complex information in visual cortex can be modulated by rapid dynamics on scales of tens of milliseconds. Copyright © 2015 the American Physiological Society.

Ventral and dorsal streams processing visual motion perception (FDG-PET study)

PubMed Central

2012-01-01

Background Earlier functional imaging studies on visually induced self-motion perception (vection) disclosed a bilateral network of activations within primary and secondary visual cortex areas which was combined with signal decreases, i.e., deactivations, in multisensory vestibular cortex areas. This finding led to the concept of a reciprocal inhibitory interaction between the visual and vestibular systems. In order to define areas involved in special aspects of self-motion perception such as intensity and duration of the perceived circular vection (CV) or the amount of head tilt, correlation analyses of the regional cerebral glucose metabolism, rCGM (measured by fluorodeoxyglucose positron-emission tomography, FDG-PET) and these perceptual covariates were performed in 14 healthy volunteers. For analyses of the visual-vestibular interaction, the CV data were compared to a random dot motion stimulation condition (not inducing vection) and a control group at rest (no stimulation at all). Results Group subtraction analyses showed that the visual-vestibular interaction was modified during CV, i.e., the activations within the cerebellar vermis and parieto-occipital areas were enhanced. The correlation analysis between the rCGM and the intensity of visually induced vection, experienced as body tilt, showed a relationship for areas of the multisensory vestibular cortical network (inferior parietal lobule bilaterally, anterior cingulate gyrus), the medial parieto-occipital cortex, the frontal eye fields and the cerebellar vermis. The “earlier” multisensory vestibular areas like the parieto-insular vestibular cortex and the superior temporal gyrus did not appear in the latter analysis. The duration of perceived vection after stimulus stop was positively correlated with rCGM in medial temporal lobe areas bilaterally, which included the (para-)hippocampus, known to be involved in various aspects of memory processing. The amount of head tilt was found to be positively correlated with the rCGM of bilateral basal ganglia regions responsible for the control of motor function of the head. Conclusions Our data gave further insights into subfunctions within the complex cortical network involved in the processing of visual-vestibular interaction during CV. Specific areas of this cortical network could be attributed to the ventral stream (“what” pathway) responsible for the duration after stimulus stop and to the dorsal stream (“where/how” pathway) responsible for intensity aspects. PMID:22800430

Visuomotor Dissociation in Cerebral Scaling of Size.

PubMed

Potgieser, Adriaan R E; de Jong, Bauke M

2016-01-01

Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in which 16 right-handed subjects copied geometric figures while the result of drawing remained out of sight. Either the size of the example figure varied while maintaining a constant size of drawing (visual incongruity) or the size of the examples remained constant while subjects were instructed to make changes in size (motor incongruity). These incongruent were compared to congruent conditions. Statistical Parametric Mapping (SPM8) revealed brain activations related to size incongruity in the dorsolateral prefrontal and inferior parietal cortex, pre-SMA / anterior cingulate and anterior insula, dominant in the right hemisphere. This pattern represented simultaneous use of a 'resized' virtual template and actual picture information requiring spatial working memory, early-stage attention shifting and inhibitory control. Activations were strongest in motor incongruity while right pre-dorsal premotor activation specifically occurred in this condition. Visual incongruity additionally relied on a ventral visual pathway. Left ventral premotor activation occurred in all variably sized drawing while constant visuomotor size, compared to congruent size variation, uniquely activated the lateral occipital cortex additional to superior parietal regions. These results highlight size as a fundamental parameter in both general hand movement and movement guided by objects perceived in the context of surrounding 3D space.

Auditory and visual connectivity gradients in frontoparietal cortex

PubMed Central

Hellyer, Peter J.; Wise, Richard J. S.; Leech, Robert

2016-01-01

Abstract A frontoparietal network of brain regions is often implicated in both auditory and visual information processing. Although it is possible that the same set of multimodal regions subserves both modalities, there is increasing evidence that there is a differentiation of sensory function within frontoparietal cortex. Magnetic resonance imaging (MRI) in humans was used to investigate whether different frontoparietal regions showed intrinsic biases in connectivity with visual or auditory modalities. Structural connectivity was assessed with diffusion tractography and functional connectivity was tested using functional MRI. A dorsal–ventral gradient of function was observed, where connectivity with visual cortex dominates dorsal frontal and parietal connections, while connectivity with auditory cortex dominates ventral frontal and parietal regions. A gradient was also observed along the posterior–anterior axis, although in opposite directions in prefrontal and parietal cortices. The results suggest that the location of neural activity within frontoparietal cortex may be influenced by these intrinsic biases toward visual and auditory processing. Thus, the location of activity in frontoparietal cortex may be influenced as much by stimulus modality as the cognitive demands of a task. It was concluded that stimulus modality was spatially encoded throughout frontal and parietal cortices, and was speculated that such an arrangement allows for top–down modulation of modality‐specific information to occur within higher‐order cortex. This could provide a potentially faster and more efficient pathway by which top–down selection between sensory modalities could occur, by constraining modulations to within frontal and parietal regions, rather than long‐range connections to sensory cortices. Hum Brain Mapp 38:255–270, 2017. © 2016 Wiley Periodicals, Inc. PMID:27571304

Spatiotemporal dynamics of brain activity during the transition from visually guided to memory-guided force control

PubMed Central

Poon, Cynthia; Chin-Cottongim, Lisa G.; Coombes, Stephen A.; Corcos, Daniel M.

2012-01-01

It is well established that the prefrontal cortex is involved during memory-guided tasks whereas visually guided tasks are controlled in part by a frontal-parietal network. However, the nature of the transition from visually guided to memory-guided force control is not as well established. As such, this study examines the spatiotemporal pattern of brain activity that occurs during the transition from visually guided to memory-guided force control. We measured 128-channel scalp electroencephalography (EEG) in healthy individuals while they performed a grip force task. After visual feedback was removed, the first significant change in event-related activity occurred in the left central region by 300 ms, followed by changes in prefrontal cortex by 400 ms. Low-resolution electromagnetic tomography (LORETA) was used to localize the strongest activity to the left ventral premotor cortex and ventral prefrontal cortex. A second experiment altered visual feedback gain but did not require memory. In contrast to memory-guided force control, altering visual feedback gain did not lead to early changes in the left central and midline prefrontal regions. Decreasing the spatial amplitude of visual feedback did lead to changes in the midline central region by 300 ms, followed by changes in occipital activity by 400 ms. The findings show that subjects rely on sensorimotor memory processes involving left ventral premotor cortex and ventral prefrontal cortex after the immediate transition from visually guided to memory-guided force control. PMID:22696535

What and where information in the caudate tail guides saccades to visual objects

PubMed Central

Yamamoto, Shinya; Monosov, Ilya E.; Yasuda, Masaharu; Hikosaka, Okihide

2012-01-01

We understand the world by making saccadic eye movements to various objects. However, it is unclear how a saccade can be aimed at a particular object, because two kinds of visual information, what the object is and where it is, are processed separately in the dorsal and ventral visual cortical pathways. Here we provide evidence suggesting that a basal ganglia circuit through the tail of the monkey caudate nucleus (CDt) guides such object-directed saccades. First, many CDt neurons responded to visual objects depending on where and what the objects were. Second, electrical stimulation in the CDt induced saccades whose directions matched the preferred directions of neurons at the stimulation site. Third, many CDt neurons increased their activity before saccades directed to the neurons’ preferred objects and directions in a free-viewing condition. Our results suggest that CDt neurons receive both ‘what’ and ‘where’ information and guide saccades to visual objects. PMID:22875934

Functional dissociation between action and perception of object shape in developmental visual object agnosia.

PubMed

Freud, Erez; Ganel, Tzvi; Avidan, Galia; Gilaie-Dotan, Sharon

2016-03-01

According to the two visual systems model, the cortical visual system is segregated into a ventral pathway mediating object recognition, and a dorsal pathway mediating visuomotor control. In the present study we examined whether the visual control of action could develop normally even when visual perceptual abilities are compromised from early childhood onward. Using his fingers, LG, an individual with a rare developmental visual object agnosia, manually estimated (perceptual condition) the width of blocks that varied in width and length (but not in overall size), or simply picked them up across their width (grasping condition). LG's perceptual sensitivity to target width was profoundly impaired in the manual estimation task compared to matched controls. In contrast, the sensitivity to object shape during grasping, as measured by maximum grip aperture (MGA), the time to reach the MGA, the reaction time and the total movement time were all normal in LG. Further analysis, however, revealed that LG's sensitivity to object shape during grasping emerged at a later time stage during the movement compared to controls. Taken together, these results demonstrate a dissociation between action and perception of object shape, and also point to a distinction between different stages of the grasping movement, namely planning versus online control. Moreover, the present study implies that visuomotor abilities can develop normally even when perceptual abilities developed in a profoundly impaired fashion. Copyright © 2016 Elsevier Ltd. All rights reserved.

The neural circuitry of visual artistic production and appreciation: A proposition.

PubMed

Chakravarty, Ambar

2012-04-01

The nondominant inferior parietal lobule is probably a major "store house" of artistic creativity. The ventromedial prefrontal lobe (VMPFL) is supposed to be involved in creative cognition and the dorsolateral prefrontal lobe (DLPFL) in creative output. The conceptual ventral and dorsal visual system pathways likely represent the inferior and superior longitudinal fasciculi. During artistic production, conceptualization is conceived in the VMPFL and the executive part is operated through the DLFPL. The latter transfers the concept to the visual brain through the superior longitudinal fasciculus (SLF), relaying on its path to the parietal cortex. The conceptualization at VMPFL is influenced by activity from the anterior temporal lobe through the uncinate fasciculus and limbic system pathways. The final visual image formed in the visual brain is subsequently transferred back to the DLPFL through the SLF and then handed over to the motor cortex for execution. During art appreciation, the image at the visual brain is transferred to the frontal lobe through the SLF and there it is matched with emotional and memory inputs from the anterior temporal lobe transmitted through the uncinate fasiculus. Beauty is perceived at the VMPFL and transferred through the uncinate fasciculus to the hippocampo-amygdaloid complex in the anterior temporal lobe. The limbic system (Papez circuit) is activated and emotion of appreciation is evoked. It is postulated that in practice the entire circuitry is activated simultaneously.

The neural circuitry of visual artistic production and appreciation: A proposition

PubMed Central

Chakravarty, Ambar

2012-01-01

The nondominant inferior parietal lobule is probably a major “store house” of artistic creativity. The ventromedial prefrontal lobe (VMPFL) is supposed to be involved in creative cognition and the dorsolateral prefrontal lobe (DLPFL) in creative output. The conceptual ventral and dorsal visual system pathways likely represent the inferior and superior longitudinal fasciculi. During artistic production, conceptualization is conceived in the VMPFL and the executive part is operated through the DLFPL. The latter transfers the concept to the visual brain through the superior longitudinal fasciculus (SLF), relaying on its path to the parietal cortex. The conceptualization at VMPFL is influenced by activity from the anterior temporal lobe through the uncinate fasciculus and limbic system pathways. The final visual image formed in the visual brain is subsequently transferred back to the DLPFL through the SLF and then handed over to the motor cortex for execution. During art appreciation, the image at the visual brain is transferred to the frontal lobe through the SLF and there it is matched with emotional and memory inputs from the anterior temporal lobe transmitted through the uncinate fasiculus. Beauty is perceived at the VMPFL and transferred through the uncinate fasciculus to the hippocampo–amygdaloid complex in the anterior temporal lobe. The limbic system (Papez circuit) is activated and emotion of appreciation is evoked. It is postulated that in practice the entire circuitry is activated simultaneously. PMID:22566716

Visual pathways from the perspective of cost functions and multi-task deep neural networks.

PubMed

Scholte, H Steven; Losch, Max M; Ramakrishnan, Kandan; de Haan, Edward H F; Bohte, Sander M

2018-01-01

Vision research has been shaped by the seminal insight that we can understand the higher-tier visual cortex from the perspective of multiple functional pathways with different goals. In this paper, we try to give a computational account of the functional organization of this system by reasoning from the perspective of multi-task deep neural networks. Machine learning has shown that tasks become easier to solve when they are decomposed into subtasks with their own cost function. We hypothesize that the visual system optimizes multiple cost functions of unrelated tasks and this causes the emergence of a ventral pathway dedicated to vision for perception, and a dorsal pathway dedicated to vision for action. To evaluate the functional organization in multi-task deep neural networks, we propose a method that measures the contribution of a unit towards each task, applying it to two networks that have been trained on either two related or two unrelated tasks, using an identical stimulus set. Results show that the network trained on the unrelated tasks shows a decreasing degree of feature representation sharing towards higher-tier layers while the network trained on related tasks uniformly shows high degree of sharing. We conjecture that the method we propose can be used to analyze the anatomical and functional organization of the visual system and beyond. We predict that the degree to which tasks are related is a good descriptor of the degree to which they share downstream cortical-units. Copyright © 2017 Elsevier Ltd. All rights reserved.

Learning to See Words

PubMed Central

2011-01-01

Skilled reading requires recognizing written words rapidly; functional neuroimaging research has clarified how the written word initiates a series of responses in visual cortex. These responses are communicated to circuits in ventral occipitotemporal (VOT) cortex that learn to identify words rapidly. Structural neuroimaging has further clarified aspects of the white matter pathways that communicate reading signals between VOT and language systems. We review this circuitry, its development, and its deficiencies in poor readers. This review emphasizes data that measure the cortical responses and white matter pathways in individual subjects rather than group differences. Such methods have the potential to clarify why a child has difficulty learning to read and to offer guidance about the interventions that may be useful for that child. PMID:21801018

Acute adaptation of the vestibuloocular reflex: signal processing by floccular and ventral parafloccular Purkinje cells.

PubMed

Hirata, Y; Highstein, S M

2001-05-01

The gain of the vertical vestibuloocular reflex (VVOR), defined as eye velocity/head velocity was adapted in squirrel monkeys by employing visual-vestibular mismatch stimuli. VVOR gain, measured in the dark, could be trained to values between 0.4 and 1.5. Single-unit activity of vertical zone Purkinje cells was recorded from the flocculus and ventral paraflocculus in alert squirrel monkeys before and during the gain change training. Our goal was to evaluate the site(s) of learning of the gain change. To aid in the evaluation, a model of the vertical optokinetic reflex (VOKR) and VVOR was constructed consisting of floccular and nonfloccular systems divided into subsystems based on the known anatomy and input and output parameters. Three kinds of input to floccular Purkinje cells via mossy fibers were explicitly described, namely vestibular, visual (retinal slip), and efference copy of eye movement. The characteristics of each subsystem (gain and phase) were identified at different VOR gains by reconstructing single-unit activity of Purkinje cells during VOKR and VVOR with multiple linear regression models consisting of sensory input and motor output signals. Model adequacy was checked by evaluating the residual following the regressions and by predicting Purkinje cells' activity during visual-vestibular mismatch paradigms. As a result, parallel changes in identified characteristics with VVOR adaptation were found in the prefloccular/floccular subsystem that conveys vestibular signals and in the nonfloccular subsystem that conveys vestibular signals, while no change was found in other subsystems, namely prefloccular/floccular subsystems conveying efference copy or visual signals, nonfloccular subsystem conveying visual signals, and postfloccular subsystem transforming Purkinje cell activity to eye movements. The result suggests multiple sites for VVOR motor learning including both flocculus and nonflocculus pathways. The gain change in the nonfloccular vestibular subsystem was in the correct direction to cause VOR gain adaptation while the change in the prefloccular/floccular vestibular subsystem was incorrect (anti-compensatory). This apparent incorrect directional change might serve to prevent instability of the VOR caused by positive feedback via the efference copy pathway.

[Symptoms and lesion localization in visual agnosia].

PubMed

Suzuki, Kyoko

2004-11-01

There are two cortical visual processing streams, the ventral and dorsal stream. The ventral visual stream plays the major role in constructing our perceptual representation of the visual world and the objects within it. Disturbance of visual processing at any stage of the ventral stream could result in impairment of visual recognition. Thus we need systematic investigations to diagnose visual agnosia and its type. Two types of category-selective visual agnosia, prosopagnosia and landmark agnosia, are different from others in that patients could recognize a face as a face and buildings as buildings, but could not identify an individual person or building. Neuronal bases of prosopagnosia and landmark agnosia are distinct. Importance of the right fusiform gyrus for face recognition was confirmed by both clinical and neuroimaging studies. Landmark agnosia is related to lesions in the right parahippocampal gyrus. Enlarged lesions including both the right fusiform and parahippocampal gyri can result in prosopagnosia and landmark agnosia at the same time. Category non-selective visual agnosia is related to bilateral occipito-temporal lesions, which is in agreement with the results of neuroimaging studies that revealed activation of the bilateral occipito-temporal during object recognition tasks.

Ventral Fronto-Temporal Pathway Supporting Cognitive Control of Episodic Memory Retrieval

PubMed Central

Barredo, Jennifer; Öztekin, Ilke; Badre, David

2015-01-01

Achieving our goals often requires guiding access to relevant information from memory. Such goal-directed retrieval requires interactions between systems supporting cognitive control, including ventrolateral prefrontal cortex (VLPFC), and those supporting declarative memory, such as the medial temporal lobes (MTL). However, the pathways by which VLPFC interacts with MTL during retrieval are underspecified. Prior neuroanatomical evidence suggests that a polysynaptic ventral fronto-temporal pathway may support VLPFC–MTL interactions. To test this hypothesis, human participants were scanned using fMRI during performance of a source-monitoring task. The strength of source information was varied via repetition during encoding. Single encoding events should produce a weaker memory trace, thus recovering source information about these items should demand greater cognitive control. Results demonstrated that cortical targets along the ventral path—anterior VLPFC, temporal pole, anterior parahippocampus, and hippocampus—exhibited increases in univariate BOLD response correlated with increases in controlled retrieval demand, independent of factors related to response selection. Further, a functional connectivity analysis indicated that these regions functionally couple and are distinguishable from a dorsal pathway related to response selection demands. These data support a ventral retrieval pathway linking PFC and MTL. PMID:24177990

Variation in White Matter Connectivity Predicts the Ability to Remember Faces and Discriminate Their Emotions

PubMed Central

Unger, Ashley; Alm, Kylie H.; Collins, Jessica A.; O’Leary, Jacqueline M.; Olson, Ingrid R.

2017-01-01

Objective The extended face network contains clusters of neurons that perform distinct functions on facial stimuli. Regions in the posterior ventral visual stream appear to perform basic perceptual functions on faces, while more anterior regions, such as the ventral anterior temporal lobe and amygdala, function to link mnemonic and affective information to faces. Anterior and posterior regions are interconnected by a long-range white matter tracts however it is not known if variation in connectivity of these pathways explains cognitive performance. Methods Here, we used diffusion imaging and deterministic tractography in a cohort of 28 neurologically normal adults ages 18–28 to examine microstructural properties of visual fiber pathways and their relationship to certain mnemonic and affective functions involved in face processing. We investigated how inter-individual variability in two tracts, the inferior longitudinal fasciculus (ILF) and the inferior fronto-occipital fasciculus (IFOF), related to performance on tests of facial emotion recognition and face memory. Results Results revealed that microstructure of both tracts predicted variability in behavioral performance indexed by both tasks, suggesting that the ILF and IFOF play a role in facilitating our ability to discriminate emotional expressions in faces, as well as to remember unique faces. Variation in a control tract, the uncinate fasciculus, did not predict performance on these tasks. Conclusions These results corroborate and extend the findings of previous neuropsychology studies investigating the effects of damage to the ILF and IFOF, and demonstrate that differences in face processing abilities are related to white matter microstructure, even in healthy individuals. PMID:26888615

Threat as a feature in visual semantic object memory.

PubMed

Calley, Clifford S; Motes, Michael A; Chiang, H-Sheng; Buhl, Virginia; Spence, Jeffrey S; Abdi, Hervé; Anand, Raksha; Maguire, Mandy; Estevez, Leonardo; Briggs, Richard; Freeman, Thomas; Kraut, Michael A; Hart, John

2013-08-01

Threatening stimuli have been found to modulate visual processes related to perception and attention. The present functional magnetic resonance imaging (fMRI) study investigated whether threat modulates visual object recognition of man-made and naturally occurring categories of stimuli. Compared with nonthreatening pictures, threatening pictures of real items elicited larger fMRI BOLD signal changes in medial visual cortices extending inferiorly into the temporo-occipital (TO) "what" pathways. This region elicited greater signal changes for threatening items compared to nonthreatening from both the natural-occurring and man-made stimulus supraordinate categories, demonstrating a featural component to these visual processing areas. Two additional loci of signal changes within more lateral inferior TO areas (bilateral BA18 and 19 as well as the right ventral temporal lobe) were detected for a category-feature interaction, with stronger responses to man-made (category) threatening (feature) stimuli than to natural threats. The findings are discussed in terms of visual recognition of processing efficiently or rapidly groups of items that confer an advantage for survival. Copyright © 2012 Wiley Periodicals, Inc.

The neural basis of visual word form processing: a multivariate investigation.

PubMed

Nestor, Adrian; Behrmann, Marlene; Plaut, David C

2013-07-01

Current research on the neurobiological bases of reading points to the privileged role of a ventral cortical network in visual word processing. However, the properties of this network and, in particular, its selectivity for orthographic stimuli such as words and pseudowords remain topics of significant debate. Here, we approached this issue from a novel perspective by applying pattern-based analyses to functional magnetic resonance imaging data. Specifically, we examined whether, where and how, orthographic stimuli elicit distinct patterns of activation in the human cortex. First, at the category level, multivariate mapping found extensive sensitivity throughout the ventral cortex for words relative to false-font strings. Secondly, at the identity level, the multi-voxel pattern classification provided direct evidence that different pseudowords are encoded by distinct neural patterns. Thirdly, a comparison of pseudoword and face identification revealed that both stimulus types exploit common neural resources within the ventral cortical network. These results provide novel evidence regarding the involvement of the left ventral cortex in orthographic stimulus processing and shed light on its selectivity and discriminability profile. In particular, our findings support the existence of sublexical orthographic representations within the left ventral cortex while arguing for the continuity of reading with other visual recognition skills.

Spatiotemporal dynamics underlying object completion in human ventral visual cortex.

PubMed

Tang, Hanlin; Buia, Calin; Madhavan, Radhika; Crone, Nathan E; Madsen, Joseph R; Anderson, William S; Kreiman, Gabriel

2014-08-06

Natural vision often involves recognizing objects from partial information. Recognition of objects from parts presents a significant challenge for theories of vision because it requires spatial integration and extrapolation from prior knowledge. Here we recorded intracranial field potentials of 113 visually selective electrodes from epilepsy patients in response to whole and partial objects. Responses along the ventral visual stream, particularly the inferior occipital and fusiform gyri, remained selective despite showing only 9%-25% of the object areas. However, these visually selective signals emerged ∼100 ms later for partial versus whole objects. These processing delays were particularly pronounced in higher visual areas within the ventral stream. This latency difference persisted when controlling for changes in contrast, signal amplitude, and the strength of selectivity. These results argue against a purely feedforward explanation of recognition from partial information, and provide spatiotemporal constraints on theories of object recognition that involve recurrent processing. Copyright © 2014 Elsevier Inc. All rights reserved.

From attentional gating in macaque primary visual cortex to dyslexia in humans.

PubMed

Vidyasagar, T R

2001-01-01

Selective attention is an important aspect of brain function that we need in coping with the immense and constant barrage of sensory information. One model of attention (Feature Integration Theory) that suggests an early selection of spatial locations of objects via an attentional spotlight would also solve the 'binding problem' (that is how do different attributes of each object get correctly bound together?). Our experiments have demonstrated modulation of specific locations of interest at the level of the primary visual cortex both in visual discrimination and memory tasks, where the actual locations of the targets was also important in being able to perform the task. It is suggested that the feedback mediating the modulation arises from the posterior parietal cortex, which would also be consistent with its known role in attentional control. In primates, the magnocellular (M) and parvocellular (P) pathways are the two major streams of inputs from the retina, carrying distinctly different types of information and they remain fairly segregated in their projections to the primary visual cortex and further into the extra-striate regions. The P inputs go mainly into the ventral (temporal) stream, while the dorsal (parietal) stream is dominated by M inputs. A theory of attentional gating is proposed here where the M dominated dorsal stream gates the P inputs into the ventral stream. This framework is used to provide a neural explanation of the processes involved in reading and in learning to read. This scheme also explains how a magnocellular deficit could cause the common reading impairment, dyslexia.

Bilateral Theta-Burst TMS to Influence Global Gestalt Perception

PubMed Central

Ritzinger, Bernd; Huberle, Elisabeth; Karnath, Hans-Otto

2012-01-01

While early and higher visual areas along the ventral visual pathway in the inferotemporal cortex are critical for the recognition of individual objects, the neural representation of human perception of complex global visual scenes remains under debate. Stroke patients with a selective deficit in the perception of a complex global Gestalt with intact recognition of individual objects – a deficit termed simultanagnosia – greatly helped to study this question. Interestingly, simultanagnosia typically results from bilateral lesions of the temporo-parietal junction (TPJ). The present study aimed to verify the relevance of this area for human global Gestalt perception. We applied continuous theta-burst TMS either unilaterally (left or right) or bilateral simultaneously over TPJ. Healthy subjects were presented with hierarchically organized visual stimuli that allowed parametrical degrading of the object at the global level. Identification of the global Gestalt was significantly modulated only for the bilateral TPJ stimulation condition. Our results strengthen the view that global Gestalt perception in the human brain involves TPJ and is co-dependent on both hemispheres. PMID:23110106

Bilateral theta-burst TMS to influence global gestalt perception.

PubMed

Ritzinger, Bernd; Huberle, Elisabeth; Karnath, Hans-Otto

2012-01-01

While early and higher visual areas along the ventral visual pathway in the inferotemporal cortex are critical for the recognition of individual objects, the neural representation of human perception of complex global visual scenes remains under debate. Stroke patients with a selective deficit in the perception of a complex global Gestalt with intact recognition of individual objects - a deficit termed simultanagnosia - greatly helped to study this question. Interestingly, simultanagnosia typically results from bilateral lesions of the temporo-parietal junction (TPJ). The present study aimed to verify the relevance of this area for human global Gestalt perception. We applied continuous theta-burst TMS either unilaterally (left or right) or bilateral simultaneously over TPJ. Healthy subjects were presented with hierarchically organized visual stimuli that allowed parametrical degrading of the object at the global level. Identification of the global Gestalt was significantly modulated only for the bilateral TPJ stimulation condition. Our results strengthen the view that global Gestalt perception in the human brain involves TPJ and is co-dependent on both hemispheres.

Experimental performance of three design factors for ventral nozzles for SSTOVL aircraft

NASA Technical Reports Server (NTRS)

Esker, Barbara S.; Perusek, Gail P.

1992-01-01

An experimental study of three variations of a ventral nozzle system for supersonic short-takeoff and vertical-landing (SSTOVL) aircraft was performed at the NASA LeRC Powered Lift Facility. These test results include the effects of an annular duct flow into the ventral duct, a blocked tailpipe, and a short ventral duct length. An analytical study was also performed on the short ventral duct configuration using the PARC3D computational dynamics code. Data presented include pressure losses, thrust and flow performance, internal flow visualization, and pressure distributions at the exit plane of the ventral nozzle.

Interactions between dorsal and ventral streams for controlling skilled grasp

PubMed Central

van Polanen, Vonne; Davare, Marco

2015-01-01

The two visual systems hypothesis suggests processing of visual information into two distinct routes in the brain: a dorsal stream for the control of actions and a ventral stream for the identification of objects. Recently, increasing evidence has shown that the dorsal and ventral streams are not strictly independent, but do interact with each other. In this paper, we argue that the interactions between dorsal and ventral streams are important for controlling complex object-oriented hand movements, especially skilled grasp. Anatomical studies have reported the existence of direct connections between dorsal and ventral stream areas. These physiological interconnections appear to be gradually more active as the precision demands of the grasp become higher. It is hypothesised that the dorsal stream needs to retrieve detailed information about object identity, stored in ventral stream areas, when the object properties require complex fine-tuning of the grasp. In turn, the ventral stream might receive up to date grasp-related information from dorsal stream areas to refine the object internal representation. Future research will provide direct evidence for which specific areas of the two streams interact, the timing of their interactions and in which behavioural context they occur. PMID:26169317

Do Object-Category Selective Regions in the Ventral Visual Stream Represent Perceived Distance Information?

ERIC Educational Resources Information Center

Amit, Elinor; Mehoudar, Eyal; Trope, Yaacov; Yovel, Galit

2012-01-01

It is well established that scenes and objects elicit a highly selective response in specific brain regions in the ventral visual cortex. An inherent difference between these categories that has not been explored yet is their perceived distance from the observer (i.e. scenes are distal whereas objects are proximal). The current study aimed to test…

How Visual Is the Visual Cortex? Comparing Connectional and Functional Fingerprints between Congenitally Blind and Sighted Individuals.

PubMed

Wang, Xiaoying; Peelen, Marius V; Han, Zaizhu; He, Chenxi; Caramazza, Alfonso; Bi, Yanchao

2015-09-09

Classical animal visual deprivation studies and human neuroimaging studies have shown that visual experience plays a critical role in shaping the functionality and connectivity of the visual cortex. Interestingly, recent studies have additionally reported circumscribed regions in the visual cortex in which functional selectivity was remarkably similar in individuals with and without visual experience. Here, by directly comparing resting-state and task-based fMRI data in congenitally blind and sighted human subjects, we obtained large-scale continuous maps of the degree to which connectional and functional "fingerprints" of ventral visual cortex depend on visual experience. We found a close agreement between connectional and functional maps, pointing to a strong interdependence of connectivity and function. Visual experience (or the absence thereof) had a pronounced effect on the resting-state connectivity and functional response profile of occipital cortex and the posterior lateral fusiform gyrus. By contrast, connectional and functional fingerprints in the anterior medial and posterior lateral parts of the ventral visual cortex were statistically indistinguishable between blind and sighted individuals. These results provide a large-scale mapping of the influence of visual experience on the development of both functional and connectivity properties of visual cortex, which serves as a basis for the formulation of new hypotheses regarding the functionality and plasticity of specific subregions. Significance statement: How is the functionality and connectivity of the visual cortex shaped by visual experience? By directly comparing resting-state and task-based fMRI data in congenitally blind and sighted subjects, we obtained large-scale continuous maps of the degree to which connectional and functional "fingerprints" of ventral visual cortex depend on visual experience. In addition to revealing regions that are strongly dependent on visual experience (early visual cortex and posterior fusiform gyrus), our results showed regions in which connectional and functional patterns are highly similar in blind and sighted individuals (anterior medial and posterior lateral ventral occipital temporal cortex). These results serve as a basis for the formulation of new hypotheses regarding the functionality and plasticity of specific subregions of the visual cortex. Copyright © 2015 the authors 0270-6474/15/3512545-15$15.00/0.

Evolution and Optimality of Similar Neural Mechanisms for Perception and Action during Search

PubMed Central

Zhang, Sheng; Eckstein, Miguel P.

2010-01-01

A prevailing theory proposes that the brain's two visual pathways, the ventral and dorsal, lead to differing visual processing and world representations for conscious perception than those for action. Others have claimed that perception and action share much of their visual processing. But which of these two neural architectures is favored by evolution? Successful visual search is life-critical and here we investigate the evolution and optimality of neural mechanisms mediating perception and eye movement actions for visual search in natural images. We implement an approximation to the ideal Bayesian searcher with two separate processing streams, one controlling the eye movements and the other stream determining the perceptual search decisions. We virtually evolved the neural mechanisms of the searchers' two separate pathways built from linear combinations of primary visual cortex receptive fields (V1) by making the simulated individuals' probability of survival depend on the perceptual accuracy finding targets in cluttered backgrounds. We find that for a variety of targets, backgrounds, and dependence of target detectability on retinal eccentricity, the mechanisms of the searchers' two processing streams converge to similar representations showing that mismatches in the mechanisms for perception and eye movements lead to suboptimal search. Three exceptions which resulted in partial or no convergence were a case of an organism for which the targets are equally detectable across the retina, an organism with sufficient time to foveate all possible target locations, and a strict two-pathway model with no interconnections and differential pre-filtering based on parvocellular and magnocellular lateral geniculate cell properties. Thus, similar neural mechanisms for perception and eye movement actions during search are optimal and should be expected from the effects of natural selection on an organism with limited time to search for food that is not equi-detectable across its retina and interconnected perception and action neural pathways. PMID:20838589

Neuronal connections of direct and indirect pathways for stable value memory in caudal basal ganglia.

PubMed

Amita, Hidetoshi; Kim, Hyoung F; Smith, Mitchell; Gopal, Atul; Hikosaka, Okihide

2018-05-08

Direct and indirect pathways in the basal ganglia work together for controlling behavior. However, it is still a controversial topic whether these pathways are segregated or merged with each other. To address this issue, we studied the connections of these two pathways in the caudal parts of the basal ganglia of rhesus monkeys using anatomical tracers. Our previous studies showed that the caudal basal ganglia control saccades by conveying long-term values (stable values) of many visual objects toward the superior colliculus. In experiment 1, we injected a tracer in the caudate tail (CDt), and found local dense plexuses of axon terminals in the caudal-dorsal-lateral part of substantia nigra pars reticulata (cdlSNr) and the caudal-ventral part of globus pallidus externus (cvGPe). These anterograde projections may correspond to the direct and indirect pathways, respectively. To verify this in experiment 2, we injected different tracers into cdlSNr and cvGPe, and found many retrogradely labeled neurons in CDt and, in addition, the caudal-ventral part of the putamen (cvPut). These cdlSNr-projecting and cvGPe-projecting neurons were found intermingled in both CDt and cvPut (which we call 'striatum tail'). A small but significant proportion of neurons (< 15%) were double-labeled, indicating that they projected to both cdlSNr and cvGPe. These anatomical results suggest that stable value signals (good vs. bad) are sent from the striatum tail to cdlSNr and cvGPe in a biased (but not exclusive) manner. These connections may play an important role in biasing saccades toward higher-valued objects and away from lower-valued objects. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Early White-Matter Abnormalities of the Ventral Frontostriatal Pathway in Fragile X Syndrome

ERIC Educational Resources Information Center

Haas, Brian W.; Barnea-Goraly, Naama; Lightbody, Amy A.; Patnaik, Swetapadma S.; Hoeft, Fumiko; Hazlett, Heather; Piven, Joseph; Reiss, Allan L.

2009-01-01

Aim: Fragile X syndrome is associated with cognitive deficits in inhibitory control and with abnormal neuronal morphology and development. Method: In this study, we used a diffusion tensor imaging (DTI) tractography approach to reconstruct white-matter fibers in the ventral frontostriatal pathway in young males with fragile X syndrome (n = 17;…

Symbol processing in the left angular gyrus: evidence from passive perception of digits.

PubMed

Price, Gavin R; Ansari, Daniel

2011-08-01

Arabic digits are one of the most ubiquitous symbol sets in the world. While there have been many investigations into the neural processing of the semantic information digits represent (e.g. through numerical comparison tasks), little is known about the neural mechanisms which support the processing of digits as visual symbols. To characterise the component neurocognitive mechanisms which underlie numerical cognition, it is essential to understand the processing of digits as a visual category, independent of numerical magnitude processing. The 'Triple Code Model' (Dehaene, 1992; Dehaene and Cohen, 1995) posits an asemantic visual code for processing Arabic digits in the ventral visual stream, yet there is currently little empirical evidence in support of this code. This outstanding question was addressed in the current functional Magnetic Resonance (fMRI) study by contrasting brain responses during the passive viewing of digits versus letters and novel symbols at short (50 ms) and long (500 ms) presentation times. The results of this study reveal increased activation for familiar symbols (digits and letters) relative to unfamiliar symbols (scrambled digits and letters) at long presentation durations in the left dorsal Angular gyrus (dAG). Furthermore, increased activation for Arabic digits was observed in the left ventral Angular gyrus (vAG) in comparison to letters, scrambled digits and scrambled letters at long presentation durations, but no digit specific activation in any region at short presentation durations. These results suggest an absence of a digit specific 'Visual Number Form Area' (VNFA) in the ventral visual cortex, and provide evidence for the role of the left ventral AG during the processing of digits in the absence of any explicit processing demands. We conclude that Arabic digit processing depends specifically on the left AG rather than a ventral visual stream VNFA. Copyright © 2011 Elsevier Inc. All rights reserved.

Neural organization of ventral white matter tracts parallels the initial steps of reading development: A DTI tractography study.

PubMed

Vanderauwera, Jolijn; De Vos, Astrid; Forkel, Stephanie J; Catani, Marco; Wouters, Jan; Vandermosten, Maaike; Ghesquière, Pol

2018-05-18

Insight in the developmental trajectory of the neuroanatomical reading correlates is important to understand related cognitive processes and disorders. In adults, a dual pathway model has been suggested encompassing a dorsal phonological and a ventral orthographic white matter system. This dichotomy seems not present in pre-readers, and the specific role of ventral white matter in reading remains unclear. Therefore, the present longitudinal study investigated the relation between ventral white matter and cognitive processes underlying reading in children with a broad range of reading skills (n = 61). Ventral pathways of the reading network were manually traced using diffusion tractography: the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF). Pathways were examined pre-reading (5-6 years) and after two years of reading acquisition (7-8 years). Dimension reduction for the cognitive measures resulted in one component for pre-reading cognitive measures and a separate phonological and orthographic component for the early reading measures. Regression analyses revealed a relation between the pre-reading cognitive component and bilateral IFOF and left ILF. Interestingly, exclusively the left IFOF was related to the orthographic component, whereas none of the pathways was related to the phonological component. Hence, the left IFOF seems to serve as the lexical reading route, already in the earliest reading stages. Copyright © 2018 Elsevier Inc. All rights reserved.

Exploration of complex visual feature spaces for object perception

PubMed Central

Leeds, Daniel D.; Pyles, John A.; Tarr, Michael J.

2014-01-01

The mid- and high-level visual properties supporting object perception in the ventral visual pathway are poorly understood. In the absence of well-specified theory, many groups have adopted a data-driven approach in which they progressively interrogate neural units to establish each unit's selectivity. Such methods are challenging in that they require search through a wide space of feature models and stimuli using a limited number of samples. To more rapidly identify higher-level features underlying human cortical object perception, we implemented a novel functional magnetic resonance imaging method in which visual stimuli are selected in real-time based on BOLD responses to recently shown stimuli. This work was inspired by earlier primate physiology work, in which neural selectivity for mid-level features in IT was characterized using a simple parametric approach (Hung et al., 2012). To extend such work to human neuroimaging, we used natural and synthetic object stimuli embedded in feature spaces constructed on the basis of the complex visual properties of the objects themselves. During fMRI scanning, we employed a real-time search method to control continuous stimulus selection within each image space. This search was designed to maximize neural responses across a pre-determined 1 cm3 brain region within ventral cortex. To assess the value of this method for understanding object encoding, we examined both the behavior of the method itself and the complex visual properties the method identified as reliably activating selected brain regions. We observed: (1) Regions selective for both holistic and component object features and for a variety of surface properties; (2) Object stimulus pairs near one another in feature space that produce responses at the opposite extremes of the measured activity range. Together, these results suggest that real-time fMRI methods may yield more widely informative measures of selectivity within the broad classes of visual features associated with cortical object representation. PMID:25309408

Cerebral activations related to writing and drawing with each hand.

PubMed

Potgieser, Adriaan R E; van der Hoorn, Anouk; de Jong, Bauke M

2015-01-01

Writing is a sequential motor action based on sensorimotor integration in visuospatial and linguistic functional domains. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand. In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing. Sixteen healthy right-handed subjects were scanned during audition-guided writing of short sentences and simple figure drawing without visual feedback. Tapping with a pencil served as a basic control task for the two higher-order motor conditions. Activation differences were assessed with Statistical Parametric Mapping (SPM). Writing and drawing showed parietal-premotor and posterior inferior temporal activations in both hemispheres when compared to tapping. Drawing activations were rather symmetrical for each hand. Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of particularly the right hemisphere. Writing contrasted to drawing revealed left-sided activations in the dorsal and ventral premotor cortex, Broca's area, pre-Supplementary Motor Area and posterior middle and inferior temporal gyri, without parietal activation. The audition-driven postero-inferior temporal activations indicated retrieval of virtual visual form characteristics in writing and drawing, with additional activation concerning word form in the left hemisphere. Similar parietal processing in writing and drawing pointed at a common mechanism by which such visually formatted information is used for subsequent sensorimotor integration along a dorsal visuomotor pathway. In this, the left posterior middle temporal gyrus subserves phonological-orthographical conversion, dissociating dorsal parietal-premotor circuitry from perisylvian circuitry including Broca's area.

Cerebral Activations Related to Writing and Drawing with Each Hand

PubMed Central

Potgieser, Adriaan R. E.; van der Hoorn, Anouk; de Jong, Bauke M.

2015-01-01

Background Writing is a sequential motor action based on sensorimotor integration in visuospatial and linguistic functional domains. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand. In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing. Methods Sixteen healthy right-handed subjects were scanned during audition-guided writing of short sentences and simple figure drawing without visual feedback. Tapping with a pencil served as a basic control task for the two higher-order motor conditions. Activation differences were assessed with Statistical Parametric Mapping (SPM). Results Writing and drawing showed parietal-premotor and posterior inferior temporal activations in both hemispheres when compared to tapping. Drawing activations were rather symmetrical for each hand. Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of particularly the right hemisphere. Writing contrasted to drawing revealed left-sided activations in the dorsal and ventral premotor cortex, Broca’s area, pre-Supplementary Motor Area and posterior middle and inferior temporal gyri, without parietal activation. Discussion The audition-driven postero-inferior temporal activations indicated retrieval of virtual visual form characteristics in writing and drawing, with additional activation concerning word form in the left hemisphere. Similar parietal processing in writing and drawing pointed at a common mechanism by which such visually formatted information is used for subsequent sensorimotor integration along a dorsal visuomotor pathway. In this, the left posterior middle temporal gyrus subserves phonological-orthographical conversion, dissociating dorsal parietal-premotor circuitry from perisylvian circuitry including Broca's area. PMID:25955655

Intrinsic Connections of the Core Auditory Cortical Regions and Rostral Supratemporal Plane in the Macaque Monkey

PubMed Central

Scott, Brian H.; Leccese, Paul A.; Saleem, Kadharbatcha S.; Kikuchi, Yukiko; Mullarkey, Matthew P.; Fukushima, Makoto; Mishkin, Mortimer; Saunders, Richard C.

2017-01-01

Abstract In the ventral stream of the primate auditory cortex, cortico-cortical projections emanate from the primary auditory cortex (AI) along 2 principal axes: one mediolateral, the other caudorostral. Connections in the mediolateral direction from core, to belt, to parabelt, have been well described, but less is known about the flow of information along the supratemporal plane (STP) in the caudorostral dimension. Neuroanatomical tracers were injected throughout the caudorostral extent of the auditory core and rostral STP by direct visualization of the cortical surface. Auditory cortical areas were distinguished by SMI-32 immunostaining for neurofilament, in addition to established cytoarchitectonic criteria. The results describe a pathway comprising step-wise projections from AI through the rostral and rostrotemporal fields of the core (R and RT), continuing to the recently identified rostrotemporal polar field (RTp) and the dorsal temporal pole. Each area was strongly and reciprocally connected with the areas immediately caudal and rostral to it, though deviations from strictly serial connectivity were observed. In RTp, inputs converged from core, belt, parabelt, and the auditory thalamus, as well as higher order cortical regions. The results support a rostrally directed flow of auditory information with complex and recurrent connections, similar to the ventral stream of macaque visual cortex. PMID:26620266

White matter anisotropy in the ventral language pathway predicts sound-to-word learning success

PubMed Central

Wong, Francis C. K.; Chandrasekaran, Bharath; Garibaldi, Kyla; Wong, Patrick C. M.

2011-01-01

According to the dual stream model of auditory language processing, the dorsal stream is responsible for mapping sound to articulation while the ventral stream plays the role of mapping sound to meaning. Most researchers agree that the arcuate fasciculus (AF) is the neuroanatomical correlate of the dorsal steam, however, less is known about what constitutes the ventral one. Nevertheless two hypotheses exist, one suggests that the segment of the AF that terminates in middle temporal gyrus corresponds to the ventral stream and the other suggests that it is the extreme capsule that underlies this sound to meaning pathway. The goal of this study is to evaluate these two competing hypotheses. We trained participants with a sound-to-word learning paradigm in which they learned to use a foreign phonetic contrast for signaling word meaning. Using diffusion tensor imaging (DTI), a brain imaging tool to investigate white matter connectivity in humans, we found that fractional anisotropy in the left parietal-temporal region positively correlated with the performance in sound-to-word learning. In addition, fiber tracking revealed a ventral pathway, composed of the extreme capsule and the inferior longitudinal fasciculus, that mediated auditory comprehension. Our findings provide converging evidence supporting the importance of the ventral steam, an extreme capsule system, in the frontal-temporal language network. Implications for current models of speech processing will also be discussed. PMID:21677162

Altered structure-function relations of semantic processing in youths with high-functioning autism: a combined diffusion and functional MRI study.

PubMed

Lo, Yu-Chun; Chou, Tai-Li; Fan, Li-Ying; Gau, Susan Shur-Fen; Chiu, Yen-Nan; Tseng, Wen-Yih Isaac

2013-12-01

Deficits in language and communication are among the core symptoms of autism, a common neurodevelopmental disorder with long-term impairment. Despite the striking nature of the autistic language impairment, knowledge about its corresponding alterations in the brain is still evolving. We hypothesized that the dual stream language network is altered in autism, and that this alteration could be revealed by changes in the relationships between microstructural integrity and functional activation. The study recruited 20 right-handed male youths with autism and 20 carefully matched individually, typically developing (TD) youths. Microstructural integrity of the left dorsal and left ventral pathways responsible for language processing and the functional activation of the connected brain regions were investigated by using diffusion spectrum imaging and functional magnetic resonance imaging of a semantic task, respectively. Youths with autism had significantly poorer language function, and lower functional activation in left dorsal and left ventral regions of the language network, compared with TD youths. The TD group showed a significant correlation of the functional activation of the left dorsal region with microstructural integrity of the left ventral pathway, whereas the autism group showed a significant correlation of the functional activation of the left ventral region with microstructural integrity of the left dorsal pathway, and moreover verbal comprehension index was correlated with microstructural integrity of the left ventral pathway. These altered structure-function relationships in autism suggest possible involvement of the dual pathways in supporting deficient semantic processing. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.

The Cortical Connectivity of the Prefrontal Cortex in the Monkey Brain

PubMed Central

Yeterian, Edward H.; Pandya, Deepak N.; Tomaiuolo, Francesco; Petrides, Michael

2011-01-01

One dimension of understanding the functions of the prefrontal cortex is knowledge of cortical connectivity. We have surveyed three aspects of prefrontal cortical connections: local projections (within the frontal lobe), the termination patterns of long association (post-Rolandic) projections, and the trajectories of major fiber pathways. The local connections appear to be organized in relation to dorsal (hippocampal origin) and ventral (paleocortical origin) architectonic trends. According to the proposal of a dual origin of the cerebral cortex, cortical areas can be traced as originating from archicortex (hippocampus) on the one hand, and paleocortex, on the other hand, in a stepwise manner (e.g., Sanides, 1969; Pandya and Yeterian, 1985). Prefrontal areas within each trend are connected with less architectonically differentiated areas, and, on the other hand, with more differentiated areas. Such organization may allow for the systematic exchange of information within each architectonic trend. The long connections of the prefrontal cortex with post-Rolandic regions seem to be organized preferentially in relation to dorsal and ventral prefrontal architectonic trends. Prefrontal areas are connected with post-Rolandic auditory, visual and somatosensory association areas, and with multimodal and paralimbic regions. This long connectivity likely works in conjunction with local connections to serve prefrontal cortical functions. The afferent and efferent connections of the prefrontal cortex with post-Rolandic regions are conveyed by specific long association pathways. These pathways as well appear to be organized in relation to dorsal and ventral prefrontal architectonic trends. Finally, although prefrontal areas have preferential connections in relation to dual architectonic trends, it is clear that there are interconnections between and among areas in each trend, which may provide a substrate for the overall integrative function of the prefrontal cortex. Prefrontal corticocortical connectivity may help to elucidate both region-specific and integrative perspectives on the functions of the prefrontal cortex. PMID:21481342

Investigating category- and shape-selective neural processing in ventral and dorsal visual stream under interocular suppression.

PubMed

Ludwig, Karin; Kathmann, Norbert; Sterzer, Philipp; Hesselmann, Guido

2015-01-01

Recent behavioral and neuroimaging studies using continuous flash suppression (CFS) have suggested that action-related processing in the dorsal visual stream might be independent of perceptual awareness, in line with the "vision-for-perception" versus "vision-for-action" distinction of the influential dual-stream theory. It remains controversial if evidence suggesting exclusive dorsal stream processing of tool stimuli under CFS can be explained by their elongated shape alone or by action-relevant category representations in dorsal visual cortex. To approach this question, we investigated category- and shape-selective functional magnetic resonance imaging-blood-oxygen level-dependent responses in both visual streams using images of faces and tools. Multivariate pattern analysis showed enhanced decoding of elongated relative to non-elongated tools, both in the ventral and dorsal visual stream. The second aim of our study was to investigate whether the depth of interocular suppression might differentially affect processing in dorsal and ventral areas. However, parametric modulation of suppression depth by varying the CFS mask contrast did not yield any evidence for differential modulation of category-selective activity. Together, our data provide evidence for shape-selective processing under CFS in both dorsal and ventral stream areas and, therefore, do not support the notion that dorsal "vision-for-action" processing is exclusively preserved under interocular suppression. © 2014 Wiley Periodicals, Inc.

Are patients with Parkinson’s disease blind to blindsight?

PubMed Central

Stebbins, Glenn; Schiltz, Christine; Goetz, Christopher G.

2014-01-01

In Parkinson’s disease, visual dysfunction is prominent. Visual hallucinations can be a major hallmark of late stage disease, but numerous visual deficits also occur in early stage Parkinson’s disease. Specific retinopathy, deficits in the primary visual pathway and the secondary ventral and dorsal pathways, as well as dysfunction of the attention pathways have all been posited as causes of hallucinations in Parkinson’s disease. We present data from patients with Parkinson’s disease that contrast with a known neuro-ophthalmological syndrome, termed ‘blindsight’. In this syndrome, there is an absence of conscious object identification, but preserved ‘guess’ of the location of a stimulus, preserved reflexive saccades and motion perception and preserved autonomical and expressive reactions to negative emotional facial expressions. We propose that patients with Parkinson’s disease have the converse of blindsight, being ‘blind to blindsight’. As such they preserve conscious vision, but show erroneous ‘guess’ localization of visual stimuli, poor saccades and motion perception, and poor emotional face perception with blunted autonomic reaction. Although a large data set on these deficits in Parkinson’s disease has been accumulated, consolidation into one specific syndrome has not been proposed. Focusing on neuropathological and physiological data from two phylogenetically old and subconscious pathways, the retino-colliculo-thalamo-amygdala and the retino-geniculo-extrastriate pathways, we propose that aberrant function of these systems, including pathologically inhibited superior colliculus activity, deficient corollary discharges to the frontal eye fields, dysfunctional pulvinar, claustrum and amygdaloid subnuclei of the amygdala, the latter progressively burdened with Lewy bodies, underlie this syndrome. These network impairments are further corroborated by the concept of the ‘silent amygdala’. Functionally being ‘blind to blindsight’ may facilitate the highly distinctive ‘presence’ or ‘passage’ hallucinations of Parkinson’s disease and can help to explain handicaps in driving capacities and dysfunctional ‘theory of mind’. We propose this synthesis to prompt refined neuropathological and neuroimaging studies on the pivotal nuclei in these pathways in order to better understand the networks underpinning this newly conceptualized syndrome in Parkinson’s disease. PMID:24764573

Affective blindsight in the absence of input from face processing regions in occipital-temporal cortex.

PubMed

Striemer, Christopher L; Whitwell, Robert L; Goodale, Melvyn A

2017-11-12

Previous research suggests that the implicit recognition of emotional expressions may be carried out by pathways that bypass primary visual cortex (V1) and project to the amygdala. Some of the strongest evidence supporting this claim comes from case studies of "affective blindsight" in which patients with V1 damage can correctly guess whether an unseen face was depicting a fearful or happy expression. In the current study, we report a new case of affective blindsight in patient MC who is cortically blind following extensive bilateral lesions to V1, as well as face and object processing regions in her ventral visual stream. Despite her large lesions, MC has preserved motion perception which is related to sparing of the motion sensitive region MT+ in both hemispheres. To examine affective blindsight in MC we asked her to perform gender and emotion discrimination tasks in which she had to guess, using a two-alternative forced-choice procedure, whether the face presented was male or female, happy or fearful, or happy or angry. In addition, we also tested MC in a four-alternative forced-choice target localization task. Results indicated that MC was not able to determine the gender of the faces (53% accuracy), or localize targets in a forced-choice task. However, she was able to determine, at above chance levels, whether the face presented was depicting a happy or fearful (67%, p = .006), or a happy or angry (64%, p = .025) expression. Interestingly, although MC was better than chance at discriminating between emotions in faces when asked to make rapid judgments, her performance fell to chance when she was asked to provide subjective confidence ratings about her performance. These data lend further support to the idea that there is a non-conscious visual pathway that bypasses V1 which is capable of processing affective signals from facial expressions without input from higher-order face and object processing regions in the ventral visual stream. Copyright © 2017 Elsevier Ltd. All rights reserved.

Requirement of Xmsx-1 in the BMP-triggered ventralization of Xenopus embryos.

PubMed

Yamamoto, T S; Takagi, C; Ueno, N

2000-03-01

Signaling triggered by polypeptide growth factors leads to the activation of their target genes. Several homeobox genes are known to be induced in response to polypeptide growth factors in early Xenopus development. In particular, Xmsx-1, an amphibian homologue of vertebrate Msx-1, is well characterized as a target gene of bone morphogenetic protein (BMP). Here, using a dominant-negative form of Xmsx-1 (VP-Xmsx-1), which is a fusion protein made with the virus-derived VP16 activation domain, we have examined whether Xmsx-1 activity is required in the endogenous ventralizing pathway. VP-Xmsx-1 induced a secondary body axis, complete with muscle and neural tissues, when overexpressed in ventral blastomeres, suggesting that Xmsx-1 activity is necessary for both mesoderm and ectoderm to be ventralized. We have also examined the epistatic relationship between Xmsx-1 and another ventralizing homeobox protein, Xvent-1, and show that Xmsx-1 is likely to be acting upstream of Xvent-1. We propose that Xmsx-1 is required in the BMP-stimulated ventralization pathway that involves the downstream activation of Xvent-1.

The time-course of activation in the dorsal and ventral visual streams during landmark cueing and perceptual discrimination tasks.

PubMed

Lambert, Anthony J; Wootton, Adrienne

2017-08-01

Different patterns of high density EEG activity were elicited by the same peripheral stimuli, in the context of Landmark Cueing and Perceptual Discrimination tasks. The C1 component of the visual event-related potential (ERP) at parietal - occipital electrode sites was larger in the Landmark Cueing task, and source localisation suggested greater activation in the superior parietal lobule (SPL) in this task, compared to the Perceptual Discrimination task, indicating stronger early recruitment of the dorsal visual stream. In the Perceptual Discrimination task, source localisation suggested widespread activation of the inferior temporal gyrus (ITG) and fusiform gyrus (FFG), structures associated with the ventral visual stream, during the early phase of the P1 ERP component. Moreover, during a later epoch (171-270ms after stimulus onset) increased temporal-occipital negativity, and stronger recruitment of ITG and FFG were observed in the Perceptual Discrimination task. These findings illuminate the contrasting functions of the dorsal and ventral visual streams, to support rapid shifts of attention in response to contextual landmarks, and conscious discrimination, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Perception of shapes targeting local and global processes in autism spectrum disorders.

PubMed

Grinter, Emma J; Maybery, Murray T; Pellicano, Elizabeth; Badcock, Johanna C; Badcock, David R

2010-06-01

Several researchers have found evidence for impaired global processing in the dorsal visual stream in individuals with autism spectrum disorders (ASDs). However, support for a similar pattern of visual processing in the ventral visual stream is less consistent. Critical to resolving the inconsistency is the assessment of local and global form processing ability. Within the visual domain, radial frequency (RF) patterns - shapes formed by sinusoidally varying the radius of a circle to add 'bumps' of a certain number to a circle - can be used to examine local and global form perception. Typically developing children and children with an ASD discriminated between circles and RF patterns that are processed either locally (RF24) or globally (RF3). Children with an ASD required greater shape deformation to identify RF3 shapes compared to typically developing children, consistent with difficulty in global processing in the ventral stream. No group difference was observed for RF24 shapes, suggesting intact local ventral-stream processing. These outcomes support the position that a deficit in global visual processing is present in ASDs, consistent with the notion of Weak Central Coherence.

Aging reduces neural specialization in ventral visual cortex

PubMed Central

Park, Denise C.; Polk, Thad A.; Park, Rob; Minear, Meredith; Savage, Anna; Smith, Mason R.

2004-01-01

The present study investigated whether neural structures become less functionally differentiated and specialized with age. We studied ventral visual cortex, an area of the brain that responds selectively to visual categories (faces, places, and words) in young adults, and that shows little atrophy with age. Functional MRI was used to estimate neural activity in this cortical area, while young and old adults viewed faces, houses, pseudowords, and chairs. The results demonstrated significantly less neural specialization for these stimulus categories in older adults across a range of analyses. PMID:15322270

Rise and fall of the two visual systems theory.

PubMed

Rossetti, Yves; Pisella, Laure; McIntosh, Robert D

2017-06-01

Among the many dissociations describing the visual system, the dual theory of two visual systems, respectively dedicated to perception and action, has yielded a lot of support. There are psychophysical, anatomical and neuropsychological arguments in favor of this theory. Several behavioral studies that used sensory and motor psychophysical parameters observed differences between perceptive and motor responses. The anatomical network of the visual system in the non-human primate was very readily organized according to two major pathways, dorsal and ventral. Neuropsychological studies, exploring optic ataxia and visual agnosia as characteristic deficits of these two pathways, led to the proposal of a functional double dissociation between visuomotor and visual perceptual functions. After a major wave of popularity that promoted great advances, particularly in knowledge of visuomotor functions, the guiding theory is now being reconsidered. Firstly, the idea of a double dissociation between optic ataxia and visual form agnosia, as cleanly separating visuomotor from visual perceptual functions, is no longer tenable; optic ataxia does not support a dissociation between perception and action and might be more accurately viewed as a negative image of action blindsight. Secondly, dissociations between perceptive and motor responses highlighted in the framework of this theory concern a very elementary level of action, even automatically guided action routines. Thirdly, the very rich interconnected network of the visual brain yields few arguments in favor of a strict perception/action dissociation. Overall, the dissociation between motor function and perceptive function explored by these behavioral and neuropsychological studies can help define an automatic level of action organization deficient in optic ataxia and preserved in action blindsight, and underlines the renewed need to consider the perception-action circle as a functional ensemble. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Alpha-band rhythm modulation under the condition of subliminal face presentation: MEG study.

PubMed

Sakuraba, Satoshi; Kobayashi, Hana; Sakai, Shinya; Yokosawa, Koichi

2013-01-01

The human brain has two streams to process visual information: a dorsal stream and a ventral stream. Negative potential N170 or its magnetic counterpart M170 is known as the face-specific signal originating from the ventral stream. It is possible to present a visual image unconsciously by using continuous flash suppression (CFS), which is a visual masking technique adopting binocular rivalry. In this work, magnetoencephalograms were recorded during presentation of the three invisible images: face images, which are processed by the ventral stream; tool images, which could be processed by the dorsal stream, and a blank image. Alpha-band activities detected by sensors that are sensitive to M170 were compared. The alpha-band rhythm was suppressed more during presentation of face images than during presentation of the blank image (p=.028). The suppression remained for about 1 s after ending presentations. However, no significant difference was observed between tool and other images. These results suggest that alpha-band rhythm can be modulated also by unconscious visual images.

The relationship of global form and motion detection to reading fluency.

PubMed

Englund, Julia A; Palomares, Melanie

2012-08-15

Visual motion processing in typical and atypical readers has suggested aspects of reading and motion processing share a common cortical network rooted in dorsal visual areas. Few studies have examined the relationship between reading performance and visual form processing, which is mediated by ventral cortical areas. We investigated whether reading fluency correlates with coherent motion detection thresholds in typically developing children using random dot kinematograms. As a comparison, we also evaluated the correlation between reading fluency and static form detection thresholds. Results show that both dorsal and ventral visual functions correlated with components of reading fluency, but that they have different developmental characteristics. Motion coherence thresholds correlated with reading rate and accuracy, which both improved with chronological age. Interestingly, when controlling for non-verbal abilities and age, reading accuracy significantly correlated with thresholds for coherent form detection but not coherent motion detection in typically developing children. Dorsal visual functions that mediate motion coherence seem to be related maturation of broad cognitive functions including non-verbal abilities and reading fluency. However, ventral visual functions that mediate form coherence seem to be specifically related to accurate reading in typically developing children. Copyright © 2012 Elsevier Ltd. All rights reserved.

Magnocellular-dorsal pathway and sub-lexical route in developmental dyslexia

PubMed Central

Gori, Simone; Cecchini, Paolo; Bigoni, Anna; Molteni, Massimo; Facoetti, Andrea

2014-01-01

Although developmental dyslexia (DD) is frequently associate with a phonological deficit, the underlying neurobiological cause remains undetermined. Recently, a new model, called “temporal sampling framework” (TSF), provided an innovative prospect in the DD study. TSF suggests that deficits in syllabic perception at a specific temporal frequencies are the critical basis for the poor reading performance in DD. This approach was presented as a possible neurobiological substrate of the phonological deficit of DD but the TSF can also easily be applied to the visual modality deficits. The deficit in the magnocellular-dorsal (M-D) pathway - often found in individuals with DD - fits well with a temporal oscillatory deficit specifically related to this visual pathway. This study investigated the visual M-D and parvocellular-ventral (P-V) pathways in dyslexic and in chronological age and IQ-matched normally reading children by measuring temporal (frequency doubling illusion) and static stimuli sensitivity, respectively. A specific deficit in M-D temporal oscillation was found. Importantly, the M-D deficit was selectively shown in poor phonological decoders. M-D deficit appears to be frequent because 75% of poor pseudo-word readers were at least 1 SD below the mean of the controls. Finally, a replication study by using a new group of poor phonological decoders and reading level controls suggested a crucial role of M-D deficit in DD. These results showed that a M-D deficit might impair the sub-lexical mechanisms that are critical for reading development. The possible link between these findings and TSF is discussed. PMID:25009484

Exploring the Early Organization and Maturation of Linguistic Pathways in the Human Infant Brain.

PubMed

Dubois, Jessica; Poupon, Cyril; Thirion, Bertrand; Simonnet, Hina; Kulikova, Sofya; Leroy, François; Hertz-Pannier, Lucie; Dehaene-Lambertz, Ghislaine

2016-05-01

Linguistic processing is based on a close collaboration between temporal and frontal regions connected by two pathways: the "dorsal" and "ventral pathways" (assumed to support phonological and semantic processing, respectively, in adults). We investigated here the development of these pathways at the onset of language acquisition, during the first post-natal weeks, using cross-sectional diffusion imaging in 21 healthy infants (6-22 weeks of age) and 17 young adults. We compared the bundle organization and microstructure at these two ages using tractography and original clustering analyses of diffusion tensor imaging parameters. We observed structural similarities between both groups, especially concerning the dorsal/ventral pathway segregation and the arcuate fasciculus asymmetry. We further highlighted the developmental tempos of the linguistic bundles: The ventral pathway maturation was more advanced than the dorsal pathway maturation, but the latter catches up during the first post-natal months. Its fast development during this period might relate to the learning of speech cross-modal representations and to the first combinatorial analyses of the speech input. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

An endocrine pathway in the prostate, ERbeta, AR, 5alpha-androstane-3beta,17beta-diol, and CYP7B1, regulates prostate growth.

PubMed

Weihua, Zhang; Lathe, Richard; Warner, Margaret; Gustafsson, Jan-Ake

2002-10-15

Epithelial proliferation of the ventral prostate in rodents peaks between 2 and 4 weeks of age, and by week 8, proliferating cells are rare. We have used ERbeta(-/-) and CYP7B1(-/-) mice to investigate the role of ERbeta and one of its ligands, 5alpha-androstane-3beta,17beta-diol (3betaAdiol), in growth of the ventral prostate. Before puberty, ERbeta was found in quiescent but not in proliferating cells, and proliferating cells occurred more frequently in ventral prostates of ERbeta(-/-) mice than in wild-type littermates. Treatment with 3betaAdiol decreased proliferation in wild-type but not in ERbeta(-/-) mice. In rats, treatment with 3betaAdiol from postnatal day 2 to 28 resulted in reduction in growth of ventral prostates. The prostates of CYP7B1(-/-) mice were hypoproliferative before puberty and smaller than those of their wild-type littermates after puberty. Because CYP7B1 represents the major pathway for inactivating 3betaAdiol in the prostate, we suggest that ERbeta, 3betaAdiol, and CYP7B1 are the components of a pathway that regulates growth of the rodent ventral prostate. In this pathway, ERbeta is an antiproliferative receptor, 3betaAdiol is an ERbeta ligand, and CYP7B1 is the enzyme that regulates ERbeta function by regulating the level of 3betaAdiol.

Gamma-oscillations modulated by picture naming and word reading: Intracranial recording in epileptic patients

PubMed Central

Wu, Helen C.; Nagasawa, Tetsuro; Brown, Erik C.; Juhasz, Csaba; Rothermel, Robert; Hoechstetter, Karsten; Shah, Aashit; Mittal, Sandeep; Fuerst, Darren; Sood, Sandeep; Asano, Eishi

2011-01-01

Objective We measured cortical gamma-oscillations in response to visual-language tasks consisting of picture naming and word reading in an effort to better understand human visual-language pathways. Methods We studied six patients with focal epilepsy who underwent extraoperative electrocorticography (ECoG) recording. Patients were asked to overtly name images presented sequentially in the picture naming task and to overtly read written words in the reading task. Results Both tasks commonly elicited gamma-augmentation (maximally at 80–100 Hz) on ECoG in the occipital, inferior-occipital-temporal and inferior-Rolandic areas, bilaterally. Picture naming, compared to reading task, elicited greater gamma-augmentation in portions of pre-motor areas as well as occipital and inferior-occipital-temporal areas, bilaterally. In contrast, word reading elicited greater gamma-augmentation in portions of bilateral occipital, left occipital-temporal and left superior-posterior-parietal areas. Gamma-attenuation was elicited by both tasks in portions of posterior cingulate and ventral premotor-prefrontal areas bilaterally. The number of letters in a presented word was positively correlated to the degree of gamma-augmentation in the medial occipital areas. Conclusions Gamma-augmentation measured on ECoG identified cortical areas commonly and differentially involved in picture naming and reading tasks. Longer words may activate the primary visual cortex for the more peripheral field. Significance The present study increases our understanding of the visual-language pathways. PMID:21498109

Task alters category representations in prefrontal but not high-level visual cortex.

PubMed

Bugatus, Lior; Weiner, Kevin S; Grill-Spector, Kalanit

2017-07-15

A central question in neuroscience is how cognitive tasks affect category representations across the human brain. Regions in lateral occipito-temporal cortex (LOTC), ventral temporal cortex (VTC), and ventro-lateral prefrontal cortex (VLFPC) constitute the extended "what" pathway, which is considered instrumental for visual category processing. However, it is unknown (1) whether distributed responses across LOTC, VTC, and VLPFC explicitly represent category, task, or some combination of both, and (2) in what way representations across these subdivisions of the extended 'what' pathway may differ. To fill these gaps in knowledge, we scanned 12 participants using fMRI to test the effect of category and task on distributed responses across LOTC, VTC, and VLPFC. Results reveal that task and category modulate responses in both high-level visual regions, as well as prefrontal cortex. However, we found fundamentally different types of representations across the brain. Distributed responses in high-level visual regions are more strongly driven by category than task, and exhibit task-independent category representations. In contrast, distributed responses in prefrontal cortex are more strongly driven by task than category, and contain task-dependent category representations. Together, these findings of differential representations across the brain support a new idea that LOTC and VTC maintain stable category representations allowing efficient processing of visual information, while prefrontal cortex contains flexible representations in which category information may emerge only when relevant to the task. Copyright © 2017 Elsevier Inc. All rights reserved.

The selectivity of responses to red-green colour and achromatic contrast in the human visual cortex: an fMRI adaptation study.

PubMed

Mullen, Kathy T; Chang, Dorita H F; Hess, Robert F

2015-12-01

There is controversy as to how responses to colour in the human brain are organized within the visual pathways. A key issue is whether there are modular pathways that respond selectively to colour or whether there are common neural substrates for both colour and achromatic (Ach) contrast. We used functional magnetic resonance imaging (fMRI) adaptation to investigate the responses of early and extrastriate visual areas to colour and Ach contrast. High-contrast red-green (RG) and Ach sinewave rings (0.5 cycles/degree, 2 Hz) were used as both adapting stimuli and test stimuli in a block design. We found robust adaptation to RG or Ach contrast in all visual areas. Cross-adaptation between RG and Ach contrast occurred in all areas indicating the presence of integrated, colour and Ach responses. Notably, we revealed contrasting trends for the two test stimuli. For the RG test, unselective processing (robust adaptation to both RG and Ach contrast) was most evident in the early visual areas (V1 and V2), but selective responses, revealed as greater adaptation between the same stimuli than cross-adaptation between different stimuli, emerged in the ventral cortex, in V4 and VO in particular. For the Ach test, unselective responses were again most evident in early visual areas but Ach selectivity emerged in the dorsal cortex (V3a and hMT+). Our findings support a strong presence of integrated mechanisms for colour and Ach contrast across the visual hierarchy, with a progression towards selective processing in extrastriate visual areas. © 2015 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Are face representations depth cue invariant?

PubMed

Dehmoobadsharifabadi, Armita; Farivar, Reza

2016-06-01

The visual system can process three-dimensional depth cues defining surfaces of objects, but it is unclear whether such information contributes to complex object recognition, including face recognition. The processing of different depth cues involves both dorsal and ventral visual pathways. We investigated whether facial surfaces defined by individual depth cues resulted in meaningful face representations-representations that maintain the relationship between the population of faces as defined in a multidimensional face space. We measured face identity aftereffects for facial surfaces defined by individual depth cues (Experiments 1 and 2) and tested whether the aftereffect transfers across depth cues (Experiments 3 and 4). Facial surfaces and their morphs to the average face were defined purely by one of shading, texture, motion, or binocular disparity. We obtained identification thresholds for matched (matched identity between adapting and test stimuli), non-matched (non-matched identity between adapting and test stimuli), and no-adaptation (showing only the test stimuli) conditions for each cue and across different depth cues. We found robust face identity aftereffect in both experiments. Our results suggest that depth cues do contribute to forming meaningful face representations that are depth cue invariant. Depth cue invariance would require integration of information across different areas and different pathways for object recognition, and this in turn has important implications for cortical models of visual object recognition.

Feature integration and object representations along the dorsal stream visual hierarchy

PubMed Central

Perry, Carolyn Jeane; Fallah, Mazyar

2014-01-01

The visual system is split into two processing streams: a ventral stream that receives color and form information and a dorsal stream that receives motion information. Each stream processes that information hierarchically, with each stage building upon the previous. In the ventral stream this leads to the formation of object representations that ultimately allow for object recognition regardless of changes in the surrounding environment. In the dorsal stream, this hierarchical processing has classically been thought to lead to the computation of complex motion in three dimensions. However, there is evidence to suggest that there is integration of both dorsal and ventral stream information into motion computation processes, giving rise to intermediate object representations, which facilitate object selection and decision making mechanisms in the dorsal stream. First we review the hierarchical processing of motion along the dorsal stream and the building up of object representations along the ventral stream. Then we discuss recent work on the integration of ventral and dorsal stream features that lead to intermediate object representations in the dorsal stream. Finally we propose a framework describing how and at what stage different features are integrated into dorsal visual stream object representations. Determining the integration of features along the dorsal stream is necessary to understand not only how the dorsal stream builds up an object representation but also which computations are performed on object representations instead of local features. PMID:25140147

Implicit integration in a case of integrative visual agnosia.

PubMed

Aviezer, Hillel; Landau, Ayelet N; Robertson, Lynn C; Peterson, Mary A; Soroker, Nachum; Sacher, Yaron; Bonneh, Yoram; Bentin, Shlomo

2007-05-15

We present a case (SE) with integrative visual agnosia following ischemic stroke affecting the right dorsal and the left ventral pathways of the visual system. Despite his inability to identify global hierarchical letters [Navon, D. (1977). Forest before trees: The precedence of global features in visual perception. Cognitive Psychology, 9, 353-383], and his dense object agnosia, SE showed normal global-to-local interference when responding to local letters in Navon hierarchical stimuli and significant picture-word identity priming in a semantic decision task for words. Since priming was absent if these features were scrambled, it stands to reason that these effects were not due to priming by distinctive features. The contrast between priming effects induced by coherent and scrambled stimuli is consistent with implicit but not explicit integration of features into a unified whole. We went on to show that possible/impossible object decisions were facilitated by words in a word-picture priming task, suggesting that prompts could activate perceptually integrated images in a backward fashion. We conclude that the absence of SE's ability to identify visual objects except through tedious serial construction reflects a deficit in accessing an integrated visual representation through bottom-up visual processing alone. However, top-down generated images can help activate these visual representations through semantic links.

Introducing memory and association mechanism into a biologically inspired visual model.

PubMed

Qiao, Hong; Li, Yinlin; Tang, Tang; Wang, Peng

2014-09-01

A famous biologically inspired hierarchical model (HMAX model), which was proposed recently and corresponds to V1 to V4 of the ventral pathway in primate visual cortex, has been successfully applied to multiple visual recognition tasks. The model is able to achieve a set of position- and scale-tolerant recognition, which is a central problem in pattern recognition. In this paper, based on some other biological experimental evidence, we introduce the memory and association mechanism into the HMAX model. The main contributions of the work are: 1) mimicking the active memory and association mechanism and adding the top down adjustment to the HMAX model, which is the first try to add the active adjustment to this famous model and 2) from the perspective of information, algorithms based on the new model can reduce the computation storage and have a good recognition performance. The new model is also applied to object recognition processes. The primary experimental results show that our method is efficient with a much lower memory requirement.

Ventral pallidum roles in reward and motivation.

PubMed

Smith, Kyle S; Tindell, Amy J; Aldridge, J Wayne; Berridge, Kent C

2009-01-23

In recent years the ventral pallidum has become a focus of great research interest as a mechanism of reward and incentive motivation. As a major output for limbic signals, the ventral pallidum was once associated primarily with motor functions rather than regarded as a reward structure in its own right. However, ample evidence now suggests that ventral pallidum function is a major mechanism of reward in the brain. We review data indicating that (1) an intact ventral pallidum is necessary for normal reward and motivation, (2) stimulated activation of ventral pallidum is sufficient to cause reward and motivation enhancements, and (3) activation patterns in ventral pallidum neurons specifically encode reward and motivation signals via phasic bursts of excitation to incentive and hedonic stimuli. We conclude that the ventral pallidum may serve as an important 'limbic final common pathway' for mesocorticolimbic processing of many rewards.

Visual processing of music notation: a study of event-related potentials.

PubMed

Lee, Horng-Yih; Wang, Yu-Sin

2011-04-01

In reading music, the acquisition of pitch information depends mostly on the spatial position of notes, hence more spatial processing, whereas the acquisition of temporal information depends mostly on the visual features of notes and object recognition. This study used both electrophysiological and behavioral methods to compare the processing of pitch and duration in reading single musical notes. It was observed that in the early stage of note reading, identification of pitch could elicit greater N1 and N2 amplitude than identification of duration at the parietal lobe electrodes. In the later stages of note reading, identifying pitch elicited a greater negative slow wave at parietal electrodes than did identifying note duration. The sustained contribution of parietal processes for pitch suggests that the dorsal pathway is essential for pitch processing. However, the duration task did not elicit greater amplitude of any early ERP components than the pitch task at temporal electrodes. Accordingly, a double dissociation, suggesting involvement of the dorsal visual stream, was not observed in spatial pitch processing and ventral visual stream in processing of note durations.

Reduced ventral cingulum integrity and increased behavioral problems in children with isolated optic nerve hypoplasia and mild to moderate or no visual impairment.

PubMed

Webb, Emma A; O'Reilly, Michelle A; Clayden, Jonathan D; Seunarine, Kiran K; Dale, Naomi; Salt, Alison; Clark, Chris A; Dattani, Mehul T

2013-01-01

To assess the prevalence of behavioral problems in children with isolated optic nerve hypoplasia, mild to moderate or no visual impairment, and no developmental delay. To identify white matter abnormalities that may provide neural correlates for any behavioral abnormalities identified. Eleven children with isolated optic nerve hypoplasia (mean age 5.9 years) underwent behavioral assessment and brain diffusion tensor imaging, Twenty four controls with isolated short stature (mean age 6.4 years) underwent MRI, 11 of whom also completed behavioral assessments. Fractional anisotropy images were processed using tract-based spatial statistics. Partial correlation between ventral cingulum, corpus callosum and optic radiation fractional anisotropy, and child behavioral checklist scores (controlled for age at scan and sex) was performed. Children with optic nerve hypoplasia had significantly higher scores on the child behavioral checklist (p<0.05) than controls (4 had scores in the clinically significant range). Ventral cingulum, corpus callosum and optic radiation fractional anisotropy were significantly reduced in children with optic nerve hypoplasia. Right ventral cingulum fractional anisotropy correlated with total and externalising child behavioral checklist scores (r = -0.52, p<0.02, r = -0.46, p<0.049 respectively). There were no significant correlations between left ventral cingulum, corpus callosum or optic radiation fractional anisotropy and behavioral scores. Our findings suggest that children with optic nerve hypoplasia and mild to moderate or no visual impairment require behavioral assessment to determine the presence of clinically significant behavioral problems. Reduced structural integrity of the ventral cingulum correlated with behavioral scores, suggesting that these white matter abnormalities may be clinically significant. The presence of reduced fractional anisotropy in the optic radiations of children with mild to moderate or no visual impairment raises questions as to the pathogenesis of these changes which will need to be addressed by future studies.

Attention supports verbal short-term memory via competition between dorsal and ventral attention networks.

PubMed

Majerus, Steve; Attout, Lucie; D'Argembeau, Arnaud; Degueldre, Christian; Fias, Wim; Maquet, Pierre; Martinez Perez, Trecy; Stawarczyk, David; Salmon, Eric; Van der Linden, Martial; Phillips, Christophe; Balteau, Evelyne

2012-05-01

Interactions between the neural correlates of short-term memory (STM) and attention have been actively studied in the visual STM domain but much less in the verbal STM domain. Here we show that the same attention mechanisms that have been shown to shape the neural networks of visual STM also shape those of verbal STM. Based on previous research in visual STM, we contrasted the involvement of a dorsal attention network centered on the intraparietal sulcus supporting task-related attention and a ventral attention network centered on the temporoparietal junction supporting stimulus-related attention. We observed that, with increasing STM load, the dorsal attention network was activated while the ventral attention network was deactivated, especially during early maintenance. Importantly, activation in the ventral attention network increased in response to task-irrelevant stimuli briefly presented during the maintenance phase of the STM trials but only during low-load STM conditions, which were associated with the lowest levels of activity in the dorsal attention network during encoding and early maintenance. By demonstrating a trade-off between task-related and stimulus-related attention networks during verbal STM, this study highlights the dynamics of attentional processes involved in verbal STM.

Damage to ventral and dorsal language pathways in acute aphasia

PubMed Central

Hartwigsen, Gesa; Kellmeyer, Philipp; Glauche, Volkmar; Mader, Irina; Klöppel, Stefan; Suchan, Julia; Karnath, Hans-Otto; Weiller, Cornelius; Saur, Dorothee

2013-01-01

Converging evidence from neuroimaging studies and computational modelling suggests an organization of language in a dual dorsal–ventral brain network: a dorsal stream connects temporoparietal with frontal premotor regions through the superior longitudinal and arcuate fasciculus and integrates sensorimotor processing, e.g. in repetition of speech. A ventral stream connects temporal and prefrontal regions via the extreme capsule and mediates meaning, e.g. in auditory comprehension. The aim of our study was to test, in a large sample of 100 aphasic stroke patients, how well acute impairments of repetition and comprehension correlate with lesions of either the dorsal or ventral stream. We combined voxelwise lesion-behaviour mapping with the dorsal and ventral white matter fibre tracts determined by probabilistic fibre tracking in our previous study in healthy subjects. We found that repetition impairments were mainly associated with lesions located in the posterior temporoparietal region with a statistical lesion maximum in the periventricular white matter in projection of the dorsal superior longitudinal and arcuate fasciculus. In contrast, lesions associated with comprehension deficits were found more ventral-anterior in the temporoprefrontal region with a statistical lesion maximum between the insular cortex and the putamen in projection of the ventral extreme capsule. Individual lesion overlap with the dorsal fibre tract showed a significant negative correlation with repetition performance, whereas lesion overlap with the ventral fibre tract revealed a significant negative correlation with comprehension performance. To summarize, our results from patients with acute stroke lesions support the claim that language is organized along two segregated dorsal–ventral streams. Particularly, this is the first lesion study demonstrating that task performance on auditory comprehension measures requires an interaction between temporal and prefrontal brain regions via the ventral extreme capsule pathway. PMID:23378217

An endocrine pathway in the prostate, ERβ, AR, 5α-androstane-3β,17β-diol, and CYP7B1, regulates prostate growth

PubMed Central

Weihua, Zhang; Lathe, Richard; Warner, Margaret; Gustafsson, Jan-Åke

2002-01-01

Epithelial proliferation of the ventral prostate in rodents peaks between 2 and 4 weeks of age, and by week 8, proliferating cells are rare. We have used ERβ−/− and CYP7B1−/− mice to investigate the role of ERβ and one of its ligands, 5α-androstane-3β,17β-diol (3βAdiol), in growth of the ventral prostate. Before puberty, ERβ was found in quiescent but not in proliferating cells, and proliferating cells occurred more frequently in ventral prostates of ERβ−/− mice than in wild-type littermates. Treatment with 3βAdiol decreased proliferation in wild-type but not in ERβ−/− mice. In rats, treatment with 3βAdiol from postnatal day 2 to 28 resulted in reduction in growth of ventral prostates. The prostates of CYP7B1−/− mice were hypoproliferative before puberty and smaller than those of their wild-type littermates after puberty. Because CYP7B1 represents the major pathway for inactivating 3βAdiol in the prostate, we suggest that ERβ, 3βAdiol, and CYP7B1 are the components of a pathway that regulates growth of the rodent ventral prostate. In this pathway, ERβ is an antiproliferative receptor, 3βAdiol is an ERβ ligand, and CYP7B1 is the enzyme that regulates ERβ function by regulating the level of 3βAdiol. PMID:12370428

Visual brain plasticity induced by central and peripheral visual field loss.

PubMed

Sanda, Nicolae; Cerliani, Leonardo; Authié, Colas N; Sabbah, Norman; Sahel, José-Alain; Habas, Christophe; Safran, Avinoam B; Thiebaut de Schotten, Michel

2018-06-23

Disorders that specifically affect central and peripheral vision constitute invaluable models to study how the human brain adapts to visual deafferentation. We explored cortical changes after the loss of central or peripheral vision. Cortical thickness (CoTks) and resting-state cortical entropy (rs-CoEn), as a surrogate for neural and synaptic complexity, were extracted in 12 Stargardt macular dystrophy, 12 retinitis pigmentosa (tunnel vision stage), and 14 normally sighted subjects. When compared to controls, both groups with visual loss exhibited decreased CoTks in dorsal area V3d. Peripheral visual field loss also showed a specific CoTks decrease in early visual cortex and ventral area V4, while central visual field loss in dorsal area V3A. Only central visual field loss exhibited increased CoEn in LO-2 area and FG1. Current results revealed biomarkers of brain plasticity within the dorsal and the ventral visual streams following central and peripheral visual field defects.

Intrinsic Connections of the Core Auditory Cortical Regions and Rostral Supratemporal Plane in the Macaque Monkey.

PubMed

Scott, Brian H; Leccese, Paul A; Saleem, Kadharbatcha S; Kikuchi, Yukiko; Mullarkey, Matthew P; Fukushima, Makoto; Mishkin, Mortimer; Saunders, Richard C

2017-01-01

In the ventral stream of the primate auditory cortex, cortico-cortical projections emanate from the primary auditory cortex (AI) along 2 principal axes: one mediolateral, the other caudorostral. Connections in the mediolateral direction from core, to belt, to parabelt, have been well described, but less is known about the flow of information along the supratemporal plane (STP) in the caudorostral dimension. Neuroanatomical tracers were injected throughout the caudorostral extent of the auditory core and rostral STP by direct visualization of the cortical surface. Auditory cortical areas were distinguished by SMI-32 immunostaining for neurofilament, in addition to established cytoarchitectonic criteria. The results describe a pathway comprising step-wise projections from AI through the rostral and rostrotemporal fields of the core (R and RT), continuing to the recently identified rostrotemporal polar field (RTp) and the dorsal temporal pole. Each area was strongly and reciprocally connected with the areas immediately caudal and rostral to it, though deviations from strictly serial connectivity were observed. In RTp, inputs converged from core, belt, parabelt, and the auditory thalamus, as well as higher order cortical regions. The results support a rostrally directed flow of auditory information with complex and recurrent connections, similar to the ventral stream of macaque visual cortex. Published by Oxford University Press 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Dissociated α-band modulations in the dorsal and ventral visual pathways in visuospatial attention and perception.

PubMed

Capilla, Almudena; Schoffelen, Jan-Mathijs; Paterson, Gavin; Thut, Gregor; Gross, Joachim

2014-02-01

Modulations of occipito-parietal α-band (8-14 Hz) power that are opposite in direction (α-enhancement vs. α-suppression) and origin of generation (ipsilateral vs. contralateral to the locus of attention) are a robust correlate of anticipatory visuospatial attention. Yet, the neural generators of these α-band modulations, their interdependence across homotopic areas, and their respective contribution to subsequent perception remain unclear. To shed light on these questions, we employed magnetoencephalography, while human volunteers performed a spatially cued detection task. Replicating previous findings, we found α-power enhancement ipsilateral to the attended hemifield and contralateral α-suppression over occipito-parietal sensors. Source localization (beamforming) analysis showed that α-enhancement and suppression were generated in 2 distinct brain regions, located in the dorsal and ventral visual streams, respectively. Moreover, α-enhancement and suppression showed different dynamics and contribution to perception. In contrast to the initial and transient dorsal α-enhancement, α-suppression in ventro-lateral occipital cortex was sustained and influenced subsequent target detection. This anticipatory biasing of ventro-lateral extrastriate α-activity probably reflects increased receptivity in the brain region specialized in processing upcoming target features. Our results add to current models on the role of α-oscillations in attention orienting by showing that α-enhancement and suppression can be dissociated in time, space, and perceptual relevance.

Notochord alters the permissiveness of myotome for pathfinding by an identified motoneuron in embryonic zebrafish.

PubMed

Beattie, C E; Eisen, J S

1997-02-01

During zebrafish development, identified motoneurons innervate cell-specific regions of each trunk myotome. One motoneuron, CaP, extends an axon along the medial surface of the ventral myotome. To learn how this pathway is established during development, the CaP axon was used as an assay to ask whether other regions of the myotome were permissive for normal CaP pathfinding. Native myotomes were replaced with donor myotomes in normal or reversed dorsoventral orientations and CaP pathfinding was assayed. Ventral myotomes were permissive for CaP axons, even when they were taken from older embryos, suggesting that the CaP pathway remained present on ventral myotome throughout development. Dorsal myotomes from young embryos were also permissive for CaP axons, however, older dorsal myotomes were non-permissive, showing that permissiveness of dorsal myotome for normal CaP pathfinding diminished over time. This process appears to depend on signals from the embryo, since dorsal myotomes matured in vitro remained permissive for CaP axons. Genetic mosaics between wild-type and floating head mutant embryos revealed notochord involvement in dorsal myotome change of permissiveness. Dorsal and ventral myotomes from both younger and older floating head mutant embryos were permissive for CaP axons. These data suggest that initially both dorsal and ventral myotomes are permissive for CaP axons but as development proceeds, there is a notochord-dependent decrease in permissiveness of dorsal myotome for CaP axonal outgrowth. This change participates in restricting the CaP pathway to the ventral myotome and thus to neuromuscular specificity.

Effects of attention and laterality on motion and orientation discrimination in deaf signers.

PubMed

Bosworth, Rain G; Petrich, Jennifer A F; Dobkins, Karen R

2013-06-01

Previous studies have asked whether visual sensitivity and attentional processing in deaf signers are enhanced or altered as a result of their different sensory experiences during development, i.e., auditory deprivation and exposure to a visual language. In particular, deaf and hearing signers have been shown to exhibit a right visual field/left hemisphere advantage for motion processing, while hearing nonsigners do not. To examine whether this finding extends to other aspects of visual processing, we compared deaf signers and hearing nonsigners on motion, form, and brightness discrimination tasks. Secondly, to examine whether hemispheric lateralities are affected by attention, we employed a dual-task paradigm to measure form and motion thresholds under "full" vs. "poor" attention conditions. Deaf signers, but not hearing nonsigners, exhibited a right visual field advantage for motion processing. This effect was also seen for form processing and not for the brightness task. Moreover, no group differences were observed in attentional effects, and the motion and form visual field asymmetries were not modulated by attention, suggesting they occur at early levels of sensory processing. In sum, the results show that processing of motion and form, believed to be mediated by dorsal and ventral visual pathways, respectively, are left-hemisphere dominant in deaf signers. Published by Elsevier Inc.

Delayed action does not always require the ventral stream: a study on a patient with visual form agnosia.

PubMed

Hesse, Constanze; Schenk, Thomas

2014-05-01

It has been suggested that while movements directed at visible targets are processed within the dorsal stream, movements executed after delay rely on the visual representations of the ventral stream (Milner & Goodale, 2006). This interpretation is supported by the observation that a patient with ventral stream damage (D.F.) has trouble performing accurate movements after a delay, but performs normally when the target is visible during movement programming. We tested D.F.'s visuomotor performance in a letter-posting task whilst varying the amount of visual feedback available. Additionally, we also varied whether D.F. received tactile feedback at the end of each trial (posting through a letter box vs posting on a screen) and whether environmental cues were available during the delay period (removing the target only vs suppressing vision completely with shutter glasses). We found that in the absence of environmental cues patient D.F. was unaffected by the introduction of delay and performed as accurately as healthy controls. However, when environmental cues and vision of the moving hand were available during and after the delay period, D.F.'s visuomotor performance was impaired. Thus, while healthy controls benefit from the availability of environmental landmarks and/or visual feedback of the moving hand, such cues seem less beneficial to D.F. Taken together our findings suggest that ventral stream damage does not always impact the ability to make delayed movements but compromises the ability to use environmental landmarks and visual feedback efficiently. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anatomical Evidence for Classical and Extra-classical Receptive Field Completion Across the Discontinuous Horizontal Meridian Representation of Primate Area V2

PubMed Central

Jeffs, Janelle; Ichida, Jennifer M.; Federer, Frederick

2009-01-01

In primates, a split of the horizontal meridian (HM) representation at the V2 rostral border divides this area into dorsal (V2d) and ventral (V2v) halves (representing lower and upper visual quadrants, respectively), causing retinotopically neighboring loci across the HM to be distant within V2. How is perceptual continuity maintained across this discontinuous HM representation? Injections of neuroanatomical tracers in marmoset V2d demonstrated that cells near the V2d rostral border can maintain retinotopic continuity within their classical and extra-classical receptive field (RF), by making both local and long-range intra- and interareal connections with ventral cortex representing the upper visual quadrant. V2d neurons located <0.9–1.3 mm from the V2d rostral border, whose RFs presumably do not cross the HM, make nonretinotopic horizontal connections with V2v neurons in the supra- and infragranular layers. V2d neurons located <0.6–0.9 mm from the border, whose RFs presumably cross the HM, in addition make retinotopic local connections with V2v neurons in layer 4. V2d neurons also make interareal connections with upper visual field regions of extrastriate cortex, but not of MT or MTc outside the foveal representation. Labeled connections in ventral cortex appear to represent the “missing” portion of the connectional fields in V2d across the HM. We conclude that connections between dorsal and ventral cortex can create visual field continuity within a second-order discontinuous visual topography. PMID:18755777

An odd manifestation of the Capgras syndrome: loss of familiarity even with the sexual partner.

PubMed

Thomas Antérion, C; Convers, P; Desmales, S; Borg, C; Laurent, B

2008-06-01

We report the case of a patient who presented visual hallucinations and identification disorders associated with a Capgras syndrome. During the Capgras periods, there was not only a misidentification of his wife's face, but also a more global perceptive and emotional sexual identification disorder. Thus, he had sexual intercourse with his wife's "double" without having the slightest recollection feeling of familiarity towards his "wife" and even changed his sexual habits. To the best of our knowledge, he is the only neurological patient who made his wife a mistress. Starting from this global familiarity loss, we discuss the mechanism of Capgras delusion with reference to the role of the implicit system of face recognition. Such behavior of familiarity loss not only with face but also with all intimacy aspects argues for a specific disconnection between the ventral visual pathway of face identification and the limbic system involved in emotional and episodic memory contents.

γ-oscillations modulated by picture naming and word reading: intracranial recording in epileptic patients.

PubMed

Wu, Helen C; Nagasawa, Tetsuro; Brown, Erik C; Juhasz, Csaba; Rothermel, Robert; Hoechstetter, Karsten; Shah, Aashit; Mittal, Sandeep; Fuerst, Darren; Sood, Sandeep; Asano, Eishi

2011-10-01

We measured cortical gamma-oscillations in response to visual-language tasks consisting of picture naming and word reading in an effort to better understand human visual-language pathways. We studied six patients with focal epilepsy who underwent extraoperative electrocorticography (ECoG) recording. Patients were asked to overtly name images presented sequentially in the picture naming task and to overtly read written words in the reading task. Both tasks commonly elicited gamma-augmentation (maximally at 80-100 Hz) on ECoG in the occipital, inferior-occipital-temporal and inferior-Rolandic areas, bilaterally. Picture naming, compared to reading task, elicited greater gamma-augmentation in portions of pre-motor areas as well as occipital and inferior-occipital-temporal areas, bilaterally. In contrast, word reading elicited greater gamma-augmentation in portions of bilateral occipital, left occipital-temporal and left superior-posterior-parietal areas. Gamma-attenuation was elicited by both tasks in portions of posterior cingulate and ventral premotor-prefrontal areas bilaterally. The number of letters in a presented word was positively correlated to the degree of gamma-augmentation in the medial occipital areas. Gamma-augmentation measured on ECoG identified cortical areas commonly and differentially involved in picture naming and reading tasks. Longer words may activate the primary visual cortex for the more peripheral field. The present study increases our understanding of the visual-language pathways. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Colour discrimination and categorisation in Williams syndrome.

PubMed

Farran, Emily K; Cranwell, Matthew B; Alvarez, James; Franklin, Anna

2013-10-01

Individuals with Williams syndrome (WS) present with impaired functioning of the dorsal visual stream relative to the ventral visual stream. As such, little attention has been given to ventral stream functions in WS. We investigated colour processing, a predominantly ventral stream function, for the first time in nineteen individuals with Williams syndrome. Colour discrimination was assessed using the Farnsworth-Munsell 100 hue test. Colour categorisation was assessed using a match-to-sample test and a colour naming task. A visual search task was also included as a measure of sensitivity to the size of perceptual colour difference. Results showed that individuals with WS have reduced colour discrimination relative to typically developing participants matched for chronological age; performance was commensurate with a typically developing group matched for non-verbal ability. In contrast, categorisation was typical in WS, although there was some evidence that sensitivity to the size of perceptual colour differences was reduced in this group. Copyright © 2013 Elsevier Ltd. All rights reserved.

Differential Tuning of Ventral and Dorsal Streams during the Generation of Common and Uncommon Tool Uses.

PubMed

Matheson, Heath E; Buxbaum, Laurel J; Thompson-Schill, Sharon L

2017-11-01

Our use of tools is situated in different contexts. Prior evidence suggests that diverse regions within the ventral and dorsal streams represent information supporting common tool use. However, given the flexibility of object concepts, these regions may be tuned to different types of information when generating novel or uncommon uses of tools. To investigate this, we collected fMRI data from participants who reported common or uncommon tool uses in response to visually presented familiar objects. We performed a pattern dissimilarity analysis in which we correlated cortical patterns with behavioral measures of visual, action, and category information. The results showed that evoked cortical patterns within the dorsal tool use network reflected action and visual information to a greater extent in the uncommon use group, whereas evoked neural patterns within the ventral tool use network reflected categorical information more strongly in the common use group. These results reveal the flexibility of cortical representations of tool use and the situated nature of cortical representations more generally.

Holistic neural coding of Chinese character forms in bilateral ventral visual system.

PubMed

Mo, Ce; Yu, Mengxia; Seger, Carol; Mo, Lei

2015-02-01

How are Chinese characters recognized and represented in the brain of skilled readers? Functional MRI fast adaptation technique was used to address this question. We found that neural adaptation effects were limited to identical characters in bilateral ventral visual system while no activation reduction was observed for partially overlapping characters regardless of the spatial location of the shared sub-character components, suggesting highly selective neuronal tuning to whole characters. The consistent neural profile across the entire ventral visual cortex indicates that Chinese characters are represented as mutually distinctive wholes rather than combinations of sub-character components, which presents a salient contrast to the left-lateralized, simple-to-complex neural representations of alphabetic words. Our findings thus revealed the cultural modulation effect on both local neuronal activity patterns and functional anatomical regions associated with written symbol recognition. Moreover, the cross-language discrepancy in written symbol recognition mechanism might stem from the language-specific early-stage learning experience. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Basomedial amygdala mediates top-down control of anxiety and fear.

PubMed

Adhikari, Avishek; Lerner, Talia N; Finkelstein, Joel; Pak, Sally; Jennings, Joshua H; Davidson, Thomas J; Ferenczi, Emily; Gunaydin, Lisa A; Mirzabekov, Julie J; Ye, Li; Kim, Sung-Yon; Lei, Anna; Deisseroth, Karl

2015-11-12

Anxiety-related conditions are among the most difficult neuropsychiatric diseases to treat pharmacologically, but respond to cognitive therapies. There has therefore been interest in identifying relevant top-down pathways from cognitive control regions in medial prefrontal cortex (mPFC). Identification of such pathways could contribute to our understanding of the cognitive regulation of affect, and provide pathways for intervention. Previous studies have suggested that dorsal and ventral mPFC subregions exert opposing effects on fear, as do subregions of other structures. However, precise causal targets for top-down connections among these diverse possibilities have not been established. Here we show that the basomedial amygdala (BMA) represents the major target of ventral mPFC in amygdala in mice. Moreover, BMA neurons differentiate safe and aversive environments, and BMA activation decreases fear-related freezing and high-anxiety states. Lastly, we show that the ventral mPFC-BMA projection implements top-down control of anxiety state and learned freezing, both at baseline and in stress-induced anxiety, defining a broadly relevant new top-down behavioural regulation pathway.

Basomedial amygdala mediates top–down control of anxiety and fear

PubMed Central

Adhikari, Avishek; Lerner, Talia N.; Finkelstein, Joel; Pak, Sally; Jennings, Joshua H.; Davidson, Thomas J.; Ferenczi, Emily; Gunaydin, Lisa A.; Mirzabekov, Julie J.; Ye, Li; Kim, Sung-Yon; Lei, Anna; Deisseroth, Karl

2016-01-01

Anxiety-related conditions are among the most difficult neuropsychiatric diseases to treat pharmacologically, but respond to cognitive therapies. There has therefore been interest in identifying relevant top-down pathways from cognitive control regions in medial prefrontal cortex (mPFC). Identification of such pathways could contribute to our understanding of the cognitive regulation of affect, and provide pathways for intervention. Previous studies have suggested that dorsal and ventral mPFC subregions exert opposing effects on fear, as do subregions of other structures. However, precise causal targets for top-down connections among these diverse possibilities have not been established. Here we show that the basomedial amygdala (BMA) represents the major target of ventral mPFC in amygdala in mice. Moreover, BMA neurons differentiate safe and aversive environments, and BMA activation decreases fear-related freezing and high-anxiety states. Lastly, we show that the ventral mPFC–BMA projection implements top-down control of anxiety state and learned freezing, both at baseline and in stress-induced anxiety, defining a broadly relevant new top-down behavioural regulation pathway. PMID:26536109

Rostral Ventral Medulla Cholinergic Mechanism in Pain-Induced Analgesia

PubMed Central

Gear, Robert W.; Levine, Jon D.

2009-01-01

The ascending nociceptive control (ANC), a novel spinostriatal pain modulation pathway, mediates a form of pain-induced analgesia referred to as noxious stimulus-induced antinociception (NSIA). ANC includes specific spinal cord mechanisms as well as circuitry in nucleus accumbens, a major component of the ventral striatum. Here, using the trigeminal jaw-opening reflex (JOR) in the rat as a nociceptive assay, we show that microinjection of the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine into the rostral ventral medulla (RVM) blocks NSIA, implicating RVM as a potentially important link between ANC and the PAG – RVM – spinal descending pain modulation system. A circuit connecting nucleus accumbens to the RVM is proposed as a novel striato-RVM pathway. PMID:19699268

Amygdaloid projections to the ventral striatum in mice: direct and indirect chemosensory inputs to the brain reward system.

PubMed

Novejarque, Amparo; Gutiérrez-Castellanos, Nicolás; Lanuza, Enrique; Martínez-García, Fernando

2011-01-01

Rodents constitute good models for studying the neural basis of sociosexual behavior. Recent findings in mice have revealed the molecular identity of the some pheromonal molecules triggering intersexual attraction. However, the neural pathways mediating this basic sociosexual behavior remain elusive. Since previous work indicates that the dopaminergic tegmento-striatal pathway is not involved in pheromone reward, the present report explores alternative pathways linking the vomeronasal system with the tegmento-striatal system (the limbic basal ganglia) by means of tract-tracing experiments studying direct and indirect projections from the chemosensory amygdala to the ventral striato-pallidum. Amygdaloid projections to the nucleus accumbens, olfactory tubercle, and adjoining structures are studied by analyzing the retrograde transport in the amygdala from dextran amine and fluorogold injections in the ventral striatum, as well as the anterograde labeling found in the ventral striato-pallidum after dextran amine injections in the amygdala. This combination of anterograde and retrograde tracing experiments reveals direct projections from the vomeronasal cortex to the ventral striato-pallidum, as well as indirect projections through different nuclei of the basolateral amygdala. Direct projections innervate mainly the olfactory tubercle and the islands of Calleja, whereas indirect projections are more widespread and reach the same structures and the shell and core of nucleus accumbens. These pathways are likely to mediate innate responses to pheromones (direct projections) and conditioned responses to associated chemosensory and non-chemosensory stimuli (indirect projections). Comparative studies indicate that similar connections are present in all the studied amniote vertebrates and might constitute the basic circuitry for emotional responses to conspecifics in most vertebrates, including humans.

Amygdaloid Projections to the Ventral Striatum in Mice: Direct and Indirect Chemosensory Inputs to the Brain Reward System

PubMed Central

Novejarque, Amparo; Gutiérrez-Castellanos, Nicolás; Lanuza, Enrique; Martínez-García, Fernando

2011-01-01

Rodents constitute good models for studying the neural basis of sociosexual behavior. Recent findings in mice have revealed the molecular identity of the some pheromonal molecules triggering intersexual attraction. However, the neural pathways mediating this basic sociosexual behavior remain elusive. Since previous work indicates that the dopaminergic tegmento-striatal pathway is not involved in pheromone reward, the present report explores alternative pathways linking the vomeronasal system with the tegmento-striatal system (the limbic basal ganglia) by means of tract-tracing experiments studying direct and indirect projections from the chemosensory amygdala to the ventral striato-pallidum. Amygdaloid projections to the nucleus accumbens, olfactory tubercle, and adjoining structures are studied by analyzing the retrograde transport in the amygdala from dextran amine and fluorogold injections in the ventral striatum, as well as the anterograde labeling found in the ventral striato-pallidum after dextran amine injections in the amygdala. This combination of anterograde and retrograde tracing experiments reveals direct projections from the vomeronasal cortex to the ventral striato-pallidum, as well as indirect projections through different nuclei of the basolateral amygdala. Direct projections innervate mainly the olfactory tubercle and the islands of Calleja, whereas indirect projections are more widespread and reach the same structures and the shell and core of nucleus accumbens. These pathways are likely to mediate innate responses to pheromones (direct projections) and conditioned responses to associated chemosensory and non-chemosensory stimuli (indirect projections). Comparative studies indicate that similar connections are present in all the studied amniote vertebrates and might constitute the basic circuitry for emotional responses to conspecifics in most vertebrates, including humans. PMID:22007159

Functional correlates of the anterolateral processing hierarchy in human auditory cortex.

PubMed

Chevillet, Mark; Riesenhuber, Maximilian; Rauschecker, Josef P

2011-06-22

Converging evidence supports the hypothesis that an anterolateral processing pathway mediates sound identification in auditory cortex, analogous to the role of the ventral cortical pathway in visual object recognition. Studies in nonhuman primates have characterized the anterolateral auditory pathway as a processing hierarchy, composed of three anatomically and physiologically distinct initial stages: core, belt, and parabelt. In humans, potential homologs of these regions have been identified anatomically, but reliable and complete functional distinctions between them have yet to be established. Because the anatomical locations of these fields vary across subjects, investigations of potential homologs between monkeys and humans require these fields to be defined in single subjects. Using functional MRI, we presented three classes of sounds (tones, band-passed noise bursts, and conspecific vocalizations), equivalent to those used in previous monkey studies. In each individual subject, three regions showing functional similarities to macaque core, belt, and parabelt were readily identified. Furthermore, the relative sizes and locations of these regions were consistent with those reported in human anatomical studies. Our results demonstrate that the functional organization of the anterolateral processing pathway in humans is largely consistent with that of nonhuman primates. Because our scanning sessions last only 15 min/subject, they can be run in conjunction with other scans. This will enable future studies to characterize functional modules in human auditory cortex at a level of detail previously possible only in visual cortex. Furthermore, the approach of using identical schemes in both humans and monkeys will aid with establishing potential homologies between them.

Emotion modulates activity in the 'what' but not 'where' auditory processing pathway.

PubMed

Kryklywy, James H; Macpherson, Ewan A; Greening, Steven G; Mitchell, Derek G V

2013-11-15

Auditory cortices can be separated into dissociable processing pathways similar to those observed in the visual domain. Emotional stimuli elicit enhanced neural activation within sensory cortices when compared to neutral stimuli. This effect is particularly notable in the ventral visual stream. Little is known, however, about how emotion interacts with dorsal processing streams, and essentially nothing is known about the impact of emotion on auditory stimulus localization. In the current study, we used fMRI in concert with individualized auditory virtual environments to investigate the effect of emotion during an auditory stimulus localization task. Surprisingly, participants were significantly slower to localize emotional relative to neutral sounds. A separate localizer scan was performed to isolate neural regions sensitive to stimulus location independent of emotion. When applied to the main experimental task, a significant main effect of location, but not emotion, was found in this ROI. A whole-brain analysis of the data revealed that posterior-medial regions of auditory cortex were modulated by sound location; however, additional anterior-lateral areas of auditory cortex demonstrated enhanced neural activity to emotional compared to neutral stimuli. The latter region resembled areas described in dual pathway models of auditory processing as the 'what' processing stream, prompting a follow-up task to generate an identity-sensitive ROI (the 'what' pathway) independent of location and emotion. Within this region, significant main effects of location and emotion were identified, as well as a significant interaction. These results suggest that emotion modulates activity in the 'what,' but not the 'where,' auditory processing pathway. Copyright © 2013 Elsevier Inc. All rights reserved.

Ulinastatin attenuates neuropathic pain induced by L5-VRT via the calcineurin/IL-10 pathway.

PubMed

Ouyang, Handong; Nie, Bilin; Wang, Peizong; Li, Qiang; Huang, Wan; Xin, Wenjun; Zeng, Weian; Liu, Xianguo

2016-01-01

Previous studies have shown that ulinastatin, an effective inhibitor of the inflammatory response in clinical applications, can attenuate hyperalgesia in rodents. However, the underlying mechanism remains unclear. In the present study, we first examined the change in the calcineurin level, which plays an important role in regulating cytokine release in the nervous system, following lumbar 5 ventral root transection in the rat. Furthermore, we determined whether intraperitoneal (i.p.) injection of ulinastatin attenuated pain behavior via inhibition of the calcineurin-mediated inflammatory response induced by lumbar 5 ventral root transection. The results showed that the paw withdrawal threshold and paw withdrawal latency were significantly decreased following lumbar 5 ventral root transection compared to the sham group. Neuropathic pain induced by lumbar 5 ventral root transection significantly decreased the expression of calcineurin in the DRG, and calcineurin was mostly located with NF-200-positive cells, IB4-positive cells, and CGRP-positive cells and less with GFAP-positive satellite cells. Furthermore, intrathecal (i.t.) injection of exogenous calcineurin attenuated the pain behavior induced by lumbar 5 ventral root transection. Importantly, intraperitoneal injection of ulinastatin alleviated the pain behavior and calcineurin downregulation induced by lumbar 5 ventral root transection. Lastly, the cytokine IL-10 was significantly decreased following lumbar 5 ventral root transection, and application of calcineurin (intrathecal) or ulinastatin (intraperitoneal) inhibited the IL-10 downregulation induced by lumbar 5 ventral root transection. These results suggested that ulinastatin, by acting on the CN/IL-10 pathway, might be a novel and effective drug for the treatment of neuropathic pain. © The Author(s) 2016.

Ulinastatin attenuates neuropathic pain induced by L5-VRT via the calcineurin/IL-10 pathway

PubMed Central

Ouyang, Handong; Nie, Bilin; Wang, Peizong; Li, Qiang; Huang, Wan; Xin, Wenjun; Liu, Xianguo

2016-01-01

Previous studies have shown that ulinastatin, an effective inhibitor of the inflammatory response in clinical applications, can attenuate hyperalgesia in rodents. However, the underlying mechanism remains unclear. In the present study, we first examined the change in the calcineurin level, which plays an important role in regulating cytokine release in the nervous system, following lumbar 5 ventral root transection in the rat. Furthermore, we determined whether intraperitoneal (i.p.) injection of ulinastatin attenuated pain behavior via inhibition of the calcineurin-mediated inflammatory response induced by lumbar 5 ventral root transection. The results showed that the paw withdrawal threshold and paw withdrawal latency were significantly decreased following lumbar 5 ventral root transection compared to the sham group. Neuropathic pain induced by lumbar 5 ventral root transection significantly decreased the expression of calcineurin in the DRG, and calcineurin was mostly located with NF-200-positive cells, IB4-positive cells, and CGRP-positive cells and less with GFAP-positive satellite cells. Furthermore, intrathecal (i.t.) injection of exogenous calcineurin attenuated the pain behavior induced by lumbar 5 ventral root transection. Importantly, intraperitoneal injection of ulinastatin alleviated the pain behavior and calcineurin downregulation induced by lumbar 5 ventral root transection. Lastly, the cytokine IL-10 was significantly decreased following lumbar 5 ventral root transection, and application of calcineurin (intrathecal) or ulinastatin (intraperitoneal) inhibited the IL-10 downregulation induced by lumbar 5 ventral root transection. These results suggested that ulinastatin, by acting on the CN/IL-10 pathway, might be a novel and effective drug for the treatment of neuropathic pain. PMID:27175013

Hand shape selection in pantomimed grasping: Interaction between the dorsal and the ventral visual streams and convergence on the ventral premotor area

PubMed Central

Makuuchi, Michiru; Someya, Yoshiaki; Ogawa, Seiji; Takayama, Yoshihiro

2011-01-01

In visually guided grasping, possible hand shapes are computed from the geometrical features of the object, while prior knowledge about the object and the goal of the action influence both the computation and the selection of the hand shape. We investigated the system dynamics of the human brain for the pantomiming of grasping with two aspects accentuated. One is object recognition, with the use of objects for daily use. The subjects mimed grasping movements appropriate for an object presented in a photograph either by precision or power grip. The other is the selection of grip hand shape. We manipulated the selection demands for the grip hand shape by having the subjects use the same or different grip type in the second presentation of the identical object. Effective connectivity analysis revealed that the increased selection demands enhance the interaction between the anterior intraparietal sulcus (AIP) and posterior inferior temporal gyrus (pITG), and drive the converging causal influences from the AIP, pITG, and dorsolateral prefrontal cortex to the ventral premotor area (PMv). These results suggest that the dorsal and ventral visual areas interact in the pantomiming of grasping, while the PMv integrates the neural information of different regions to select the hand posture. The present study proposes system dynamics in visually guided movement toward meaningful objects, but further research is needed to examine if the same dynamics is found also in real grasping. PMID:21739528

Increasingly complex representations of natural movies across the dorsal stream are shared between subjects.

PubMed

Güçlü, Umut; van Gerven, Marcel A J

2017-01-15

Recently, deep neural networks (DNNs) have been shown to provide accurate predictions of neural responses across the ventral visual pathway. We here explore whether they also provide accurate predictions of neural responses across the dorsal visual pathway, which is thought to be devoted to motion processing and action recognition. This is achieved by training deep neural networks to recognize actions in videos and subsequently using them to predict neural responses while subjects are watching natural movies. Moreover, we explore whether dorsal stream representations are shared between subjects. In order to address this question, we examine if individual subject predictions can be made in a common representational space estimated via hyperalignment. Results show that a DNN trained for action recognition can be used to accurately predict how dorsal stream responds to natural movies, revealing a correspondence in representations of DNN layers and dorsal stream areas. It is also demonstrated that models operating in a common representational space can generalize to responses of multiple or even unseen individual subjects to novel spatio-temporal stimuli in both encoding and decoding settings, suggesting that a common representational space underlies dorsal stream responses across multiple subjects. Copyright © 2015 Elsevier Inc. All rights reserved.

Understanding human visual systems and its impact on our intelligent instruments

NASA Astrophysics Data System (ADS)

Strojnik Scholl, Marija; Páez, Gonzalo; Scholl, Michelle K.

2013-09-01

We review the evolution of machine vision and comment on the cross-fertilization from the neural sciences onto flourishing fields of neural processing, parallel processing, and associative memory in optical sciences and computing. Then we examine how the intensive efforts in mapping the human brain have been influenced by concepts in computer sciences, control theory, and electronic circuits. We discuss two neural paths that employ the input from the vision sense to determine the navigational options and object recognition. They are ventral temporal pathway for object recognition (what?) and dorsal parietal pathway for navigation (where?), respectively. We describe the reflexive and conscious decision centers in cerebral cortex involved with visual attention and gaze control. Interestingly, these require return path though the midbrain for ocular muscle control. We find that the cognitive psychologists currently study human brain employing low-spatial-resolution fMRI with temporal response on the order of a second. In recent years, the life scientists have concentrated on insect brains to study neural processes. We discuss how reflexive and conscious gaze-control decisions are made in the frontal eye field and inferior parietal lobe, constituting the fronto-parietal attention network. We note that ethical and experiential learnings impact our conscious decisions.

Visual Sexual Stimulation and Erection, a Brief Review with New fMRI Data.

PubMed

Wu, Sharon L; Chow, Maggie S M; L, Jiang Y; Yang, Jingjin; Zhou, Hao; Yew, David T

2017-05-31

This review examines brain sites involved in sexual stimulation. New data on brain activation sites in individuals having erections concomitant with visual erotic stimulation were documented. The activation was chiefly at the midbrain around the cerebral peduncle, and in the pons centering on the tegmentum, they are indicated by blood oxygenation level dependent (BOLD) images captured by functional magnetic resonance imaging (fMRI). The cerebellum and inferior temporal lobe were activated more extensively in individuals viewing pornographic movie with a concomitant erection than those without. Similarly, individuals with erection had activations in the midbrain and pons, while drug addicts had neither erections nor any of these brainstem active sites. From our observation in the new data, we deduced three possible transmitters might be involved in erection: i) cholinergic neurons forming descending pathways and associated with motor activity ii) gamma-aminobutyric acid (GABA), directly or indirectly via decreasing pathways, modulating autonomic vascular responses in the penile vasculature causing the filling of blood iii) GABA decreases to stimulate dopamine increase in ventral tegmentum of the brain, leading to euphoric responses. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Glycinergic Pathways of the Central Auditory System and Adjacent Reticular Formation of the Rat.

NASA Astrophysics Data System (ADS)

Hunter, Chyren

The development of techniques to visualize and identify specific transmitters of neuronal circuits has stimulated work on the characterization of pathways in the rat central nervous system that utilize the inhibitory amino acid glycine as its neurotransmitter. Glycine is a major inhibitory transmitter in the spinal cord and brainstem of vertebrates where it satisfies the major criteria for neurotransmitter action. Some of these characteristics are: uneven distribution in brain, high affinity reuptake mechanisms, inhibitory neurophysiological actions on certain neuronal populations, uneven receptor distribution and the specific antagonism of its actions by the convulsant alkaloid strychnine. Behaviorally, antagonism of glycinergic neurotransmission in the medullary reticular formation is linked to the development of myoclonus and seizures which may be initiated by auditory as well as other stimuli. In the present study, decreases in the concentration of glycine as well as the density of glycine receptors in the medulla with aging were found and may be responsible for the lowered threshold for strychnine seizures observed in older rats. Neuroanatomical pathways in the central auditory system and medullary and pontine reticular formation (RF) were investigated using retrograde transport of tritiated glycine to identify glycinergic pathways; immunohistochemical techniques were used to corroborate the location of glycine neurons. Within the central auditory system, retrograde transport studies using tritiated glycine demonstrated an ipsilateral glycinergic pathway linking nuclei of the ascending auditory system. This pathway has its cell bodies in the medial nucleus of the trapezoid body (MNTB) and projects to the ventrocaudal division of the ventral nucleus of the lateral lemniscus (VLL). Collaterals of this glycinergic projection terminate in the ipsilateral lateral superior olive (LSO). Other glycinergic pathways found were afferent to the VLL and have their origin in the ventral and lateral nuclei of the trapezoid body (MVPO and LVPO). Bilateral projections from the nucleus reticularis pontis oralis (RPOo), to the VLL were also identified as glycinergic. This projection may link motor output systems to ascending auditory input, generating the auditory behavioral responses seen with glycine antagonism in animal models of myoclonus and seizure.

Network analysis of corticocortical connections reveals ventral and dorsal processing streams in mouse visual cortex

PubMed Central

Wang, Quanxin; Sporns, Olaf; Burkhalter, Andreas

2012-01-01

Much of the information used for visual perception and visually guided actions is processed in complex networks of connections within the cortex. To understand how this works in the normal brain and to determine the impact of disease, mice are promising models. In primate visual cortex, information is processed in a dorsal stream specialized for visuospatial processing and guided action and a ventral stream for object recognition. Here, we traced the outputs of 10 visual areas and used quantitative graph analytic tools of modern network science to determine, from the projection strengths in 39 cortical targets, the community structure of the network. We found a high density of the cortical graph that exceeded that previously shown in monkey. Each source area showed a unique distribution of projection weights across its targets (i.e. connectivity profile) that was well-fit by a lognormal function. Importantly, the community structure was strongly dependent on the location of the source area: outputs from medial/anterior extrastriate areas were more strongly linked to parietal, motor and limbic cortex, whereas lateral extrastriate areas were preferentially connected to temporal and parahippocampal cortex. These two subnetworks resemble dorsal and ventral cortical streams in primates, demonstrating that the basic layout of cortical networks is conserved across species. PMID:22457489

Do Visual Illusions Probe the Visual Brain?: Illusions in Action without a Dorsal Visual Stream

ERIC Educational Resources Information Center

Coello, Yann; Danckert, James; Blangero, Annabelle; Rossetti, Yves

2007-01-01

Visual illusions have been shown to affect perceptual judgements more so than motor behaviour, which was interpreted as evidence for a functional division of labour within the visual system. The dominant perception-action theory argues that perception involves a holistic processing of visual objects or scenes, performed within the ventral,…

A fish eye out of water: epithelial surface projections on aerial and aquatic corneas of the 'four-eyed fish' Anableps anableps.

PubMed

Simmich, Joshua; Temple, Shelby E; Collin, Shaun P

2012-03-01

Vertebrate corneas feature a variety of microprojections, to which a tear film adheres. These microprojections are formed by folds in epithelial cell membranes, which increase surface area, stabilise the tear film and enhance movement of nutritional and waste products across cell membranes. Differences in corneal microprojections among vertebrates have been correlated with habitat and differ markedly between terrestrial and aquatic species. This study investigated epithelial microprojections of both the aerial (dorsal) and aquatic (ventral) corneal surfaces of the 'four-eyed fish' Anableps anableps using scanning electron microscopy. The central region of the dorsal cornea, which projects above the water, had a density of 16,387 ± 3,995 cells per mm(2) , while the central region of the ventral cornea (underwater) had a density of 22,428 ± 6,387 cells per mm(2), a difference that suggests an environmental adaptation along the two visual axes. Both corneal surfaces were found to possess microridges rather than microvilli or microplicae characteristic of terrestrial/aerial vertebrates. Microridges were 142 ± 9 nm wide and did not differ (p = 0.757) between dorsal and ventral corneas. Microridges were consistently separated by a distance of 369 ± 9 nm across both corneas. Dorsal-ventral differences in corneal epithelial cell density in Anableps anableps suggest a difference in osmotic pressure of the two corneas. The modest differences in the microprojections indicate that the need to secure the tear film underlying each optical axis is of prime importance, due to the likelihood that a persistent layer of water normally covers both dorsal and ventral corneal surfaces and that maintaining a transparent optical pathway for vision is critical for a species prone to predation from both above and below the water's surface. © 2012 The Authors. Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

The anatomy of object recognition--visual form agnosia caused by medial occipitotemporal stroke.

PubMed

Karnath, Hans-Otto; Rüter, Johannes; Mandler, André; Himmelbach, Marc

2009-05-06

The influential model on visual information processing by Milner and Goodale (1995) has suggested a dissociation between action- and perception-related processing in a dorsal versus ventral stream projection. It was inspired substantially by the observation of a double dissociation of disturbed visual action versus perception in patients with optic ataxia on the one hand and patients with visual form agnosia (VFA) on the other. Unfortunately, almost all cases with VFA reported so far suffered from inhalational intoxication, the majority with carbon monoxide (CO). Since CO induces a diffuse and widespread pattern of neuronal and white matter damage throughout the whole brain, precise conclusions from these patients with VFA on the selective role of ventral stream structures for shape and orientation perception were difficult. Here, we report patient J.S., who demonstrated VFA after a well circumscribed brain lesion due to stroke etiology. Like the famous patient D.F. with VFA after CO intoxication studied by Milner, Goodale, and coworkers (Goodale et al., 1991, 1994; Milner et al., 1991; Servos et al., 1995; Mon-Williams et al., 2001a,b; Wann et al., 2001; Westwood et al., 2002; McIntosh et al., 2004; Schenk and Milner, 2006), J.S. showed an obvious dissociation between disturbed visual perception of shape and orientation information on the one side and preserved visuomotor abilities based on the same information on the other. In both hemispheres, damage primarily affected the fusiform and the lingual gyri as well as the adjacent posterior cingulate gyrus. We conclude that these medial structures of the ventral occipitotemporal cortex are integral for the normal flow of shape and of contour information into the ventral stream system allowing to recognize objects.

Direct evidence for the contributive role of the right inferior fronto-occipital fasciculus in non-verbal semantic cognition.

PubMed

Herbet, Guillaume; Moritz-Gasser, Sylvie; Duffau, Hugues

2017-05-01

The neural foundations underlying semantic processing have been extensively investigated, highlighting a pivotal role of the ventral stream. However, although studies concerning the involvement of the left ventral route in verbal semantics are proficient, the potential implication of the right ventral pathway in non-verbal semantics has been to date unexplored. To gain insights on this matter, we used an intraoperative direct electrostimulation to map the structures mediating the non-verbal semantic system in the right hemisphere. Thirteen patients presenting with a right low-grade glioma located within or close to the ventral stream were included. During the 'awake' procedure, patients performed both a visual non-verbal semantic task and a verbal (control) task. At the cortical level, in the right hemisphere, we found non-verbal semantic-related sites (n = 7 in 6 patients) in structures commonly associated with verbal semantic processes in the left hemisphere, including the superior temporal gyrus, the pars triangularis, and the dorsolateral prefrontal cortex. At the subcortical level, we found non-verbal semantic-related sites in all but one patient (n = 15 sites in 12 patients). Importantly, all these responsive stimulation points were located on the spatial course of the right inferior fronto-occipital fasciculus (IFOF). These findings provide direct support for a critical role of the right IFOF in non-verbal semantic processing. Based upon these original data, and in connection with previous findings showing the involvement of the left IFOF in non-verbal semantic processing, we hypothesize the existence of a bilateral network underpinning the non-verbal semantic system, with a homotopic connectional architecture.

Visual processing deficits in 22q11.2 Deletion Syndrome.

PubMed

Biria, Marjan; Tomescu, Miralena I; Custo, Anna; Cantonas, Lucia M; Song, Kun-Wei; Schneider, Maude; Murray, Micah M; Eliez, Stephan; Michel, Christoph M; Rihs, Tonia A

2018-01-01

Carriers of the rare 22q11.2 microdeletion present with a high percentage of positive and negative symptoms and a high genetic risk for schizophrenia. Visual processing impairments have been characterized in schizophrenia, but less so in 22q11.2 Deletion Syndrome (DS). Here, we focus on visual processing using high-density EEG and source imaging in 22q11.2DS participants (N = 25) and healthy controls (N = 26) with an illusory contour discrimination task. Significant differences between groups emerged at early and late stages of visual processing. In 22q11.2DS, we first observed reduced amplitudes over occipital channels and reduced source activations within dorsal and ventral visual stream areas during the P1 (100-125 ms) and within ventral visual cortex during the N1 (150-170 ms) visual evoked components. During a later window implicated in visual completion (240-285 ms), we observed an increase in global amplitudes in 22q11.2DS. The increased surface amplitudes for illusory contours at this window were inversely correlated with positive subscales of prodromal symptoms in 22q11.2DS. The reduced activity of ventral and dorsal visual areas during early stages points to an impairment in visual processing seen both in schizophrenia and 22q11.2DS. During intervals related to perceptual closure, the inverse correlation of high amplitudes with positive symptoms suggests that participants with 22q11.2DS who show an increased brain response to illusory contours during the relevant window for contour processing have less psychotic symptoms and might thus be at a reduced prodromal risk for schizophrenia.

The functional architecture of the ventral temporal cortex and its role in categorization

PubMed Central

Grill-Spector, Kalanit; Weiner, Kevin S.

2014-01-01

Visual categorization is thought to occur in the human ventral temporal cortex (VTC), but how this categorization is achieved is still largely unknown. In this Review, we consider the computations and representations that are necessary for categorization and examine how the microanatomical and macroanatomical layout of the VTC might optimize them to achieve rapid and flexible visual categorization. We propose that efficient categorization is achieved by organizing representations in a nested spatial hierarchy in the VTC. This spatial hierarchy serves as a neural infrastructure for the representational hierarchy of visual information in the VTC and thereby enables flexible access to category information at several levels of abstraction. PMID:24962370

Ventral medullary neurones excited from the hypothalamic and mid-brain defence areas.

PubMed

Hilton, S M; Smith, P R

1984-07-01

In cats anaesthetised with chloralose, the ventral medulla was explored in and around the strip previously identified as the location of the efferent pathway from the hypothalamic and mid-brain defence areas to the spinal cord, in a search for neurones excited by electrical stimulation of the defence areas. Such units were found mostly in the caudal part of this strip, at a depth of not more than 500 microns from the surface. Nearly all were located in the ventral part of nucleus paragigantocellularis lateralis (PGL) at the level of the rostral pole of the inferior olive. There was evidence of temporal and spatial facilitation, indicating a convergent excitatory input from the defence areas onto neurones in PGL. This is consistent with earlier evidence of a synaptic relay in the efferent pathway at this site. When the pathway is blocked at this site, arterial blood pressure falls profoundly, so activity in these neurones may be essential for the normal level of sympathetic nerve activity.

Transport for language south of the Sylvian fissure: The routes and history of the main tracts and stations in the ventral language network.

PubMed

Bajada, Claude J; Lambon Ralph, Matthew A; Cloutman, Lauren L

2015-08-01

It is now ten years since a 'ventral language pathway' was demonstrated in vivo in the human brain. In the intervening decade, this result has been replicated and expanded to include multiple possible pathways and functions. Despite this considerable level of research interest, age-old debates regarding the origin, course, termination and, indeed, the very existence of the tracts identified still remain. The current review examines four major tracts associated with the ventral 'semantic' language network, with the aim of elucidating and clarifying their structural and functional roles. Historical and modern conceptualisations of the tracts' neuroanatomical origins and terminations will be discussed, and key discrepancies and debates examined. It is argued that much of the controversy regarding the language pathways has resulted from inconsistencies in terminology, and the lack of a white matter 'lingua franca'. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

A double dissociation of dorsal and ventral hippocampal function on a learning and memory task mediated by the dorso-lateral striatum.

PubMed

McDonald, Robert J; Jones, Jana; Richards, Blake; Hong, Nancy S

2006-09-01

The objectives of this research were to further delineate the neural circuits subserving proposed memory-based behavioural subsystems in the hippocampal formation. These studies were guided by anatomical evidence showing a topographical organization of the hippocampal formation. Briefly, perpendicular to the medial/lateral entorhinal cortex division there is a second system of parallel circuits that separates the dorsal and ventral hippocampus. Recent work from this laboratory has provided evidence that the hippocampus incidentally encodes a context-specific inhibitory association during acquisition of a visual discrimination task. One question that emerges from this dataset is whether the dorsal or ventral hippocampus makes a unique contribution to this newly described function. Rats with neurotoxic lesions of the dorsal or ventral hippocampus were assessed on the acquisition of the visual discrimination task. Following asymptotic performance they were given reversal training in either the same or a different context from the original training. The results showed that the context-specific inhibition effect is mediated by a circuit that includes the ventral but not the dorsal hippocampus. Results from a control procedure showed that rats with either dorso-lateral striatum damage or dorsal hippocampal lesions were impaired on a tactile/spatial discrimination. Taken together, the results represent a double dissociation of learning and memory function between the ventral and dorsal hippocampus. The formation of an incidental inhibitory association was dependent on ventral but not dorsal hippocampal circuitry, and the opposite dependence was found for the spatial component of a tactile/spatial discrimination.

Essential roles of zebrafish bmp2a, fgf10, and fgf24 in the specification of the ventral pancreas

PubMed Central

Naye, François; Voz, Marianne L.; Detry, Nathalie; Hammerschmidt, Matthias; Peers, Bernard; Manfroid, Isabelle

2012-01-01

In vertebrates, pancreas and liver arise from bipotential progenitors located in the embryonic gut endoderm. Bone morphogenic protein (BMP) and fibroblast growth factor (FGF) signaling pathways have been shown to induce hepatic specification while repressing pancreatic fate. Here we show that BMP and FGF factors also play crucial function, at slightly later stages, in the specification of the ventral pancreas. By analyzing the pancreatic markers pdx1, ptf1a, and hlxb9la in different zebrafish models of BMP loss of function, we demonstrate that the BMP pathway is required between 20 and 24 h postfertilization to specify the ventral pancreatic bud. Knockdown experiments show that bmp2a, expressed in the lateral plate mesoderm at these stages, is essential for ventral pancreas specification. Bmp2a action is not restricted to the pancreatic domain and is also required for the proper expression of hepatic markers. By contrast, through the analysis of fgf10−/−; fgf24−/− embryos, we reveal the specific role of these two FGF ligands in the induction of the ventral pancreas and in the repression of the hepatic fate. These mutants display ventral pancreas agenesis and ectopic masses of hepatocytes. Overall, these data highlight the dynamic role of BMP and FGF in the patterning of the hepatopancreatic region. PMID:22219376

Hedgehog-responsive candidate cell of origin for diffuse intrinsic pontine glioma

PubMed Central

Monje, Michelle; Mitra, Siddhartha S.; Freret, Morgan E.; Raveh, Tal B.; Kim, James; Masek, Marilyn; Attema, Joanne L.; Haddix, Terri; Edwards, Michael S. B.; Fisher, Paul G.; Weissman, Irving L.; Rowitch, David H.; Vogel, Hannes; Wong, Albert J.; Beachy, Philip A.

2011-01-01

Diffuse intrinsic pontine gliomas (DIPGs) are highly aggressive tumors of childhood that are almost universally fatal. Our understanding of this devastating cancer is limited by a dearth of available tissue for study and by the lack of a faithful animal model. Intriguingly, DIPGs are restricted to the ventral pons and occur during a narrow window of middle childhood, suggesting dysregulation of a postnatal neurodevelopmental process. Here, we report the identification of a previously undescribed population of immunophenotypic neural precursor cells in the human and murine brainstem whose temporal and spatial distributions correlate closely with the incidence of DIPG and highlight a candidate cell of origin. Using early postmortem DIPG tumor tissue, we have established in vitro and xenograft models and find that the Hedgehog (Hh) signaling pathway implicated in many developmental and oncogenic processes is active in DIPG tumor cells. Modulation of Hh pathway activity has functional consequences for DIPG self-renewal capacity in neurosphere culture. The Hh pathway also appears to be active in normal ventral pontine precursor-like cells of the mouse, and unregulated pathway activity results in hypertrophy of the ventral pons. Together, these findings provide a foundation for understanding the cellular and molecular origins of DIPG, and suggest that the Hh pathway represents a potential therapeutic target in this devastating pediatric tumor. PMID:21368213

Assessing visual requirements for social context-dependent activation of the songbird song system

PubMed Central

Hara, Erina; Kubikova, Lubica; Hessler, Neal A.; Jarvis, Erich D.

2008-01-01

Social context has been shown to have a profound influence on brain activation in a wide range of vertebrate species. Best studied in songbirds, when males sing undirected song, the level of neural activity and expression of immediate early genes (IEGs) in several song nuclei is dramatically higher or lower than when they sing directed song to other birds, particularly females. This differential social context-dependent activation is independent of auditory input and is not simply dependent on the motor act of singing. These findings suggested that the critical sensory modality driving social context-dependent differences in the brain could be visual cues. Here, we tested this hypothesis by examining IEG activation in song nuclei in hemispheres to which visual input was normal or blocked. We found that covering one eye blocked visually induced IEG expression throughout both contralateral visual pathways of the brain, and reduced activation of the contralateral ventral tegmental area, a non-visual midbrain motivation-related area affected by social context. However, blocking visual input had no effect on the social context-dependent activation of the contralateral song nuclei during female-directed singing. Our findings suggest that individual sensory modalities are not direct driving forces for the social context differences in song nuclei during singing. Rather, these social context differences in brain activation appear to depend more on the general sense that another individual is present. PMID:18826930

Distinctive Correspondence Between Separable Visual Attention Functions and Intrinsic Brain Networks

PubMed Central

Ruiz-Rizzo, Adriana L.; Neitzel, Julia; Müller, Hermann J.; Sorg, Christian; Finke, Kathrin

2018-01-01

Separable visual attention functions are assumed to rely on distinct but interacting neural mechanisms. Bundesen's “theory of visual attention” (TVA) allows the mathematical estimation of independent parameters that characterize individuals' visual attentional capacity (i.e., visual processing speed and visual short-term memory storage capacity) and selectivity functions (i.e., top-down control and spatial laterality). However, it is unclear whether these parameters distinctively map onto different brain networks obtained from intrinsic functional connectivity, which organizes slowly fluctuating ongoing brain activity. In our study, 31 demographically homogeneous healthy young participants performed whole- and partial-report tasks and underwent resting-state functional magnetic resonance imaging (rs-fMRI). Report accuracy was modeled using TVA to estimate, individually, the four TVA parameters. Networks encompassing cortical areas relevant for visual attention were derived from independent component analysis of rs-fMRI data: visual, executive control, right and left frontoparietal, and ventral and dorsal attention networks. Two TVA parameters were mapped on particular functional networks. First, participants with higher (vs. lower) visual processing speed showed lower functional connectivity within the ventral attention network. Second, participants with more (vs. less) efficient top-down control showed higher functional connectivity within the dorsal attention network and lower functional connectivity within the visual network. Additionally, higher performance was associated with higher functional connectivity between networks: specifically, between the ventral attention and right frontoparietal networks for visual processing speed, and between the visual and executive control networks for top-down control. The higher inter-network functional connectivity was related to lower intra-network connectivity. These results demonstrate that separable visual attention parameters that are assumed to constitute relatively stable traits correspond distinctly to the functional connectivity both within and between particular functional networks. This implies that individual differences in basic attention functions are represented by differences in the coherence of slowly fluctuating brain activity. PMID:29662444

Distinctive Correspondence Between Separable Visual Attention Functions and Intrinsic Brain Networks.

PubMed

Ruiz-Rizzo, Adriana L; Neitzel, Julia; Müller, Hermann J; Sorg, Christian; Finke, Kathrin

2018-01-01

Separable visual attention functions are assumed to rely on distinct but interacting neural mechanisms. Bundesen's "theory of visual attention" (TVA) allows the mathematical estimation of independent parameters that characterize individuals' visual attentional capacity (i.e., visual processing speed and visual short-term memory storage capacity) and selectivity functions (i.e., top-down control and spatial laterality). However, it is unclear whether these parameters distinctively map onto different brain networks obtained from intrinsic functional connectivity, which organizes slowly fluctuating ongoing brain activity. In our study, 31 demographically homogeneous healthy young participants performed whole- and partial-report tasks and underwent resting-state functional magnetic resonance imaging (rs-fMRI). Report accuracy was modeled using TVA to estimate, individually, the four TVA parameters. Networks encompassing cortical areas relevant for visual attention were derived from independent component analysis of rs-fMRI data: visual, executive control, right and left frontoparietal, and ventral and dorsal attention networks. Two TVA parameters were mapped on particular functional networks. First, participants with higher (vs. lower) visual processing speed showed lower functional connectivity within the ventral attention network. Second, participants with more (vs. less) efficient top-down control showed higher functional connectivity within the dorsal attention network and lower functional connectivity within the visual network. Additionally, higher performance was associated with higher functional connectivity between networks: specifically, between the ventral attention and right frontoparietal networks for visual processing speed, and between the visual and executive control networks for top-down control. The higher inter-network functional connectivity was related to lower intra-network connectivity. These results demonstrate that separable visual attention parameters that are assumed to constitute relatively stable traits correspond distinctly to the functional connectivity both within and between particular functional networks. This implies that individual differences in basic attention functions are represented by differences in the coherence of slowly fluctuating brain activity.

UNC-108/Rab2 Regulates Postendocytic Trafficking in Caenorhabditis elegans

PubMed Central

Chun, Denise K.; McEwen, Jason M.; Burbea, Michelle

2008-01-01

After endocytosis, membrane proteins are often sorted between two alternative pathways: a recycling pathway and a degradation pathway. Relatively little is known about how trafficking through these alternative pathways is differentially regulated. Here, we identify UNC-108/Rab2 as a regulator of postendocytic trafficking in both neurons and coelomocytes. Mutations in the Caenorhabditis elegans Rab2 gene unc-108, caused the green fluorescent protein (GFP)-tagged glutamate receptor GLR-1 (GLR-1::GFP) to accumulate in the ventral cord and in neuronal cell bodies. In neuronal cell bodies of unc-108/Rab2 mutants, GLR-1::GFP was found in tubulovesicular structures that colocalized with markers for early and recycling endosomes, including Syntaxin-13 and Rab8. GFP-tagged Syntaxin-13 also accumulated in the ventral cord of unc-108/Rab2 mutants. UNC-108/Rab2 was not required for ubiquitin-mediated sorting of GLR-1::GFP into the multivesicular body (MVB) degradation pathway. Mutations disrupting the MVB pathway and unc-108/Rab2 mutations had additive effects on GLR-1::GFP levels in the ventral cord. In coelomocytes, postendocytic trafficking of the marker Texas Red-bovine serum albumin was delayed. These results demonstrate that UNC-108/Rab2 regulates postendocytic trafficking, most likely at the level of early or recycling endosomes, and that UNC-108/Rab2 and the MVB pathway define alternative postendocytic trafficking mechanisms that operate in parallel. These results define a new function for Rab2 in protein trafficking. PMID:18434599

Neural Representations of Natural and Scrambled Movies Progressively Change from Rat Striate to Temporal Cortex

PubMed Central

Vinken, Kasper; Van den Bergh, Gert; Vermaercke, Ben; Op de Beeck, Hans P.

2016-01-01

In recent years, the rodent has come forward as a candidate model for investigating higher level visual abilities such as object vision. This view has been backed up substantially by evidence from behavioral studies that show rats can be trained to express visual object recognition and categorization capabilities. However, almost no studies have investigated the functional properties of rodent extrastriate visual cortex using stimuli that target object vision, leaving a gap compared with the primate literature. Therefore, we recorded single-neuron responses along a proposed ventral pathway in rat visual cortex to investigate hallmarks of primate neural object representations such as preference for intact versus scrambled stimuli and category-selectivity. We presented natural movies containing a rat or no rat as well as their phase-scrambled versions. Population analyses showed increased dissociation in representations of natural versus scrambled stimuli along the targeted stream, but without a clear preference for natural stimuli. Along the measured cortical hierarchy the neural response seemed to be driven increasingly by features that are not V1-like and destroyed by phase-scrambling. However, there was no evidence for category selectivity for the rat versus nonrat distinction. Together, these findings provide insights about differences and commonalities between rodent and primate visual cortex. PMID:27146315

Dorsal and ventral working memory-related brain areas support distinct processes in contextual cueing.

PubMed

Manginelli, Angela A; Baumgartner, Florian; Pollmann, Stefan

2013-02-15

Behavioral evidence suggests that the use of implicitly learned spatial contexts for improved visual search may depend on visual working memory resources. Working memory may be involved in contextual cueing in different ways: (1) for keeping implicitly learned working memory contents available during search or (2) for the capture of attention by contexts retrieved from memory. We mapped brain areas that were modulated by working memory capacity. Within these areas, activation was modulated by contextual cueing along the descending segment of the intraparietal sulcus, an area that has previously been related to maintenance of explicit memories. Increased activation for learned displays, but not modulated by the size of contextual cueing, was observed in the temporo-parietal junction area, previously associated with the capture of attention by explicitly retrieved memory items, and in the ventral visual cortex. This pattern of activation extends previous research on dorsal versus ventral stream functions in memory guidance of attention to the realm of attentional guidance by implicit memory. Copyright © 2012 Elsevier Inc. All rights reserved.

Functional redundancy of ventral spinal locomotor pathways.

PubMed

Loy, David N; Magnuson, David S K; Zhang, Y Ping; Onifer, Stephen M; Mills, Michael D; Cao, Qi-lin; Darnall, Jessica B; Fajardo, Lily C; Burke, Darlene A; Whittemore, Scott R

2002-01-01

Identification of long tracts responsible for the initiation of spontaneous locomotion is critical for spinal cord injury (SCI) repair strategies. Pathways derived from the mesencephalic locomotor region and pontomedullary medial reticular formation responsible for fictive locomotion in decerebrate preparations project to the thoracolumbar levels of the spinal cord via reticulospinal axons in the ventrolateral funiculus (VLF). However, white matter regions critical for spontaneous over-ground locomotion remain unclear because cats, monkeys, and humans display varying degrees of locomotor recovery after ventral SCIs. We studied the contributions of myelinated tracts in the VLF and ventral columns (VC) to spontaneous over-ground locomotion in the adult rat using demyelinating lesions. Animals received ethidium bromide plus photon irradiation producing discrete demyelinating lesions sufficient to stop axonal conduction in the VLF, VC, VLF-VC, or complete ventral white matter (CV). Behavior [open-field Basso, Beattie, and Bresnahan (BBB) scores and grid walking] and transcranial magnetic motor-evoked potentials (tcMMEP) were studied at 1, 2, and 4 weeks after lesion. VLF lesions resulted in complete loss or severe attenuation of tcMMEPs, with mean BBB scores of 18.0, and no grid walking deficits. VC lesions produced behavior similar to VLF-lesioned animals but did not significantly affect tcMMEPs. VC-VLF and CV lesions resulted in complete loss of tcMMEP signals with mean BBB scores of 12.7 and 6.5, respectively. Our data support a diffuse arrangement of axons within the ventral white matter that may comprise a system of multiple descending pathways subserving spontaneous over-ground locomotion in the intact animal.

The dissociations of visual processing of "hole" and "no-hole" stimuli: An functional magnetic resonance imaging study.

PubMed

Meng, Qianli; Huang, Yan; Cui, Ding; He, Lixia; Chen, Lin; Ma, Yuanye; Zhao, Xudong

2018-05-01

"Where to begin" is a fundamental question of vision. A "Global-first" topological approach proposed that the first step in object representation was to extract topological properties, especially whether the object had a hole or not. Numerous psychophysical studies found that the hole (closure) could be rapidly recognized by visual system as a primitive property. However, neuroimaging studies showed that the temporal lobe (IT), which lied at a late stage of ventral pathway, was involved as a dedicated region. It appeared paradoxical that IT served as a key region for processing the early component of visual information. Did there exist a distinct fast route to transit hole information to IT? We hypothesized that a fast noncortical pathway might participate in processing holes. To address this issue, a backward masking paradigm combined with functional magnetic resonance imaging (fMRI) was applied to measure neural responses to hole and no-hole stimuli in anatomically defined cortical and subcortical regions of interest (ROIs) under different visual awareness levels by modulating masking delays. For no-hole stimuli, the neural activation of cortical sites was greatly attenuated when the no-hole perception was impaired by strong masking, whereas an enhanced neural response to hole stimuli in non-cortical sites was obtained when the stimulus was rendered more invisible. The results suggested that whereas the cortical route was required to drive a perceptual response for no-hole stimuli, a subcortical route might be involved in coding the hole feature, resulting in a rapid hole perception in primitive vision.

High-level, but not low-level, motion perception is impaired in patients with schizophrenia.

PubMed

Kandil, Farid I; Pedersen, Anya; Wehnes, Jana; Ohrmann, Patricia

2013-01-01

Smooth pursuit eye movements are compromised in patients with schizophrenia and their first-degree relatives. Although research has demonstrated that the motor components of smooth pursuit eye movements are intact, motion perception has been shown to be impaired. In particular, studies have consistently revealed deficits in performance on tasks specific to the high-order motion area V5 (middle temporal area, MT) in patients with schizophrenia. In contrast, data from low-level motion detectors in the primary visual cortex (V1) have been inconsistent. To differentiate between low-level and high-level visual motion processing, we applied a temporal-order judgment task for motion events and a motion-defined figure-ground segregation task using patients with schizophrenia and healthy controls. Successful judgments in both tasks rely on the same low-level motion detectors in the V1; however, the first task is further processed in the higher-order motion area MT in the magnocellular (dorsal) pathway, whereas the second task requires subsequent computations in the parvocellular (ventral) pathway in visual area V4 and the inferotemporal cortex (IT). These latter structures are supposed to be intact in schizophrenia. Patients with schizophrenia revealed a significantly impaired temporal resolution on the motion-based temporal-order judgment task but only mild impairment in the motion-based segregation task. These results imply that low-level motion detection in V1 is not, or is only slightly, compromised; furthermore, our data restrain the locus of the well-known deficit in motion detection to areas beyond the primary visual cortex.

The magnocellular visual pathway and facial emotion misattribution errors in schizophrenia.

PubMed

Bedwell, Jeffrey S; Chan, Chi C; Cohen, Ovad; Karbi, Yinnon; Shamir, Eyal; Rassovsky, Yuri

2013-07-01

Many individuals with schizophrenia show impairment in labeling the emotion depicted by faces, and tend to ascribe anger or fear to neutral expressions. Preliminary research has linked some of these difficulties to dysfunction in the magnocellular (M) visual pathway, which has direct projections to subcortical emotion processing regions. The current study attempted to clarify these relationships using a novel paradigm that included a red background. Diffuse red light is known to suppress the M-pathway in nonpsychiatric adults, and there is preliminary evidence that it may have the opposite (stimulating) effect in schizophrenia-spectrum disorders (SSDs). Twenty-five individuals with SSDs were compared with 31 nonpsychiatric controls using a facial emotion identification task depicting happy, angry, fearful, and sad emotions on red, green, and gray backgrounds. There was a robust interaction of group by change in errors to the red (vs. green) background for misattributing fear expressions as depicting anger (p=.001, ή(2)=.18). Specifically, controls showed a significant decrease in this type of error with the red background (p=.003, d=0.77), while the SSD group tended to increase this type of error (p=.07, d=0.54). These findings suggest that the well-established M-pathway abnormalities in SSDs may contribute to the heightened misperception of other emotions such as anger, which in turn may cause social misperceptions in the environment and elicit symptoms such as paranoia and social withdrawal. As the ventral striatum plays a primary role in identifying anger and receives efferent input from the M-pathway, it may serve as the neuroanatomical substrate in the perception of anger. Copyright © 2013 Elsevier Inc. All rights reserved.

The Impact of Density and Ratio on Object-Ensemble Representation in Human Anterior-Medial Ventral Visual Cortex

PubMed Central

Cant, Jonathan S.; Xu, Yaoda

2015-01-01

Behavioral research has demonstrated that observers can extract summary statistics from ensembles of multiple objects. We recently showed that a region of anterior-medial ventral visual cortex, overlapping largely with the scene-sensitive parahippocampal place area (PPA), participates in object-ensemble representation. Here we investigated the encoding of ensemble density in this brain region using fMRI-adaptation. In Experiment 1, we varied density by changing the spacing between objects and found no sensitivity in PPA to such density changes. Thus, density may not be encoded in PPA, possibly because object spacing is not perceived as an intrinsic ensemble property. In Experiment 2, we varied relative density by changing the ratio of 2 types of objects comprising an ensemble, and observed significant sensitivity in PPA to such ratio change. Although colorful ensembles were shown in Experiment 2, Experiment 3 demonstrated that sensitivity to object ratio change was not driven mainly by a change in the ratio of colors. Thus, while anterior-medial ventral visual cortex is insensitive to density (object spacing) changes, it does code relative density (object ratio) within an ensemble. Object-ensemble processing in this region may thus depend on high-level visual information, such as object ratio, rather than low-level information, such as spacing/spatial frequency. PMID:24964917

Task-dependent enhancement of facial expression and identity representations in human cortex.

PubMed

Dobs, Katharina; Schultz, Johannes; Bülthoff, Isabelle; Gardner, Justin L

2018-05-15

What cortical mechanisms allow humans to easily discern the expression or identity of a face? Subjects detected changes in expression or identity of a stream of dynamic faces while we measured BOLD responses from topographically and functionally defined areas throughout the visual hierarchy. Responses in dorsal areas increased during the expression task, whereas responses in ventral areas increased during the identity task, consistent with previous studies. Similar to ventral areas, early visual areas showed increased activity during the identity task. If visual responses are weighted by perceptual mechanisms according to their magnitude, these increased responses would lead to improved attentional selection of the task-appropriate facial aspect. Alternatively, increased responses could be a signature of a sensitivity enhancement mechanism that improves representations of the attended facial aspect. Consistent with the latter sensitivity enhancement mechanism, attending to expression led to enhanced decoding of exemplars of expression both in early visual and dorsal areas relative to attending identity. Similarly, decoding identity exemplars when attending to identity was improved in dorsal and ventral areas. We conclude that attending to expression or identity of dynamic faces is associated with increased selectivity in representations consistent with sensitivity enhancement. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

How bumblebees use lateral and ventral optic flow cues for position control in environments of different proximity.

PubMed

Linander, Nellie; Baird, Emily; Dacke, Marie

2017-05-01

Flying insects frequently navigate through environments of different complexity. In this study, buff-tailed bumblebees (Bombus terrestris L.) were trained to fly along tunnels of different widths, from 60 to 240 cm. In tunnel widths of 60 and 120 cm, bumblebees control their lateral position by balancing the magnitude of translational optic flow experienced in the lateral visual field of each eye. In wider tunnels, bumblebees use translational optic flow cues in the ventral visual field to control their lateral position and to steer along straight tracks. Our results also suggest that bumblebees prefer to fly over surfaces that provide strong ventral optic flow cues, rather than over featureless ones. Together, these strategies allow bumblebees to minimize the risk of collision and to maintain relatively straight flight paths in a broad range of environments.

The Contribution of Object Shape and Surface Properties to Object Ensemble Representation in Anterior-medial Ventral Visual Cortex.

PubMed

Cant, Jonathan S; Xu, Yaoda

2017-02-01

Our visual system can extract summary statistics from large collections of objects without forming detailed representations of the individual objects in the ensemble. In a region in ventral visual cortex encompassing the collateral sulcus and the parahippocampal gyrus and overlapping extensively with the scene-selective parahippocampal place area (PPA), we have previously reported fMRI adaptation to object ensembles when ensemble statistics repeated, even when local image features differed across images (e.g., two different images of the same strawberry pile). We additionally showed that this ensemble representation is similar to (but still distinct from) how visual texture patterns are processed in this region and is not explained by appealing to differences in the color of the elements that make up the ensemble. To further explore the nature of ensemble representation in this brain region, here we used PPA as our ROI and investigated in detail how the shape and surface properties (i.e., both texture and color) of the individual objects constituting an ensemble affect the ensemble representation in anterior-medial ventral visual cortex. We photographed object ensembles of stone beads that varied in shape and surface properties. A given ensemble always contained beads of the same shape and surface properties (e.g., an ensemble of star-shaped rose quartz beads). A change to the shape and/or surface properties of all the beads in an ensemble resulted in a significant release from adaptation in PPA compared with conditions in which no ensemble feature changed. In contrast, in the object-sensitive lateral occipital area (LO), we only observed a significant release from adaptation when the shape of the ensemble elements varied, and found no significant results in additional scene-sensitive regions, namely, the retrosplenial complex and occipital place area. Together, these results demonstrate that the shape and surface properties of the individual objects comprising an ensemble both contribute significantly to object ensemble representation in anterior-medial ventral visual cortex and further demonstrate a functional dissociation between object- (LO) and scene-selective (PPA) visual cortical regions and within the broader scene-processing network itself.

Multisensory and modality specific processing of visual speech in different regions of the premotor cortex

PubMed Central

Callan, Daniel E.; Jones, Jeffery A.; Callan, Akiko

2014-01-01

Behavioral and neuroimaging studies have demonstrated that brain regions involved with speech production also support speech perception, especially under degraded conditions. The premotor cortex (PMC) has been shown to be active during both observation and execution of action (“Mirror System” properties), and may facilitate speech perception by mapping unimodal and multimodal sensory features onto articulatory speech gestures. For this functional magnetic resonance imaging (fMRI) study, participants identified vowels produced by a speaker in audio-visual (saw the speaker's articulating face and heard her voice), visual only (only saw the speaker's articulating face), and audio only (only heard the speaker's voice) conditions with varying audio signal-to-noise ratios in order to determine the regions of the PMC involved with multisensory and modality specific processing of visual speech gestures. The task was designed so that identification could be made with a high level of accuracy from visual only stimuli to control for task difficulty and differences in intelligibility. The results of the functional magnetic resonance imaging (fMRI) analysis for visual only and audio-visual conditions showed overlapping activity in inferior frontal gyrus and PMC. The left ventral inferior premotor cortex (PMvi) showed properties of multimodal (audio-visual) enhancement with a degraded auditory signal. The left inferior parietal lobule and right cerebellum also showed these properties. The left ventral superior and dorsal premotor cortex (PMvs/PMd) did not show this multisensory enhancement effect, but there was greater activity for the visual only over audio-visual conditions in these areas. The results suggest that the inferior regions of the ventral premotor cortex are involved with integrating multisensory information, whereas, more superior and dorsal regions of the PMC are involved with mapping unimodal (in this case visual) sensory features of the speech signal with articulatory speech gestures. PMID:24860526

The moon illusion and size-distance scaling--evidence for shared neural patterns.

PubMed

Weidner, Ralph; Plewan, Thorsten; Chen, Qi; Buchner, Axel; Weiss, Peter H; Fink, Gereon R

2014-08-01

A moon near to the horizon is perceived larger than a moon at the zenith, although--obviously--the moon does not change its size. In this study, the neural mechanisms underlying the "moon illusion" were investigated using a virtual 3-D environment and fMRI. Illusory perception of an increased moon size was associated with increased neural activity in ventral visual pathway areas including the lingual and fusiform gyri. The functional role of these areas was further explored in a second experiment. Left V3v was found to be involved in integrating retinal size and distance information, thus indicating that the brain regions that dynamically integrate retinal size and distance play a key role in generating the moon illusion.

Non-canonical Phototransduction Mediates Synchronization of the Drosophila melanogaster Circadian Clock and Retinal Light Responses.

PubMed

Ogueta, Maite; Hardie, Roger C; Stanewsky, Ralf

2018-06-04

The daily light-dark cycles represent a key signal for synchronizing circadian clocks. Both insects and mammals possess dedicated "circadian" photoreceptors but also utilize the visual system for clock resetting. In Drosophila, circadian clock resetting is achieved by the blue-light photoreceptor cryptochrome (CRY), which is expressed within subsets of the brain clock neurons. In addition, rhodopsin-expressing photoreceptor cells contribute to light synchronization. Light resets the molecular clock by CRY-dependent degradation of the clock protein Timeless (TIM), although in specific subsets of key circadian pacemaker neurons, including the small ventral lateral neurons (s-LNvs), TIM and Period (PER) oscillations can be synchronized by light independent of CRY and canonical visual Rhodopsin phototransduction. Here, we show that at least three of the seven Drosophila rhodopsins can utilize an alternative transduction mechanism involving the same α-subunit of the heterotrimeric G protein operating in canonical visual phototransduction (Gq). Surprisingly, in mutants lacking the canonical phospholipase C-β (PLC-β) encoded by the no receptor potential A (norpA) gene, we uncovered a novel transduction pathway using a different PLC-β encoded by the Plc21C gene. This novel pathway is important for behavioral clock resetting to semi-natural light-dark cycles and mediates light-dependent molecular synchronization within the s-LNv clock neurons. The same pathway appears to be responsible for norpA-independent light responses in the compound eye. We show that Rhodopsin 5 (Rh5) and Rh6, present in the R8 subset of retinal photoreceptor cells, drive both the long-term circadian and rapid light responses in the eye. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Sparing of Sensitivity to Biological Motion but Not of Global Motion after Early Visual Deprivation

ERIC Educational Resources Information Center

Hadad, Bat-Sheva; Maurer, Daphne; Lewis, Terri L.

2012-01-01

Patients deprived of visual experience during infancy by dense bilateral congenital cataracts later show marked deficits in the perception of global motion (dorsal visual stream) and global form (ventral visual stream). We expected that they would also show marked deficits in sensitivity to biological motion, which is normally processed in the…

Effects of congruent and incongruent visual cues on speech perception and brain activity in cochlear implant users.

PubMed

Song, Jae-Jin; Lee, Hyo-Jeong; Kang, Hyejin; Lee, Dong Soo; Chang, Sun O; Oh, Seung Ha

2015-03-01

While deafness-induced plasticity has been investigated in the visual and auditory domains, not much is known about language processing in audiovisual multimodal environments for patients with restored hearing via cochlear implant (CI) devices. Here, we examined the effect of agreeing or conflicting visual inputs on auditory processing in deaf patients equipped with degraded artificial hearing. Ten post-lingually deafened CI users with good performance, along with matched control subjects, underwent H 2 (15) O-positron emission tomography scans while carrying out a behavioral task requiring the extraction of speech information from unimodal auditory stimuli, bimodal audiovisual congruent stimuli, and incongruent stimuli. Regardless of congruency, the control subjects demonstrated activation of the auditory and visual sensory cortices, as well as the superior temporal sulcus, the classical multisensory integration area, indicating a bottom-up multisensory processing strategy. Compared to CI users, the control subjects exhibited activation of the right ventral premotor-supramarginal pathway. In contrast, CI users activated primarily the visual cortices more in the congruent audiovisual condition than in the null condition. In addition, compared to controls, CI users displayed an activation focus in the right amygdala for congruent audiovisual stimuli. The most notable difference between the two groups was an activation focus in the left inferior frontal gyrus in CI users confronted with incongruent audiovisual stimuli, suggesting top-down cognitive modulation for audiovisual conflict. Correlation analysis revealed that good speech performance was positively correlated with right amygdala activity for the congruent condition, but negatively correlated with bilateral visual cortices regardless of congruency. Taken together these results suggest that for multimodal inputs, cochlear implant users are more vision-reliant when processing congruent stimuli and are disturbed more by visual distractors when confronted with incongruent audiovisual stimuli. To cope with this multimodal conflict, CI users activate the left inferior frontal gyrus to adopt a top-down cognitive modulation pathway, whereas normal hearing individuals primarily adopt a bottom-up strategy.

Visual and Haptic Shape Processing in the Human Brain: Unisensory Processing, Multisensory Convergence, and Top-Down Influences.

PubMed

Lee Masson, Haemy; Bulthé, Jessica; Op de Beeck, Hans P; Wallraven, Christian

2016-08-01

Humans are highly adept at multisensory processing of object shape in both vision and touch. Previous studies have mostly focused on where visually perceived object-shape information can be decoded, with haptic shape processing receiving less attention. Here, we investigate visuo-haptic shape processing in the human brain using multivoxel correlation analyses. Importantly, we use tangible, parametrically defined novel objects as stimuli. Two groups of participants first performed either a visual or haptic similarity-judgment task. The resulting perceptual object-shape spaces were highly similar and matched the physical parameter space. In a subsequent fMRI experiment, objects were first compared within the learned modality and then in the other modality in a one-back task. When correlating neural similarity spaces with perceptual spaces, visually perceived shape was decoded well in the occipital lobe along with the ventral pathway, whereas haptically perceived shape information was mainly found in the parietal lobe, including frontal cortex. Interestingly, ventrolateral occipito-temporal cortex decoded shape in both modalities, highlighting this as an area capable of detailed visuo-haptic shape processing. Finally, we found haptic shape representations in early visual cortex (in the absence of visual input), when participants switched from visual to haptic exploration, suggesting top-down involvement of visual imagery on haptic shape processing. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Diversity of vestibular nuclei neurons targeted by cerebellar nodulus inhibition

PubMed Central

Meng, Hui; Blázquez, Pablo M; Dickman, J David; Angelaki, Dora E

2014-01-01

Abstract A functional role of the cerebellar nodulus and ventral uvula (lobules X and IXc,d of the vermis) for vestibular processing has been strongly suggested by direct reciprocal connections with the vestibular nuclei, as well as direct vestibular afferent inputs as mossy fibres. Here we have explored the types of neurons in the macaque vestibular nuclei targeted by nodulus/ventral uvula inhibition using orthodromic identification from the caudal vermis. We found that all nodulus-target neurons are tuned to vestibular stimuli, and most are insensitive to eye movements. Such non-eye-movement neurons are thought to project to vestibulo-spinal and/or thalamo-cortical pathways. Less than 20% of nodulus-target neurons were sensitive to eye movements, suggesting that the caudal vermis can also directly influence vestibulo-ocular pathways. In general, response properties of nodulus-target neurons were diverse, spanning the whole continuum previously described in the vestibular nuclei. Most nodulus-target cells responded to both rotation and translation stimuli and only a few were selectively tuned to translation motion only. Other neurons were sensitive to net linear acceleration, similar to otolith afferents. These results demonstrate that, unlike the flocculus and ventral paraflocculus which target a particular cell group, nodulus/ventral uvula inhibition targets a large diversity of cell types in the vestibular nuclei, consistent with a broad functional significance contributing to vestibulo-ocular, vestibulo-thalamic and vestibulo-spinal pathways. PMID:24127616

What puts the how in where? Tool use and the divided visual streams hypothesis.

PubMed

Frey, Scott H

2007-04-01

An influential theory suggests that the dorsal (occipito-parietal) visual stream computes representations of objects for purposes of guiding actions (determining 'how') independently of ventral (occipito-temporal) stream processes supporting object recognition and semantic processing (determining 'what'). Yet, the ability of the dorsal stream alone to account for one of the most common forms of human action, tool use, is limited. While experience-dependent modifications to existing dorsal stream representations may explain simple tool use behaviors (e.g., using sticks to extend reach) found among a variety of species, skillful use of manipulable artifacts (e.g., cups, hammers, pencils) requires in addition access to semantic representations of objects' functions and uses. Functional neuroimaging suggests that this latter information is represented in a left-lateralized network of temporal, frontal and parietal areas. I submit that the well-established dominance of the human left hemisphere in the representation of familiar skills stems from the ability for this acquired knowledge to influence the organization of actions within the dorsal pathway.

Behaviorally Relevant Abstract Object Identity Representation in the Human Parietal Cortex

PubMed Central

Jeong, Su Keun

2016-01-01

The representation of object identity is fundamental to human vision. Using fMRI and multivoxel pattern analysis, here we report the representation of highly abstract object identity information in human parietal cortex. Specifically, in superior intraparietal sulcus (IPS), a region previously shown to track visual short-term memory capacity, we found object identity representations for famous faces varying freely in viewpoint, hairstyle, facial expression, and age; and for well known cars embedded in different scenes, and shown from different viewpoints and sizes. Critically, these parietal identity representations were behaviorally relevant as they closely tracked the perceived face-identity similarity obtained in a behavioral task. Meanwhile, the task-activated regions in prefrontal and parietal cortices (excluding superior IPS) did not exhibit such abstract object identity representations. Unlike previous studies, we also failed to observe identity representations in posterior ventral and lateral visual object-processing regions, likely due to the greater amount of identity abstraction demanded by our stimulus manipulation here. Our MRI slice coverage precluded us from examining identity representation in anterior temporal lobe, a likely region for the computing of identity information in the ventral region. Overall, we show that human parietal cortex, part of the dorsal visual processing pathway, is capable of holding abstract and complex visual representations that are behaviorally relevant. These results argue against a “content-poor” view of the role of parietal cortex in attention. Instead, the human parietal cortex seems to be “content rich” and capable of directly participating in goal-driven visual information representation in the brain. SIGNIFICANCE STATEMENT The representation of object identity (including faces) is fundamental to human vision and shapes how we interact with the world. Although object representation has traditionally been associated with human occipital and temporal cortices, here we show, by measuring fMRI response patterns, that a region in the human parietal cortex can robustly represent task-relevant object identities. These representations are invariant to changes in a host of visual features, such as viewpoint, and reflect an abstract level of representation that has not previously been reported in the human parietal cortex. Critically, these neural representations are behaviorally relevant as they closely track the perceived object identities. Human parietal cortex thus participates in the moment-to-moment goal-directed visual information representation in the brain. PMID:26843642

Memory-guided reaching in a patient with visual hemiagnosia.

PubMed

Cornelsen, Sonja; Rennig, Johannes; Himmelbach, Marc

2016-06-01

The two-visual-systems hypothesis (TVSH) postulates that memory-guided movements rely on intact functions of the ventral stream. Its particular importance for memory-guided actions was initially inferred from behavioral dissociations in the well-known patient DF. Despite of rather accurate reaching and grasping movements to visible targets, she demonstrated grossly impaired memory-guided grasping as much as impaired memory-guided reaching. These dissociations were later complemented by apparently reversed dissociations in patients with dorsal damage and optic ataxia. However, grasping studies in DF and optic ataxia patients differed with respect to the retinotopic position of target objects, questioning the interpretation of the respective findings as a double dissociation. In contrast, the findings for reaching errors in both types of patients came from similar peripheral target presentations. However, new data on brain structural changes and visuomotor deficits in DF also questioned the validity of a double dissociation in reaching. A severe visuospatial short-term memory deficit in DF further questioned the specificity of her memory-guided reaching deficit. Therefore, we compared movement accuracy in visually-guided and memory-guided reaching in a new patient who suffered a confined unilateral damage to the ventral visual system due to stroke. Our results indeed support previous descriptions of memory-guided movements' inaccuracies in DF. Furthermore, our data suggest that recently discovered optic-ataxia like misreaching in DF is most likely caused by her parieto-occipital and not by her ventral stream damage. Finally, multiple visuospatial memory measurements in HWS suggest that inaccuracies in memory-guided reaching tasks in patients with ventral damage cannot be explained by visuospatial short-term memory or perceptual deficits, but by a specific deficit in visuomotor processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Still holding after all these years: An action-perception dissociation in patient DF.

PubMed

Ganel, Tzvi; Goodale, Melvyn A

2017-09-23

Patient DF, who has bilateral damage in the ventral visual stream, is perhaps the best known individual with visual form agnosia in the world, and has been the focus of scores of research papers over the past twenty-five years. The remarkable dissociation she exhibits between a profound deficit in perceptual report and a preserved ability to generate relatively normal visuomotor behaviour was early on a cornerstone in Goodale and Milner's (1992) two visual systems hypothesis. In recent years, however, there has been a greater emphasis on the damage that is evident in the posterior regions of her parietal cortex in both hemispheres. Deficits in several aspects of visuomotor control in the visual periphery have been demonstrated, leading some researchers to conclude that the double dissociation between vision-for-perception and vision-for-action in DF and patients with classic optic ataxia can no longer be assumed to be strong evidence for the division of labour between the dorsal and ventral streams of visual processing. In this short review, we argue that this is not the case. Indeed, after evaluating DF's performance and the location of her brain lesions, a clear picture of a double dissociation between DF and patients with optic ataxia is revealed. More than quarter of a century after the initial presentation of DF's unique case, she continues to provide compelling evidence for the idea that the ventral stream is critical for the perception of the shape and orientation of objects but not the visual control of skilled actions directed at those objects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Differential processing of binocular and monocular gloss cues in human visual cortex

PubMed Central

Di Luca, Massimiliano; Ban, Hiroshi; Muryy, Alexander; Fleming, Roland W.

2016-01-01

The visual impression of an object's surface reflectance (“gloss”) relies on a range of visual cues, both monocular and binocular. Whereas previous imaging work has identified processing within ventral visual areas as important for monocular cues, little is known about cortical areas involved in processing binocular cues. Here, we used human functional MRI (fMRI) to test for brain areas selectively involved in the processing of binocular cues. We manipulated stereoscopic information to create four conditions that differed in their disparity structure and in the impression of surface gloss that they evoked. We performed multivoxel pattern analysis to find areas whose fMRI responses allow classes of stimuli to be distinguished based on their depth structure vs. material appearance. We show that higher dorsal areas play a role in processing binocular gloss information, in addition to known ventral areas involved in material processing, with ventral area lateral occipital responding to both object shape and surface material properties. Moreover, we tested for similarities between the representation of gloss from binocular cues and monocular cues. Specifically, we tested for transfer in the decoding performance of an algorithm trained on glossy vs. matte objects defined by either binocular or by monocular cues. We found transfer effects from monocular to binocular cues in dorsal visual area V3B/kinetic occipital (KO), suggesting a shared representation of the two cues in this area. These results indicate the involvement of mid- to high-level visual circuitry in the estimation of surface material properties, with V3B/KO potentially playing a role in integrating monocular and binocular cues. PMID:26912596

The homeobox gene mirror links EGF signalling to embryonic dorso-ventral axis formation through notch activation.

PubMed

Jordan, K C; Clegg, N J; Blasi, J A; Morimoto, A M; Sen, J; Stein, D; McNeill, H; Deng, W M; Tworoger, M; Ruohola-Baker, H

2000-04-01

Recent studies in vertebrates and Drosophila melanogaster have revealed that Fringe-mediated activation of the Notch pathway has a role in patterning cell layers during organogenesis. In these processes, a homeobox-containing transcription factor is responsible for spatially regulating fringe (fng) expression and thus directing activation of the Notch pathway along the fng expression border. Here we show that this may be a general mechanism for patterning epithelial cell layers. At three stages in Drosophila oogenesis, mirror (mirr) and fng have complementary expression patterns in the follicle-cell epithelial layer, and at all three stages loss of mirr enlarges, and ectopic expression of mirr restricts, fng expression, with consequences for follicle-cell patterning. These morphological changes are similar to those caused by Notch mutations. Ectopic expression of mirr in the posterior follicle cells induces a stripe of rhomboid (rho) expression and represses pipe (pip), a gene with a role in the establishment of the dorsal-ventral axis, at a distance. Ectopic Notch activation has a similar long-range effect on pip. Our results suggest that Mirror and Notch induce secretion of diffusible morphogens and we have identified TGF-beta (encoded by dpp) as such a molecule in germarium. We also found that mirr expression in dorsal follicle cells is induced by the EGF-receptor (EGFR) pathway and that mirr then represses pip expression in all but the ventral follicle cells, connecting EGFR activation in the dorsal follicle cells to repression of pip in the dorsal and lateral follicle cells. Our results suggest that the differentiation of ventral follicle cells is not a direct consequence of germline signalling, but depends on long-range signals from dorsal follicle cells, and provide a link between early and late events in Drosophila embryonic dorsal-ventral axis formation.

Emerging category representation in the visual forebrain hierarchy of pigeons (Columba livia).

PubMed

Azizi, Amir Hossein; Pusch, Roland; Koenen, Charlotte; Klatt, Sebastian; Bröcker, Franziska; Thiele, Samuel; Kellermann, Janosch; Güntürkün, Onur; Cheng, Sen

2018-06-06

Recognizing and categorizing visual stimuli are cognitive functions vital for survival, and an important feature of visual systems in primates as well as in birds. Visual stimuli are processed along the ventral visual pathway. At every stage in the hierarchy, neurons respond selectively to more complex features, transforming the population representation of the stimuli. It is therefore easier to read-out category information in higher visual areas. While explicit category representations have been observed in the primate brain, less is known on equivalent processes in the avian brain. Even though their brain anatomies are radically different, it has been hypothesized that visual object representations are comparable across mammals and birds. In the present study, we investigated category representations in the pigeon visual forebrain using recordings from single cells responding to photographs of real-world objects. Using a linear classifier, we found that the population activity in the visual associative area mesopallium ventrolaterale (MVL) distinguishes between animate and inanimate objects, although this distinction is not required by the task. By contrast, a population of cells in the entopallium, a region that is lower in the hierarchy of visual areas and that is related to the primate extrastriate cortex, lacked this information. A model that pools responses of simple cells, which function as edge detectors, can account for the animate vs. inanimate categorization in the MVL, but performance in the model is based on different features than in MVL. Therefore, processing in MVL cells is very likely more abstract than simple computations on the output of edge detectors. Copyright © 2018. Published by Elsevier B.V.

Reading Without the Left Ventral Occipito-Temporal Cortex

ERIC Educational Resources Information Center

Seghier, Mohamed L.; Neufeld, Nicholas H.; Zeidman, Peter; Leff, Alex P.; Mechelli, Andrea; Nagendran, Arjuna; Riddoch, Jane M.; Humphreys, Glyn W.; Price, Cathy J.

2012-01-01

The left ventral occipito-temporal cortex (LvOT) is thought to be essential for the rapid parallel letter processing that is required for skilled reading. Here we investigate whether rapid written word identification in skilled readers can be supported by neural pathways that do not involve LvOT. Hypotheses were derived from a stroke patient who…

Antagonizing the Spemann organizer: role of the homeobox gene Xvent-1.

PubMed Central

Gawantka, V; Delius, H; Hirschfeld, K; Blumenstock, C; Niehrs, C

1995-01-01

We have identified a novel homeobox gene, Xvent-1, that is differentially expressed in the ventral marginal zone of the early Xenopus gastrula. Evidence is presented from mRNA microinjection experiments for a role for this gene in dorsoventral patterning of mesoderm. First, Xvent-1 is induced by BMP-4, a gene known to be a key regulator of ventral mesoderm development. Second, Xvent-1 and the organizer-specific gene goosecoid are able to interact, directly or indirectly, in a cross-regulatory loop suppressing each other's expression, consistent with their mutually exclusive expression in the marginal zone. Third, microinjection of Xvent-1 mRNA ventralizes dorsal mesoderm. The results suggest that Xvent-1 functions in a ventral signaling pathway that maintains the ventral mesodermal state and antagonizes the Spemann organizer. Images PMID:8557046

Color-Biased Regions of the Ventral Visual Pathway Lie between Face- and Place-Selective Regions in Humans, as in Macaques

PubMed Central

Conway, Bevil R.; Kanwisher, Nancy G.

2016-01-01

The existence of color-processing regions in the human ventral visual pathway (VVP) has long been known from patient and imaging studies, but their location in the cortex relative to other regions, their selectivity for color compared with other properties (shape and object category), and their relationship to color-processing regions found in nonhuman primates remain unclear. We addressed these questions by scanning 13 subjects with fMRI while they viewed two versions of movie clips (colored, achromatic) of five different object classes (faces, scenes, bodies, objects, scrambled objects). We identified regions in each subject that were selective for color, faces, places, and object shape, and measured responses within these regions to the 10 conditions in independently acquired data. We report two key findings. First, the three previously reported color-biased regions (located within a band running posterior–anterior along the VVP, present in most of our subjects) were sandwiched between face-selective cortex and place-selective cortex, forming parallel bands of face, color, and place selectivity that tracked the fusiform gyrus/collateral sulcus. Second, the posterior color-biased regions showed little or no selectivity for object shape or for particular stimulus categories and showed no interaction of color preference with stimulus category, suggesting that they code color independently of shape or stimulus category; moreover, the shape-biased lateral occipital region showed no significant color bias. These observations mirror results in macaque inferior temporal cortex (Lafer-Sousa and Conway, 2013), and taken together, these results suggest a homology in which the entire tripartite face/color/place system of primates migrated onto the ventral surface in humans over the course of evolution. SIGNIFICANCE STATEMENT Here we report that color-biased cortex is sandwiched between face-selective and place-selective cortex on the bottom surface of the brain in humans. This face/color/place organization mirrors that seen on the lateral surface of the temporal lobe in macaques, suggesting that the entire tripartite system is homologous between species. This result validates the use of macaques as a model for human vision, making possible more powerful investigations into the connectivity, precise neural codes, and development of this part of the brain. In addition, we find substantial segregation of color from shape selectivity in posterior regions, as observed in macaques, indicating a considerable dissociation of the processing of shape and color in both species. PMID:26843649

Perception of Shapes Targeting Local and Global Processes in Autism Spectrum Disorders

ERIC Educational Resources Information Center

Grinter, Emma J.; Maybery, Murray T.; Pellicano, Elizabeth; Badcock, Johanna C.; Badcock, David R.

2010-01-01

Background: Several researchers have found evidence for impaired global processing in the dorsal visual stream in individuals with autism spectrum disorders (ASDs). However, support for a similar pattern of visual processing in the ventral visual stream is less consistent. Critical to resolving the inconsistency is the assessment of local and…

Weighing the evidence for a dorsal processing bias under continuous flash suppression.

PubMed

Ludwig, Karin; Hesselmann, Guido

2015-09-01

With the introduction of continuous flash suppression (CFS) as a method to render stimuli invisible and study unconscious visual processing, a novel hypothesis has gained popularity. It states that processes typically ascribed to the dorsal visual stream can escape CFS and remain functional, while ventral stream processes are suppressed when stimuli are invisible under CFS. This notion of a CFS-specific "dorsal processing bias" has been argued to be in line with core characteristics of the influential dual-stream hypothesis of visual processing which proposes a dissociation between dorsally mediated vision-for-action and ventrally mediated vision-for-perception. Here, we provide an overview of neuroimaging and behavioral studies that either examine this dorsal processing bias or base their conclusions on it. We show that both evidence for preserved ventral processing as well as lack of dorsal processing can be found in studies using CFS. To reconcile the diverging results, differences in the paradigms and their effects are worthy of future research. We conclude that given the current level of information a dorsal processing bias under CFS cannot be universally assumed. Copyright © 2014 Elsevier Inc. All rights reserved.

Distinct Visual Evoked Potential Morphological Patterns for Apparent Motion Processing in School-Aged Children.

PubMed

Campbell, Julia; Sharma, Anu

2016-01-01

Measures of visual cortical development in children demonstrate high variability and inconsistency throughout the literature. This is partly due to the specificity of the visual system in processing certain features. It may then be advantageous to activate multiple cortical pathways in order to observe maturation of coinciding networks. Visual stimuli eliciting the percept of apparent motion and shape change is designed to simultaneously activate both dorsal and ventral visual streams. However, research has shown that such stimuli also elicit variable visual evoked potential (VEP) morphology in children. The aim of this study was to describe developmental changes in VEPs, including morphological patterns, and underlying visual cortical generators, elicited by apparent motion and shape change in school-aged children. Forty-one typically developing children underwent high-density EEG recordings in response to a continuously morphing, radially modulated, circle-star grating. VEPs were then compared across the age groups of 5-7, 8-10, and 11-15 years according to latency and amplitude. Current density reconstructions (CDR) were performed on VEP data in order to observe activated cortical regions. It was found that two distinct VEP morphological patterns occurred in each age group. However, there were no major developmental differences between the age groups according to each pattern. CDR further demonstrated consistent visual generators across age and pattern. These results describe two novel VEP morphological patterns in typically developing children, but with similar underlying cortical sources. The importance of these morphological patterns is discussed in terms of future studies and the investigation of a relationship to visual cognitive performance.

Distinct Visual Evoked Potential Morphological Patterns for Apparent Motion Processing in School-Aged Children

PubMed Central

Campbell, Julia; Sharma, Anu

2016-01-01

Measures of visual cortical development in children demonstrate high variability and inconsistency throughout the literature. This is partly due to the specificity of the visual system in processing certain features. It may then be advantageous to activate multiple cortical pathways in order to observe maturation of coinciding networks. Visual stimuli eliciting the percept of apparent motion and shape change is designed to simultaneously activate both dorsal and ventral visual streams. However, research has shown that such stimuli also elicit variable visual evoked potential (VEP) morphology in children. The aim of this study was to describe developmental changes in VEPs, including morphological patterns, and underlying visual cortical generators, elicited by apparent motion and shape change in school-aged children. Forty-one typically developing children underwent high-density EEG recordings in response to a continuously morphing, radially modulated, circle-star grating. VEPs were then compared across the age groups of 5–7, 8–10, and 11–15 years according to latency and amplitude. Current density reconstructions (CDR) were performed on VEP data in order to observe activated cortical regions. It was found that two distinct VEP morphological patterns occurred in each age group. However, there were no major developmental differences between the age groups according to each pattern. CDR further demonstrated consistent visual generators across age and pattern. These results describe two novel VEP morphological patterns in typically developing children, but with similar underlying cortical sources. The importance of these morphological patterns is discussed in terms of future studies and the investigation of a relationship to visual cognitive performance. PMID:27445738

The vertical occipital fasciculus: a century of controversy resolved by in vivo measurements.

PubMed

Yeatman, Jason D; Weiner, Kevin S; Pestilli, Franco; Rokem, Ariel; Mezer, Aviv; Wandell, Brian A

2014-12-02

The vertical occipital fasciculus (VOF) is the only major fiber bundle connecting dorsolateral and ventrolateral visual cortex. Only a handful of studies have examined the anatomy of the VOF or its role in cognition in the living human brain. Here, we trace the contentious history of the VOF, beginning with its original discovery in monkey by Wernicke (1881) and in human by Obersteiner (1888), to its disappearance from the literature, and recent reemergence a century later. We introduce an algorithm to identify the VOF in vivo using diffusion-weighted imaging and tractography, and show that the VOF can be found in every hemisphere (n = 74). Quantitative T1 measurements demonstrate that tissue properties, such as myelination, in the VOF differ from neighboring white-matter tracts. The terminations of the VOF are in consistent positions relative to cortical folding patterns in the dorsal and ventral visual streams. Recent findings demonstrate that these same anatomical locations also mark cytoarchitectonic and functional transitions in dorsal and ventral visual cortex. We conclude that the VOF is likely to serve a unique role in the communication of signals between regions on the ventral surface that are important for the perception of visual categories (e.g., words, faces, bodies, etc.) and regions on the dorsal surface involved in the control of eye movements, attention, and motion perception.

Maternal control of the Drosophila dorsal–ventral body axis

PubMed Central

Stein, David S.; Stevens, Leslie M.

2016-01-01

The pathway that generates the dorsal–ventral (DV) axis of the Drosophila embryo has been the subject of intense investigation over the previous three decades. The initial asymmetric signal originates during oogenesis by the movement of the oocyte nucleus to an anterior corner of the oocyte, which establishes DV polarity within the follicle through signaling between Gurken, the Drosophila Transforming Growth Factor (TGF)-α homologue secreted from the oocyte, and the Drosophila Epidermal Growth Factor Receptor (EGFR) that is expressed by the follicular epithelium cells that envelop the oocyte. Follicle cells that are not exposed to Gurken follow a ventral fate and express Pipe, a sulfotransferase that enzymatically modifies components of the inner vitelline membrane layer of the eggshell, thereby transferring DV spatial information from the follicle to the egg. These ventrally sulfated eggshell proteins comprise a localized cue that directs the ventrally restricted formation of the active Spätzle ligand within the perivitelline space between the eggshell and the embryonic membrane. Spätzle activates Toll, a transmembrane receptor in the embryonic membrane. Transmission of the Toll signal into the embryo leads to the formation of a ventral-to-dorsal gradient of the transcription factor Dorsal within the nuclei of the syncytial blastoderm stage embryo. Dorsal controls the spatially specific expression of a large constellation of zygotic target genes, the Dorsal gene regulatory network, along the embryonic DV circumference. This article reviews classic studies and integrates them with the details of more recent work that has advanced our understanding of the complex pathway that establishes Drosophila embryo DV polarity. PMID:25124754

Strong rightward lateralization of the dorsal attentional network in left-handers with right sighting-eye: an evolutionary advantage.

PubMed

Petit, Laurent; Zago, Laure; Mellet, Emmanuel; Jobard, Gaël; Crivello, Fabrice; Joliot, Marc; Mazoyer, Bernard; Tzourio-Mazoyer, Nathalie

2015-03-01

Hemispheric lateralization for spatial attention and its relationships with manual preference strength and eye preference were studied in a sample of 293 healthy individuals balanced for manual preference. Functional magnetic resonance imaging was used to map this large sample while performing visually guided saccadic eye movements. This activated a bilateral distributed cortico-subcortical network in which dorsal and ventral attentional/saccadic pathways elicited rightward asymmetrical activation depending on manual preference strength and sighting eye. While the ventral pathway showed a strong rightward asymmetry irrespective of both manual preference strength and eye preference, the dorsal frontoparietal network showed a robust rightward asymmetry in strongly left-handers, even more pronounced in left-handed subjects with a right sighting-eye. Our findings brings support to the hypothesis that the origin of the rightward hemispheric dominance for spatial attention may have a manipulo-spatial origin neither perceptual nor motor per se but rather reflecting a mechanism by which a spatial context is mapped onto the perceptual and motor activities, including the exploration of the spatial environment with eyes and hands. Within this context, strongly left-handers with a right sighting-eye may benefit from the advantage of having the same right hemispheric control of their dominant hand and visuospatial attention processing. We suggest that this phenomenon explains why left-handed right sighting-eye athletes can outperform their competitors in sporting duels and that the prehistoric and historical constancy of the left-handers ratio over the general population may relate in part on the hemispheric specialization of spatial attention. © 2014 Wiley Periodicals, Inc.

A neural model of the temporal dynamics of figure-ground segregation in motion perception.

PubMed

Raudies, Florian; Neumann, Heiko

2010-03-01

How does the visual system manage to segment a visual scene into surfaces and objects and manage to attend to a target object? Based on psychological and physiological investigations, it has been proposed that the perceptual organization and segmentation of a scene is achieved by the processing at different levels of the visual cortical hierarchy. According to this, motion onset detection, motion-defined shape segregation, and target selection are accomplished by processes which bind together simple features into fragments of increasingly complex configurations at different levels in the processing hierarchy. As an alternative to this hierarchical processing hypothesis, it has been proposed that the processing stages for feature detection and segregation are reflected in different temporal episodes in the response patterns of individual neurons. Such temporal epochs have been observed in the activation pattern of neurons as low as in area V1. Here, we present a neural network model of motion detection, figure-ground segregation and attentive selection which explains these response patterns in an unifying framework. Based on known principles of functional architecture of the visual cortex, we propose that initial motion and motion boundaries are detected at different and hierarchically organized stages in the dorsal pathway. Visual shapes that are defined by boundaries, which were generated from juxtaposed opponent motions, are represented at different stages in the ventral pathway. Model areas in the different pathways interact through feedforward and modulating feedback, while mutual interactions enable the communication between motion and form representations. Selective attention is devoted to shape representations by sending modulating feedback signals from higher levels (working memory) to intermediate levels to enhance their responses. Areas in the motion and form pathway are coupled through top-down feedback with V1 cells at the bottom end of the hierarchy. We propose that the different temporal episodes in the response pattern of V1 cells, as recorded in recent experiments, reflect the strength of modulating feedback signals. This feedback results from the consolidated shape representations from coherent motion patterns and the attentive modulation of responses along the cortical hierarchy. The model makes testable predictions concerning the duration and delay of the temporal episodes of V1 cell responses as well as their response variations that were caused by modulating feedback signals. Copyright 2009 Elsevier Ltd. All rights reserved.

Functional selectivity for face processing in the temporal voice area of early deaf individuals

PubMed Central

van Ackeren, Markus J.; Rabini, Giuseppe; Zonca, Joshua; Foa, Valentina; Baruffaldi, Francesca; Rezk, Mohamed; Pavani, Francesco; Rossion, Bruno; Collignon, Olivier

2017-01-01

Brain systems supporting face and voice processing both contribute to the extraction of important information for social interaction (e.g., person identity). How does the brain reorganize when one of these channels is absent? Here, we explore this question by combining behavioral and multimodal neuroimaging measures (magneto-encephalography and functional imaging) in a group of early deaf humans. We show enhanced selective neural response for faces and for individual face coding in a specific region of the auditory cortex that is typically specialized for voice perception in hearing individuals. In this region, selectivity to face signals emerges early in the visual processing hierarchy, shortly after typical face-selective responses in the ventral visual pathway. Functional and effective connectivity analyses suggest reorganization in long-range connections from early visual areas to the face-selective temporal area in individuals with early and profound deafness. Altogether, these observations demonstrate that regions that typically specialize for voice processing in the hearing brain preferentially reorganize for face processing in born-deaf people. Our results support the idea that cross-modal plasticity in the case of early sensory deprivation relates to the original functional specialization of the reorganized brain regions. PMID:28652333

A vertebrate retina with segregated colour and polarization sensitivity.

PubMed

Novales Flamarique, Iñigo

2017-09-13

Besides colour and intensity, some invertebrates are able to independently detect the polarization of light. Among vertebrates, such separation of visual modalities has only been hypothesized for some species of anchovies whose cone photoreceptors have unusual ultrastructure that varies with retinal location. Here, I tested this hypothesis by performing physiological experiments of colour and polarization discrimination using the northern anchovy, Engraulis mordax Optic nerve recordings showed that the ventro-temporal (VT), but not the ventro-nasal (VN), retina was polarization sensitive, and this coincided with the exclusive presence of polarization-sensitive photoreceptors in the VT retina. Spectral (colour) sensitivity recordings from the VN retina indicated the contribution of two spectral cone mechanisms to the optic nerve response, whereas only one contributed to the VT retina. This was supported by the presence of only one visual pigment in the VT retina and two in the VN retina, suggesting that only the VN retina was associated with colour sensitivity. Behavioural tests further demonstrated that anchovies could discriminate colour and the polarization of light using the ventral retina. Thus, in analogy with the visual system of some invertebrates, the northern anchovy has a retina with segregated retinal pathways for colour and polarization vision. © 2017 The Author(s).

Basolateral Amygdala Projections to Ventral Hippocampus Modulate the Consolidation of Footshock, but Not Contextual, Learning in Rats

ERIC Educational Resources Information Center

Huff, Mary L.; Emmons, Eric B.; Narayanan, Nandakumar S.; LaLumiere, Ryan T.

2016-01-01

The basolateral amygdala (BLA) modulates memory consolidation for a variety of types of learning, whereas other brain regions play more selective roles in specific kinds of learning suggesting a role for differential consolidation via distinct BLA pathways. The ventral hippocampus (VH), an efferent target of the BLA, has been suggested to…

Mirror System Activity for Action and Language Is Embedded in the Integration of Dorsal and Ventral Pathways

ERIC Educational Resources Information Center

Arbib, Michael A.

2010-01-01

We develop the view that the involvement of mirror neurons in embodied experience grounds brain structures that underlie language, but that many other brain regions are involved. We stress the cooperation between the dorsal and ventral streams in praxis and language. Both have perceptual and motor schemas but the perceptual schemas in the dorsal…

Genetic and cellular mechanisms of the formation of Esophageal Atresia and Tracheoesophageal Fistula

PubMed Central

Jacobs, Ian J.; Que, Jianwen

2015-01-01

Foregut separation involves dynamic changes in the activities of signaling pathways and transcription factors. Recent mouse genetic studies demonstrate that some of these pathways interact with each other to form a complex network, leading to a unique dorsal-ventral patterning in the early foregut. In this review we will discuss how this unique dorsal-ventral patterning is set prior to the foregut separation and how disruption of this patterning affects the separation process. We will further discuss the roles of downstream targets of these pathways in regulating separation at cellular and molecular levels. Understanding the mechanism of normal separation process will provide us insights into the pathobiology of a relatively common birth defect Esophageal Atresia (EA) with/without Tracheo-esophageal Fistula (TEF). PMID:23679023

Efficient visual object and word recognition relies on high spatial frequency coding in the left posterior fusiform gyrus: evidence from a case-series of patients with ventral occipito-temporal cortex damage.

PubMed

Roberts, Daniel J; Woollams, Anna M; Kim, Esther; Beeson, Pelagie M; Rapcsak, Steven Z; Lambon Ralph, Matthew A

2013-11-01

Recent visual neuroscience investigations suggest that ventral occipito-temporal cortex is retinotopically organized, with high acuity foveal input projecting primarily to the posterior fusiform gyrus (pFG), making this region crucial for coding high spatial frequency information. Because high spatial frequencies are critical for fine-grained visual discrimination, we hypothesized that damage to the left pFG should have an adverse effect not only on efficient reading, as observed in pure alexia, but also on the processing of complex non-orthographic visual stimuli. Consistent with this hypothesis, we obtained evidence that a large case series (n = 20) of patients with lesions centered on left pFG: 1) Exhibited reduced sensitivity to high spatial frequencies; 2) demonstrated prolonged response latencies both in reading (pure alexia) and object naming; and 3) were especially sensitive to visual complexity and similarity when discriminating between novel visual patterns. These results suggest that the patients' dual reading and non-orthographic recognition impairments have a common underlying mechanism and reflect the loss of high spatial frequency visual information normally coded in the left pFG.

The Toll pathway is required in the epidermis for muscle development in the Drosophila embryo

NASA Technical Reports Server (NTRS)

Halfon, M. S.; Keshishian, H.

1998-01-01

The Toll signaling pathway functions in several Drosophila processes, including dorsal-ventral pattern formation and the immune response. Here, we demonstrate that this pathway is required in the epidermis for proper muscle development. Previously, we showed that the zygotic Toll protein is necessary for normal muscle development; in the absence of zygotic Toll, close to 50% of hemisegments have muscle patterning defects consisting of missing, duplicated and misinserted muscle fibers (Halfon, M.S., Hashimoto, C., and Keshishian, H., Dev. Biol. 169, 151-167, 1995). We have now also analyzed the requirements for easter, spatzle, tube, and pelle, all of which function in the Toll-mediated dorsal-ventral patterning pathway. We find that spatzle, tube, and pelle, but not easter, are necessary for muscle development. Mutations in these genes give a phenotype identical to that seen in Toll mutants, suggesting that elements of the same pathway used for Toll signaling in dorsal-ventral development are used during muscle development. By expressing the Toll cDNA under the control of distinct Toll enhancer elements in Toll mutant flies, we have examined the spatial requirements for Toll expression during muscle development. Expression of Toll in a subset of epidermal cells that includes the epidermal muscle attachment cells, but not Toll expression in the musculature, is necessary for proper muscle development. Our results suggest that signals received by the epidermis early during muscle development are an important part of the muscle patterning process.

A Task-Dependent Causal Role for Low-Level Visual Processes in Spoken Word Comprehension

ERIC Educational Resources Information Center

Ostarek, Markus; Huettig, Falk

2017-01-01

It is well established that the comprehension of spoken words referring to object concepts relies on high-level visual areas in the ventral stream that build increasingly abstract representations. It is much less clear whether basic low-level visual representations are also involved. Here we asked in what task situations low-level visual…

Analysis of haptic information in the cerebral cortex

PubMed Central

2016-01-01

Haptic sensing of objects acquires information about a number of properties. This review summarizes current understanding about how these properties are processed in the cerebral cortex of macaques and humans. Nonnoxious somatosensory inputs, after initial processing in primary somatosensory cortex, are partially segregated into different pathways. A ventrally directed pathway carries information about surface texture into parietal opercular cortex and thence to medial occipital cortex. A dorsally directed pathway transmits information regarding the location of features on objects to the intraparietal sulcus and frontal eye fields. Shape processing occurs mainly in the intraparietal sulcus and lateral occipital complex, while orientation processing is distributed across primary somatosensory cortex, the parietal operculum, the anterior intraparietal sulcus, and a parieto-occipital region. For each of these properties, the respective areas outside primary somatosensory cortex also process corresponding visual information and are thus multisensory. Consistent with the distributed neural processing of haptic object properties, tactile spatial acuity depends on interaction between bottom-up tactile inputs and top-down attentional signals in a distributed neural network. Future work should clarify the roles of the various brain regions and how they interact at the network level. PMID:27440247

Neuronal and oscillatory activity during reward processing in the human ventral striatum.

PubMed

Lega, Bradley C; Kahana, Michael J; Jaggi, Jurg; Baltuch, Gordon H; Zaghloul, Kareem

2011-11-16

Accumulated evidence from animal studies implicates the ventral striatum in the processing of reward information. Recently, deep brain stimulation (DBS) surgery has enabled researchers to analyze neurophysiological recordings from humans engaged in reward tasks. We present data recorded from the human ventral striatum during deep brain stimulation surgery as a participant played a video game coupled to the receipt of visual reward images. To our knowledge, we identify the first instances of reward-sensitive single unit activity in the human ventral striatum. Local field potential data suggest that alpha oscillations are sensitive to positive feedback, whereas beta oscillations exhibit significantly higher power during unrewarded trials. We report evidence of alpha-gamma cross-frequency coupling that differentiates between positive and negative feedback. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Stereoscopic processing of crossed and uncrossed disparities in the human visual cortex.

PubMed

Li, Yuan; Zhang, Chuncheng; Hou, Chunping; Yao, Li; Zhang, Jiacai; Long, Zhiying

2017-12-21

Binocular disparity provides a powerful cue for depth perception in a stereoscopic environment. Despite increasing knowledge of the cortical areas that process disparity from neuroimaging studies, the neural mechanism underlying disparity sign processing [crossed disparity (CD)/uncrossed disparity (UD)] is still poorly understood. In the present study, functional magnetic resonance imaging (fMRI) was used to explore different neural features that are relevant to disparity-sign processing. We performed an fMRI experiment on 27 right-handed healthy human volunteers by using both general linear model (GLM) and multi-voxel pattern analysis (MVPA) methods. First, GLM was used to determine the cortical areas that displayed different responses to different disparity signs. Second, MVPA was used to determine how the cortical areas discriminate different disparity signs. The GLM analysis results indicated that shapes with UD induced significantly stronger activity in the sub-region (LO) of the lateral occipital cortex (LOC) than those with CD. The results of MVPA based on region of interest indicated that areas V3d and V3A displayed higher accuracy in the discrimination of crossed and uncrossed disparities than LOC. The results of searchlight-based MVPA indicated that the dorsal visual cortex showed significantly higher prediction accuracy than the ventral visual cortex and the sub-region LO of LOC showed high accuracy in the discrimination of crossed and uncrossed disparities. The results may suggest the dorsal visual areas are more discriminative to the disparity signs than the ventral visual areas although they are not sensitive to the disparity sign processing. Moreover, the LO in the ventral visual cortex is relevant to the recognition of shapes with different disparity signs and discriminative to the disparity sign.

Differential processing of binocular and monocular gloss cues in human visual cortex.

PubMed

Sun, Hua-Chun; Di Luca, Massimiliano; Ban, Hiroshi; Muryy, Alexander; Fleming, Roland W; Welchman, Andrew E

2016-06-01

The visual impression of an object's surface reflectance ("gloss") relies on a range of visual cues, both monocular and binocular. Whereas previous imaging work has identified processing within ventral visual areas as important for monocular cues, little is known about cortical areas involved in processing binocular cues. Here, we used human functional MRI (fMRI) to test for brain areas selectively involved in the processing of binocular cues. We manipulated stereoscopic information to create four conditions that differed in their disparity structure and in the impression of surface gloss that they evoked. We performed multivoxel pattern analysis to find areas whose fMRI responses allow classes of stimuli to be distinguished based on their depth structure vs. material appearance. We show that higher dorsal areas play a role in processing binocular gloss information, in addition to known ventral areas involved in material processing, with ventral area lateral occipital responding to both object shape and surface material properties. Moreover, we tested for similarities between the representation of gloss from binocular cues and monocular cues. Specifically, we tested for transfer in the decoding performance of an algorithm trained on glossy vs. matte objects defined by either binocular or by monocular cues. We found transfer effects from monocular to binocular cues in dorsal visual area V3B/kinetic occipital (KO), suggesting a shared representation of the two cues in this area. These results indicate the involvement of mid- to high-level visual circuitry in the estimation of surface material properties, with V3B/KO potentially playing a role in integrating monocular and binocular cues. Copyright © 2016 the American Physiological Society.

Encoding model of temporal processing in human visual cortex.

PubMed

Stigliani, Anthony; Jeska, Brianna; Grill-Spector, Kalanit

2017-12-19

How is temporal information processed in human visual cortex? Visual input is relayed to V1 through segregated transient and sustained channels in the retina and lateral geniculate nucleus (LGN). However, there is intense debate as to how sustained and transient temporal channels contribute to visual processing beyond V1. The prevailing view associates transient processing predominately with motion-sensitive regions and sustained processing with ventral stream regions, while the opposing view suggests that both temporal channels contribute to neural processing beyond V1. Using fMRI, we measured cortical responses to time-varying stimuli and then implemented a two temporal channel-encoding model to evaluate the contributions of each channel. Different from the general linear model of fMRI that predicts responses directly from the stimulus, the encoding approach first models neural responses to the stimulus from which fMRI responses are derived. This encoding approach not only predicts cortical responses to time-varying stimuli from milliseconds to seconds but also, reveals differential contributions of temporal channels across visual cortex. Consistent with the prevailing view, motion-sensitive regions and adjacent lateral occipitotemporal regions are dominated by transient responses. However, ventral occipitotemporal regions are driven by both sustained and transient channels, with transient responses exceeding the sustained. These findings propose a rethinking of temporal processing in the ventral stream and suggest that transient processing may contribute to rapid extraction of the content of the visual input. Importantly, our encoding approach has vast implications, because it can be applied with fMRI to decipher neural computations in millisecond resolution in any part of the brain. Copyright © 2017 the Author(s). Published by PNAS.

Experimental and analytical study of close-coupled ventral nozzles for ASTOVL aircraft

NASA Technical Reports Server (NTRS)

Mcardle, Jack G.; Smith, C. Frederic

1990-01-01

Flow in a generic ventral nozzle system was studied experimentally and analytically with a block version of the PARC3D computational fluid dynamics program (a full Navier-Stokes equation solver) in order to evaluate the program's ability to predict system performance and internal flow patterns. For the experimental work a one-third-size model tailpipe with a single large rectangular ventral nozzle mounted normal to the tailpipe axis was tested with unheated air at steady-state pressure ratios up to 4.0. The end of the tailpipe was closed to simulate a blocked exhaust nozzle. Measurements showed about 5 1/2 percent flow-turning loss, reasonable nozzle performance coefficients, and a significant aftward axial component of thrust due to flow turning loss, reasonable nozzle performance coefficients, and a significant aftward axial component of thrust due to flow turning more than 90 deg. Flow behavior into and through the ventral duct is discussed and illustrated with paint streak flow visualization photographs. For the analytical work the same ventral system configuration was modeled with two computational grids to evaluate the effect of grid density. Both grids gave good results. The finer-grid solution produced more detailed flow patterns and predicted performance parameters, such as thrust and discharge coefficient, within 1 percent of the measured values. PARC3D flow visualization images are shown for comparison with the paint streak photographs. Modeling and computational issues encountered in the analytical work are discussed.

How (and why) the visual control of action differs from visual perception

PubMed Central

Goodale, Melvyn A.

2014-01-01

Vision not only provides us with detailed knowledge of the world beyond our bodies, but it also guides our actions with respect to objects and events in that world. The computations required for vision-for-perception are quite different from those required for vision-for-action. The former uses relational metrics and scene-based frames of reference while the latter uses absolute metrics and effector-based frames of reference. These competing demands on vision have shaped the organization of the visual pathways in the primate brain, particularly within the visual areas of the cerebral cortex. The ventral ‘perceptual’ stream, projecting from early visual areas to inferior temporal cortex, helps to construct the rich and detailed visual representations of the world that allow us to identify objects and events, attach meaning and significance to them and establish their causal relations. By contrast, the dorsal ‘action’ stream, projecting from early visual areas to the posterior parietal cortex, plays a critical role in the real-time control of action, transforming information about the location and disposition of goal objects into the coordinate frames of the effectors being used to perform the action. The idea of two visual systems in a single brain might seem initially counterintuitive. Our visual experience of the world is so compelling that it is hard to believe that some other quite independent visual signal—one that we are unaware of—is guiding our movements. But evidence from a broad range of studies from neuropsychology to neuroimaging has shown that the visual signals that give us our experience of objects and events in the world are not the same ones that control our actions. PMID:24789899

Development of visual category selectivity in ventral visual cortex does not require visual experience

PubMed Central

van den Hurk, Job; Van Baelen, Marc; Op de Beeck, Hans P.

2017-01-01

To what extent does functional brain organization rely on sensory input? Here, we show that for the penultimate visual-processing region, ventral-temporal cortex (VTC), visual experience is not the origin of its fundamental organizational property, category selectivity. In the fMRI study reported here, we presented 14 congenitally blind participants with face-, body-, scene-, and object-related natural sounds and presented 20 healthy controls with both auditory and visual stimuli from these categories. Using macroanatomical alignment, response mapping, and surface-based multivoxel pattern analysis, we demonstrated that VTC in blind individuals shows robust discriminatory responses elicited by the four categories and that these patterns of activity in blind subjects could successfully predict the visual categories in sighted controls. These findings were confirmed in a subset of blind participants born without eyes and thus deprived from all light perception since conception. The sounds also could be decoded in primary visual and primary auditory cortex, but these regions did not sustain generalization across modalities. Surprisingly, although not as strong as visual responses, selectivity for auditory stimulation in visual cortex was stronger in blind individuals than in controls. The opposite was observed in primary auditory cortex. Overall, we demonstrated a striking similarity in the cortical response layout of VTC in blind individuals and sighted controls, demonstrating that the overall category-selective map in extrastriate cortex develops independently from visual experience. PMID:28507127

The Dorsal Rather than Ventral Pathway Better Reflects Individual Syntactic Abilities in Second Language

PubMed Central

Yamamoto, Kayako; Sakai, Kuniyoshi L.

2016-01-01

The left inferior frontal gyrus (IFG) has been reported to be critically involved in syntactic processing, not only in first language (L1), but in second language (L2). Indeed, the leftward lateralization of the IFG has been shown to be correlated with the performance of a syntactic task in L2. Given that posterior language-related regions are systematically connected with the left IFG, the next question is which of the dorsal and ventral pathways is more critical to the individual syntactic abilities in L2. Here we used diffusion magnetic resonance imaging (MRI) and tractography with newly developed semi-automatic methods of defining seeds and selecting regions of interest (ROIs). We calculated mean thickness and fractional anisotropy (FA) in each ROI for the arcuate fasciculus (Arcuate) of the dorsal pathway, as well as for the inferior fronto-occipital fasciculus (IFOF) of the ventral pathway. In Experiment I, we performed partial correlation analyses between FA and the accuracy of the syntactic task, removing the effects of the accuracy of a spelling task, gender, and handedness. Among the two pathways in each hemisphere, only FA of the left Arcuate was significantly correlated with individual accuracy of the syntactic task. In Experiment II, we recruited monozygotic twins and examined to what extent their L2 abilities and their structural properties were similar. Within twin pairs, the highest significant correlation was observed for reaction times of the spelling task, while the correlation for the accuracy of the syntactic task was marginal; these two correlation coefficients were significantly different. Moreover, the thickness of the left Arcuate was highly correlated within pairs, while its FA, as well as the thickness/FA in the ventral pathways, was not significantly correlated. The correlation coefficient for the thickness of the left Arcuate was significantly larger than that of the left IFOF. These results suggest that the thickness of the left Arcuate is more associated with the shared genetic/environmental factors, whereas both of mutually correlated FA in the left Arcuate and individual syntactic abilities in L2 may be less prone to these shared factors. PMID:27378889

Influences of High-Level Features, Gaze, and Scene Transitions on the Reliability of BOLD Responses to Natural Movie Stimuli

PubMed Central

Lu, Kun-Han; Hung, Shao-Chin; Wen, Haiguang; Marussich, Lauren; Liu, Zhongming

2016-01-01

Complex, sustained, dynamic, and naturalistic visual stimulation can evoke distributed brain activities that are highly reproducible within and across individuals. However, the precise origins of such reproducible responses remain incompletely understood. Here, we employed concurrent functional magnetic resonance imaging (fMRI) and eye tracking to investigate the experimental and behavioral factors that influence fMRI activity and its intra- and inter-subject reproducibility during repeated movie stimuli. We found that widely distributed and highly reproducible fMRI responses were attributed primarily to the high-level natural content in the movie. In the absence of such natural content, low-level visual features alone in a spatiotemporally scrambled control stimulus evoked significantly reduced degree and extent of reproducible responses, which were mostly confined to the primary visual cortex (V1). We also found that the varying gaze behavior affected the cortical response at the peripheral part of V1 and in the oculomotor network, with minor effects on the response reproducibility over the extrastriate visual areas. Lastly, scene transitions in the movie stimulus due to film editing partly caused the reproducible fMRI responses at widespread cortical areas, especially along the ventral visual pathway. Therefore, the naturalistic nature of a movie stimulus is necessary for driving highly reliable visual activations. In a movie-stimulation paradigm, scene transitions and individuals’ gaze behavior should be taken as potential confounding factors in order to properly interpret cortical activity that supports natural vision. PMID:27564573

Premotor cortex is sensitive to auditory-visual congruence for biological motion.

PubMed

Wuerger, Sophie M; Parkes, Laura; Lewis, Penelope A; Crocker-Buque, Alex; Rutschmann, Roland; Meyer, Georg F

2012-03-01

The auditory and visual perception systems have developed special processing strategies for ecologically valid motion stimuli, utilizing some of the statistical properties of the real world. A well-known example is the perception of biological motion, for example, the perception of a human walker. The aim of the current study was to identify the cortical network involved in the integration of auditory and visual biological motion signals. We first determined the cortical regions of auditory and visual coactivation (Experiment 1); a conjunction analysis based on unimodal brain activations identified four regions: middle temporal area, inferior parietal lobule, ventral premotor cortex, and cerebellum. The brain activations arising from bimodal motion stimuli (Experiment 2) were then analyzed within these regions of coactivation. Auditory footsteps were presented concurrently with either an intact visual point-light walker (biological motion) or a scrambled point-light walker; auditory and visual motion in depth (walking direction) could either be congruent or incongruent. Our main finding is that motion incongruency (across modalities) increases the activity in the ventral premotor cortex, but only if the visual point-light walker is intact. Our results extend our current knowledge by providing new evidence consistent with the idea that the premotor area assimilates information across the auditory and visual modalities by comparing the incoming sensory input with an internal representation.

Semantics of the visual environment encoded in parahippocampal cortex

PubMed Central

Bonner, Michael F.; Price, Amy Rose; Peelle, Jonathan E.; Grossman, Murray

2016-01-01

Semantic representations capture the statistics of experience and store this information in memory. A fundamental component of this memory system is knowledge of the visual environment, including knowledge of objects and their associations. Visual semantic information underlies a range of behaviors, from perceptual categorization to cognitive processes such as language and reasoning. Here we examine the neuroanatomic system that encodes visual semantics. Across three experiments, we found converging evidence indicating that knowledge of verbally mediated visual concepts relies on information encoded in a region of the ventral-medial temporal lobe centered on parahippocampal cortex. In an fMRI study, this region was strongly engaged by the processing of concepts relying on visual knowledge but not by concepts relying on other sensory modalities. In a study of patients with the semantic variant of primary progressive aphasia (semantic dementia), atrophy that encompassed this region was associated with a specific impairment in verbally mediated visual semantic knowledge. Finally, in a structural study of healthy adults from the fMRI experiment, gray matter density in this region related to individual variability in the processing of visual concepts. The anatomic location of these findings aligns with recent work linking the ventral-medial temporal lobe with high-level visual representation, contextual associations, and reasoning through imagination. Together this work suggests a critical role for parahippocampal cortex in linking the visual environment with knowledge systems in the human brain. PMID:26679216

Semantics of the Visual Environment Encoded in Parahippocampal Cortex.

PubMed

Bonner, Michael F; Price, Amy Rose; Peelle, Jonathan E; Grossman, Murray

2016-03-01

Semantic representations capture the statistics of experience and store this information in memory. A fundamental component of this memory system is knowledge of the visual environment, including knowledge of objects and their associations. Visual semantic information underlies a range of behaviors, from perceptual categorization to cognitive processes such as language and reasoning. Here we examine the neuroanatomic system that encodes visual semantics. Across three experiments, we found converging evidence indicating that knowledge of verbally mediated visual concepts relies on information encoded in a region of the ventral-medial temporal lobe centered on parahippocampal cortex. In an fMRI study, this region was strongly engaged by the processing of concepts relying on visual knowledge but not by concepts relying on other sensory modalities. In a study of patients with the semantic variant of primary progressive aphasia (semantic dementia), atrophy that encompassed this region was associated with a specific impairment in verbally mediated visual semantic knowledge. Finally, in a structural study of healthy adults from the fMRI experiment, gray matter density in this region related to individual variability in the processing of visual concepts. The anatomic location of these findings aligns with recent work linking the ventral-medial temporal lobe with high-level visual representation, contextual associations, and reasoning through imagination. Together, this work suggests a critical role for parahippocampal cortex in linking the visual environment with knowledge systems in the human brain.

Impaired recognition of faces and objects in dyslexia: Evidence for ventral stream dysfunction?

PubMed

Sigurdardottir, Heida Maria; Ívarsson, Eysteinn; Kristinsdóttir, Kristjana; Kristjánsson, Árni

2015-09-01

The objective of this study was to establish whether or not dyslexics are impaired at the recognition of faces and other complex nonword visual objects. This would be expected based on a meta-analysis revealing that children and adult dyslexics show functional abnormalities within the left fusiform gyrus, a brain region high up in the ventral visual stream, which is thought to support the recognition of words, faces, and other objects. 20 adult dyslexics (M = 29 years) and 20 matched typical readers (M = 29 years) participated in the study. One dyslexic-typical reader pair was excluded based on Adult Reading History Questionnaire scores and IS-FORM reading scores. Performance was measured on 3 high-level visual processing tasks: the Cambridge Face Memory Test, the Vanderbilt Holistic Face Processing Test, and the Vanderbilt Expertise Test. People with dyslexia are impaired in their recognition of faces and other visually complex objects. Their holistic processing of faces appears to be intact, suggesting that dyslexics may instead be specifically impaired at part-based processing of visual objects. The difficulty that people with dyslexia experience with reading might be the most salient manifestation of a more general high-level visual deficit. (c) 2015 APA, all rights reserved).

Neural Integration in Body Perception.

PubMed

Ramsey, Richard

2018-06-19

The perception of other people is instrumental in guiding social interactions. For example, the appearance of the human body cues a wide range of inferences regarding sex, age, health, and personality, as well as emotional state and intentions, which influence social behavior. To date, most neuroscience research on body perception has aimed to characterize the functional contribution of segregated patches of cortex in the ventral visual stream. In light of the growing prominence of network architectures in neuroscience, the current article reviews neuroimaging studies that measure functional integration between different brain regions during body perception. The review demonstrates that body perception is not restricted to processing in the ventral visual stream but instead reflects a functional alliance between the ventral visual stream and extended neural systems associated with action perception, executive functions, and theory of mind. Overall, these findings demonstrate how body percepts are constructed through interactions in distributed brain networks and underscore that functional segregation and integration should be considered together when formulating neurocognitive theories of body perception. Insight from such an updated model of body perception generalizes to inform the organizational structure of social perception and cognition more generally and also informs disorders of body image, such as anorexia nervosa, which may rely on atypical integration of body-related information.

Cortical and subcortical afferents to the nucleus reticularis tegmenti pontis and basal pontine nuclei in the macaque monkey.

PubMed

Giolli, R A; Gregory, K M; Suzuki, D A; Blanks, R H; Lui, F; Betelak, K F

2001-01-01

Anatomical findings are presented that identify cortical and subcortical sources of afferents to the nucleus reticularis tegmenti pontis (NRTP) and basal pontine nuclei. Projections from the middle temporal visual area (MT), medial superior temporal visual area (MST), lateral intraparietal area (LIP), and areas 7a and 7b to the basal pontine nuclei were studied using 3H-leucine autoradiography. The results complemented a parallel study of retrograde neuronal labeling attributable to injecting WGA-HRP into NRTP and neighboring pontine nuclei. Small 3H-leucine injections confined to MT, MST, LIP, area 7a, or area 7b, produced multiple patches of pontine terminal label distributed as follows: (1) An injection within MT produced terminal label limited to the dorsolateral and lateral pontine nuclei. (2) Injections restricted to MST or LIP showed patches of terminal label in the dorsal, dorsolateral, lateral, and peduncular pontine nuclei. (3) Area 7a targets the dorsal, dorsolateral, lateral, peduncular, and ventral pontine nuclei, whereas area 7b projects, additionally, to the dorsomedial and paramedian pontine nuclei. Notably, no projections were seen to NRTP from any of these cortical areas. In contrast, injections made by other investigators into cortical areas anterior to the central sulcus revealed cerebrocortical afferents to NRTP, in addition to nuclei of the basal pontine gray. With our pontine WGA-HRP injections, retrograde neuronal labeling was observed over a large extent of the frontal cortex continuing onto the medial surface which included the lining of the cingulate sulcus and cingulate gyrus. Significant subcortical sources for afferents to the NRTP and basal pontine nuclei were the zona incerta, ventral mesencephalic tegmentum, dorsomedial hypothalamic area, rostral interstitial nucleus of the medial longitudinal fasciculus, red nucleus, and subthalamic nucleus. The combined anterograde and retrograde labeling data indicated that visuo-motor cortico-pontine pathways arising from parietal cortices target only the basal pontine gray, whereas the NRTP, together with select pontine nuclei, is a recipient of afferents from frontal cortical areas. The present findings implicate the existence of parallel direct and indirect cortico-pontine pathways from frontal motor-related cortices to NRTP and neighboring pontine nuclei.

The Impact of Density and Ratio on Object-Ensemble Representation in Human Anterior-Medial Ventral Visual Cortex.

PubMed

Cant, Jonathan S; Xu, Yaoda

2015-11-01

Behavioral research has demonstrated that observers can extract summary statistics from ensembles of multiple objects. We recently showed that a region of anterior-medial ventral visual cortex, overlapping largely with the scene-sensitive parahippocampal place area (PPA), participates in object-ensemble representation. Here we investigated the encoding of ensemble density in this brain region using fMRI-adaptation. In Experiment 1, we varied density by changing the spacing between objects and found no sensitivity in PPA to such density changes. Thus, density may not be encoded in PPA, possibly because object spacing is not perceived as an intrinsic ensemble property. In Experiment 2, we varied relative density by changing the ratio of 2 types of objects comprising an ensemble, and observed significant sensitivity in PPA to such ratio change. Although colorful ensembles were shown in Experiment 2, Experiment 3 demonstrated that sensitivity to object ratio change was not driven mainly by a change in the ratio of colors. Thus, while anterior-medial ventral visual cortex is insensitive to density (object spacing) changes, it does code relative density (object ratio) within an ensemble. Object-ensemble processing in this region may thus depend on high-level visual information, such as object ratio, rather than low-level information, such as spacing/spatial frequency. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Art for reward's sake: visual art recruits the ventral striatum.

PubMed

Lacey, Simon; Hagtvedt, Henrik; Patrick, Vanessa M; Anderson, Amy; Stilla, Randall; Deshpande, Gopikrishna; Hu, Xiaoping; Sato, João R; Reddy, Srinivas; Sathian, K

2011-03-01

A recent study showed that people evaluate products more positively when they are physically associated with art images than similar non-art images. Neuroimaging studies of visual art have investigated artistic style and esthetic preference but not brain responses attributable specifically to the artistic status of images. Here we tested the hypothesis that the artistic status of images engages reward circuitry, using event-related functional magnetic resonance imaging (fMRI) during viewing of art and non-art images matched for content. Subjects made animacy judgments in response to each image. Relative to non-art images, art images activated, on both subject- and item-wise analyses, reward-related regions: the ventral striatum, hypothalamus and orbitofrontal cortex. Neither response times nor ratings of familiarity or esthetic preference for art images correlated significantly with activity that was selective for art images, suggesting that these variables were not responsible for the art-selective activations. Investigation of effective connectivity, using time-varying, wavelet-based, correlation-purged Granger causality analyses, further showed that the ventral striatum was driven by visual cortical regions when viewing art images but not non-art images, and was not driven by regions that correlated with esthetic preference for either art or non-art images. These findings are consistent with our hypothesis, leading us to propose that the appeal of visual art involves activation of reward circuitry based on artistic status alone and independently of its hedonic value. Copyright © 2010 Elsevier Inc. All rights reserved.

ART FOR REWARD’S SAKE: VISUAL ART RECRUITS THE VENTRAL STRIATUM

PubMed Central

Lacey, Simon; Hagtvedt, Henrik; Patrick, Vanessa M.; Anderson, Amy; Stilla, Randall; Deshpande, Gopikrishna; Hu, Xiaoping; Sato, João R.; Reddy, Srinivas; Sathian, K.

2010-01-01

A recent study showed that people evaluate products more positively when they are physically associated with art images than similar non-art images. Neuroimaging studies of visual art have investigated artistic style and esthetic preference but not brain responses attributable specifically to the artistic status of images. Here we tested the hypothesis that the artistic status of images engages reward circuitry, using event-related functional magnetic resonance imaging (fMRI) during viewing of art and non-art images matched for content. Subjects made animacy judgments in response to each image. Relative to non-art images, art images activated, on both subject- and item-wise analyses, reward-related regions: the ventral striatum, hypothalamus and orbitofrontal cortex. Neither response times nor ratings of familiarity or esthetic preference for art images correlated significantly with activity that was selective for art images, suggesting that these variables were not responsible for the art-selective activations. Investigation of effective connectivity, using time-varying, wavelet-based, correlation-purged Granger causality analyses, further showed that the ventral striatum was driven by visual cortical regions when viewing art images but not non-art images, and was not driven by regions that correlated with esthetic preference for either art or non -art images. These findings are consistent with our hypothesis, leading us to propose that the appeal of visual art involves activation of reward circuitry based on artistic status alone and independently of its hedonic value. PMID:21111833

How cortical neurons help us see: visual recognition in the human brain

PubMed Central

Blumberg, Julie; Kreiman, Gabriel

2010-01-01

Through a series of complex transformations, the pixel-like input to the retina is converted into rich visual perceptions that constitute an integral part of visual recognition. Multiple visual problems arise due to damage or developmental abnormalities in the cortex of the brain. Here, we provide an overview of how visual information is processed along the ventral visual cortex in the human brain. We discuss how neurophysiological recordings in macaque monkeys and in humans can help us understand the computations performed by visual cortex. PMID:20811161

Role of temporal processing stages by inferior temporal neurons in facial recognition.

PubMed

Sugase-Miyamoto, Yasuko; Matsumoto, Narihisa; Kawano, Kenji

2011-01-01

In this review, we focus on the role of temporal stages of encoded facial information in the visual system, which might enable the efficient determination of species, identity, and expression. Facial recognition is an important function of our brain and is known to be processed in the ventral visual pathway, where visual signals are processed through areas V1, V2, V4, and the inferior temporal (IT) cortex. In the IT cortex, neurons show selective responses to complex visual images such as faces, and at each stage along the pathway the stimulus selectivity of the neural responses becomes sharper, particularly in the later portion of the responses. In the IT cortex of the monkey, facial information is represented by different temporal stages of neural responses, as shown in our previous study: the initial transient response of face-responsive neurons represents information about global categories, i.e., human vs. monkey vs. simple shapes, whilst the later portion of these responses represents information about detailed facial categories, i.e., expression and/or identity. This suggests that the temporal stages of the neuronal firing pattern play an important role in the coding of visual stimuli, including faces. This type of coding may be a plausible mechanism underlying the temporal dynamics of recognition, including the process of detection/categorization followed by the identification of objects. Recent single-unit studies in monkeys have also provided evidence consistent with the important role of the temporal stages of encoded facial information. For example, view-invariant facial identity information is represented in the response at a later period within a region of face-selective neurons. Consistent with these findings, temporally modulated neural activity has also been observed in human studies. These results suggest a close correlation between the temporal processing stages of facial information by IT neurons and the temporal dynamics of face recognition.

Role of Temporal Processing Stages by Inferior Temporal Neurons in Facial Recognition

PubMed Central

Sugase-Miyamoto, Yasuko; Matsumoto, Narihisa; Kawano, Kenji

2011-01-01

In this review, we focus on the role of temporal stages of encoded facial information in the visual system, which might enable the efficient determination of species, identity, and expression. Facial recognition is an important function of our brain and is known to be processed in the ventral visual pathway, where visual signals are processed through areas V1, V2, V4, and the inferior temporal (IT) cortex. In the IT cortex, neurons show selective responses to complex visual images such as faces, and at each stage along the pathway the stimulus selectivity of the neural responses becomes sharper, particularly in the later portion of the responses. In the IT cortex of the monkey, facial information is represented by different temporal stages of neural responses, as shown in our previous study: the initial transient response of face-responsive neurons represents information about global categories, i.e., human vs. monkey vs. simple shapes, whilst the later portion of these responses represents information about detailed facial categories, i.e., expression and/or identity. This suggests that the temporal stages of the neuronal firing pattern play an important role in the coding of visual stimuli, including faces. This type of coding may be a plausible mechanism underlying the temporal dynamics of recognition, including the process of detection/categorization followed by the identification of objects. Recent single-unit studies in monkeys have also provided evidence consistent with the important role of the temporal stages of encoded facial information. For example, view-invariant facial identity information is represented in the response at a later period within a region of face-selective neurons. Consistent with these findings, temporally modulated neural activity has also been observed in human studies. These results suggest a close correlation between the temporal processing stages of facial information by IT neurons and the temporal dynamics of face recognition. PMID:21734904

A novel function for the IκB inhibitor Cactus in promoting Dorsal nuclear localization and activity in the Drosophila embryo.

PubMed

Cardoso, Maira Arruda; Fontenele, Marcio; Lim, Bomyi; Bisch, Paulo Mascarello; Shvartsman, Stanislav Y; Araujo, Helena Marcolla

2017-08-15

The evolutionarily conserved Toll signaling pathway controls innate immunity across phyla and embryonic patterning in insects. In the Drosophila embryo, Toll is required to establish gene expression domains along the dorsal-ventral axis. Pathway activation induces degradation of the IκB inhibitor Cactus, resulting in a ventral-to-dorsal nuclear gradient of the NFκB effector Dorsal. Here, we investigate how cactus modulates Toll signals through its effects on the Dorsal gradient and on Dorsal target genes. Quantitative analysis using a series of loss- and gain-of-function conditions shows that the ventral and lateral aspects of the Dorsal gradient can behave differently with respect to Cactus fluctuations. In lateral and dorsal embryo domains, loss of Cactus allows more Dorsal to translocate to the nucleus. Unexpectedly, cactus loss-of-function alleles decrease Dorsal nuclear localization ventrally, where Toll signals are high. Overexpression analysis suggests that this ability of Cactus to enhance Toll stems from the mobilization of a free Cactus pool induced by the Calpain A protease. These results indicate that Cactus acts to bolster Dorsal activation, in addition to its role as a NFκB inhibitor, ensuring a correct response to Toll signals. © 2017. Published by The Company of Biologists Ltd.

Neural correlates of auditory scene analysis and perception

PubMed Central

Cohen, Yale E.

2014-01-01

The auditory system is designed to transform acoustic information from low-level sensory representations into perceptual representations. These perceptual representations are the computational result of the auditory system's ability to group and segregate spectral, spatial and temporal regularities in the acoustic environment into stable perceptual units (i.e., sounds or auditory objects). Current evidence suggests that the cortex--specifically, the ventral auditory pathway--is responsible for the computations most closely related to perceptual representations. Here, we discuss how the transformations along the ventral auditory pathway relate to auditory percepts, with special attention paid to the processing of vocalizations and categorization, and explore recent models of how these areas may carry out these computations. PMID:24681354

Two visual systems in monitoring of dynamic traffic: effects of visual disruption.

PubMed

Zheng, Xianjun Sam; McConkie, George W

2010-05-01

Studies from neurophysiology and neuropsychology provide support for two separate object- and location-based visual systems, ventral and dorsal. In the driving context, a study was conducted using a change detection paradigm to explore drivers' ability to monitor the dynamic traffic flow, and the effects of visual disruption on these two visual systems. While driving, a discrete change, such as vehicle location, color, or identity, was occasionally made in one of the vehicles on the road ahead of the driver. Experiment results show that without visual disruption, all changes were detected very well; yet, these equally perceivable changes were disrupted differently by a brief blank display (150 ms): the detection of location changes was especially reduced. The disruption effects were also bigger for the parked vehicle compared to the moving ones. The findings support the different roles for two visual systems in monitoring the dynamic traffic: the "where", dorsal system, tracks vehicle spatiotemporal information on perceptual level, encoding information in a coarse and transient manner; whereas the "what", ventral system, monitors vehicles' featural information, encoding information more accurately and robustly. Both systems work together contributing to the driver's situation awareness of traffic. Benefits and limitations of using the driving simulation are also discussed. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Cocaine Inhibition of Synaptic Transmission in the Ventral Pallidum Is Pathway-Specific and Mediated by Serotonin.

PubMed

Matsui, Aya; Alvarez, Veronica A

2018-06-26

The ventral pallidum (VP) is part of the basal ganglia circuitry and a target of both direct and indirect pathway projections from the nucleus accumbens. VP is important in cocaine reinforcement, and the firing of VP neurons is modulated in vivo during cocaine self-administration. This modulation of firing is thought to be indirect via cocaine actions on dopamine in the accumbens. Here, we show that cocaine directly inhibits synaptic transmission evoked by selective stimulation of indirect pathway projections to VP neurons. The inhibition is independent of dopamine receptor activation, absent in 5-HT1B knockout mice, and mimicked by a serotonin transporter (SERT) blocker. SERT-expressing neurons in dorsal raphe project to the VP. Optogenetic stimulation of these projections evokes serotonin transients and effectively inhibits GABAergic transmission to VP neurons. This study shows that cocaine increases endogenous serotonin in the VP to suppress synaptic transmission selectively from indirect pathway projections to VP neurons. Published by Elsevier Inc.

White matter pathways for prosodic structure building: A case study.

PubMed

Sammler, Daniela; Cunitz, Katrin; Gierhan, Sarah M E; Anwander, Alfred; Adermann, Jens; Meixensberger, Jürgen; Friederici, Angela D

2018-05-11

The relevance of left dorsal and ventral fiber pathways for syntactic and semantic comprehension is well established, while pathways for prosody are little explored. The present study examined linguistic prosodic structure building in a patient whose right arcuate/superior longitudinal fascicles and posterior corpus callosum were transiently compromised by a vasogenic peritumoral edema. Compared to ten matched healthy controls, the patient's ability to detect irregular prosodic structure significantly improved between pre- and post-surgical assessment. This recovery was accompanied by an increase in average fractional anisotropy (FA) in right dorsal and posterior transcallosal fiber tracts. Neither general cognitive abilities nor (non-prosodic) syntactic comprehension nor FA in right ventral and left dorsal fiber tracts showed a similar pre-post increase. Together, these findings suggest a contribution of right dorsal and inter-hemispheric pathways to prosody perception, including the right-dorsal tracking and structuring of prosodic pitch contours that is transcallosally informed by concurrent syntactic information. Copyright © 2018 Elsevier Inc. All rights reserved.

Visual search for object categories is predicted by the representational architecture of high-level visual cortex

PubMed Central

Alvarez, George A.; Nakayama, Ken; Konkle, Talia

2016-01-01

Visual search is a ubiquitous visual behavior, and efficient search is essential for survival. Different cognitive models have explained the speed and accuracy of search based either on the dynamics of attention or on similarity of item representations. Here, we examined the extent to which performance on a visual search task can be predicted from the stable representational architecture of the visual system, independent of attentional dynamics. Participants performed a visual search task with 28 conditions reflecting different pairs of categories (e.g., searching for a face among cars, body among hammers, etc.). The time it took participants to find the target item varied as a function of category combination. In a separate group of participants, we measured the neural responses to these object categories when items were presented in isolation. Using representational similarity analysis, we then examined whether the similarity of neural responses across different subdivisions of the visual system had the requisite structure needed to predict visual search performance. Overall, we found strong brain/behavior correlations across most of the higher-level visual system, including both the ventral and dorsal pathways when considering both macroscale sectors as well as smaller mesoscale regions. These results suggest that visual search for real-world object categories is well predicted by the stable, task-independent architecture of the visual system. NEW & NOTEWORTHY Here, we ask which neural regions have neural response patterns that correlate with behavioral performance in a visual processing task. We found that the representational structure across all of high-level visual cortex has the requisite structure to predict behavior. Furthermore, when directly comparing different neural regions, we found that they all had highly similar category-level representational structures. These results point to a ubiquitous and uniform representational structure in high-level visual cortex underlying visual object processing. PMID:27832600

Visual Space and Object Space in the Cerebral Cortex of Retinal Disease Patients

PubMed Central

Spileers, Werner; Wagemans, Johan; Op de Beeck, Hans P.

2014-01-01

The lower areas of the hierarchically organized visual cortex are strongly retinotopically organized, with strong responses to specific retinotopic stimuli, and no response to other stimuli outside these preferred regions. Higher areas in the ventral occipitotemporal cortex show a weak eccentricity bias, and are mainly sensitive for object category (e.g., faces versus buildings). This study investigated how the mapping of eccentricity and category sensitivity using functional magnetic resonance imaging is affected by a retinal lesion in two very different low vision patients: a patient with a large central scotoma, affecting central input to the retina (juvenile macular degeneration), and a patient where input to the peripheral retina is lost (retinitis pigmentosa). From the retinal degeneration, we can predict specific losses of retinotopic activation. These predictions were confirmed when comparing stimulus activations with a no-stimulus fixation baseline. At the same time, however, seemingly contradictory patterns of activation, unexpected given the retinal degeneration, were observed when different stimulus conditions were directly compared. These unexpected activations were due to position-specific deactivations, indicating the importance of investigating absolute activation (relative to a no-stimulus baseline) rather than relative activation (comparing different stimulus conditions). Data from two controls, with simulated scotomas that matched the lesions in the two patients also showed that retinotopic mapping results could be explained by a combination of activations at the stimulated locations and deactivations at unstimulated locations. Category sensitivity was preserved in the two patients. In sum, when we take into account the full pattern of activations and deactivations elicited in retinotopic cortex and throughout the ventral object vision pathway in low vision patients, the pattern of (de)activation is consistent with the retinal loss. PMID:24505449

Synaesthetic colour in the brain: beyond colour areas. A functional magnetic resonance imaging study of synaesthetes and matched controls.

PubMed

van Leeuwen, Tessa M; Petersson, Karl Magnus; Hagoort, Peter

2010-08-10

In synaesthesia, sensations in a particular modality cause additional experiences in a second, unstimulated modality (e.g., letters elicit colour). Understanding how synaesthesia is mediated in the brain can help to understand normal processes of perceptual awareness and multisensory integration. In several neuroimaging studies, enhanced brain activity for grapheme-colour synaesthesia has been found in ventral-occipital areas that are also involved in real colour processing. Our question was whether the neural correlates of synaesthetically induced colour and real colour experience are truly shared. First, in a free viewing functional magnetic resonance imaging (fMRI) experiment, we located main effects of synaesthesia in left superior parietal lobule and in colour related areas. In the left superior parietal lobe, individual differences between synaesthetes (projector-associator distinction) also influenced brain activity, confirming the importance of the left superior parietal lobe for synaesthesia. Next, we applied a repetition suppression paradigm in fMRI, in which a decrease in the BOLD (blood-oxygenated-level-dependent) response is generally observed for repeated stimuli. We hypothesized that synaesthetically induced colours would lead to a reduction in BOLD response for subsequently presented real colours, if the neural correlates were overlapping. We did find BOLD suppression effects induced by synaesthesia, but not within the colour areas. Because synaesthetically induced colours were not able to suppress BOLD effects for real colour, we conclude that the neural correlates of synaesthetic colour experience and real colour experience are not fully shared. We propose that synaesthetic colour experiences are mediated by higher-order visual pathways that lie beyond the scope of classical, ventral-occipital visual areas. Feedback from these areas, in which the left parietal cortex is likely to play an important role, may induce V4 activation and the percept of synaesthetic colour.

BMP regulates regional gene expression in the dorsal otocyst through canonical and non-canonical intracellular pathways

PubMed Central

2016-01-01

The inner ear consists of two otocyst-derived, structurally and functionally distinct components: the dorsal vestibular and ventral auditory compartments. BMP signaling is required to form the vestibular compartment, but how it complements other required signaling molecules and acts intracellularly is unknown. Using spatially and temporally controlled delivery of signaling pathway regulators to developing chick otocysts, we show that BMP signaling regulates the expression of Dlx5 and Hmx3, both of which encode transcription factors essential for vestibular formation. However, although BMP regulates Dlx5 through the canonical SMAD pathway, surprisingly, it regulates Hmx3 through a non-canonical pathway involving both an increase in cAMP-dependent protein kinase A activity and the GLI3R to GLI3A ratio. Thus, both canonical and non-canonical BMP signaling establish the precise spatiotemporal expression of Dlx5 and Hmx3 during dorsal vestibular development. The identification of the non-canonical pathway suggests an intersection point between BMP and SHH signaling, which is required for ventral auditory development. PMID:27151948

Multiple-region directed functional connectivity based on phase delays.

PubMed

Goelman, Gadi; Dan, Rotem

2017-03-01

Network analysis is increasingly advancing the field of neuroimaging. Neural networks are generally constructed from pairwise interactions with an assumption of linear relations between them. Here, a high-order statistical framework to calculate directed functional connectivity among multiple regions, using wavelet analysis and spectral coherence has been presented. The mathematical expression for 4 regions was derived and used to characterize a quartet of regions as a linear, combined (nonlinear), or disconnected network. Phase delays between regions were used to obtain network's temporal hierarchy and directionality. The validity of the mathematical derivation along with the effects of coupling strength and noise on its outcomes were studied by computer simulations of the Kuramoto model. The simulations demonstrated correct directionality for a large range of coupling strength and low sensitivity to Gaussian noise compared with pairwise coherences. The analysis was applied to resting-state fMRI data of 40 healthy young subjects to characterize the ventral visual system, motor system and default mode network (DMN). It was shown that the ventral visual system was predominantly composed of linear networks while the motor system and the DMN were composed of combined (nonlinear) networks. The ventral visual system exhibits its known temporal hierarchy, the motor system exhibits center ↔ out hierarchy and the DMN has dorsal ↔ ventral and anterior ↔ posterior organizations. The analysis can be applied in different disciplines such as seismology, or economy and in a variety of brain data including stimulus-driven fMRI, electrophysiology, EEG, and MEG, thus open new horizons in brain research. Hum Brain Mapp 38:1374-1386, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Peripersonal and extrapersonal visuospatial neglect in different frames of reference: A brain lesion-symptom mapping study.

PubMed

Ten Brink, Antonia F; Matthijs Biesbroek, J; Oort, Quirien; Visser-Meily, Johanna M A; Nijboer, Tanja C W

2018-06-22

Visuospatial neglect can occur in peripersonal and extrapersonal space. The dorsal visual pathway is hypothesized to be associated with peripersonal, and the ventral pathway with extrapersonal neglect. We aimed to evaluate neural substrates of peripersonal versus extrapersonal neglect, separately for egocentric and allocentric frames of reference. This was a retrospective study, including stroke patients admitted for inpatient rehabilitation. Approximately 1 month post-stroke onset, computerized cancellation (egocentric) and bisection tasks (egocentric and allocentric) were administered at 30 cm and 120 cm. We collected CT or MRI scans and performed voxel-based lesion-symptom mapping for the cancellation, and subtraction analyses for the line bisection task. We included 98 patients for the cancellation and 129 for the bisection analyses. The right parahippocampal gyrus, hippocampus, and thalamus were associated with egocentric peripersonal neglect as measured with cancellation. These areas were also associated with extrapersonal neglect, together with the right superior parietal lobule, angular gyrus, supramarginal gyrus, lateral occipital cortex, planum temporale and superior temporal gyrus. Lesions in the right parietal, temporal and frontal areas were associated with both peripersonal and extrapersonal egocentric neglect as measured with bisection. For allocentric neglect no clear pattern of associated brain regions was observed. We found right hemispheric anatomical correlates for peripersonal and extrapersonal neglect. However, no brain areas were uniquely associated with peripersonal neglect, meaning we could not conclusively verify the ventral/dorsal hypothesis. Several areas were uniquely associated with egocentric extrapersonal neglect, suggesting that these brain areas can be specifically involved in extrapersonal, but not in peripersonal, attention processes. Copyright © 2018. Published by Elsevier B.V.

Premotor activations in response to visually presented single letters depend on the hand used to write: a study on left-handers.

PubMed

Longcamp, Marieke; Anton, Jean-Luc; Roth, Muriel; Velay, Jean-Luc

2005-01-01

In a previous fMRI study on right-handers (Rhrs), we reported that part of the left ventral premotor cortex (BA6) was activated when alphabetical characters were passively observed and that the same region was also involved in handwriting [Longcamp, M., Anton, J. L., Roth, M., & Velay, J. L. (2003). Visual presentation of single letters activates a premotor area involved in writing. NeuroImage, 19, 1492-1500]. We therefore suggested that letter-viewing may induce automatic involvement of handwriting movements. In the present study, in order to confirm this hypothesis, we carried out a similar fMRI experiment on a group of left-handed subjects (Lhrs). We reasoned that if the above assumption was correct, visual perception of letters by Lhrs might automatically activate cortical motor areas coding for left-handed writing movements, i.e., areas located in the right hemisphere. The visual stimuli used here were either single letters, single pseudoletters, or a control stimulus. The subjects were asked to watch these stimuli attentively, and no response was required. The results showed that a ventral premotor cortical area (BA6) in the right hemisphere was specifically activated when Lhrs looked at letters and not at pseudoletters. This right area was symmetrically located with respect to the left one activated under the same circumstances in Rhrs. This finding supports the hypothesis that visual perception of written language evokes covert motor processes. In addition, a bilateral area, also located in the premotor cortex (BA6), but more ventrally and medially, was found to be activated in response to both letters and pseudoletters. This premotor region, which was not activated correspondingly in Rhrs, might be involved in the processing of graphic stimuli, whatever their degree of familiarity.

Increased biomagnetic activity in the ventral pathway in mild cognitive impairment.

PubMed

Maestú, F; Campo, P; Del Río, D; Moratti, S; Gil-Gregorio, P; Fernández, A; Capilla, A; Ortiz, T

2008-06-01

Mild cognitive impairment (MCI) patients represent an intermediary state between healthy aging and dementia. MCI activation profiles, recorded during a memory task, have been studied either through high spatial resolution or high temporal resolution techniques. However, little is known about the benefit of combining both dimensions. Here, we investigate, by means of magnetoencephalography (MEG), whether spatio-temporal profiles of neuromagnetic activity could differentiate between MCI and age-matched elderly participants. Taking the advantage of the high temporal resolution and good spatial resolution of MEG, neuromagnetic activity from 15 elderly MCI patients and 20 age-matched controls was recorded during the performance of a modified version of the Sternberg paradigm. Behavioral performance was similar in both groups. A between group analysis revealed that MCI patients showed bilateral higher activity in the ventral pathway, in both the target and the non-target stimuli. A within-group analysis of the target stimuli, indicates a lack of asymmetry through all late latency windows in both groups. MCI patients showed a compensatory mechanism represented by an increased bilateral activity of the ventral pathway in order to achieve a behavioral performance similar to the control group. This spatio-temporal pattern of activity could be another tool to differentiate between healthy aging and MCI patients.

Tract-based spatial statistics analysis of white matter changes in children with anisometropic amblyopia.

PubMed

Li, Qian; Zhai, Liying; Jiang, Qinying; Qin, Wen; Li, Qingji; Yin, Xiaohui; Guo, Mingxia

2015-06-15

Amblyopia is a neurological disorder of vision that follows abnormal binocular interaction or visual deprivation during early life. Previous studies have reported multiple functional or structural cortical alterations. Although white matter was also studied, it still cannot be clarified clearly which fasciculus was affected by amblyopia. In the present study, tract-based spatial statistics analysis was applied to diffusion tensor imaging (DTI) to investigate potential diffusion changes of neural tracts in anisometropic amblyopia. Fractional anisotropy (FA) value was calculated and compared between 20 amblyopic children and 18 healthy age-matched controls. In contrast to the controls, significant decreases in FA values were found in right optic radiation (OR), left inferior longitudinal fasciculus/inferior fronto-occipital fasciculus (ILF/IFO) and right superior longitudinal fasciculus (SLF) in the amblyopia. Furthermore, FA values of these identified tracts showed positive correlation with visual acuity. It can be inferred that abnormal visual input not only hinders OR from well developed, but also impairs fasciculi associated with dorsal and ventral visual pathways, which may be responsible for the amblyopic deficiency in object discrimination and stereopsis. Increased FA was detected in right posterior part of corpus callosum (CC) with a medium effect size, which may be due to compensation effect. DTI with subsequent measurement of FA is a useful tool for investigating neuronal tract involvement in amblyopia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Functional neuroanatomy of the ventral striopallidal GABA pathway. New sites of intervention in the treatment of schizophrenia.

PubMed

O'Connor, W T

2001-08-15

Microdialysis was employed to investigate the dopamine, cholecystokinin (CCK) and neurotensin receptor regulation of ventral striopallidal GABA transmission by intra-accumbens perfusion with selective receptor ligands and monitoring local or ipsilateral ventral pallidal GABA release. In the dual probe studies intra-accumbens perfusion with the dopamine D1 and D2 receptor agonists SKF28293 and pergolide had no effect on ventral pallidal GABA, while both the D1 and D2 receptor antagonists SCH23390 and raclopride increased ventral pallidal GABA release. In contrast, intra-accumbens CCK decreased ventral pallidal GABA release and this was reversed by local perfusion with the CCK2 receptor antagonist PD134308 but not the CCK1 receptor antagonist L-364,718. In a single probe study intra-accumbens neurotensin increased local GABA release, which was strongly potentiated when the peptidase inhibitor phosphodiepryl 08 was perfused together with neurotensin. In addition, the neurotensin receptor antagonist SR48692 counteracted this phosphodiepryl 08 induced potentiated increased in GABA release. Taken together, these findings indicate that mesolimbic dopamine and CCK exert a respective tonic and phasic inhibition of ventral pallidal GABA release while the antipsychotic activity associated with D1 and D2 receptor antagonists may be explained by their ability to increase ventral striopallidal GABA transmission. Furthermore, the findings suggest that CCK2 receptor antagonists and neurotensin endopeptidase inhibitors may be useful antipsychotics.

Regional Brain Activity in Abstinent Methamphetamine Dependent Males Following Cue Exposure.

PubMed

Malcolm, Robert; Myrick, Hugh; Li, Xingbao; Henderson, Scott; Brady, Kathleen T; George, Mark S; See, Ronald E

Neuroimaging of drug-associated cue presentations has aided in understanding the neurobiological substrates of craving and relapse for cocaine, alcohol, and nicotine. However, imaging of cue-reactivity in methamphetamine addiction has been much less studied. Nine caucasian male methamphetamine-dependent subjects and nine healthy controls were scanned in a Phillips 3.0T MRI scan when they viewed a randomized presentation of visual cues of methamphetamine, neutral objects, and rest conditions. Functional Imaging data were analyzed with Statistical Parametric Mapping software 5 (SPM 5). Methamphetamine subjects had significant brain activation in the ventral striatum and medial frontal cortex in comparison to meth pictures and neutral pictures in healthy controls (p<0.005, threshold 15 voxels). Interestingly the ventral striatum activation significantly correlated with the days since the last use of meth (r=-0.76, p=0.017). No significant activity was found in healthy control group. The preliminary data suggest that methamphetamine dependent subjects, when exposed to methamphetamine-associated visual cues, have increased brain activity in ventral striatum, caudate nucleus and medial frontal cortex which subserve craving, drug-seeking, and drug use.

A computational model of the development of separate representations of facial identity and expression in the primate visual system.

PubMed

Tromans, James Matthew; Harris, Mitchell; Stringer, Simon Maitland

2011-01-01

Experimental studies have provided evidence that the visual processing areas of the primate brain represent facial identity and facial expression within different subpopulations of neurons. For example, in non-human primates there is evidence that cells within the inferior temporal gyrus (TE) respond primarily to facial identity, while cells within the superior temporal sulcus (STS) respond to facial expression. More recently, it has been found that the orbitofrontal cortex (OFC) of non-human primates contains some cells that respond exclusively to changes in facial identity, while other cells respond exclusively to facial expression. How might the primate visual system develop physically separate representations of facial identity and expression given that the visual system is always exposed to simultaneous combinations of facial identity and expression during learning? In this paper, a biologically plausible neural network model, VisNet, of the ventral visual pathway is trained on a set of carefully-designed cartoon faces with different identities and expressions. The VisNet model architecture is composed of a hierarchical series of four Self-Organising Maps (SOMs), with associative learning in the feedforward synaptic connections between successive layers. During learning, the network develops separate clusters of cells that respond exclusively to either facial identity or facial expression. We interpret the performance of the network in terms of the learning properties of SOMs, which are able to exploit the statistical indendependence between facial identity and expression.

Radiographic and ultrasonographic characteristics of ventral abdominal hernia in pigeons (Columba livia).

PubMed

Amer, Mohammed S; Hassan, Elham A; Torad, Faisal A

2018-02-20

Five female egg-laying pigeons presented with painless, reducible, ventral abdominal swellings located between the keel and the pubis, or close to the cloaca. Based on clinical, radiographic, and ultrasonographic examination, these pigeons were diagnosed with ventral abdominal hernia requiring surgical interference. Reduction was successfully performed under general anesthesia. Radiographic and ultrasonographic examinations were beneficial for confirming the diagnosis and visualizing the hernial content for surgical planning. Lateral radiographs were more helpful than ventrodorsal radiographs for identification of the hernial content and its continuation with the abdominal muscles. Ultrasonographic examination offered a non-invasive diagnostic tool that allowed for the differentiation of hernia from other abdominal swellings. In addition, it played a beneficial role in identification of the hernial content and follow up after surgical interference. In conclusion, radiographic and ultrasonographic examinations were beneficial in the diagnosis, surgical planning, and follow up after surgical interference of ventral abdominal hernia in pigeons.

Eye movement-invariant representations in the human visual system.

PubMed

Nishimoto, Shinji; Huth, Alexander G; Bilenko, Natalia Y; Gallant, Jack L

2017-01-01

During natural vision, humans make frequent eye movements but perceive a stable visual world. It is therefore likely that the human visual system contains representations of the visual world that are invariant to eye movements. Here we present an experiment designed to identify visual areas that might contain eye-movement-invariant representations. We used functional MRI to record brain activity from four human subjects who watched natural movies. In one condition subjects were required to fixate steadily, and in the other they were allowed to freely make voluntary eye movements. The movies used in each condition were identical. We reasoned that the brain activity recorded in a visual area that is invariant to eye movement should be similar under fixation and free viewing conditions. In contrast, activity in a visual area that is sensitive to eye movement should differ between fixation and free viewing. We therefore measured the similarity of brain activity across repeated presentations of the same movie within the fixation condition, and separately between the fixation and free viewing conditions. The ratio of these measures was used to determine which brain areas are most likely to contain eye movement-invariant representations. We found that voxels located in early visual areas are strongly affected by eye movements, while voxels in ventral temporal areas are only weakly affected by eye movements. These results suggest that the ventral temporal visual areas contain a stable representation of the visual world that is invariant to eye movements made during natural vision.

Visual Receptive Field Heterogeneity and Functional Connectivity of Adjacent Neurons in Primate Frontoparietal Association Cortices.

PubMed

Viswanathan, Pooja; Nieder, Andreas

2017-09-13

The basic organization principles of the primary visual cortex (V1) are commonly assumed to also hold in the association cortex such that neurons within a cortical column share functional connectivity patterns and represent the same region of the visual field. We mapped the visual receptive fields (RFs) of neurons recorded at the same electrode in the ventral intraparietal area (VIP) and the lateral prefrontal cortex (PFC) of rhesus monkeys. We report that the spatial characteristics of visual RFs between adjacent neurons differed considerably, with increasing heterogeneity from VIP to PFC. In addition to RF incongruences, we found differential functional connectivity between putative inhibitory interneurons and pyramidal cells in PFC and VIP. These findings suggest that local RF topography vanishes with hierarchical distance from visual cortical input and argue for increasingly modified functional microcircuits in noncanonical association cortices that contrast V1. SIGNIFICANCE STATEMENT Our visual field is thought to be represented faithfully by the early visual brain areas; all the information from a certain region of the visual field is conveyed to neurons situated close together within a functionally defined cortical column. We examined this principle in the association areas, PFC, and ventral intraparietal area of rhesus monkeys and found that adjacent neurons represent markedly different areas of the visual field. This is the first demonstration of such noncanonical organization of these brain areas. Copyright © 2017 the authors 0270-6474/17/378919-10$15.00/0.

Arterial spin labeling fMRI measurements of decreased blood flow in primary visual cortex correlates with decreased visual function in human glaucoma.

PubMed

Duncan, Robert O; Sample, Pamela A; Bowd, Christopher; Weinreb, Robert N; Zangwill, Linda M

2012-05-01

Altered metabolic activity has been identified as a potential contributing factor to the neurodegeneration associated with primary open angle glaucoma (POAG). Consequently, we sought to determine whether there is a relationship between the loss of visual function in human glaucoma and resting blood perfusion within primary visual cortex (V1). Arterial spin labeling (ASL) functional magnetic resonance imaging (fMRI) was conducted in 10 participants with POAG. Resting cerebral blood flow (CBF) was measured from dorsal and ventral V1. Behavioral measurements of visual function were obtained using standard automated perimetry (SAP), short-wavelength automated perimetry (SWAP), and frequency-doubling technology perimetry (FDT). Measurements of CBF were compared to differences in visual function for the superior and inferior hemifield. Differences in CBF between ventral and dorsal V1 were correlated with differences in visual function for the superior versus inferior visual field. A statistical bootstrapping analysis indicated that the observed correlations between fMRI responses and measurements of visual function for SAP (r=0.49), SWAP (r=0.63), and FDT (r=0.43) were statistically significant (all p<0.05). Resting blood perfusion in human V1 is correlated with the loss of visual function in POAG. Altered CBF may be a contributing factor to glaucomatous optic neuropathy, or it may be an indication of post-retinal glaucomatous neurodegeneration caused by damage to the retinal ganglion cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

Object representations in ventral and dorsal visual streams: fMRI repetition effects depend on attention and part–whole configuration

PubMed Central

Thoma, Volker; Henson, Richard N.

2011-01-01

The effects of attention and object configuration on the neural responses to short-lag visual image repetition were investigated with fMRI. Attention to one of two object images in a prime display was cued spatially. The images were either intact or split vertically; a manipulation that negates the influence of view-based representations. A subsequent single intact probe image was named covertly. Behavioural priming observed as faster button presses was found for attended primes in both intact and split configurations, but only for uncued primes in the intact configuration. In a voxel-wise analysis, fMRI repetition suppression (RS) was observed in a left mid-fusiform region for attended primes, both intact and split, whilst a right intraparietal region showed repetition enhancement (RE) for intact primes, regardless of attention. In a factorial analysis across regions of interest (ROIs) defined from independent localiser contrasts, RS for attended objects in the ventral stream was significantly left-lateralised, whilst repetition effects in ventral and dorsal ROIs correlated with the amount of priming in specific conditions. These fMRI results extend hybrid theories of object recognition, implicating left ventral stream regions in analytic processing (requiring attention), consistent with prior hypotheses about hemispheric specialisation, and implicating dorsal stream regions in holistic processing (independent of attention). PMID:21554967

Nucleus Accumbens Adenosine A2A Receptors Regulate Exertion of Effort by Acting on the Ventral Striatopallidal Pathway

PubMed Central

Mingote, Susana; Font, Laura; Farrar, Andrew M.; Vontell, Regina; Worden, Lila T.; Stopper, Colin M.; Port, Russell G.; Sink, Kelly S.; Bunce, Jamie G.; Chrobak, James J.; Salamone, John D.

2009-01-01

Goal-directed actions are sensitive to work-related response costs, and dopamine in nucleus accumbens is thought to modulate the exertion of effort in motivated behavior. Dopamine-rich striatal areas such as nucleus accumbens also contain high numbers of adenosine A2A receptors, and, for that reason, the behavioral and neurochemical effects of the adenosine A2A receptor agonist CGS 21680 [2-p-(2-carboxyethyl) phenethylamino-5′-N-ethylcarboxamidoadenosine] were investigated. Stimulation of accumbens adenosine A2A receptors disrupted performance of an instrumental task with high work demands (i.e., an interval lever-pressing schedule with a ratio requirement attached) but had little effect on a task with a lower work requirement. Immunohistochemical studies revealed that accumbens neurons that project to the ventral pallidum showed adenosine A2A receptors immunoreactivity. Moreover, activation of accumbens A2A receptors by local injections of CGS 21680 increased extracellular GABA levels in the ventral pallidum. Combined contralateral injections of CGS 21680 into the accumbens and the GABAA agonist muscimol into ventral pallidum (i.e., “disconnection” methods) also impaired response output, indicating that these structures are part of a common neural circuitry regulating the exertion of effort. Thus, accumbens adenosine A2A receptors appear to regulate behavioral activation and effort-related processes by modulating the activity of the ventral striatopallidal pathway. Research on the effort-related functions of these forebrain systems may lead to a greater understanding of pathological features of motivation, such as psychomotor slowing, anergia, and fatigue in depression. PMID:18768698

Explicit Encoding of Multimodal Percepts by Single Neurons in the Human Brain

PubMed Central

Quiroga, Rodrigo Quian; Kraskov, Alexander; Koch, Christof; Fried, Itzhak

2010-01-01

Summary Different pictures of Marilyn Monroe can evoke the same percept, even if greatly modified as in Andy Warhol’s famous portraits. But how does the brain recognize highly variable pictures as the same percept? Various studies have provided insights into how visual information is processed along the “ventral pathway,” via both single-cell recordings in monkeys [1, 2] and functional imaging in humans [3, 4]. Interestingly, in humans, the same “concept” of Marilyn Monroe can be evoked with other stimulus modalities, for instance by hearing or reading her name. Brain imaging studies have identified cortical areas selective to voices [5, 6] and visual word forms [7, 8]. However, how visual, text, and sound information can elicit a unique percept is still largely unknown. By using presentations of pictures and of spoken and written names, we show that (1) single neurons in the human medial temporal lobe (MTL) respond selectively to representations of the same individual across different sensory modalities; (2) the degree of multimodal invariance increases along the hierarchical structure within the MTL; and (3) such neuronal representations can be generated within less than a day or two. These results demonstrate that single neurons can encode percepts in an explicit, selective, and invariant manner, even if evoked by different sensory modalities. PMID:19631538

Defective chromatic and achromatic visual pathways in developmental dyslexia: Cues for an integrated intervention programme.

PubMed

Bonfiglio, Luca; Bocci, Tommaso; Minichilli, Fabrizio; Crecchi, Alessandra; Barloscio, Davide; Spina, Donata Maria; Rossi, Bruno; Sartucci, Ferdinando

2017-01-01

As well as obtaining confirmation of the magnocellular system involvement in developmental dyslexia (DD); the aim was primarily to search for a possible involvement of the parvocellular system; and, furthermore, to complete the assessment of the visual chromatic axis by also analysing the koniocellular system. Visual evoked potentials (VEPs) in response to achromatic stimuli with low luminance contrast and low spatial frequency, and isoluminant red/green and blue/yellow stimuli with high spatial frequency were recorded in 10 dyslexic children and 10 age- and sex-matched, healthy subjects. Dyslexic children showed delayed VEPs to both achromatic stimuli (magnocellular-dorsal stream) and isoluminant red/green and blue/yellow stimuli (parvocellular-ventral and koniocellular streams). To our knowledge, this is the first time that a dysfunction of colour vision has been brought to light in an objective way (i.e., by means of electrophysiological methods) in children with DD. These results give rise to speculation concerning the need for a putative approach for promoting both learning how to read and/or improving existing reading skills of children with or at risk of DD. The working hypothesis would be to combine two integrated interventions in a single programme aimed at fostering the function of both the magnocellular and the parvocellular streams.

Dynamic Target Match Signals in Perirhinal Cortex Can Be Explained by Instantaneous Computations That Act on Dynamic Input from Inferotemporal Cortex

PubMed Central

Pagan, Marino

2014-01-01

Finding sought objects requires the brain to combine visual and target signals to determine when a target is in view. To investigate how the brain implements these computations, we recorded neural responses in inferotemporal cortex (IT) and perirhinal cortex (PRH) as macaque monkeys performed a delayed-match-to-sample target search task. Our data suggest that visual and target signals were combined within or before IT in the ventral visual pathway and then passed onto PRH, where they were reformatted into a more explicit target match signal over ∼10–15 ms. Accounting for these dynamics in PRH did not require proposing dynamic computations within PRH itself but, rather, could be attributed to instantaneous PRH computations performed upon an input representation from IT that changed with time. We found that the dynamics of the IT representation arose from two commonly observed features: individual IT neurons whose response preferences were not simply rescaled with time and variable response latencies across the population. Our results demonstrate that these types of time-varying responses have important consequences for downstream computation and suggest that dynamic representations can arise within a feedforward framework as a consequence of instantaneous computations performed upon time-varying inputs. PMID:25122904

Impaired integration of object knowledge and visual input in a case of ventral simultanagnosia with bilateral damage to area V4.

PubMed

Leek, E Charles; d'Avossa, Giovanni; Tainturier, Marie-Josèphe; Roberts, Daniel J; Yuen, Sung Lai; Hu, Mo; Rafal, Robert

2012-01-01

This study examines how brain damage can affect the cognitive processes that support the integration of sensory input and prior knowledge during shape perception. It is based on the first detailed study of acquired ventral simultanagnosia, which was found in a patient (M.T.) with posterior occipitotemporal lesions encompassing V4 bilaterally. Despite showing normal object recognition for single items in both accuracy and response times (RTs), and intact low-level vision assessed across an extensive battery of tests, M.T. was impaired in object identification with overlapping figures displays. Task performance was modulated by familiarity: Unlike controls, M.T. was faster with overlapping displays of abstract shapes than with overlapping displays of common objects. His performance with overlapping common object displays was also influenced by both the semantic relatedness and visual similarity of the display items. These findings challenge claims that visual perception is driven solely by feedforward mechanisms and show how brain damage can selectively impair high-level perceptual processes supporting the integration of stored knowledge and visual sensory input.

Face and location processing in children with early unilateral brain injury.

PubMed

Paul, Brianna; Appelbaum, Mark; Carapetian, Stephanie; Hesselink, John; Nass, Ruth; Trauner, Doris; Stiles, Joan

2014-07-01

Human visuospatial functions are commonly divided into those dependent on the ventral visual stream (ventral occipitotemporal regions), which allows for processing the 'what' of an object, and the dorsal visual stream (dorsal occipitoparietal regions), which allows for processing 'where' an object is in space. Information about the development of each of the two streams has been accumulating, but very little is known about the effects of injury, particularly very early injury, on this developmental process. Using a set of computerized dorsal and ventral stream tasks matched for stimuli, required response, and difficulty (for typically-developing individuals), we sought to compare the differential effects of injury to the two systems by examining performance in individuals with perinatal brain injury (PBI), who present with selective deficits in visuospatial processing from a young age. Thirty participants (mean=15.1 years) with early unilateral brain injury (15 right hemisphere PBI, 15 left hemisphere PBI) and 16 matched controls participated. On our tasks children with PBI performed more poorly than controls (lower accuracy and longer response times), and this was particularly prominent for the ventral stream task. Lateralization of PBI was also a factor, as the dorsal stream task did not seem to be associated with lateralized deficits, with both PBI groups showing only subtle decrements in performance, while the ventral stream task elicited deficits from RPBI children that do not appear to improve with age. Our findings suggest that early injury results in lesion-specific visuospatial deficits that persist into adolescence. Further, as the stimuli used in our ventral stream task were faces, our findings are consistent with what is known about the neural systems for face processing, namely, that they are established relatively early, follow a comparatively rapid developmental trajectory (conferring a vulnerability to early insult), and are biased toward the right hemisphere. Copyright © 2014 Elsevier Inc. All rights reserved.

Representation of Glossy Material Surface in Ventral Superior Temporal Sulcal Area of Common Marmosets

PubMed Central

Miyakawa, Naohisa; Banno, Taku; Abe, Hiroshi; Tani, Toshiki; Suzuki, Wataru; Ichinohe, Noritaka

2017-01-01

The common marmoset (Callithrix jacchus) is one of the smallest species of primates, with high visual recognition abilities that allow them to judge the identity and quality of food and objects in their environment. To address the cortical processing of visual information related to material surface features in marmosets, we presented a set of stimuli that have identical three-dimensional shapes (bone, torus or amorphous) but different material appearances (ceramic, glass, fur, leather, metal, stone, wood, or matte) to anesthetized marmoset, and recorded multiunit activities from an area ventral to the superior temporal sulcus (STS) using multi-shanked, and depth resolved multi-electrode array. Out of 143 visually responsive multiunits recorded from four animals, 29% had significant main effect only of the material, 3% only of the shape and 43% of both the material and the shape. Furthermore, we found neuronal cluster(s), in which most cells: (1) showed a significant main effect in material appearance; (2) the best stimulus was a glossy material (glass or metal); and (3) had reduced response to the pixel-shuffled version of the glossy material images. The location of the gloss-selective area was in agreement with previous macaque studies, showing activation in the ventral bank of STS. Our results suggest that perception of gloss is an important ability preserved across wide range of primate species. PMID:28367117

Representation of Glossy Material Surface in Ventral Superior Temporal Sulcal Area of Common Marmosets.

PubMed

Miyakawa, Naohisa; Banno, Taku; Abe, Hiroshi; Tani, Toshiki; Suzuki, Wataru; Ichinohe, Noritaka

2017-01-01

The common marmoset ( Callithrix jacchus ) is one of the smallest species of primates, with high visual recognition abilities that allow them to judge the identity and quality of food and objects in their environment. To address the cortical processing of visual information related to material surface features in marmosets, we presented a set of stimuli that have identical three-dimensional shapes (bone, torus or amorphous) but different material appearances (ceramic, glass, fur, leather, metal, stone, wood, or matte) to anesthetized marmoset, and recorded multiunit activities from an area ventral to the superior temporal sulcus (STS) using multi-shanked, and depth resolved multi-electrode array. Out of 143 visually responsive multiunits recorded from four animals, 29% had significant main effect only of the material, 3% only of the shape and 43% of both the material and the shape. Furthermore, we found neuronal cluster(s), in which most cells: (1) showed a significant main effect in material appearance; (2) the best stimulus was a glossy material (glass or metal); and (3) had reduced response to the pixel-shuffled version of the glossy material images. The location of the gloss-selective area was in agreement with previous macaque studies, showing activation in the ventral bank of STS. Our results suggest that perception of gloss is an important ability preserved across wide range of primate species.

Processing of Own Hand Visual Feedback during Object Grasping in Ventral Premotor Mirror Neurons.

PubMed

Maranesi, Monica; Livi, Alessandro; Bonini, Luca

2015-08-26

Mirror neurons (MNs) discharge during action execution as well as during observation of others' actions. Our own actions are those that we have the opportunity to observe more frequently, but no study thus far to our knowledge has addressed the issue of whether, and to what extent, MNs can code own hand visual feedback (HVF) during object grasping. Here, we show that MNs of the ventral premotor area F5 of macaque monkeys are particularly sensitive to HVF relative to non-MNs simultaneously recorded in the same penetrations. Importantly, the HVF effect is more evident on MN activity during hand-object interaction than during the hand-shaping phase. Furthermore, the increase of MN activity induced by HVF and others' actions observed from a subjective perspective were positively correlated. These findings indicate that at least part of ventral premotor MNs can process the visual information coming from own hand interacting with objects, likely playing a role in self-action monitoring. We show that mirror neurons (MNs) of area F5 of the macaque, in addition to encoding others' observed actions, are particularly sensitive, relative to simultaneously recorded non-MNs, to the sight of the monkey's own hand during object grasping, likely playing a role in self-action monitoring. Copyright © 2015 the authors 0270-6474/15/3511824-06$15.00/0.

Balanced increases in selectivity and tolerance produce constant sparseness along the ventral visual stream

PubMed Central

Rust, Nicole C.; DiCarlo, James J.

2012-01-01

While popular accounts suggest that neurons along the ventral visual processing stream become increasingly selective for particular objects, this appears at odds with the fact that inferior temporal cortical (IT) neurons are broadly tuned. To explore this apparent contradiction, we compared processing in two ventral stream stages (V4 and IT) in the rhesus macaque monkey. We confirmed that IT neurons are indeed more selective for conjunctions of visual features than V4 neurons, and that this increase in feature conjunction selectivity is accompanied by an increase in tolerance (“invariance”) to identity-preserving transformations (e.g. shifting, scaling) of those features. We report here that V4 and IT neurons are, on average, tightly matched in their tuning breadth for natural images (“sparseness”), and that the average V4 or IT neuron will produce a robust firing rate response (over 50% of its peak observed firing rate) to ~10% of all natural images. We also observed that sparseness was positively correlated with conjunction selectivity and negatively correlated with tolerance within both V4 and IT, consistent with selectivity-building and invariance-building computations that offset one another to produce sparseness. Our results imply that the conjunction-selectivity-building and invariance-building computations necessary to support object recognition are implemented in a balanced fashion to maintain sparseness at each stage of processing. PMID:22836252

Enhanced Fine-Form Perception Does Not Contribute to Gestalt Face Perception in Autism Spectrum Disorder

PubMed Central

Maekawa, Toshihiko; Miyanaga, Yuka; Takahashi, Kenji; Takamiya, Naomi; Ogata, Katsuya; Tobimatsu, Shozo

2017-01-01

Individuals with autism spectrum disorder (ASD) show superior performance in processing fine detail, but often exhibit impaired gestalt face perception. The ventral visual stream from the primary visual cortex (V1) to the fusiform gyrus (V4) plays an important role in form (including faces) and color perception. The aim of this study was to investigate how the ventral stream is functionally altered in ASD. Visual evoked potentials were recorded in high-functioning ASD adults (n = 14) and typically developing (TD) adults (n = 14). We used three types of visual stimuli as follows: isoluminant chromatic (red/green, RG) gratings, high-contrast achromatic (black/white, BW) gratings with high spatial frequency (HSF, 5.3 cycles/degree), and face (neutral, happy, and angry faces) stimuli. Compared with TD controls, ASD adults exhibited longer N1 latency for RG, shorter N1 latency for BW, and shorter P1 latency, but prolonged N170 latency, for face stimuli. Moreover, a greater difference in latency between P1 and N170, or between N1 for BW and N170 (i.e., the prolongation of cortico-cortical conduction time between V1 and V4) was observed in ASD adults. These findings indicate that ASD adults have enhanced fine-form (local HSF) processing, but impaired color processing at V1. In addition, they exhibit impaired gestalt face processing due to deficits in integration of multiple local HSF facial information at V4. Thus, altered ventral stream function may contribute to abnormal social processing in ASD. PMID:28146575

Ventral pallidal projections to mediodorsal thalamus and ventral tegmental area play distinct roles in outcome-specific Pavlovian-instrumental transfer.

PubMed

Leung, Beatrice K; Balleine, Bernard W

2015-03-25

Outcome-specific Pavlovian-instrumental transfer (PIT) demonstrates the way that reward-related cues influence choice between instrumental actions. The nucleus accumbens shell (NAc-S) contributes critically to this effect, particularly through its output to the rostral medial ventral pallidum (VP-m). Using rats, we investigated in two experiments the role in the PIT effect of the two major outputs of this VP-m region innervated by the NAc-S, the mediodorsal thalamus (MD) and the ventral tegmental area (VTA). First, two retrograde tracers were injected into the MD and VTA to compare the neuronal activity of the two populations of projection neurons in the VP-m during PIT relative to controls. Second, the functional role of the connection between the VP-m and the MD or VTA was assessed using asymmetrical pharmacological manipulations before a PIT test. It was found that, whereas neurons in the VP-m projecting to the MD showed significantly more neuronal activation during PIT than those projecting to the VTA, neuronal activation of these latter neurons correlated with the size of the PIT effect. Disconnection of the two pathways during PIT also revealed different deficits in performance: disrupting the VP-m to MD pathway removed the response biasing effects of reward-related cues, whereas disrupting the VP-m to VTA pathway preserved the response bias but altered the overall rate of responding. The current results therefore suggest that the VP-m exerts distinct effects on the VTA and MD and that these latter structures mediate the motivational and cognitive components of specific PIT, respectively. Copyright © 2015 the authors 0270-6474/15/354953-12$15.00/0.

Structural and functional integration between dorsal and ventral language streams as revealed by blunt dissection and direct electrical stimulation.

PubMed

Sarubbo, Silvio; De Benedictis, Alessandro; Merler, Stefano; Mandonnet, Emmanuel; Barbareschi, Mattia; Dallabona, Monica; Chioffi, Franco; Duffau, Hugues

2016-11-01

The most accepted framework of language processing includes a dorsal phonological and a ventral semantic pathway, connecting a wide network of distributed cortical hubs. However, the cortico-subcortical connectivity and the reciprocal anatomical relationships of this dual-stream system are not completely clarified. We performed an original blunt microdissection of 10 hemispheres with the exposition of locoregional short fibers and six long-range fascicles involved in language elaboration. Special attention was addressed to the analysis of termination sites and anatomical relationships between long- and short-range fascicles. We correlated these anatomical findings with a topographical analysis of 93 functional responses located at the terminal sites of the language bundles, collected by direct electrical stimulation in 108 right-handers. The locations of phonological and semantic paraphasias, verbal apraxia, speech arrest, pure anomia, and alexia were statistically analyzed, and the respective barycenters were computed in the MNI space. We found that terminations of main language bundles and functional responses have a wider distribution in respect to the classical definition of language territories. Our analysis showed that dorsal and ventral streams have a similar anatomical layer organization. These pathways are parallel and relatively segregated over their subcortical course while their terminal fibers are strictly overlapped at the cortical level. Finally, the anatomical features of the U-fibers suggested a role of locoregional integration between the phonological, semantic, and executive subnetworks of language, in particular within the inferoventral frontal lobe and the temporoparietal junction, which revealed to be the main criss-cross regions between the dorsal and ventral pathways. Hum Brain Mapp 37:3858-3872, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Uncoupling neurogenic gene networks in the Drosophila embryo.

PubMed

Rogers, William A; Goyal, Yogesh; Yamaya, Kei; Shvartsman, Stanislav Y; Levine, Michael S

2017-04-01

The EGF signaling pathway specifies neuronal identities in the Drosophila embryo by regulating developmental patterning genes such as intermediate neuroblasts defective ( ind ). EGFR is activated in the ventral midline and neurogenic ectoderm by the Spitz ligand, which is processed by the Rhomboid protease. CRISPR/Cas9 was used to delete defined rhomboid enhancers mediating expression at each site of Spitz processing. Surprisingly, the neurogenic ectoderm, not the ventral midline, was found to be the dominant source of EGF patterning activity. We suggest that Drosophila is undergoing an evolutionary transition in central nervous system (CNS)-organizing activity from the ventral midline to the neurogenic ectoderm. © 2017 Rogers et al.; Published by Cold Spring Harbor Laboratory Press.

Laterotopic representation of left-right information onto the dorso-ventral axis of a zebrafish midbrain target nucleus.

PubMed

Aizawa, Hidenori; Bianco, Isaac H; Hamaoka, Takanori; Miyashita, Toshio; Uemura, Osamu; Concha, Miguel L; Russell, Claire; Wilson, Stephen W; Okamoto, Hitoshi

2005-02-08

The habenulae are part of an evolutionarily highly conserved limbic-system conduction pathway that connects telencephalic nuclei to the interpeduncular nucleus (IPN) of the midbrain . In zebrafish, unilateral activation of the Nodal signaling pathway in the left brain specifies the laterality of the asymmetry of habenular size . We show "laterotopy" in the habenulo-interpeduncular projection in zebrafish, i.e., the stereotypic, topographic projection of left-sided habenular axons to the dorsal region of the IPN and of right-sided habenular axons to the ventral IPN. This asymmetric projection is accounted for by a prominent left-right (LR) difference in the size ratio of the medial and lateral habenular sub-nuclei, each of which specifically projects either to ventral or dorsal IPN targets. Asymmetric Nodal signaling directs the orientation of laterotopy but is dispensable for the establishment of laterotopy itself. Our results reveal a mechanism by which information distributed between left and right sides of the brain can be transmitted bilaterally without loss of LR coding, which may play a crucial role in functional lateralization of the vertebrate brain .

Competing signals drive telencephalon diversity.

PubMed

Sylvester, J B; Rich, C A; Yi, C; Peres, J N; Houart, C; Streelman, J T

2013-01-01

The telencephalon is the most complex brain region, controlling communication, emotion, movement and memory. Its adult derivatives develop from the dorsal pallium and ventral subpallium. Despite knowledge of genes required in these territories, we do not understand how evolution has shaped telencephalon diversity. Here, using rock- and sand-dwelling cichlid fishes from Lake Malawi, we demonstrate that differences in strength and timing of opposing Hedgehog and Wingless signals establish evolutionary divergence in dorsal-ventral telencephalon patterning. Rock dwellers exhibit early, extensive Hedgehog activity in the ventral forebrain resulting in expression of foxg1 before dorsal Wingless signals, and a larger subpallium. Sand dwellers show rapid deployment of Wingless, later foxg1 expression and a larger pallium. Manipulation of the Hedgehog and Wingless pathways in cichlid and zebrafish embryos is sufficient to mimic differences between rock- versus sand-dweller brains. Our data suggest that competing ventral Hedgehog and dorsal Wingless signals mediate evolutionary diversification of the telencephalon.

Genetic pathways for differentiation of the peripheral nervous system in ascidians

PubMed Central

Waki, Kana; Imai, Kaoru S.; Satou, Yutaka

2015-01-01

Ascidians belong to tunicates, the sister group of vertebrates. Peripheral nervous systems (PNSs) including epidermal sensory neurons (ESNs) in the trunk and dorsal tail regions of ascidian larvae are derived from cells adjacent to the neural plate, as in vertebrates. On the other hand, peripheral ESNs in the ventral tail region are derived from the ventral ectoderm under the control of BMP signalling, reminiscent of sensory neurons of amphioxus and protostomes. In this study, we show that two distinct mechanisms activate a common gene circuit consisting of Msx, Ascl.b, Tox, Delta.b and Pou4 in the dorsal and ventral regions to differentiate ESNs. Our results suggest that ventral ESNs of the ascidian larva are not directly homologous to vertebrate PNSs. The dorsal ESNs might have arisen via co-option of the original PNS gene circuit to the neural plate border in an ancestral chordate. PMID:26515371

Separate Circuitries Encode the Hedonic and Nutritional Values of Sugar

PubMed Central

Tellez, Luis A.; Han, Wenfei; Zhang, Xiaobing; Ferreira, Tatiana L.; Perez, Isaac O.; Shammah-Lagnado, Sara J.; van den Pol, Anthony N.; de Araujo, Ivan E.

2016-01-01

Sugar exerts its potent reinforcing effects via both gustatory and post-ingestive pathways. It is however unknown if sweetness and nutritional signals engage segregated brain networks to motivate ingestion. We show in mice that separate basal ganglia circuitries mediate the hedonic and nutritional actions of sugar. We found that, during sugar intake, suppressing hedonic value inhibited dopamine release in ventral but not dorsal striatum, whereas suppressing nutritional value inhibited dopamine release in dorsal but not ventral striatum. Consistently, cell-specific ablation of dopamine-excitable cells in dorsal, but not ventral, striatum inhibited sugar’s ability to drive the ingestion of unpalatable solutions. Conversely, optogenetic stimulation of dopamine-excitable cells in dorsal, but not ventral, striatum substituted for sugar in its ability to drive the ingestion of unpalatable solutions. Our data demonstrate that sugar recruits a distributed dopamine-excitable striatal circuitry that acts to prioritize energy seeking over taste quality. PMID:26807950

Separate circuitries encode the hedonic and nutritional values of sugar.

PubMed

Tellez, Luis A; Han, Wenfei; Zhang, Xiaobing; Ferreira, Tatiana L; Perez, Isaac O; Shammah-Lagnado, Sara J; van den Pol, Anthony N; de Araujo, Ivan E

2016-03-01

Sugar exerts its potent reinforcing effects via both gustatory and post-ingestive pathways. It is, however, unknown whether sweetness and nutritional signals engage segregated brain networks to motivate ingestion. We found in mice that separate basal ganglia circuitries mediated the hedonic and nutritional actions of sugar. During sugar intake, suppressing hedonic value inhibited dopamine release in ventral, but not dorsal, striatum, whereas suppressing nutritional value inhibited dopamine release in dorsal, but not ventral, striatum. Consistently, cell-specific ablation of dopamine-excitable cells in dorsal, but not ventral, striatum inhibited sugar's ability to drive the ingestion of unpalatable solutions. Conversely, optogenetic stimulation of dopamine-excitable cells in dorsal, but not ventral, striatum substituted for sugar in its ability to drive the ingestion of unpalatable solutions. Our data indicate that sugar recruits a distributed dopamine-excitable striatal circuitry that acts to prioritize energy-seeking over taste quality.

Neural organization and visual processing in the anterior optic tubercle of the honeybee brain.

PubMed

Mota, Theo; Yamagata, Nobuhiro; Giurfa, Martin; Gronenberg, Wulfila; Sandoz, Jean-Christophe

2011-08-10

The honeybee Apis mellifera represents a valuable model for studying the neural segregation and integration of visual information. Vision in honeybees has been extensively studied at the behavioral level and, to a lesser degree, at the physiological level using intracellular electrophysiological recordings of single neurons. However, our knowledge of visual processing in honeybees is still limited by the lack of functional studies of visual processing at the circuit level. Here we contribute to filling this gap by providing a neuroanatomical and neurophysiological characterization at the circuit level of a practically unstudied visual area of the bee brain, the anterior optic tubercle (AOTu). First, we analyzed the internal organization and neuronal connections of the AOTu. Second, we established a novel protocol for performing optophysiological recordings of visual circuit activity in the honeybee brain and studied the responses of AOTu interneurons during stimulation of distinct eye regions. Our neuroanatomical data show an intricate compartmentalization and connectivity of the AOTu, revealing a dorsoventral segregation of the visual input to the AOTu. Light stimuli presented in different parts of the visual field (dorsal, lateral, or ventral) induce distinct patterns of activation in AOTu output interneurons, retaining to some extent the dorsoventral input segregation revealed by our neuroanatomical data. In particular, activity patterns evoked by dorsal and ventral eye stimulation are clearly segregated into distinct AOTu subunits. Our results therefore suggest an involvement of the AOTu in the processing of dorsoventrally segregated visual information in the honeybee brain.

Altered structural and effective connectivity in anorexia and bulimia nervosa in circuits that regulate energy and reward homeostasis.

PubMed

Frank, G K W; Shott, M E; Riederer, J; Pryor, T L

2016-11-01

Anorexia and bulimia nervosa are severe eating disorders that share many behaviors. Structural and functional brain circuits could provide biological links that those disorders have in common. We recruited 77 young adult women, 26 healthy controls, 26 women with anorexia and 25 women with bulimia nervosa. Probabilistic tractography was used to map white matter connectivity strength across taste and food intake regulating brain circuits. An independent multisample greedy equivalence search algorithm tested effective connectivity between those regions during sucrose tasting. Anorexia and bulimia nervosa had greater structural connectivity in pathways between insula, orbitofrontal cortex and ventral striatum, but lower connectivity from orbitofrontal cortex and amygdala to the hypothalamus (P<0.05, corrected for comorbidity, medication and multiple comparisons). Functionally, in controls the hypothalamus drove ventral striatal activity, but in anorexia and bulimia nervosa effective connectivity was directed from anterior cingulate via ventral striatum to the hypothalamus. Across all groups, sweetness perception was predicted by connectivity strength in pathways connecting to the middle orbitofrontal cortex. This study provides evidence that white matter structural as well as effective connectivity within the energy-homeostasis and food reward-regulating circuitry is fundamentally different in anorexia and bulimia nervosa compared with that in controls. In eating disorders, anterior cingulate cognitive-emotional top down control could affect food reward and eating drive, override hypothalamic inputs to the ventral striatum and enable prolonged food restriction.

Representational Account of Memory: Insights from Aging and Synesthesia.

PubMed

Pfeifer, Gaby; Ward, Jamie; Chan, Dennis; Sigala, Natasha

2016-12-01

The representational account of memory envisages perception and memory to be on a continuum rather than in discretely divided brain systems [Bussey, T. J., & Saksida, L. M. Memory, perception, and the ventral visual-perirhinal-hippocampal stream: Thinking outside of the boxes. Hippocampus, 17, 898-908, 2007]. We tested this account using a novel between-group design with young grapheme-color synesthetes, older adults, and young controls. We investigated how the disparate sensory-perceptual abilities between these groups translated into associative memory performance for visual stimuli that do not induce synesthesia. ROI analyses of the entire ventral visual stream showed that associative retrieval (a pair-associate retrieved in the absence of a visual stimulus) yielded enhanced activity in young and older adults' visual regions relative to synesthetes, whereas associative recognition (deciding whether a visual stimulus was the correct pair-associate) was characterized by enhanced activity in synesthetes' visual regions relative to older adults. Whole-brain analyses at associative retrieval revealed an effect of age in early visual cortex, with older adults showing enhanced activity relative to synesthetes and young adults. At associative recognition, the group effect was reversed: Synesthetes showed significantly enhanced activity relative to young and older adults in early visual regions. The inverted group effects observed between retrieval and recognition indicate that reduced sensitivity in visual cortex (as in aging) comes with increased activity during top-down retrieval and decreased activity during bottom-up recognition, whereas enhanced sensitivity (as in synesthesia) shows the opposite pattern. Our results provide novel evidence for the direct contribution of perceptual mechanisms to visual associative memory based on the examples of synesthesia and aging.

Pre-Orthographic Character String Processing and Parietal Cortex: A Role for Visual Attention in Reading?

ERIC Educational Resources Information Center

Lobier, Muriel; Peyrin, Carole; Le Bas, Jean-Francois; Valdois, Sylviane

2012-01-01

The visual front-end of reading is most often associated with orthographic processing. The left ventral occipito-temporal cortex seems to be preferentially tuned for letter string and word processing. In contrast, little is known of the mechanisms responsible for pre-orthographic processing: the processing of character strings regardless of…

Developmental Differences for Word Processing in the Ventral Stream

ERIC Educational Resources Information Center

Olulade, Olumide A.; Flowers, D. Lynn; Napoliello, Eileen M.; Eden, Guinevere F.

2013-01-01

The visual word form system (VWFS), located in the occipito-temporal cortex, is involved in orthographic processing of visually presented words (Cohen et al., 2002). Recent fMRI studies in children and adults have demonstrated a gradient of increasing word-selectivity along the posterior-to-anterior axis of this system (Vinckier et al., 2007), yet…

Cortical activation during Braille reading is influenced by early visual experience in subjects with severe visual disability: a correlational fMRI study.

PubMed

Melzer, P; Morgan, V L; Pickens, D R; Price, R R; Wall, R S; Ebner, F F

2001-11-01

Functional magnetic resonance imaging was performed on blind adults resting and reading Braille. The strongest activation was found in primary somatic sensory/motor cortex on both cortical hemispheres. Additional foci of activation were situated in the parietal, temporal, and occipital lobes where visual information is processed in sighted persons. The regions were differentiated most in the correlation of their time courses of activation with resting and reading. Differences in magnitude and expanse of activation were substantially less significant. Among the traditionally visual areas, the strength of correlation was greatest in posterior parietal cortex and moderate in occipitotemporal, lateral occipital, and primary visual cortex. It was low in secondary visual cortex as well as in dorsal and ventral inferior temporal cortex and posterior middle temporal cortex. Visual experience increased the strength of correlation in all regions except dorsal inferior temporal and posterior parietal cortex. The greatest statistically significant increase, i.e., approximately 30%, was in ventral inferior temporal and posterior middle temporal cortex. In these regions, words are analyzed semantically, which may be facilitated by visual experience. In contrast, visual experience resulted in a slight, insignificant diminution of the strength of correlation in dorsal inferior temporal cortex where language is analyzed phonetically. These findings affirm that posterior temporal regions are engaged in the processing of written language. Moreover, they suggest that this function is modified by early visual experience. Furthermore, visual experience significantly strengthened the correlation of activation and Braille reading in occipital regions traditionally involved in the processing of visual features and object recognition suggesting a role for visual imagery. Copyright 2001 Wiley-Liss, Inc.

Color signals through dorsal and ventral visual pathways

PubMed Central

Conway, Bevil R.

2014-01-01

Explanations for color phenomena are often sought in the retina, LGN and V1, yet it is becoming increasingly clear that a complete account will take us further along the visual-processing pathway. Working out which areas are involved is not trivial. Responses to S-cone activation are often assumed to indicate that an area or neuron is involved in color perception. However, work tracing S-cone signals into extrastriate cortex has challenged this assumption: S-cone responses have been found in brain regions, such as MT, not thought to play a major role in color perception. Here we review the processing of S-cone signals across cortex and present original data on S-cone responses measured with fMRI in alert macaque, focusing on one area in which S-cone signals seem likely to contribute to color (V4/posterior inferior temporal cortex), and on one area in which S signals are unlikely to play a role in color (MT). We advance a hypothesis that the S-cone signals in color-computing areas are required to achieve a balanced neural representation of perceptual color space, while the S-cone signals in non-color-areas provide a cue to illumination (not luminance) and confer sensitivity to the chromatic contrast generated by natural daylight (shadows, illuminated by ambient sky, surrounded by direct sunlight). This sensitivity would facilitate the extraction of shape-from-shadow signals to benefit global scene analysis and motion perception. PMID:24103417

Which way is up? Asymmetric spectral input along the dorsal-ventral axis influences postural responses in an amphibious annelid.

PubMed

Jellies, John

2014-11-01

Medicinal leeches are predatory annelids that exhibit countershading and reside in aquatic environments where light levels might be variable. They also leave the water and must contend with terrestrial environments. Yet, leeches generally maintain a dorsal upward position despite lacking statocysts. Leeches respond visually to both green and near-ultraviolet (UV) light. I used LEDs to test the hypothesis that ventral, but not dorsal UV would evoke compensatory movements to orient the body. Untethered leeches were tested using LEDs emitting at red (632 nm), green (513 nm), blue (455 nm) and UV (372 nm). UV light evoked responses in 100 % of trials and the leeches often rotated the ventral surface away from it. Visible light evoked no or modest responses (12-15 % of trials) and no body rotation. Electrophysiological recordings showed that ventral sensilla responded best to UV, dorsal sensilla to green. Additionally, a higher order interneuron that is engaged in a variety of parallel networks responded vigorously to UV presented ventrally, and both the visible and UV responses exhibited pronounced light adaptation. These results strongly support the suggestion that a dorsal light reflex in the leech uses spectral comparisons across the dorsal-ventral axis rather than, or in addition to, luminance.

Corollary discharge inhibition of wind-sensitive cercal giant interneurons in the singing field cricket

PubMed Central

Hedwig, Berthold

2014-01-01

Crickets carry wind-sensitive mechanoreceptors on their cerci, which, in response to the airflow produced by approaching predators, triggers escape reactions via ascending giant interneurons (GIs). Males also activate their cercal system by air currents generated due to the wing movements underlying sound production. Singing males still respond to external wind stimulation, but are not startled by the self-generated airflow. To investigate how the nervous system discriminates sensory responses to self-generated and external airflow, we intracellularly recorded wind-sensitive afferents and ventral GIs of the cercal escape pathway in fictively singing crickets, a situation lacking any self-stimulation. GI spiking was reduced whenever cercal wind stimulation coincided with singing motor activity. The axonal terminals of cercal afferents showed no indication of presynaptic inhibition during singing. In two ventral GIs, however, a corollary discharge inhibition occurred strictly in phase with the singing motor pattern. Paired intracellular recordings revealed that this inhibition was not mediated by the activity of the previously identified corollary discharge interneuron (CDI) that rhythmically inhibits the auditory pathway during singing. Cercal wind stimulation, however, reduced the spike activity of this CDI by postsynaptic inhibition. Our study reveals how precisely timed corollary discharge inhibition of ventral GIs can prevent self-generated airflow from triggering inadvertent escape responses in singing crickets. The results indicate that the responsiveness of the auditory and wind-sensitive pathway is modulated by distinct CDIs in singing crickets and that the corollary discharge inhibition in the auditory pathway can be attenuated by cercal wind stimulation. PMID:25318763

Functional neural substrates of posterior cortical atrophy patients.

PubMed

Shames, H; Raz, N; Levin, Netta

2015-07-01

Posterior cortical atrophy (PCA) is a neurodegenerative syndrome in which the most pronounced pathologic involvement is in the occipito-parietal visual regions. Herein, we aimed to better define the cortical reflection of this unique syndrome using a thorough battery of behavioral and functional MRI (fMRI) tests. Eight PCA patients underwent extensive testing to map their visual deficits. Assessments included visual functions associated with lower and higher components of the cortical hierarchy, as well as dorsal- and ventral-related cortical functions. fMRI was performed on five patients to examine the neuronal substrate of their visual functions. The PCA patient cohort exhibited stereopsis, saccadic eye movements and higher dorsal stream-related functional impairments, including simultant perception, image orientation, figure-from-ground segregation, closure and spatial orientation. In accordance with the behavioral findings, fMRI revealed intact activation in the ventral visual regions of face and object perception while more dorsal aspects of perception, including motion and gestalt perception, revealed impaired patterns of activity. In most of the patients, there was a lack of activity in the word form area, which is known to be linked to reading disorders. Finally, there was evidence of reduced cortical representation of the peripheral visual field, corresponding to the behaviorally assessed peripheral visual deficit. The findings are discussed in the context of networks extending from parietal regions, which mediate navigationally related processing, visually guided actions, eye movement control and working memory, suggesting that damage to these networks might explain the wide range of deficits in PCA patients.

New Insights in Trigeminal Anatomy: A Double Orofacial Tract for Nociceptive Input

PubMed Central

Henssen, Dylan J. H. A.; Kurt, Erkan; Kozicz, Tamas; van Dongen, Robert; Bartels, Ronald H. M. A.; van Cappellen van Walsum, Anne-Marie

2016-01-01

Orofacial pain in patients relies on the anatomical pathways that conduct nociceptive information, originating from the periphery towards the trigeminal sensory nucleus complex (TSNC) and finally, to the thalami and the somatosensorical cortical regions. The anatomy and function of the so-called trigeminothalamic tracts have been investigated before. In these animal-based studies from the previous century, the intracerebral pathways were mapped using different retro- and anterograde tracing methods. We review the literature on the trigeminothalamic tracts focusing on these animal tracer studies. Subsequently, we related the observations of these studies to clinical findings using fMRI trials. The intracerebral trigeminal pathways can be subdivided into three pathways: a ventral (contralateral) and dorsal (mainly ipsilateral) trigeminothalamic tract and the intranuclear pathway. Based on the reviewed evidence we hypothesize the co-existence of an ipsilateral nociceptive conduction tract to the cerebral cortex and we translate evidence from animal-based research to the human anatomy. Our hypothesis differs from the classical idea that orofacial pain arises only from nociceptive information via the contralateral, ventral trigeminothalamic pathway. Better understanding of the histology, anatomy and connectivity of the trigeminal fibers could contribute to the discovery of a more effective pain treatment in patients suffering from various orofacial pain syndromes. PMID:27242449

Speech Cues Contribute to Audiovisual Spatial Integration

PubMed Central

Bishop, Christopher W.; Miller, Lee M.

2011-01-01

Speech is the most important form of human communication but ambient sounds and competing talkers often degrade its acoustics. Fortunately the brain can use visual information, especially its highly precise spatial information, to improve speech comprehension in noisy environments. Previous studies have demonstrated that audiovisual integration depends strongly on spatiotemporal factors. However, some integrative phenomena such as McGurk interference persist even with gross spatial disparities, suggesting that spatial alignment is not necessary for robust integration of audiovisual place-of-articulation cues. It is therefore unclear how speech-cues interact with audiovisual spatial integration mechanisms. Here, we combine two well established psychophysical phenomena, the McGurk effect and the ventriloquist's illusion, to explore this dependency. Our results demonstrate that conflicting spatial cues may not interfere with audiovisual integration of speech, but conflicting speech-cues can impede integration in space. This suggests a direct but asymmetrical influence between ventral ‘what’ and dorsal ‘where’ pathways. PMID:21909378

Inter- and Intrahemispheric Connectivity Differences When Reading Japanese Kanji and Hiragana

PubMed Central

Kawabata Duncan, Keith J.; Twomey, Tae; Parker Jones, ‘Ōiwi; Seghier, Mohamed L.; Haji, Tomoki; Sakai, Katsuyuki; Price, Cathy J.; Devlin, Joseph T.

2014-01-01

Unlike most languages that are written using a single script, Japanese uses multiple scripts including morphographic Kanji and syllabographic Hiragana and Katakana. Here, we used functional magnetic resonance imaging with dynamic causal modeling to investigate competing theories regarding the neural processing of Kanji and Hiragana during a visual lexical decision task. First, a bilateral model investigated interhemispheric connectivity between ventral occipito–temporal (vOT) cortex and Broca's area (“pars opercularis”). We found that Kanji significantly increased the connection strength from right-to-left vOT. This is interpreted in terms of increased right vOT activity for visually complex Kanji being integrated into the left (i.e. language dominant) hemisphere. Secondly, we used a unilateral left hemisphere model to test whether Kanji and Hiragana rely preferentially on ventral and dorsal paths, respectively, that is, they have different intrahemispheric functional connectivity profiles. Consistent with this hypothesis, we found that Kanji increased connectivity within the ventral path (V1 ↔ vOT ↔ Broca's area), and that Hiragana increased connectivity within the dorsal path (V1 ↔ supramarginal gyrus ↔ Broca's area). Overall, the results illustrate how the differential processing demands of Kanji and Hiragana influence both inter- and intrahemispheric interactions. PMID:23382515

Inter- and intrahemispheric connectivity differences when reading Japanese Kanji and Hiragana.

PubMed

Kawabata Duncan, Keith J; Twomey, Tae; Parker Jones, 'Ōiwi; Seghier, Mohamed L; Haji, Tomoki; Sakai, Katsuyuki; Price, Cathy J; Devlin, Joseph T

2014-06-01

Unlike most languages that are written using a single script, Japanese uses multiple scripts including morphographic Kanji and syllabographic Hiragana and Katakana. Here, we used functional magnetic resonance imaging with dynamic causal modeling to investigate competing theories regarding the neural processing of Kanji and Hiragana during a visual lexical decision task. First, a bilateral model investigated interhemispheric connectivity between ventral occipito-temporal (vOT) cortex and Broca's area ("pars opercularis"). We found that Kanji significantly increased the connection strength from right-to-left vOT. This is interpreted in terms of increased right vOT activity for visually complex Kanji being integrated into the left (i.e. language dominant) hemisphere. Secondly, we used a unilateral left hemisphere model to test whether Kanji and Hiragana rely preferentially on ventral and dorsal paths, respectively, that is, they have different intrahemispheric functional connectivity profiles. Consistent with this hypothesis, we found that Kanji increased connectivity within the ventral path (V1 ↔ vOT ↔ Broca's area), and that Hiragana increased connectivity within the dorsal path (V1 ↔ supramarginal gyrus ↔ Broca's area). Overall, the results illustrate how the differential processing demands of Kanji and Hiragana influence both inter- and intrahemispheric interactions.

Concurrent visuomotor behaviour improves form discrimination in a patient with visual form agnosia.

PubMed

Schenk, Thomas; Milner, A David

2006-09-01

It is now well established that the visual brain is divided into two visual streams, the ventral and the dorsal stream. Milner and Goodale have suggested that the ventral stream is dedicated for processing vision for perception and the dorsal stream vision for action [A.D. Milner & M.A. Goodale (1995) The Visual Brain in Action, Oxford University Press, Oxford]. However, it is possible that ongoing processes in the visuomotor stream will nevertheless have an effect on perceptual processes. This possibility was examined in the present study. We have examined the visual form-discrimination performance of the form-agnosic patient D.F. with and without a concurrent visuomotor task, and found that her performance was significantly improved in the former condition. This suggests that the visuomotor behaviour provides cues that enhance her ability to recognize the form of the target object. In control experiments we have ruled out proprioceptive and efferent cues, and therefore propose that D.F. can, to a significant degree, access the object's visuomotor representation in the dorsal stream. Moreover, we show that the grasping-induced perceptual improvement disappears if the target objects only differ with respect to their shape but not their width. This suggests that shape information per se is not used for this grasping task.

Ventrolateral Striatal Medium Spiny Neurons Positively Regulate Food-Incentive, Goal-Directed Behavior Independently of D1 and D2 Selectivity.

PubMed

Natsubori, Akiyo; Tsutsui-Kimura, Iku; Nishida, Hiroshi; Bouchekioua, Youcef; Sekiya, Hiroshi; Uchigashima, Motokazu; Watanabe, Masahiko; de Kerchove d'Exaerde, Alban; Mimura, Masaru; Takata, Norio; Tanaka, Kenji F

2017-03-08

The ventral striatum is involved in motivated behavior. Akin to the dorsal striatum, the ventral striatum contains two parallel pathways: the striatomesencephalic pathway consisting of dopamine receptor Type 1-expressing medium spiny neurons (D1-MSNs) and the striatopallidal pathway consisting of D2-MSNs. These two genetically identified pathways are thought to encode opposing functions in motivated behavior. It has also been reported that D1/D2 genetic selectivity is not attributed to the anatomical discrimination of two pathways. We wanted to determine whether D1- and D2-MSNs in the ventral striatum functioned in an opposing manner as previous observations claimed, and whether D1/D2 selectivity corresponded to a functional segregation in motivated behavior of mice. To address this question, we focused on the lateral portion of ventral striatum as a region implicated in food-incentive, goal-directed behavior, and recorded D1 or D2-MSN activity by using a gene-encoded ratiometric Ca 2+ indicator and by constructing a fiberphotometry system, and manipulated their activities via optogenetic inhibition during ongoing behaviors. We observed concurrent event-related compound Ca 2+ elevations in ventrolateral D1- and D2-MSNs, especially at trial start cue-related and first lever press-related times. D1 or D2 selective optogenetic inhibition just after the trial start cue resulted in a reduction of goal-directed behavior, indicating a shared coding of motivated behavior by both populations at this time. Only D1-selective inhibition just after the first lever press resulted in the reduction of behavior, indicating D1-MSN-specific coding at that specific time. Our data did not support opposing encoding by both populations in food-incentive, goal-directed behavior. SIGNIFICANCE STATEMENT An opposing role of dopamine receptor Type 1 or Type 2-expressing medium spiny neurons (D1-MSNs or D2-MSNs) on striatum-mediated behaviors has been widely accepted. However, this idea has been questioned by recent reports. In the present study, we measured concurrent Ca 2+ activity patterns of D1- and D2-MSNs in the ventrolateral striatum during food-incentive, goal-directed behavior in mice. According to Ca 2+ activity patterns, we conducted timing-specific optogenetic inhibition of each type of MSN. We demonstrated that both D1- and D2-MSNs in the ventrolateral striatum commonly and positively encoded action initiation, whereas only D1-MSNs positively encoded sustained motivated behavior. These findings led us to reconsider the prevailing notion of a functional segregation of MSN activity in the ventral striatum. Copyright © 2017 the authors 0270-6474/17/372724-11$15.00/0.

The Representation of Color across the Human Visual Cortex: Distinguishing Chromatic Signals Contributing to Object Form Versus Surface Color.

PubMed

Seymour, K J; Williams, M A; Rich, A N

2016-05-01

Many theories of visual object perception assume the visual system initially extracts borders between objects and their background and then "fills in" color to the resulting object surfaces. We investigated the transformation of chromatic signals across the human ventral visual stream, with particular interest in distinguishing representations of object surface color from representations of chromatic signals reflecting the retinal input. We used fMRI to measure brain activity while participants viewed figure-ground stimuli that differed either in the position or in the color contrast polarity of the foreground object (the figure). Multivariate pattern analysis revealed that classifiers were able to decode information about which color was presented at a particular retinal location from early visual areas, whereas regions further along the ventral stream exhibited biases for representing color as part of an object's surface, irrespective of its position on the retina. Additional analyses showed that although activity in V2 contained strong chromatic contrast information to support the early parsing of objects within a visual scene, activity in this area also signaled information about object surface color. These findings are consistent with the view that mechanisms underlying scene segmentation and the binding of color to object surfaces converge in V2. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

STDP in lateral connections creates category-based perceptual cycles for invariance learning with multiple stimuli.

PubMed

Evans, Benjamin D; Stringer, Simon M

2015-04-01

Learning to recognise objects and faces is an important and challenging problem tackled by the primate ventral visual system. One major difficulty lies in recognising an object despite profound differences in the retinal images it projects, due to changes in view, scale, position and other identity-preserving transformations. Several models of the ventral visual system have been successful in coping with these issues, but have typically been privileged by exposure to only one object at a time. In natural scenes, however, the challenges of object recognition are typically further compounded by the presence of several objects which should be perceived as distinct entities. In the present work, we explore one possible mechanism by which the visual system may overcome these two difficulties simultaneously, through segmenting unseen (artificial) stimuli using information about their category encoded in plastic lateral connections. We demonstrate that these experience-guided lateral interactions robustly organise input representations into perceptual cycles, allowing feed-forward connections trained with spike-timing-dependent plasticity to form independent, translation-invariant output representations. We present these simulations as a functional explanation for the role of plasticity in the lateral connectivity of visual cortex.

The evolution of the centrifugal visual system of vertebrates. A cladistic analysis and new hypotheses.

PubMed

Repérant, J; Médina, M; Ward, R; Miceli, D; Kenigfest, N B; Rio, J P; Vesselkin, N P

2007-01-01

In a recent review of the available data concerning the centrifugal visual system (CVS) of vertebrates [Repérant, J., Ward, R., Miceli, D., Rio, J.P., Médina, M., Kenigfest, N.B., Vesselkin, N.P., 2006. The centrifugal visual system of vertebrates: a comparative analysis of its functional anatomical organization, Brain Res. Rev. 52, 1-57], we have shown that this feature of the visual system is not a particularity of birds, but is a permanent component of the vertebrate central nervous system which nevertheless shows considerable morphological and functional variation from one taxonomic group to another. Given these findings, the primary objective of the present article is an attempt to specify the evolutionary significance of this phylogenetic diversity. We begin by drawing up an inventory of this variation under several headings: the intracerebral location of the retinopetal neurons; the mode of intra-retinal arborizations of the centrifugal fibres and the nature of their targets; their neurochemical properties; and the afferent supplies of these neurons. We subsequently discuss these variations, particularly that of the intracerebral location of the retinopetal neurons during development and in adult forms, using the neuromeric terminology and in the framework of cladistic analysis, and seek to interpret them in a phylogenetic context. From this analysis, it becomes evident that the CVS is not a homogeneous entity formed by neurons with a common embryological origin, but rather a collection of at least eight distinct subsystems arising in very different regions of the neuraxis. These are the olfacto-retinal, dorsal thalamo-retinal, ventral thalamo-retinal, pretecto-retinal, tecto-retinal, tegmento-mesencephalo-retinal, dorsal isthmo-retinal and ventral isthmo-retinal systems. The olfacto-retinal system, which is probably absent in Agnatha, appears to be a pleisiomorphic characteristic of all Gnathostomata, while on the other hand the tegmento-mesencephalo-retinal system appears to be present only in Agnatha. Our cladistic analysis also shows that the remaining six subsystems are polyphyletic in origin and have arisen independently on several occasions in different radiations of Gnathostoma. In conclusion, we suggest that, in the course of the palaeontological history of vertebrates, these different retinopetal pathways have been selected on the basis of widely different environmental pressures which remain to be identified.

The Functional Neuroanatomy of Human Face Perception.

PubMed

Grill-Spector, Kalanit; Weiner, Kevin S; Kay, Kendrick; Gomez, Jesse

2017-09-15

Face perception is critical for normal social functioning and is mediated by a network of regions in the ventral visual stream. In this review, we describe recent neuroimaging findings regarding the macro- and microscopic anatomical features of the ventral face network, the characteristics of white matter connections, and basic computations performed by population receptive fields within face-selective regions composing this network. We emphasize the importance of the neural tissue properties and white matter connections of each region, as these anatomical properties may be tightly linked to the functional characteristics of the ventral face network. We end by considering how empirical investigations of the neural architecture of the face network may inform the development of computational models and shed light on how computations in the face network enable efficient face perception.

The transcription factor Foxg1 regulates the competence of telencephalic cells to adopt subpallial fates in mice

PubMed Central

Manuel, Martine; Martynoga, Ben; Yu, Tian; West, John D.; Mason, John O.; Price, David J.

2010-01-01

Summary Foxg1 is required for development of the ventral telencephalon in the embryonic mammalian forebrain. Although one existing hypothesis suggests that failed ventral telencephalic development in the absence of Foxg1 is due to reduced production of the morphogens sonic hedgehog (Shh) and fibroblast growth factor 8 (Fgf8), the possibility that telencephalic cells lacking Foxg1 are intrinsically incompetent to generate the ventral telencephalon has remained untested. We examined the ability of Foxg1−/− telencephalic cells to respond to Shh and Fgf8 by examining the expression of genes whose activation requires Shh or Fgf8 in vivo and by testing their responses to Shh and Fgf8 in culture. We found that many elements of the Shh and Fgf8 signalling pathways continue to function in the absence of Foxg1 but, nevertheless, we were unable to elicit normal responses of key ventral telencephalic marker genes in Foxg1−/− telencephalic tissue following a range of in vivo and in vitro manipulations. We explored the development of Foxg1−/− cells in Foxg1−/− Foxg1+/+ chimeric embryos that contained ventral telencephalon created by normally patterned wild-type cells. We found that Foxg1−/− cells contributed to the chimeric ventral telencephalon, but that they retained abnormal specification, expressing dorsal rather than ventral telencephalic markers. These findings indicate that, in addition to regulating the production of ventralising signals, Foxg1 acts cell-autonomously in the telencephalon to ensure that cells develop the competence to adopt ventral identities. PMID:20081193

In situ hybridization analysis of the expression of futsch, tau, and MESK2 homologues in the brain of the European honeybee (Apis mellifera L.).

PubMed

Kaneko, Kumi; Hori, Sayaka; Morimoto, Mai M; Nakaoka, Takayoshi; Paul, Rajib Kumar; Fujiyuki, Tomoko; Shirai, Kenichi; Wakamoto, Akiko; Tsuboko, Satomi; Takeuchi, Hideaki; Kubo, Takeo

2010-02-16

The importance of visual sense in Hymenopteran social behavior is suggested by the existence of a Hymenopteran insect-specific neural circuit related to visual processing and the fact that worker honeybee brain changes morphologically according to its foraging experience. To analyze molecular and neural bases that underlie the visual abilities of the honeybees, we used a cDNA microarray to search for gene(s) expressed in a neural cell-type preferential manner in a visual center of the honeybee brain, the optic lobes (OLs). Expression analysis of candidate genes using in situ hybridization revealed two genes expressed in a neural cell-type preferential manner in the OLs. One is a homologue of Drosophila futsch, which encodes a microtubule-associated protein and is preferentially expressed in the monopolar cells in the lamina of the OLs. The gene for another microtubule-associated protein, tau, which functionally overlaps with futsch, was also preferentially expressed in the monopolar cells, strongly suggesting the functional importance of these two microtubule-associated proteins in monopolar cells. The other gene encoded a homologue of Misexpression Suppressor of Dominant-negative Kinase Suppressor of Ras 2 (MESK2), which might activate Ras/MAPK-signaling in Drosophila. MESK2 was expressed preferentially in a subclass of neurons located in the ventral region between the lamina and medulla neuropil in the OLs, suggesting that this subclass is a novel OL neuron type characterized by MESK2-expression. These three genes exhibited similar expression patterns in the worker, drone, and queen brains, suggesting that they function similarly irrespective of the honeybee sex or caste. Here we identified genes that are expressed in a monopolar cell (Amfutsch and Amtau) or ventral medulla-preferential manner (AmMESK2) in insect OLs. These genes may aid in visualizing neurites of monopolar cells and ventral medulla cells, as well as in analyzing the function of these neurons.

Hierarchical representation of shapes in visual cortex—from localized features to figural shape segregation

PubMed Central

Tschechne, Stephan; Neumann, Heiko

2014-01-01

Visual structures in the environment are segmented into image regions and those combined to a representation of surfaces and prototypical objects. Such a perceptual organization is performed by complex neural mechanisms in the visual cortex of primates. Multiple mutually connected areas in the ventral cortical pathway receive visual input and extract local form features that are subsequently grouped into increasingly complex, more meaningful image elements. Such a distributed network of processing must be capable to make accessible highly articulated changes in shape boundary as well as very subtle curvature changes that contribute to the perception of an object. We propose a recurrent computational network architecture that utilizes hierarchical distributed representations of shape features to encode surface and object boundary over different scales of resolution. Our model makes use of neural mechanisms that model the processing capabilities of early and intermediate stages in visual cortex, namely areas V1–V4 and IT. We suggest that multiple specialized component representations interact by feedforward hierarchical processing that is combined with feedback signals driven by representations generated at higher stages. Based on this, global configurational as well as local information is made available to distinguish changes in the object's contour. Once the outline of a shape has been established, contextual contour configurations are used to assign border ownership directions and thus achieve segregation of figure and ground. The model, thus, proposes how separate mechanisms contribute to distributed hierarchical cortical shape representation and combine with processes of figure-ground segregation. Our model is probed with a selection of stimuli to illustrate processing results at different processing stages. We especially highlight how modulatory feedback connections contribute to the processing of visual input at various stages in the processing hierarchy. PMID:25157228

Hierarchical representation of shapes in visual cortex-from localized features to figural shape segregation.

PubMed

Tschechne, Stephan; Neumann, Heiko

2014-01-01

Visual structures in the environment are segmented into image regions and those combined to a representation of surfaces and prototypical objects. Such a perceptual organization is performed by complex neural mechanisms in the visual cortex of primates. Multiple mutually connected areas in the ventral cortical pathway receive visual input and extract local form features that are subsequently grouped into increasingly complex, more meaningful image elements. Such a distributed network of processing must be capable to make accessible highly articulated changes in shape boundary as well as very subtle curvature changes that contribute to the perception of an object. We propose a recurrent computational network architecture that utilizes hierarchical distributed representations of shape features to encode surface and object boundary over different scales of resolution. Our model makes use of neural mechanisms that model the processing capabilities of early and intermediate stages in visual cortex, namely areas V1-V4 and IT. We suggest that multiple specialized component representations interact by feedforward hierarchical processing that is combined with feedback signals driven by representations generated at higher stages. Based on this, global configurational as well as local information is made available to distinguish changes in the object's contour. Once the outline of a shape has been established, contextual contour configurations are used to assign border ownership directions and thus achieve segregation of figure and ground. The model, thus, proposes how separate mechanisms contribute to distributed hierarchical cortical shape representation and combine with processes of figure-ground segregation. Our model is probed with a selection of stimuli to illustrate processing results at different processing stages. We especially highlight how modulatory feedback connections contribute to the processing of visual input at various stages in the processing hierarchy.

Retinal genes are differentially expressed in areas of primary versus secondary degeneration following partial optic nerve injury

PubMed Central

Chiha, Wissam; LeVaillant, Chrisna J.; Bartlett, Carole A.; Hewitt, Alex W.; Melton, Phillip E.; Fitzgerald, Melinda

2018-01-01

Background Partial transection (PT) of the optic nerve is an established experimental model of secondary degeneration in the central nervous system. After a dorsal transection, retinal ganglion cells (RGCs) with axons in ventral optic nerve are intact but vulnerable to secondary degeneration, whereas RGCs in dorsal retina with dorsal axons are affected by primary and secondary injuries. Using microarray, we quantified gene expression changes in dorsal and ventral retina at 1 and 7 days post PT, to characterize pathogenic pathways linked to primary and secondary degeneration. Results In comparison to uninjured retina Cryba1, Cryba2 and Crygs, were significantly downregulated in injured dorsal retina at days 1 and 7. While Ecel1, Timp1, Mt2A and CD74, which are associated with reducing excitotoxicity, oxidative stress and inflammation, were significantly upregulated. Genes associated with oxygen binding pathways, immune responses, cytokine receptor activity and apoptosis were enriched in dorsal retina at day 1 after PT. Oxygen binding and apoptosis remained enriched at day 7, as were pathways involved in extracellular matrix modification. Fewer changes were observed in ventral retina at day 1 after PT, most associated with the regulation of protein homodimerization activity. By day 7, apoptosis, matrix organization and signal transduction pathways were enriched. Discriminant analysis was also performed for specific functional gene groups to compare expression intensities at each time point. Altered expression of selected genes (ATF3, GFAP, Ecel1, TIMP1, Tp53) and proteins (GFAP, ECEL1 and ATF3) were semi-quantitatively assessed by qRT-PCR and immunohistochemistry respectively. Conclusion There was an acute and complex primary injury response in dorsal retina indicative of a dynamic interaction between neuroprotective and neurodegenerative events; ventral retina vulnerable to secondary degeneration showed a delayed injury response. Both primary and secondary injury resulted in the upregulation of numerous genes linked to RGC death, but differences in the nature of these changes strongly suggest that death occurred via different molecular mechanisms. PMID:29425209

Altered structural and effective connectivity in anorexia and bulimia nervosa in circuits that regulate energy and reward homeostasis

PubMed Central

Frank, G K W; Shott, M E; Riederer, J; Pryor, T L

2016-01-01

Anorexia and bulimia nervosa are severe eating disorders that share many behaviors. Structural and functional brain circuits could provide biological links that those disorders have in common. We recruited 77 young adult women, 26 healthy controls, 26 women with anorexia and 25 women with bulimia nervosa. Probabilistic tractography was used to map white matter connectivity strength across taste and food intake regulating brain circuits. An independent multisample greedy equivalence search algorithm tested effective connectivity between those regions during sucrose tasting. Anorexia and bulimia nervosa had greater structural connectivity in pathways between insula, orbitofrontal cortex and ventral striatum, but lower connectivity from orbitofrontal cortex and amygdala to the hypothalamus (P<0.05, corrected for comorbidity, medication and multiple comparisons). Functionally, in controls the hypothalamus drove ventral striatal activity, but in anorexia and bulimia nervosa effective connectivity was directed from anterior cingulate via ventral striatum to the hypothalamus. Across all groups, sweetness perception was predicted by connectivity strength in pathways connecting to the middle orbitofrontal cortex. This study provides evidence that white matter structural as well as effective connectivity within the energy-homeostasis and food reward-regulating circuitry is fundamentally different in anorexia and bulimia nervosa compared with that in controls. In eating disorders, anterior cingulate cognitive–emotional top down control could affect food reward and eating drive, override hypothalamic inputs to the ventral striatum and enable prolonged food restriction. PMID:27801897

Involvement of mesolimbic dopaminergic network in neuropathic pain relief by treadmill exercise

PubMed Central

Wakaizumi, Kenta; Kondo, Takashige; Hamada, Yusuke; Narita, Michiko; Kawabe, Rui; Narita, Hiroki; Watanabe, Moe; Kato, Shigeki; Senba, Emiko; Kobayashi, Kazuto; Yamanaka, Akihiro

2016-01-01

Background Exercise alleviates pain and it is a central component of treatment strategy for chronic pain in clinical setting. However, little is known about mechanism of this exercise-induced hypoalgesia. The mesolimbic dopaminergic network plays a role in positive emotions to rewards including motivation and pleasure. Pain negatively modulates these emotions, but appropriate exercise is considered to activate the dopaminergic network. We investigated possible involvement of this network as a mechanism of exercise-induced hypoalgesia. Methods In the present study, we developed a protocol of treadmill exercise, which was able to recover pain threshold under partial sciatic nerve ligation in mice, and investigated involvement of the dopaminergic reward network in exercise-induced hypoalgesia. To temporally suppress a neural activation during exercise, a genetically modified inhibitory G-protein-coupled receptor, hM4Di, was specifically expressed on dopaminergic pathway from the ventral tegmental area to the nucleus accumbens. Results The chemogenetic-specific neural suppression by Gi-DREADD system dramatically offset the effect of exercise-induced hypoalgesia in transgenic mice with hM4Di expressed on the ventral tegmental area dopamine neurons. Additionally, anti-exercise-induced hypoalgesia effect was significantly observed under the suppression of neurons projecting out of the ventral tegmental area to the nucleus accumbens as well. Conclusion Our findings suggest that the dopaminergic pathway from the ventral tegmental area to the nucleus accumbens is involved in the anti-nociception under low-intensity exercise under a neuropathic pain-like state. PMID:27909152

The role of ventral striatal cAMP signaling in stress-induced behaviors

PubMed Central

Plattner, Florian; Hayashi, Kanehiro; Hernandez, Adan; Benavides, David R.; Tassin, Tara C.; Tan, Chunfeng; Day, Jonathan; Fina, Maggy W.; Yuen, Eunice Y.; Yan, Zhen; Goldberg, Matthew S.; Nairn, Angus C.; Greengard, Paul; Nestler, Eric J.; Taussig, Ronald; Nishi, Akinori; Houslay, Miles D.; Bibb, James A.

2015-01-01

The cAMP/PKA signaling cascade is a ubiquitous pathway acting downstream of multiple neuromodulators. We found that the phosphorylation of phosphodiesterase-4 (PDE4) by cyclin-dependent protein kinase 5 (Cdk5) facilitates cAMP degradation and homeostasis of cAMP/PKA signaling. In mice, loss of Cdk5 throughout the forebrain elevated cAMP levels and increased PKA activity in striatal neurons, and altered behavioral responses to acute or chronic stressors. Ventral striatum- or D1 dopamine receptor-specific conditional knockout of Cdk5, or ventral striatum infusion of a small interfering peptide that selectively targets the regulation of PDE4 by Cdk5, all produced analogical effects on stress-induced behavioral responses. Together, our results demonstrate that altering cAMP signaling in medium spiny neurons of the ventral striatum can effectively modulate stress-induced behavioral states. We propose that targeting the Cdk5 regulation of PDE4 could be a new therapeutic approach for clinical conditions associated with stress, such as depression. PMID:26192746

Action observation circuits in the macaque monkey cortex.

PubMed

Nelissen, Koen; Borra, Elena; Gerbella, Marzio; Rozzi, Stefano; Luppino, Giuseppe; Vanduffel, Wim; Rizzolatti, Giacomo; Orban, Guy A

2011-03-09

In both monkeys and humans, the observation of actions performed by others activates cortical motor areas. An unresolved question concerns the pathways through which motor areas receive visual information describing motor acts. Using functional magnetic resonance imaging (fMRI), we mapped the macaque brain regions activated during the observation of grasping actions, focusing on the superior temporal sulcus region (STS) and the posterior parietal lobe. Monkeys viewed either videos with only the grasping hand visible or videos with the whole actor visible. Observation of both types of grasping videos activated elongated regions in the depths of both lower and upper banks of STS, as well as parietal areas PFG and anterior intraparietal (AIP). The correlation of fMRI data with connectional data showed that visual action information, encoded in the STS, is forwarded to ventral premotor cortex (F5) along two distinct functional routes. One route connects the upper bank of the STS with area PFG, which projects, in turn, to the premotor area F5c. The other connects the anterior part of the lower bank of the STS with premotor areas F5a/p via AIP. Whereas the first functional route emphasizes the agent and may relay visual information to the parieto-frontal mirror circuit involved in understanding the agent's intentions, the second route emphasizes the object of the action and may aid in understanding motor acts with respect to their immediate goal.

Recent Visual Experience Shapes Visual Processing in Rats through Stimulus-Specific Adaptation and Response Enhancement.

PubMed

Vinken, Kasper; Vogels, Rufin; Op de Beeck, Hans

2017-03-20

From an ecological point of view, it is generally suggested that the main goal of vision in rats and mice is navigation and (aerial) predator evasion [1-3]. The latter requires fast and accurate detection of a change in the visual environment. An outstanding question is whether there are mechanisms in the rodent visual system that would support and facilitate visual change detection. An experimental protocol frequently used to investigate change detection in humans is the oddball paradigm, in which a rare, unexpected stimulus is presented in a train of stimulus repetitions [4]. A popular "predictive coding" theory of cortical responses states that neural responses should decrease for expected sensory input and increase for unexpected input [5, 6]. Despite evidence for response suppression and enhancement in noninvasive scalp recordings in humans with this paradigm [7, 8], it has proven challenging to observe both phenomena in invasive action potential recordings in other animals [9-11]. During a visual oddball experiment, we recorded multi-unit spiking activity in rat primary visual cortex (V1) and latero-intermediate area (LI), which is a higher area of the rodent ventral visual stream. In rat V1, there was only evidence for response suppression related to stimulus-specific adaptation, and not for response enhancement. However, higher up in area LI, spiking activity showed clear surprise-based response enhancement in addition to stimulus-specific adaptation. These results show that neural responses along the rat ventral visual stream become increasingly sensitive to changes in the visual environment, suggesting a system specialized in the detection of unexpected events. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cell cycle regulator E2F4 is essential for the development of the ventral telencephalon.

PubMed

Ruzhynsky, Vladimir A; McClellan, Kelly A; Vanderluit, Jacqueline L; Jeong, Yongsu; Furimsky, Marosh; Park, David S; Epstein, Douglas J; Wallace, Valerie A; Slack, Ruth S

2007-05-30

Early forebrain development is characterized by extensive proliferation of neural precursors coupled with complex structural transformations; however, little is known regarding the mechanisms by which these processes are integrated. Here, we show that deficiency of the cell cycle regulatory protein, E2F4, results in the loss of ventral telencephalic structures and impaired self-renewal of neural precursor cells. The mechanism underlying aberrant ventral patterning lies in a dramatic loss of Sonic hedgehog (Shh) expression specifically in this region. The E2F4-deficient phenotype can be recapitulated by interbreeding mice heterozygous for E2F4 with those lacking one allele of Shh, suggesting a genetic interaction between these pathways. Treatment of E2F4-deficient cells with a Hh agonist rescues stem cell self-renewal and cells expressing the homeodomain proteins that specify the ventral telencephalic structures. Finally, we show that E2F4 deficiency results in impaired activity of Shh forebrain-specific enhancers. In conclusion, these studies establish a novel requirement for the cell cycle regulatory protein, E2F4, in the development of the ventral telencephalon.

Toll pathway is required for wound-induced expression of barrier repair genes in the Drosophila epidermis

PubMed Central

Capilla, Amalia; Karachentsev, Dmitry; Patterson, Rachel A.; Hermann, Anita; Juarez, Michelle T.; McGinnis, William

2017-01-01

The epidermis serves as a protective barrier in animals. After epidermal injury, barrier repair requires activation of many wound response genes in epidermal cells surrounding wound sites. Two such genes in Drosophila encode the enzymes dopa decarboxylase (Ddc) and tyrosine hydroxylase (ple). In this paper we explore the involvement of the Toll/NF-κB pathway in the localized activation of wound repair genes around epidermal breaks. Robust activation of wound-induced transcription from ple and Ddc requires Toll pathway components ranging from the extracellular ligand Spätzle to the Dif transcription factor. Epistasis experiments indicate a requirement for Spätzle ligand downstream of hydrogen peroxide and protease function, both of which are known activators of wound-induced transcription. The localized activation of Toll a few cell diameters from wound edges is reminiscent of local activation of Toll in early embryonic ventral hypoderm, consistent with the hypothesis that the dorsal–ventral patterning function of Toll arose from the evolutionary cooption of a morphogen-responsive function in wound repair. Furthermore, the combinatorial activity of Toll and other signaling pathways in activating epidermal barrier repair genes can help explain why developmental activation of the Toll, ERK, or JNK pathways alone fail to activate wound repair loci. PMID:28289197

Enhanced and bilateralized visual sensory processing in the ventral stream may be a feature of normal aging.

PubMed

De Sanctis, Pierfilippo; Katz, Richard; Wylie, Glenn R; Sehatpour, Pejman; Alexopoulos, George S; Foxe, John J

2008-10-01

Evidence has emerged for age-related amplification of basic sensory processing indexed by early components of the visual evoked potential (VEP). However, since these age-related effects have been incidental to the main focus of these studies, it is unclear whether they are performance dependent or alternately, represent intrinsic sensory processing changes. High-density VEPs were acquired from 19 healthy elderly and 15 young control participants who viewed alphanumeric stimuli in the absence of any active task. The data show both enhanced and delayed neural responses within structures of the ventral visual stream, with reduced hemispheric asymmetry in the elderly that may be indicative of a decline in hemispheric specialization. Additionally, considerably enhanced early frontal cortical activation was observed in the elderly, suggesting frontal hyper-activation. These age-related differences in early sensory processing are discussed in terms of recent proposals that normal aging involves large-scale compensatory reorganization. Our results suggest that such compensatory mechanisms are not restricted to later higher-order cognitive processes but may also be a feature of early sensory-perceptual processes.

Spatiotemporal Dynamics of Bilingual Word Processing

PubMed Central

Leonard, Matthew K.; Brown, Timothy T.; Travis, Katherine E.; Gharapetian, Lusineh; Hagler, Donald J.; Dale, Anders M.; Elman, Jeffrey L.; Halgren, Eric

2009-01-01

Studies with monolingual adults have identified successive stages occurring in different brain regions for processing single written words. We combined magnetoencephalography and magnetic resonance imaging to compare these stages between the first (L1) and second (L2) languages in bilingual adults. L1 words in a size judgment task evoked a typical left-lateralized sequence of activity first in ventral occipitotemporal cortex (VOT: previously associated with visual word-form encoding), and then ventral frontotemporal regions (associated with lexico-semantic processing). Compared to L1, words in L2 activated right VOT more strongly from ~135 ms; this activation was attenuated when words became highly familiar with repetition. At ~400ms, L2 responses were generally later than L1, more bilateral, and included the same lateral occipitotemporal areas as were activated by pictures. We propose that acquiring a language involves the recruitment of right hemisphere and posterior visual areas that are not necessary once fluency is achieved. PMID:20004256

Multi-step rhodopsin inactivation schemes can account for the size variability of single photon responses in Limulus ventral photoreceptors

PubMed Central

1994-01-01

Limulus ventral photoreceptors generate highly variable responses to the absorption of single photons. We have obtained data on the size distribution of these responses, derived the distribution predicted from simple transduction cascade models and compared the theory and data. In the simplest of models, the active state of the visual pigment (defined by its ability to activate G protein) is turned off in a single reaction. The output of such a cascade is predicted to be highly variable, largely because of stochastic variation in the number of G proteins activated. The exact distribution predicted is exponential, but we find that an exponential does not adequately account for the data. The data agree much better with the predictions of a cascade model in which the active state of the visual pigment is turned off by a multi-step process. PMID:8057085

Visual Spatial Cognition in Neurodegenerative Disease

PubMed Central

Possin, Katherine L.

2011-01-01

Visual spatial impairment is often an early symptom of neurodegenerative disease; however, this multi-faceted domain of cognition is not well-assessed by most typical dementia evaluations. Neurodegenerative diseases cause circumscribed atrophy in distinct neural networks, and accordingly, they impact visual spatial cognition in different and characteristic ways. Anatomically-focused visual spatial assessment can assist the clinician in making an early and accurate diagnosis. This article will review the literature on visual spatial cognition in neurodegenerative disease clinical syndromes, and where research is available, by neuropathologic diagnoses. Visual spatial cognition will be organized primarily according to the following schemes: bottom-up / top-down processing, dorsal / ventral stream processing, and egocentric / allocentric frames of reference. PMID:20526954

Vision for perception and vision for action in the primate brain.

PubMed

Goodale, M A

1998-01-01

Visual systems first evolved not to enable animals to see, but to provide distal sensory control of their movements. Vision as 'sight' is a relative newcomer to the evolutionary landscape, but its emergence has enabled animals to carry out complex cognitive operations on perceptual representations of the world. The two streams of visual processing that have been identified in the primate cerebral cortex are a reflection of these two functions of vision. The dorsal 'action' stream projecting from primary visual cortex to the posterior parietal cortex provides flexible control of more ancient subcortical visuomotor modules for the production of motor acts. The ventral 'perceptual' stream projecting from the primary visual cortex to the temporal lobe provides the rich and detailed representation of the world required for cognitive operations. Both streams process information about the structure of objects and about their spatial locations--and both are subject to the modulatory influences of attention. Each stream, however, uses visual information in different ways. Transformations carried out in the ventral stream permit the formation of perceptual representations that embody the enduring characteristics of objects and their relations; those carried out in the dorsal stream which utilize moment-to-moment information about objects within egocentric frames of reference, mediate the control of skilled actions. Both streams work together in the production of goal-directed behaviour.

Sleep deprivation impairs object-selective attention: a view from the ventral visual cortex.

PubMed

Lim, Julian; Tan, Jiat Chow; Parimal, Sarayu; Dinges, David F; Chee, Michael W L

2010-02-05

Most prior studies on selective attention in the setting of total sleep deprivation (SD) have focused on behavior or activation within fronto-parietal cognitive control areas. Here, we evaluated the effects of SD on the top-down biasing of activation of ventral visual cortex and on functional connectivity between cognitive control and other brain regions. Twenty-three healthy young adult volunteers underwent fMRI after a normal night of sleep (RW) and after sleep deprivation in a counterbalanced manner while performing a selective attention task. During this task, pictures of houses or faces were randomly interleaved among scrambled images. Across different blocks, volunteers responded to house but not face pictures, face but not house pictures, or passively viewed pictures without responding. The appearance of task-relevant pictures was unpredictable in this paradigm. SD resulted in less accurate detection of target pictures without affecting the mean false alarm rate or response time. In addition to a reduction of fronto-parietal activation, attending to houses strongly modulated parahippocampal place area (PPA) activation during RW, but this attention-driven biasing of PPA activation was abolished following SD. Additionally, SD resulted in a significant decrement in functional connectivity between the PPA and two cognitive control areas, the left intraparietal sulcus and the left inferior frontal lobe. SD impairs selective attention as evidenced by reduced selectivity in PPA activation. Further, reduction in fronto-parietal and ventral visual task-related activation suggests that it also affects sustained attention. Reductions in functional connectivity may be an important additional imaging parameter to consider in characterizing the effects of sleep deprivation on cognition.

Fast and Famous: Looking for the Fastest Speed at Which a Face Can be Recognized

PubMed Central

Barragan-Jason, Gladys; Besson, Gabriel; Ceccaldi, Mathieu; Barbeau, Emmanuel J.

2012-01-01

Face recognition is supposed to be fast. However, the actual speed at which faces can be recognized remains unknown. To address this issue, we report two experiments run with speed constraints. In both experiments, famous faces had to be recognized among unknown ones using a large set of stimuli to prevent pre-activation of features which would speed up recognition. In the first experiment (31 participants), recognition of famous faces was investigated using a rapid go/no-go task. In the second experiment, 101 participants performed a highly time constrained recognition task using the Speed and Accuracy Boosting procedure. Results indicate that the fastest speed at which a face can be recognized is around 360–390 ms. Such latencies are about 100 ms longer than the latencies recorded in similar tasks in which subjects have to detect faces among other stimuli. We discuss which model of activation of the visual ventral stream could account for such latencies. These latencies are not consistent with a purely feed-forward pass of activity throughout the visual ventral stream. An alternative is that face recognition relies on the core network underlying face processing identified in fMRI studies (OFA, FFA, and pSTS) and reentrant loops to refine face representation. However, the model of activation favored is that of an activation of the whole visual ventral stream up to anterior areas, such as the perirhinal cortex, combined with parallel and feed-back processes. Further studies are needed to assess which of these three models of activation can best account for face recognition. PMID:23460051

Multiple brain networks for visual self-recognition with different sensitivity for motion and body part.

PubMed

Sugiura, Motoaki; Sassa, Yuko; Jeong, Hyeonjeong; Miura, Naoki; Akitsuki, Yuko; Horie, Kaoru; Sato, Shigeru; Kawashima, Ryuta

2006-10-01

Multiple brain networks may support visual self-recognition. It has been hypothesized that the left ventral occipito-temporal cortex processes one's own face as a symbol, and the right parieto-frontal network processes self-image in association with motion-action contingency. Using functional magnetic resonance imaging, we first tested these hypotheses based on the prediction that these networks preferentially respond to a static self-face and to moving one's whole body, respectively. Brain activation specifically related to self-image during familiarity judgment was compared across four stimulus conditions comprising a two factorial design: factor Motion contrasted picture (Picture) and movie (Movie), and factor Body part a face (Face) and whole body (Body). Second, we attempted to segregate self-specific networks using a principal component analysis (PCA), assuming an independent pattern of inter-subject variability in activation over the four stimulus conditions in each network. The bilateral ventral occipito-temporal and the right parietal and frontal cortices exhibited self-specific activation. The left ventral occipito-temporal cortex exhibited greater self-specific activation for Face than for Body, in Picture, consistent with the prediction for this region. The activation profiles of the right parietal and frontal cortices did not show preference for Movie Body predicted by the assumed roles of these regions. The PCA extracted two cortical networks, one with its peaks in the right posterior, and another in frontal cortices; their possible roles in visuo-spatial and conceptual self-representations, respectively, were suggested by previous findings. The results thus supported and provided evidence of multiple brain networks for visual self-recognition.

Two different mirror neuron networks: The sensorimotor (hand) and limbic (face) pathways.

PubMed

Ferrari, P F; Gerbella, M; Coudé, G; Rozzi, S

2017-09-01

The vast majority of functional studies investigating mirror neurons (MNs) explored their properties in relation to hand actions, and very few investigated how MNs respond to mouth actions or communicative gestures. Since hand and mouth MNs were recorded in two partially overlapping sectors of the ventral precentral cortex of the macaque monkey, there is a general assumption that they share a same neuroanatomical network, with the parietal cortex as a main source of visual information. In the current review, we challenge this perspective and describe the connectivity pattern of mouth MN sector. The mouth MNs F5/opercular region is connected with premotor, parietal areas mostly related to the somatosensory and motor representation of the face/mouth, and with area PrCO, involved in processing gustatory and somatosensory intraoral input. Unlike hand MNs, mouth MNs do not receive their visual input from parietal regions. Such information related to face/communicative behaviors could come from the ventrolateral prefrontal cortex. Further strong connections derive from limbic structures involved in encoding emotional facial expressions and motivational/reward processing. These brain structures include the anterior cingulate cortex, the anterior and mid-dorsal insula, orbitofrontal cortex and the basolateral amygdala. The mirror mechanism is therefore composed and supported by at least two different anatomical pathways: one is concerned with sensorimotor transformation in relation to reaching and hand grasping within the traditional parietal-premotor circuits; the second one is linked to the mouth/face motor control and is connected with limbic structures, involved in communication/emotions and reward processing. Copyright © 2017. Published by Elsevier Ltd.

The processing of linear perspective and binocular information for action and perception.

PubMed

Bruggeman, Hugo; Yonas, Albert; Konczak, Jürgen

2007-04-08

To investigate the processing of linear perspective and binocular information for action and for the perceptual judgment of depth, we presented viewers with an actual Ames trapezoidal window. The display, when presented perpendicular to the line of sight, provided perspective information for a rectangular window slanted in depth, while binocular information specified a planar surface in the fronto-parallel plane. We compared pointing towards the display-edges with perceptual judgment of their positions in depth as the display orientation was varied under monocular and binocular view. On monocular trials, pointing and depth judgment were based on the perspective information and failed to respond accurately to changes in display orientation because pictorial information did not vary sufficiently to specify the small differences in orientation. For binocular trials, pointing was based on binocular information and precisely matched the changes in display orientation whereas depth judgment was short of such adjustment and based upon both binocular and perspective-specified slant information. The finding, that on binocular trials pointing was considerably less responsive to the illusion than perceptual judgment, supports an account of two separate processing streams in the human visual system, a ventral pathway involved in object recognition and a dorsal pathway that produces visual information for the control of actions. Previously, similar differences between perception and action were explained by an alternate explanation, that is, viewers selectively attend to different parts of a display in the two tasks. The finding that under monocular view participants responded to perspective information in both the action and the perception task rules out the attention-based argument.

Investigating the Influence of Biological Sex on the Behavioral and Neural Basis of Face Recognition

PubMed Central

2017-01-01

Abstract There is interest in understanding the influence of biological factors, like sex, on the organization of brain function. We investigated the influence of biological sex on the behavioral and neural basis of face recognition in healthy, young adults. In behavior, there were no sex differences on the male Cambridge Face Memory Test (CFMT)+ or the female CFMT+ (that we created) and no own-gender bias (OGB) in either group. We evaluated the functional topography of ventral stream organization by measuring the magnitude and functional neural size of 16 individually defined face-, two object-, and two place-related regions bilaterally. There were no sex differences in any of these measures of neural function in any of the regions of interest (ROIs) or in group level comparisons. These findings reveal that men and women have similar category-selective topographic organization in the ventral visual pathway. Next, in a separate task, we measured activation within the 16 face-processing ROIs specifically during recognition of target male and female faces. There were no sex differences in the magnitude of the neural responses in any face-processing region. Furthermore, there was no OGB in the neural responses of either the male or female participants. Our findings suggest that face recognition behavior, including the OGB, is not inherently sexually dimorphic. Face recognition is an essential skill for navigating human social interactions, which is reflected equally in the behavior and neural architecture of men and women. PMID:28497111

Investigating the Influence of Biological Sex on the Behavioral and Neural Basis of Face Recognition.

PubMed

Scherf, K Suzanne; Elbich, Daniel B; Motta-Mena, Natalie V

2017-01-01

There is interest in understanding the influence of biological factors, like sex, on the organization of brain function. We investigated the influence of biological sex on the behavioral and neural basis of face recognition in healthy, young adults. In behavior, there were no sex differences on the male Cambridge Face Memory Test (CFMT)+ or the female CFMT+ (that we created) and no own-gender bias (OGB) in either group. We evaluated the functional topography of ventral stream organization by measuring the magnitude and functional neural size of 16 individually defined face-, two object-, and two place-related regions bilaterally. There were no sex differences in any of these measures of neural function in any of the regions of interest (ROIs) or in group level comparisons. These findings reveal that men and women have similar category-selective topographic organization in the ventral visual pathway. Next, in a separate task, we measured activation within the 16 face-processing ROIs specifically during recognition of target male and female faces. There were no sex differences in the magnitude of the neural responses in any face-processing region. Furthermore, there was no OGB in the neural responses of either the male or female participants. Our findings suggest that face recognition behavior, including the OGB, is not inherently sexually dimorphic. Face recognition is an essential skill for navigating human social interactions, which is reflected equally in the behavior and neural architecture of men and women.

Experimental and analytical studies of flow through a ventral and axial exhaust nozzle system for STOVL aircraft

NASA Technical Reports Server (NTRS)

Esker, Barbara S.; Debonis, James R.

1991-01-01

Flow through a combined ventral and axial exhaust nozzle system was studied experimentally and analytically. The work is part of an ongoing propulsion technology effort at NASA Lewis Research Center for short takeoff, vertical landing (STOVL) aircraft. The experimental investigation was done on the NASA Lewis Powered Lift Facility. The experiment consisted of performance testing over a range of tailpipe pressure ratios from 1 to 3.2 and flow visualization. The analytical investigation consisted of modeling the same configuration and solving for the flow using the PARC3D computational fluid dynamics program. The comparison of experimental and analytical results was very good. The ventral nozzle performance coefficients obtained from both the experimental and analytical studies agreed within 1.2 percent. The net horizontal thrust of the nozzle system contained a significant reverse thrust component created by the flow overturning in the ventral duct. This component resulted in a low net horizontal thrust coefficient. The experimental and analytical studies showed very good agreement in the internal flow patterns.

Frequency-following and connectivity of different visual areas in response to contrast-reversal stimulation.

PubMed

Stephen, Julia M; Ranken, Doug F; Aine, Cheryl J

2006-01-01

The sensitivity of visual areas to different temporal frequencies, as well as the functional connections between these areas, was examined using magnetoencephalography (MEG). Alternating circular sinusoids (0, 3.1, 8.7 and 14 Hz) were presented to foveal and peripheral locations in the visual field to target ventral and dorsal stream structures, respectively. It was hypothesized that higher temporal frequencies would preferentially activate dorsal stream structures. To determine the effect of frequency on the cortical response we analyzed the late time interval (220-770 ms) using a multi-dipole spatio-temporal analysis approach to provide source locations and timecourses for each condition. As an exploratory aspect, we performed cross-correlation analysis on the source timecourses to determine which sources responded similarly within conditions. Contrary to predictions, dorsal stream areas were not activated more frequently during high temporal frequency stimulation. However, across cortical sources the frequency-following response showed a difference, with significantly higher power at the second harmonic for the 3.1 and 8.7 Hz stimulation and at the first and second harmonics for the 14 Hz stimulation with this pattern seen robustly in area V1. Cross-correlations of the source timecourses showed that both low- and high-order visual areas, including dorsal and ventral stream areas, were significantly correlated in the late time interval. The results imply that frequency information is transferred to higher-order visual areas without translation. Despite the less complex waveforms seen in the late interval of time, the cross-correlation results show that visual, temporal and parietal cortical areas are intricately involved in late-interval visual processing.

Two subdivisions of macaque LIP process visual-oculomotor information differently.

PubMed

Chen, Mo; Li, Bing; Guang, Jing; Wei, Linyu; Wu, Si; Liu, Yu; Zhang, Mingsha

2016-10-11

Although the cerebral cortex is thought to be composed of functionally distinct areas, the actual parcellation of area and assignment of function are still highly controversial. An example is the much-studied lateral intraparietal cortex (LIP). Despite the general agreement that LIP plays an important role in visual-oculomotor transformation, it remains unclear whether the area is primary sensory- or motor-related (the attention-intention debate). Although LIP has been considered as a functionally unitary area, its dorsal (LIPd) and ventral (LIPv) parts differ in local morphology and long-distance connectivity. In particular, LIPv has much stronger connections with two oculomotor centers, the frontal eye field and the deep layers of the superior colliculus, than does LIPd. Such anatomical distinctions imply that compared with LIPd, LIPv might be more involved in oculomotor processing. We tested this hypothesis physiologically with a memory saccade task and a gap saccade task. We found that LIP neurons with persistent memory activities in memory saccade are primarily provoked either by visual stimulation (vision-related) or by both visual and saccadic events (vision-saccade-related) in gap saccade. The distribution changes from predominantly vision-related to predominantly vision-saccade-related as the recording depth increases along the dorsal-ventral dimension. Consistently, the simultaneously recorded local field potential also changes from visual evoked to saccade evoked. Finally, local injection of muscimol (GABA agonist) in LIPv, but not in LIPd, dramatically decreases the proportion of express saccades. With these results, we conclude that LIPd and LIPv are more involved in visual and visual-saccadic processing, respectively.

Increased ventral-striatal activity during monetary decision making is a marker of problem poker gambling severity.

PubMed

Brevers, Damien; Noël, Xavier; He, Qinghua; Melrose, James A; Bechara, Antoine

2016-05-01

The aim of this study was to examine the impact of different neural systems on monetary decision making in frequent poker gamblers, who vary in their degree of problem gambling. Fifteen frequent poker players, ranging from non-problem to high-problem gambling, and 15 non-gambler controls were scanned using functional magnetic resonance imaging (fMRI) while performing the Iowa Gambling Task (IGT). During IGT deck selection, between-group fMRI analyses showed that frequent poker gamblers exhibited higher ventral-striatal but lower dorsolateral prefrontal and orbitofrontal activations as compared with controls. Moreover, using functional connectivity analyses, we observed higher ventral-striatal connectivity in poker players, and in regions involved in attentional/motor control (posterior cingulate), visual (occipital gyrus) and auditory (temporal gyrus) processing. In poker gamblers, scores of problem gambling severity were positively associated with ventral-striatal activations and with the connectivity between the ventral-striatum seed and the occipital fusiform gyrus and the middle temporal gyrus. Present results are consistent with findings from recent brain imaging studies showing that gambling disorder is associated with heightened motivational-reward processes during monetary decision making, which may hamper one's ability to moderate his level of monetary risk taking. © 2015 Society for the Study of Addiction.

Involvement of mesolimbic dopaminergic network in neuropathic pain relief by treadmill exercise: A study for specific neural control with Gi-DREADD in mice.

PubMed

Wakaizumi, Kenta; Kondo, Takashige; Hamada, Yusuke; Narita, Michiko; Kawabe, Rui; Narita, Hiroki; Watanabe, Moe; Kato, Shigeki; Senba, Emiko; Kobayashi, Kazuto; Kuzumaki, Naoko; Yamanaka, Akihiro; Morisaki, Hiroshi; Narita, Minoru

2016-01-01

Exercise alleviates pain and it is a central component of treatment strategy for chronic pain in clinical setting. However, little is known about mechanism of this exercise-induced hypoalgesia. The mesolimbic dopaminergic network plays a role in positive emotions to rewards including motivation and pleasure. Pain negatively modulates these emotions, but appropriate exercise is considered to activate the dopaminergic network. We investigated possible involvement of this network as a mechanism of exercise-induced hypoalgesia. In the present study, we developed a protocol of treadmill exercise, which was able to recover pain threshold under partial sciatic nerve ligation in mice, and investigated involvement of the dopaminergic reward network in exercise-induced hypoalgesia. To temporally suppress a neural activation during exercise, a genetically modified inhibitory G-protein-coupled receptor, hM4Di, was specifically expressed on dopaminergic pathway from the ventral tegmental area to the nucleus accumbens. The chemogenetic-specific neural suppression by Gi-DREADD system dramatically offset the effect of exercise-induced hypoalgesia in transgenic mice with hM4Di expressed on the ventral tegmental area dopamine neurons. Additionally, anti-exercise-induced hypoalgesia effect was significantly observed under the suppression of neurons projecting out of the ventral tegmental area to the nucleus accumbens as well. Our findings suggest that the dopaminergic pathway from the ventral tegmental area to the nucleus accumbens is involved in the anti-nociception under low-intensity exercise under a neuropathic pain-like state. © The Author(s) 2016.

Similarity-Based Fusion of MEG and fMRI Reveals Spatio-Temporal Dynamics in Human Cortex During Visual Object Recognition

PubMed Central

Cichy, Radoslaw Martin; Pantazis, Dimitrios; Oliva, Aude

2016-01-01

Every human cognitive function, such as visual object recognition, is realized in a complex spatio-temporal activity pattern in the brain. Current brain imaging techniques in isolation cannot resolve the brain's spatio-temporal dynamics, because they provide either high spatial or temporal resolution but not both. To overcome this limitation, we developed an integration approach that uses representational similarities to combine measurements of magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) to yield a spatially and temporally integrated characterization of neuronal activation. Applying this approach to 2 independent MEG–fMRI data sets, we observed that neural activity first emerged in the occipital pole at 50–80 ms, before spreading rapidly and progressively in the anterior direction along the ventral and dorsal visual streams. Further region-of-interest analyses established that dorsal and ventral regions showed MEG–fMRI correspondence in representations later than early visual cortex. Together, these results provide a novel and comprehensive, spatio-temporally resolved view of the rapid neural dynamics during the first few hundred milliseconds of object vision. They further demonstrate the feasibility of spatially unbiased representational similarity-based fusion of MEG and fMRI, promising new insights into how the brain computes complex cognitive functions. PMID:27235099

Neural correlates of auditory recognition memory in the primate dorsal temporal pole

PubMed Central

Ng, Chi-Wing; Plakke, Bethany

2013-01-01

Temporal pole (TP) cortex is associated with higher-order sensory perception and/or recognition memory, as human patients with damage in this region show impaired performance during some tasks requiring recognition memory (Olson et al. 2007). The underlying mechanisms of TP processing are largely based on examination of the visual nervous system in humans and monkeys, while little is known about neuronal activity patterns in the auditory portion of this region, dorsal TP (dTP; Poremba et al. 2003). The present study examines single-unit activity of dTP in rhesus monkeys performing a delayed matching-to-sample task utilizing auditory stimuli, wherein two sounds are determined to be the same or different. Neurons of dTP encode several task-relevant events during the delayed matching-to-sample task, and encoding of auditory cues in this region is associated with accurate recognition performance. Population activity in dTP shows a match suppression mechanism to identical, repeated sound stimuli similar to that observed in the visual object identification pathway located ventral to dTP (Desimone 1996; Nakamura and Kubota 1996). However, in contrast to sustained visual delay-related activity in nearby analogous regions, auditory delay-related activity in dTP is transient and limited. Neurons in dTP respond selectively to different sound stimuli and often change their sound response preferences between experimental contexts. Current findings suggest a significant role for dTP in auditory recognition memory similar in many respects to the visual nervous system, while delay memory firing patterns are not prominent, which may relate to monkeys' shorter forgetting thresholds for auditory vs. visual objects. PMID:24198324

The dual pathway model of AD/HD: an elaboration of neuro-developmental characteristics.

PubMed

Sonuga-Barke, Edmund J S

2003-11-01

The currently dominant neuro-cognitive model of Attention Deficit Hyperactivity Disorder (AD/HD) presents the condition as executive dysfunction (EDF) underpinned by disturbances in the fronto-dorsal striatal circuit and associated dopaminergic branches (e.g. meso-cortical). In contrast, motivationally-based accounts focus on altered reward processes and implicate fronto-ventral striatal reward circuits and those meso-limbic branches that terminate in the ventral striatum especially the nucleus accumbens. One such account, delay aversion (DEL), presents AD/HD as a motivational style-characterised by attempts to escape or avoid delay-arising from fundamental disturbances in these reward centres. While traditionally regarded as competing, EDF and DEL models have recently been presented as complimentary accounts of two psycho-patho-physiological subtypes of AD/HD with different developmental pathways, underpinned by different cortico-striatal circuits and modulated by different branches of the dopamine system. In the current paper we describe the development of this model in more detail. We elaborate on the neuro-circuitry possibly underpinning these two pathways and explore their developmental significance within a neuro-ecological framework.

Cholinergic Mesopontine Signals Govern Locomotion and Reward Through Dissociable Midbrain Pathways

PubMed Central

Xiao, Cheng; Cho, Jounhong Ryan; Zhou, Chunyi; Treweek, Jennifer B.; Chan, Ken; McKinney, Sheri L.; Yang, Bin; Gradinaru, Viviana

2016-01-01

The mesopontine tegmentum, including the pedunculopontine and laterodorsal tegmental nuclei (PPN and LDT), provides major cholinergic inputs to midbrain and regulates locomotion and reward. To delineate the underlying projection-specific circuit mechanisms we employed optogenetics to control mesopontine cholinergic neurons at somata and at divergent projections within distinct midbrain areas. Bidirectional manipulation of PPN cholinergic cell bodies exerted opposing effects on locomotor behavior and reinforcement learning. These motor and reward effects were separable via limiting photostimulation to PPN cholinergic terminals in the ventral substantia nigra pars compacta (vSNc) or to the ventral tegmental area (VTA), respectively. LDT cholinergic neurons also form connections with vSNc and VTA neurons, however although photo-excitation of LDT cholinergic terminals in the VTA caused positive reinforcement, LDT-to-vSNc modulation did not alter locomotion or reward. Therefore, the selective targeting of projection-specific mesopontine cholinergic pathways may offer increased benefit in treating movement and addiction disorders. PMID:27100197

Frontal-thalamic circuits associated with language

PubMed Central

Barbas, Helen; García-Cabezas, Miguel Ángel; Zikopoulos, Basilis

2012-01-01

Thalamic nuclei associated with language including the ventral lateral, ventral anterior, intralaminar and mediodorsal form a hub that uniquely receives the output of the basal ganglia and cerebellum, and is connected with frontal (premotor and prefrontal) cortices through two parallel circuits: a thalamic pathway targets the middle frontal cortical layers focally, and the other innervates widely cortical layer 1, poised to recruit other cortices and thalamic nuclei for complex cognitive operations. Return frontal pathways to the thalamus originate from cortical layers 6 and 5. Information through this integrated thalamo-cortical system is gated by the inhibitory thalamic reticular nucleus and modulated by dopamine, representing a specialization in primates. The intricate dialogue of distinct thalamic nuclei with the basal ganglia, cerebellum, and specific dorsolateral prefrontal and premotor cortices associated with language, suggests synergistic roles in the complex but seemingly effortless sequential transformation of cognitive operations for speech production in humans. PMID:23211411

The contributions of cerebro-cerebellar circuitry to executive verbal working memory.

PubMed

Marvel, Cherie L; Desmond, John E

2010-01-01

Contributions of cerebro-cerebellar function to executive verbal working memory were examined using event-related functional magnetic resonance imaging (fMRI) while 16 subjects completed two versions of the Sternberg task. In both versions subjects were presented with two or six target letters during the encoding phase, which were held in memory during the maintenance phase. A single probe letter was presented during the retrieval phase. In the "match condition", subjects decided whether the probe matched the target letters. In the "executive condition", subjects created a new probe by counting two alphabetical letters forward (e.g., f-->h) and decided whether the new probe matched the target letters. Neural activity during the match and executive conditions was compared during each phase of the task. There were four main findings. First, cerebro-cerebellar activity increased as a function of executive load. Second, the dorsal cerebellar dentate co-activated with the supplementary motor area (SMA) during encoding. This likely represented the formation of an articulatory (motor) trajectory. Third, the ventral cerebellar dentate co-activated with anterior prefrontal regions Brodmann Area (BA) 9/46 and the pre-SMA during retrieval. This likely represented the manipulation of information and formation of a response. A functional dissociation between the dorsal "motor" dentate and "cognitive" ventral dentate agrees with neuroanatomical tract tracing studies that have demonstrated separate neural pathways involving each region of the dentate: the dorsal dentate projects to frontal motor areas (including the SMA), and the ventral dentate projects to frontal cognitive areas (including BA 9/46 and the pre-SMA). Finally, activity during the maintenance phase in BA 9, anterior insula, pre-SMA and ventral dentate predicted subsequent accuracy of response to the probe during the retrieval phase. This finding underscored the significant contribution of the pre-SMA/ventral dentate pathway--observed several seconds prior to any motor response to the probe--to executive verbal working memory. Copyright (c) 2009 Elsevier Srl. All rights reserved.

The Contributions of Cerebro-Cerebellar Circuitry to Executive Verbal Working Memory

PubMed Central

Marvel, Cherie L.; Desmond, John E.

2009-01-01

Contributions of cerebro-cerebellar function to executive verbal working memory were examined using event-related functional magnetic resonance imaging (fMRI) while 16 subjects completed two versions of the Sternberg task. In both versions subjects were presented with two or six target letters during the encoding phase, which were held in memory during the maintenance phase. A single probe letter was presented during the retrieval phase. In the “match condition”, subjects decided whether the probe matched the target letters. In the “executive condition”, subjects created a new probe by counting two alphabetical letters forward (e.g., f → h) and decided whether the new probe matched the target letters. Neural activity during the match and executive conditions was compared during each phase of the task. There were four main findings. First, cerebro-cerebellar activity increased as a function of executive load. Second, the dorsal cerebellar dentate co-activated with the supplementary motor area (SMA) during encoding. This likely represented the formation of an articulatory (motor) trajectory. Third, the ventral cerebellar dentate co-activated with anterior prefrontal regions BA 9/46 and the pre-SMA during retrieval. This likely represented the manipulation of information and formation of a response. A functional dissociation between the dorsal “motor” dentate and “cognitive” ventral dentate agrees with neuroanatomical tract tracing studies that have demonstrated separate neural pathways involving each region of the dentate: the dorsal dentate projects to frontal motor areas (including the SMA), and the ventral dentate projects to frontal cognitive areas (including BA 9/46 and the pre-SMA). Finally, activity during the maintenance phase in BA 9, anterior insula, pre-SMA and ventral dentate predicted subsequent accuracy of response to the probe during the retrieval phase. This finding underscored the significant contribution of the pre-SMA/ventral dentate pathway – observed several seconds prior to any motor response to the probe -- to executive verbal working memory. PMID:19811779

Neural practice effect during cross-modal selective attention: Supra-modal and modality-specific effects.

PubMed

Xia, Jing; Zhang, Wei; Jiang, Yizhou; Li, You; Chen, Qi

2018-05-16

Practice and experiences gradually shape the central nervous system, from the synaptic level to large-scale neural networks. In natural multisensory environment, even when inundated by streams of information from multiple sensory modalities, our brain does not give equal weight to different modalities. Rather, visual information more frequently receives preferential processing and eventually dominates consciousness and behavior, i.e., visual dominance. It remains unknown, however, the supra-modal and modality-specific practice effect during cross-modal selective attention, and moreover whether the practice effect shows similar modality preferences as the visual dominance effect in the multisensory environment. To answer the above two questions, we adopted a cross-modal selective attention paradigm in conjunction with the hybrid fMRI design. Behaviorally, visual performance significantly improved while auditory performance remained constant with practice, indicating that visual attention more flexibly adapted behavior with practice than auditory attention. At the neural level, the practice effect was associated with decreasing neural activity in the frontoparietal executive network and increasing activity in the default mode network, which occurred independently of the modality attended, i.e., the supra-modal mechanisms. On the other hand, functional decoupling between the auditory and the visual system was observed with the progress of practice, which varied as a function of the modality attended. The auditory system was functionally decoupled with both the dorsal and ventral visual stream during auditory attention while was decoupled only with the ventral visual stream during visual attention. To efficiently suppress the irrelevant visual information with practice, auditory attention needs to additionally decouple the auditory system from the dorsal visual stream. The modality-specific mechanisms, together with the behavioral effect, thus support the visual dominance model in terms of the practice effect during cross-modal selective attention. Copyright © 2018 Elsevier Ltd. All rights reserved.

Top-down modulation of ventral occipito-temporal responses during visual word recognition.

PubMed

Twomey, Tae; Kawabata Duncan, Keith J; Price, Cathy J; Devlin, Joseph T

2011-04-01

Although interactivity is considered a fundamental principle of cognitive (and computational) models of reading, it has received far less attention in neural models of reading that instead focus on serial stages of feed-forward processing from visual input to orthographic processing to accessing the corresponding phonological and semantic information. In particular, the left ventral occipito-temporal (vOT) cortex is proposed to be the first stage where visual word recognition occurs prior to accessing nonvisual information such as semantics and phonology. We used functional magnetic resonance imaging (fMRI) to investigate whether there is evidence that activation in vOT is influenced top-down by the interaction of visual and nonvisual properties of the stimuli during visual word recognition tasks. Participants performed two different types of lexical decision tasks that focused on either visual or nonvisual properties of the word or word-like stimuli. The design allowed us to investigate how vOT activation during visual word recognition was influenced by a task change to the same stimuli and by a stimulus change during the same task. We found both stimulus- and task-driven modulation of vOT activation that can only be explained by top-down processing of nonvisual aspects of the task and stimuli. Our results are consistent with the hypothesis that vOT acts as an interface linking visual form with nonvisual processing in both bottom up and top down directions. Such interactive processing at the neural level is in agreement with cognitive and computational models of reading but challenges some of the assumptions made by current neuro-anatomical models of reading. Copyright © 2011 Elsevier Inc. All rights reserved.

Spatial attention improves reliability of fMRI retinotopic mapping signals in occipital and parietal cortex

PubMed Central

Bressler, David W.; Silver, Michael A.

2010-01-01

Spatial attention improves visual perception and increases the amplitude of neural responses in visual cortex. In addition, spatial attention tasks and fMRI have been used to discover topographic visual field representations in regions outside visual cortex. We therefore hypothesized that requiring subjects to attend to a retinotopic mapping stimulus would facilitate the characterization of visual field representations in a number of cortical areas. In our study, subjects attended either a central fixation point or a wedge-shaped stimulus that rotated about the fixation point. Response reliability was assessed by computing coherence between the fMRI time series and a sinusoid with the same frequency as the rotating wedge stimulus. When subjects attended to the rotating wedge instead of ignoring it, the reliability of retinotopic mapping signals increased by approximately 50% in early visual cortical areas (V1, V2, V3, V3A/B, V4) and ventral occipital cortex (VO1) and by approximately 75% in lateral occipital (LO1, LO2) and posterior parietal (IPS0, IPS1 and IPS2) cortical areas. Additionally, one 5-minute run of retinotopic mapping in the attention-to-wedge condition produced responses as reliable as the average of three to five (early visual cortex) or more than five (lateral occipital, ventral occipital, and posterior parietal cortex) attention-to-fixation runs. These results demonstrate that allocating attention to the retinotopic mapping stimulus substantially reduces the amount of scanning time needed to determine the visual field representations in occipital and parietal topographic cortical areas. Attention significantly increased response reliability in every cortical area we examined and may therefore be a general mechanism for improving the fidelity of neural representations of sensory stimuli at multiple levels of the cortical processing hierarchy. PMID:20600961

Visuoperceptive region atrophy independent of cognitive status in patients with Parkinson's disease with hallucinations.

PubMed

Goldman, Jennifer G; Stebbins, Glenn T; Dinh, Vy; Bernard, Bryan; Merkitch, Doug; deToledo-Morrell, Leyla; Goetz, Christopher G

2014-03-01

Visual hallucinations are frequent, disabling complications of advanced Parkinson's disease, but their neuroanatomical basis is incompletely understood. Previous structural brain magnetic resonance imaging studies suggest volume loss in the mesial temporal lobe and limbic regions in subjects with Parkinson's disease with visual hallucinations, relative to those without visual hallucinations. However, these studies have not always controlled for the presence of cognitive impairment or dementia, which are common co-morbidities of hallucinations in Parkinson's disease and whose neuroanatomical substrates may involve mesial temporal lobe and limbic regions. Therefore, we used structural magnetic resonance imaging to examine grey matter atrophy patterns associated with visual hallucinations, comparing Parkinson's disease hallucinators to Parkinson's disease non-hallucinators of comparable cognitive function. We studied 50 subjects with Parkinson's disease: 25 classified as current and chronic visual hallucinators and 25 as non-hallucinators, who were matched for cognitive status (demented or non-demented) and age (± 3 years). Subjects underwent (i) clinical evaluations; and (ii) brain MRI scans analysed using whole-brain voxel-based morphometry techniques. Clinically, the Parkinson's disease hallucinators did not differ in their cognitive classification or performance in any of the five assessed cognitive domains, compared with the non-hallucinators. The Parkinson's disease groups also did not differ significantly in age, motor severity, medication use or duration of disease. On imaging analyses, the hallucinators, all of whom experienced visual hallucinations, exhibited grey matter atrophy with significant voxel-wise differences in the cuneus, lingual and fusiform gyri, middle occipital lobe, inferior parietal lobule, and also cingulate, paracentral, and precentral gyri, compared with the non-hallucinators. Grey matter atrophy in the hallucinators occurred predominantly in brain regions responsible for processing visuoperceptual information including the ventral 'what' and dorsal 'where' pathways, which are important in object and facial recognition and identification of spatial locations of objects, respectively. Furthermore, the structural brain changes seen on magnetic resonance imaging occurred independently of cognitive function and age. Our findings suggest that when hallucinators and non-hallucinators are similar in their cognitive performance, the neural networks involving visuoperceptual pathways, rather than the mesial temporal lobe regions, distinctively contribute to the pathophysiology of visual hallucinations and may explain their predominantly visual nature in Parkinson's disease. Identification of distinct structural MRI differences associated with hallucinations in Parkinson's disease may permit earlier detection of at-risk patients and ultimately, development of therapies specifically targeting hallucinations and visuoperceptive functions.

Visuoperceptive region atrophy independent of cognitive status in patients with Parkinson’s disease with hallucinations

PubMed Central

Stebbins, Glenn T.; Dinh, Vy; Bernard, Bryan; Merkitch, Doug; deToledo-Morrell, Leyla; Goetz, Christopher G.

2014-01-01

Visual hallucinations are frequent, disabling complications of advanced Parkinson’s disease, but their neuroanatomical basis is incompletely understood. Previous structural brain magnetic resonance imaging studies suggest volume loss in the mesial temporal lobe and limbic regions in subjects with Parkinson’s disease with visual hallucinations, relative to those without visual hallucinations. However, these studies have not always controlled for the presence of cognitive impairment or dementia, which are common co-morbidities of hallucinations in Parkinson’s disease and whose neuroanatomical substrates may involve mesial temporal lobe and limbic regions. Therefore, we used structural magnetic resonance imaging to examine grey matter atrophy patterns associated with visual hallucinations, comparing Parkinson’s disease hallucinators to Parkinson’s disease non-hallucinators of comparable cognitive function. We studied 50 subjects with Parkinson’s disease: 25 classified as current and chronic visual hallucinators and 25 as non-hallucinators, who were matched for cognitive status (demented or non-demented) and age (±3 years). Subjects underwent (i) clinical evaluations; and (ii) brain MRI scans analysed using whole-brain voxel-based morphometry techniques. Clinically, the Parkinson’s disease hallucinators did not differ in their cognitive classification or performance in any of the five assessed cognitive domains, compared with the non-hallucinators. The Parkinson’s disease groups also did not differ significantly in age, motor severity, medication use or duration of disease. On imaging analyses, the hallucinators, all of whom experienced visual hallucinations, exhibited grey matter atrophy with significant voxel-wise differences in the cuneus, lingual and fusiform gyri, middle occipital lobe, inferior parietal lobule, and also cingulate, paracentral, and precentral gyri, compared with the non-hallucinators. Grey matter atrophy in the hallucinators occurred predominantly in brain regions responsible for processing visuoperceptual information including the ventral ‘what’ and dorsal ‘where’ pathways, which are important in object and facial recognition and identification of spatial locations of objects, respectively. Furthermore, the structural brain changes seen on magnetic resonance imaging occurred independently of cognitive function and age. Our findings suggest that when hallucinators and non-hallucinators are similar in their cognitive performance, the neural networks involving visuoperceptual pathways, rather than the mesial temporal lobe regions, distinctively contribute to the pathophysiology of visual hallucinations and may explain their predominantly visual nature in Parkinson’s disease. Identification of distinct structural MRI differences associated with hallucinations in Parkinson’s disease may permit earlier detection of at-risk patients and ultimately, development of therapies specifically targeting hallucinations and visuoperceptive functions. PMID:24480486

Intrinsic Properties Guide Proximal Abducens and Oculomotor Nerve Outgrowth in Avian Embryos

PubMed Central

Lance-Jones, Cynthia; Shah, Veeral; Noden, Drew M.; Sours, Emily

2012-01-01

Proper movement of the vertebrate eye requires the formation of precisely patterned axonal connections linking cranial somatic motoneurons, located at defined positions in the ventral midbrain and hindbrain, with extraocular muscles. The aim of this research was to assess the relative contributions of intrinsic, population-specific properties and extrinsic, outgrowth site-specific cues during the early stages of abducens and oculomotor nerve development in avian embryos. This was accomplished by surgically transposing midbrain and caudal hindbrain segments, which had been pre-labeled by electroporation with an EGFP construct. Graft-derived EGFP+ oculomotor axons entering a hindbrain microenvironment often mimicked an abducens initial pathway and coursed cranially. Similarly, some EGFP+ abducens axons entering a midbrain microenvironment mimicked an oculomotor initial pathway and coursed ventrally. Many but not all of these axons subsequently projected to extraocular muscles that they would not normally innervate. Strikingly, EGFP+ axons also took initial paths atypical for their new location. Upon exiting from a hindbrain position, most EGFP+ oculomotor axons actually coursed ventrally and joined host branchiomotor nerves, whose neurons share molecular features with oculomotor neurons. Similarly, upon exiting from a midbrain position, some EGFP+ abducens axons turned caudally, elongated parallel to the brainstem, and contacted the lateral rectus muscle, their originally correct target. These data reveal an interplay between intrinsic properties that are unique to oculomotor and abducens populations and shared ability to recognize and respond to extrinsic directional cues. The former play a prominent role in initial pathway choices, whereas the latter appear more instructive during subsequent directional choices. PMID:21739615

Opsin expression in Limulus eyes: a UV opsin is expressed in each eye type and co-expressed with a visible light-sensitive opsin in ventral larval eyes.

PubMed

Battelle, Barbara-Anne; Kempler, Karen E; Harrison, Alexandra; Dugger, Donald R; Payne, Richard

2014-09-01

The eyes of the horseshoe crab, Limulus polyphemus, are a model for studies of visual function and the visual systems of euarthropods. Much is known about the structure and function of L. polyphemus photoreceptors, much less about their photopigments. Three visible-light-sensitive L. polyphemus opsins were characterized previously (LpOps1, 2 and 5). Here we characterize a UV opsin (LpUVOps1) that is expressed in all three types of L. polyphemus eyes. It is expressed in most photoreceptors in median ocelli, the only L. polyphemus eyes in which UV sensitivity was previously detected, and in the dendrite of eccentric cells in lateral compound eyes. Therefore, eccentric cells, previously thought to be non-photosensitive second-order neurons, may actually be UV-sensitive photoreceptors. LpUVOps1 is also expressed in small photoreceptors in L. polyphemus ventral larval eyes, and intracellular recordings from these photoreceptors confirm that LpUVOps1 is an active, UV-sensitive photopigment. These photoreceptors also express LpOps5, which we demonstrate is an active, long-wavelength-sensitive photopigment. Thus small photoreceptors in ventral larval eyes, and probably those of the other larval eyes, have dual sensitivity to UV and visible light. Interestingly, the spectral tuning of small ventral photoreceptors may change day to night, because the level of LpOps5 in their rhabdoms is lower during the day than during the night, whereas LpUVOps1 levels show no diurnal change. These and previous findings show that opsin co-expression and the differential regulation of co-expressed opsins in rhabdoms is a common feature of L. polyphemus photoreceptors. © 2014. Published by The Company of Biologists Ltd.

Opsin expression in Limulus eyes: a UV opsin is expressed in each eye type and co-expressed with a visible light-sensitive opsin in ventral larval eyes

PubMed Central

Battelle, Barbara-Anne; Kempler, Karen E.; Harrison, Alexandra; Dugger, Donald R.; Payne, Richard

2014-01-01

The eyes of the horseshoe crab, Limulus polyphemus, are a model for studies of visual function and the visual systems of euarthropods. Much is known about the structure and function of L. polyphemus photoreceptors, much less about their photopigments. Three visible-light-sensitive L. polyphemus opsins were characterized previously (LpOps1, 2 and 5). Here we characterize a UV opsin (LpUVOps1) that is expressed in all three types of L. polyphemus eyes. It is expressed in most photoreceptors in median ocelli, the only L. polyphemus eyes in which UV sensitivity was previously detected, and in the dendrite of eccentric cells in lateral compound eyes. Therefore, eccentric cells, previously thought to be non-photosensitive second-order neurons, may actually be UV-sensitive photoreceptors. LpUVOps1 is also expressed in small photoreceptors in L. polyphemus ventral larval eyes, and intracellular recordings from these photoreceptors confirm that LpUVOps1 is an active, UV-sensitive photopigment. These photoreceptors also express LpOps5, which we demonstrate is an active, long-wavelength-sensitive photopigment. Thus small photoreceptors in ventral larval eyes, and probably those of the other larval eyes, have dual sensitivity to UV and visible light. Interestingly, the spectral tuning of small ventral photoreceptors may change day to night, because the level of LpOps5 in their rhabdoms is lower during the day than during the night, whereas LpUVOps1 levels show no diurnal change. These and previous findings show that opsin co-expression and the differential regulation of co-expressed opsins in rhabdoms is a common feature of L. polyphemus photoreceptors. PMID:24948643

Occipital Alpha Activity during Stimulus Processing Gates the Information Flow to Object-Selective Cortex

PubMed Central

Zumer, Johanna M.; Scheeringa, René; Schoffelen, Jan-Mathijs; Norris, David G.; Jensen, Ole

2014-01-01

Given the limited processing capabilities of the sensory system, it is essential that attended information is gated to downstream areas, whereas unattended information is blocked. While it has been proposed that alpha band (8–13 Hz) activity serves to route information to downstream regions by inhibiting neuronal processing in task-irrelevant regions, this hypothesis remains untested. Here we investigate how neuronal oscillations detected by electroencephalography in visual areas during working memory encoding serve to gate information reflected in the simultaneously recorded blood-oxygenation-level-dependent (BOLD) signals recorded by functional magnetic resonance imaging in downstream ventral regions. We used a paradigm in which 16 participants were presented with faces and landscapes in the right and left hemifields; one hemifield was attended and the other unattended. We observed that decreased alpha power contralateral to the attended object predicted the BOLD signal representing the attended object in ventral object-selective regions. Furthermore, increased alpha power ipsilateral to the attended object predicted a decrease in the BOLD signal representing the unattended object. We also found that the BOLD signal in the dorsal attention network inversely correlated with visual alpha power. This is the first demonstration, to our knowledge, that oscillations in the alpha band are implicated in the gating of information from the visual cortex to the ventral stream, as reflected in the representationally specific BOLD signal. This link of sensory alpha to downstream activity provides a neurophysiological substrate for the mechanism of selective attention during stimulus processing, which not only boosts the attended information but also suppresses distraction. Although previous studies have shown a relation between the BOLD signal from the dorsal attention network and the alpha band at rest, we demonstrate such a relation during a visuospatial task, indicating that the dorsal attention network exercises top-down control of visual alpha activity. PMID:25333286

Transformed Neural Pattern Reinstatement during Episodic Memory Retrieval.

PubMed

Xiao, Xiaoqian; Dong, Qi; Gao, Jiahong; Men, Weiwei; Poldrack, Russell A; Xue, Gui

2017-03-15

Contemporary models of episodic memory posit that remembering involves the reenactment of encoding processes. Although encoding-retrieval similarity has been consistently reported and linked to memory success, the nature of neural pattern reinstatement is poorly understood. Using high-resolution fMRI on human subjects, our results obtained clear evidence for item-specific pattern reinstatement in the frontoparietal cortex, even when the encoding-retrieval pairs shared no perceptual similarity. No item-specific pattern reinstatement was found in the ventral visual cortex. Importantly, the brain regions and voxels carrying item-specific representation differed significantly between encoding and retrieval, and the item specificity for encoding-retrieval similarity was smaller than that for encoding or retrieval, suggesting different nature of representations between encoding and retrieval. Moreover, cross-region representational similarity analysis suggests that the encoded representation in the ventral visual cortex was reinstated in the frontoparietal cortex during retrieval. Together, these results suggest that, in addition to reinstatement of the originally encoded pattern in the brain regions that perform encoding processes, retrieval may also involve the reinstatement of a transformed representation of the encoded information. These results emphasize the constructive nature of memory retrieval that helps to serve important adaptive functions. SIGNIFICANCE STATEMENT Episodic memory enables humans to vividly reexperience past events, yet how this is achieved at the neural level is barely understood. A long-standing hypothesis posits that memory retrieval involves the faithful reinstatement of encoding-related activity. We tested this hypothesis by comparing the neural representations during encoding and retrieval. We found strong pattern reinstatement in the frontoparietal cortex, but not in the ventral visual cortex, that represents visual details. Critically, even within the same brain regions, the nature of representation during retrieval was qualitatively different from that during encoding. These results suggest that memory retrieval is not a faithful replay of past event but rather involves additional constructive processes to serve adaptive functions. Copyright © 2017 the authors 0270-6474/17/372986-13$15.00/0.

Drosophila melanogaster Hedgehog cooperates with Frazzled to guide axons through a non-canonical signalling pathway.

PubMed

Ricolo, Delia; Butí, Elisenda; Araújo, Sofia J

2015-08-01

We report that the morphogen Hedgehog (Hh) is an axonal chemoattractant in the midline of Drosophila melanogaster embryos. Hh is present in the ventral nerve cord during axonal guidance and overexpression of hh in the midline causes ectopic midline crossing of FasII-positive axonal tracts. In addition, we show that Hh influences axonal guidance via a non-canonical signalling pathway dependent on Ptc. Our results reveal that the Hh pathway cooperates with the Netrin/Frazzled pathway to guide axons through the midline in invertebrates. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A method for real-time visual stimulus selection in the study of cortical object perception.

PubMed

Leeds, Daniel D; Tarr, Michael J

2016-06-01

The properties utilized by visual object perception in the mid- and high-level ventral visual pathway are poorly understood. To better establish and explore possible models of these properties, we adopt a data-driven approach in which we repeatedly interrogate neural units using functional Magnetic Resonance Imaging (fMRI) to establish each unit's image selectivity. This approach to imaging necessitates a search through a broad space of stimulus properties using a limited number of samples. To more quickly identify the complex visual features underlying human cortical object perception, we implemented a new functional magnetic resonance imaging protocol in which visual stimuli are selected in real-time based on BOLD responses to recently shown images. Two variations of this protocol were developed, one relying on natural object stimuli and a second based on synthetic object stimuli, both embedded in feature spaces based on the complex visual properties of the objects. During fMRI scanning, we continuously controlled stimulus selection in the context of a real-time search through these image spaces in order to maximize neural responses across pre-determined 1cm(3) rain regions. Elsewhere we have reported the patterns of cortical selectivity revealed by this approach (Leeds et al., 2014). In contrast, here our objective is to present more detailed methods and explore the technical and biological factors influencing the behavior of our real-time stimulus search. We observe that: 1) Searches converged more reliably when exploring a more precisely parameterized space of synthetic objects; 2) real-time estimation of cortical responses to stimuli is reasonably consistent; 3) search behavior was acceptably robust to delays in stimulus displays and subject motion effects. Overall, our results indicate that real-time fMRI methods may provide a valuable platform for continuing study of localized neural selectivity, both for visual object representation and beyond. Copyright © 2016 Elsevier Inc. All rights reserved.

Biologically Inspired Visual Model With Preliminary Cognition and Active Attention Adjustment.

PubMed

Qiao, Hong; Xi, Xuanyang; Li, Yinlin; Wu, Wei; Li, Fengfu

2015-11-01

Recently, many computational models have been proposed to simulate visual cognition process. For example, the hierarchical Max-Pooling (HMAX) model was proposed according to the hierarchical and bottom-up structure of V1 to V4 in the ventral pathway of primate visual cortex, which could achieve position- and scale-tolerant recognition. In our previous work, we have introduced memory and association into the HMAX model to simulate visual cognition process. In this paper, we improve our theoretical framework by mimicking a more elaborate structure and function of the primate visual cortex. We will mainly focus on the new formation of memory and association in visual processing under different circumstances as well as preliminary cognition and active adjustment in the inferior temporal cortex, which are absent in the HMAX model. The main contributions of this paper are: 1) in the memory and association part, we apply deep convolutional neural networks to extract various episodic features of the objects since people use different features for object recognition. Moreover, to achieve a fast and robust recognition in the retrieval and association process, different types of features are stored in separated clusters and the feature binding of the same object is stimulated in a loop discharge manner and 2) in the preliminary cognition and active adjustment part, we introduce preliminary cognition to classify different types of objects since distinct neural circuits in a human brain are used for identification of various types of objects. Furthermore, active cognition adjustment of occlusion and orientation is implemented to the model to mimic the top-down effect in human cognition process. Finally, our model is evaluated on two face databases CAS-PEAL-R1 and AR. The results demonstrate that our model exhibits its efficiency on visual recognition process with much lower memory storage requirement and a better performance compared with the traditional purely computational methods.

A method for real-time visual stimulus selection in the study of cortical object perception

PubMed Central

Leeds, Daniel D.; Tarr, Michael J.

2016-01-01

The properties utilized by visual object perception in the mid- and high-level ventral visual pathway are poorly understood. To better establish and explore possible models of these properties, we adopt a data-driven approach in which we repeatedly interrogate neural units using functional Magnetic Resonance Imaging (fMRI) to establish each unit’s image selectivity. This approach to imaging necessitates a search through a broad space of stimulus properties using a limited number of samples. To more quickly identify the complex visual features underlying human cortical object perception, we implemented a new functional magnetic resonance imaging protocol in which visual stimuli are selected in real-time based on BOLD responses to recently shown images. Two variations of this protocol were developed, one relying on natural object stimuli and a second based on synthetic object stimuli, both embedded in feature spaces based on the complex visual properties of the objects. During fMRI scanning, we continuously controlled stimulus selection in the context of a real-time search through these image spaces in order to maximize neural responses across predetermined 1 cm3 brain regions. Elsewhere we have reported the patterns of cortical selectivity revealed by this approach (Leeds 2014). In contrast, here our objective is to present more detailed methods and explore the technical and biological factors influencing the behavior of our real-time stimulus search. We observe that: 1) Searches converged more reliably when exploring a more precisely parameterized space of synthetic objects; 2) Real-time estimation of cortical responses to stimuli are reasonably consistent; 3) Search behavior was acceptably robust to delays in stimulus displays and subject motion effects. Overall, our results indicate that real-time fMRI methods may provide a valuable platform for continuing study of localized neural selectivity, both for visual object representation and beyond. PMID:26973168

End-Stopping Predicts Curvature Tuning along the Ventral Stream

PubMed Central

Hartmann, Till S.; Livingstone, Margaret S.

2017-01-01

Neurons in primate inferotemporal cortex (IT) are clustered into patches of shared image preferences. Functional imaging has shown that these patches are activated by natural categories (e.g., faces, body parts, and places), artificial categories (numerals, words) and geometric features (curvature and real-world size). These domains develop in the same cortical locations across monkeys and humans, which raises the possibility of common innate mechanisms. Although these commonalities could be high-level template-based categories, it is alternatively possible that the domain locations are constrained by low-level properties such as end-stopping, eccentricity, and the shape of the preferred images. To explore this, we looked for correlations among curvature preference, receptive field (RF) end-stopping, and RF eccentricity in the ventral stream. We recorded from sites in V1, V4, and posterior IT (PIT) from six monkeys using microelectrode arrays. Across all visual areas, we found a tendency for end-stopped sites to prefer curved over straight contours. Further, we found a progression in population curvature preferences along the visual hierarchy, where, on average, V1 sites preferred straight Gabors, V4 sites preferred curved stimuli, and many PIT sites showed a preference for curvature that was concave relative to fixation. Our results provide evidence that high-level functional domains may be mapped according to early rudimentary properties of the visual system. SIGNIFICANCE STATEMENT The macaque occipitotemporal cortex contains clusters of neurons with preferences for categories such as faces, body parts, and places. One common question is how these clusters (or “domains”) acquire their cortical position along the ventral stream. We and other investigators previously established an fMRI-level correlation among these category domains, retinotopy, and curvature preferences: for example, in inferotemporal cortex, face- and curvature-preferring domains show a central visual field bias whereas place- and rectilinear-preferring domains show a more peripheral visual field bias. Here, we have found an electrophysiological-level explanation for the correlation among domain preference, curvature, and retinotopy based on neuronal preference for short over long contours, also called end-stopping. PMID:28100746

End-Stopping Predicts Curvature Tuning along the Ventral Stream.

PubMed

Ponce, Carlos R; Hartmann, Till S; Livingstone, Margaret S

2017-01-18

Neurons in primate inferotemporal cortex (IT) are clustered into patches of shared image preferences. Functional imaging has shown that these patches are activated by natural categories (e.g., faces, body parts, and places), artificial categories (numerals, words) and geometric features (curvature and real-world size). These domains develop in the same cortical locations across monkeys and humans, which raises the possibility of common innate mechanisms. Although these commonalities could be high-level template-based categories, it is alternatively possible that the domain locations are constrained by low-level properties such as end-stopping, eccentricity, and the shape of the preferred images. To explore this, we looked for correlations among curvature preference, receptive field (RF) end-stopping, and RF eccentricity in the ventral stream. We recorded from sites in V1, V4, and posterior IT (PIT) from six monkeys using microelectrode arrays. Across all visual areas, we found a tendency for end-stopped sites to prefer curved over straight contours. Further, we found a progression in population curvature preferences along the visual hierarchy, where, on average, V1 sites preferred straight Gabors, V4 sites preferred curved stimuli, and many PIT sites showed a preference for curvature that was concave relative to fixation. Our results provide evidence that high-level functional domains may be mapped according to early rudimentary properties of the visual system. The macaque occipitotemporal cortex contains clusters of neurons with preferences for categories such as faces, body parts, and places. One common question is how these clusters (or "domains") acquire their cortical position along the ventral stream. We and other investigators previously established an fMRI-level correlation among these category domains, retinotopy, and curvature preferences: for example, in inferotemporal cortex, face- and curvature-preferring domains show a central visual field bias whereas place- and rectilinear-preferring domains show a more peripheral visual field bias. Here, we have found an electrophysiological-level explanation for the correlation among domain preference, curvature, and retinotopy based on neuronal preference for short over long contours, also called end-stopping. Copyright © 2017 the authors 0270-6474/17/370648-12$15.00/0.

The Neural Processing of Second Language Comprehension Modulated by the Degree of Proficiency: A Listening Connected Speech fMRI Study

PubMed Central

Hesling, Isabelle; Dilharreguy, Bixente; Bordessoules, Martine; Allard, Michèle

2012-01-01

While the neural network encompassing the processing of the mother tongue (L1) is well defined and has revealed the existence of a bilateral ventral pathway and a left dorsal pathway in which 3 loops have been defined, the question of the processing of a second language (L2) is still a matter of debate. Among variables accounting for the discrepancies in results, the degree of L2 proficiency appears to be one of the main factors. The present study aimed at assessing both pathways in L2, making it possible to determine the degree of mastery of the different speech components (prosody, phonology, semantics and syntax) that are intrinsically embedded within connected speech and that vary according to the degree of proficiency using high degrees of prosodic information. Two groups of high and moderate proficiency in L2 performed an fMRI comprehension task in L1 and L2. The modifications in brain activity observed within the dorsal and the ventral pathways according to L2 proficiency suggest that different processes of L2 are supported by differences in the integrated activity within distributed networks that included the left STSp, the left Spt and the left pars triangularis. PMID:22927897

Identification of a brain center whose activity discriminates a choice behavior in zebrafish

PubMed Central

Lau, Billy Y. B.; Mathur, Priya; Gould, Georgianna G.; Guo, Su

2011-01-01

The ability to make choices and carry out appropriate actions is critical for individual survival and well-being. Choice behaviors, from hard-wired to experience-dependent, have been observed across the animal kingdom. Although differential engagement of sensory neuronal pathways is a known mechanism, neurobiological substrates in the brain that underlie choice making downstream of sensory perception are not well understood. Here, we report a behavioral paradigm in zebrafish in which a half-light/half-dark visual image evokes an innate choice behavior, light avoidance. Neuronal activity mapping using the immediate early gene c-fos reveals the engagement of distinct brain regions, including the medial zone of the dorsal telencephalic region (Dm) and the dorsal nucleus of the ventral telencephalic area (Vd), the teleost anatomical homologs of the mammalian amygdala and striatum, respectively. In animals that were subjected to the identical sensory stimulus but displayed little or no avoidance, strikingly, the Dm and Vd were not engaged, despite similar levels of activation in the brain nuclei involved in visual processing. Based on these findings and previous connectivity data, we propose a neural circuitry model in which the Dm serves as a brain center, the activity of which predicates this choice behavior in zebrafish. PMID:21262817

Semantic attributes are encoded in human electrocorticographic signals during visual object recognition.

PubMed

Rupp, Kyle; Roos, Matthew; Milsap, Griffin; Caceres, Carlos; Ratto, Christopher; Chevillet, Mark; Crone, Nathan E; Wolmetz, Michael

2017-03-01

Non-invasive neuroimaging studies have shown that semantic category and attribute information are encoded in neural population activity. Electrocorticography (ECoG) offers several advantages over non-invasive approaches, but the degree to which semantic attribute information is encoded in ECoG responses is not known. We recorded ECoG while patients named objects from 12 semantic categories and then trained high-dimensional encoding models to map semantic attributes to spectral-temporal features of the task-related neural responses. Using these semantic attribute encoding models, untrained objects were decoded with accuracies comparable to whole-brain functional Magnetic Resonance Imaging (fMRI), and we observed that high-gamma activity (70-110Hz) at basal occipitotemporal electrodes was associated with specific semantic dimensions (manmade-animate, canonically large-small, and places-tools). Individual patient results were in close agreement with reports from other imaging modalities on the time course and functional organization of semantic processing along the ventral visual pathway during object recognition. The semantic attribute encoding model approach is critical for decoding objects absent from a training set, as well as for studying complex semantic encodings without artificially restricting stimuli to a small number of semantic categories. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Neural Signatures of Stimulus Features in Visual Working Memory—A Spatiotemporal Approach

PubMed Central

Jackson, Margaret C.; Klein, Christoph; Mohr, Harald; Shapiro, Kimron L.; Linden, David E. J.

2010-01-01

We examined the neural signatures of stimulus features in visual working memory (WM) by integrating functional magnetic resonance imaging (fMRI) and event-related potential data recorded during mental manipulation of colors, rotation angles, and color–angle conjunctions. The N200, negative slow wave, and P3b were modulated by the information content of WM, and an fMRI-constrained source model revealed a progression in neural activity from posterior visual areas to higher order areas in the ventral and dorsal processing streams. Color processing was associated with activity in inferior frontal gyrus during encoding and retrieval, whereas angle processing involved right parietal regions during the delay interval. WM for color–angle conjunctions did not involve any additional neural processes. The finding that different patterns of brain activity underlie WM for color and spatial information is consistent with ideas that the ventral/dorsal “what/where” segregation of perceptual processing influences WM organization. The absence of characteristic signatures of conjunction-related brain activity, which was generally intermediate between the 2 single conditions, suggests that conjunction judgments are based on the coordinated activity of these 2 streams. PMID:19429863

BOLD repetition decreases in object-responsive ventral visual areas depend on spatial attention.

PubMed

Eger, E; Henson, R N A; Driver, J; Dolan, R J

2004-08-01

Functional imaging studies of priming-related repetition phenomena have become widely used to study neural object representation. Although blood oxygenation level-dependent (BOLD) repetition decreases can sometimes be observed without awareness of repetition, any role for spatial attention in BOLD repetition effects remains largely unknown. We used fMRI in 13 healthy subjects to test whether BOLD repetition decreases for repeated objects in ventral visual cortices depend on allocation of spatial attention to the prime. Subjects performed a size-judgment task on a probe object that had been attended or ignored in a preceding prime display of 2 lateralized objects. Reaction times showed faster responses when the probe was the same object as the attended prime, independent of the view tested (identical vs. mirror image). No behavioral effect was evident from unattended primes. BOLD repetition decreases for attended primes were found in lateral occipital and fusiform regions bilaterally, which generalized across identical and mirror-image repeats. No repetition decreases were observed for ignored primes. Our results suggest a critical role for attention in achieving visual representations of objects that lead to both BOLD signal decreases and behavioral priming on repeated presentation.

Involvement of the ventral premotor cortex in controlling image motion of the hand during performance of a target-capturing task.

PubMed

Ochiai, Tetsuji; Mushiake, Hajime; Tanji, Jun

2005-07-01

The ventral premotor cortex (PMv) has been implicated in the visual guidance of movement. To examine whether neuronal activity in the PMv is involved in controlling the direction of motion of a visual image of the hand or the actual movement of the hand, we trained a monkey to capture a target that was presented on a video display using the same side of its hand as was displayed on the video display. We found that PMv neurons predominantly exhibited premovement activity that reflected the image motion to be controlled, rather than the physical motion of the hand. We also found that the activity of half of such direction-selective PMv neurons depended on which side (left versus right) of the video image of the hand was used to capture the target. Furthermore, this selectivity for a portion of the hand was not affected by changing the starting position of the hand movement. These findings suggest that PMv neurons play a crucial role in determining which part of the body moves in which direction, at least under conditions in which a visual image of a limb is used to guide limb movements.

Comparison of visual receptive fields in the dorsolateral prefrontal cortex and ventral intraparietal area in macaques.

PubMed

Viswanathan, Pooja; Nieder, Andreas

2017-12-01

The concept of receptive field (RF) describes the responsiveness of neurons to sensory space. Neurons in the primate association cortices have long been known to be spatially selective but a detailed characterisation and direct comparison of RFs between frontal and parietal association cortices are missing. We sampled the RFs of a large number of neurons from two interconnected areas of the frontal and parietal lobes, the dorsolateral prefrontal cortex (dlPFC) and ventral intraparietal area (VIP), of rhesus monkeys by systematically presenting a moving bar during passive fixation. We found that more than half of neurons in both areas showed spatial selectivity. Single neurons in both areas could be assigned to five classes according to the spatial response patterns: few non-uniform RFs with multiple discrete response maxima could be dissociated from the vast majority of uniform RFs showing a single maximum; the latter were further classified into full-field and confined foveal, contralateral and ipsilateral RFs. Neurons in dlPFC showed a preference for the contralateral visual space and collectively encoded the contralateral visual hemi-field. In contrast, VIP neurons preferred central locations, predominantly covering the foveal visual space. Putative pyramidal cells with broad-spiking waveforms in PFC had smaller RFs than putative interneurons showing narrow-spiking waveforms, but distributed similarly across the visual field. In VIP, however, both putative pyramidal cells and interneurons had similar RFs at similar eccentricities. We provide a first, thorough characterisation of visual RFs in two reciprocally connected areas of a fronto-parietal cortical network. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Disentangling visual imagery and perception of real-world objects

PubMed Central

Lee, Sue-Hyun; Kravitz, Dwight J.; Baker, Chris I.

2011-01-01

During mental imagery, visual representations can be evoked in the absence of “bottom-up” sensory input. Prior studies have reported similar neural substrates for imagery and perception, but studies of brain-damaged patients have revealed a double dissociation with some patients showing preserved imagery in spite of impaired perception and others vice versa. Here, we used fMRI and multi-voxel pattern analysis to investigate the specificity, distribution, and similarity of information for individual seen and imagined objects to try and resolve this apparent contradiction. In an event-related design, participants either viewed or imagined individual named object images on which they had been trained prior to the scan. We found that the identity of both seen and imagined objects could be decoded from the pattern of activity throughout the ventral visual processing stream. Further, there was enough correspondence between imagery and perception to allow discrimination of individual imagined objects based on the response during perception. However, the distribution of object information across visual areas was strikingly different during imagery and perception. While there was an obvious posterior-anterior gradient along the ventral visual stream for seen objects, there was an opposite gradient for imagined objects. Moreover, the structure of representations (i.e. the pattern of similarity between responses to all objects) was more similar during imagery than perception in all regions along the visual stream. These results suggest that while imagery and perception have similar neural substrates, they involve different network dynamics, resolving the tension between previous imaging and neuropsychological studies. PMID:22040738

Representation of vestibular and visual cues to self-motion in ventral intraparietal (VIP) cortex

PubMed Central

Chen, Aihua; Deangelis, Gregory C.; Angelaki, Dora E.

2011-01-01

Convergence of vestibular and visual motion information is important for self-motion perception. One cortical area that combines vestibular and optic flow signals is the ventral intraparietal area (VIP). We characterized unisensory and multisensory responses of macaque VIP neurons to translations and rotations in three dimensions. Approximately half of VIP cells show significant directional selectivity in response to optic flow, half show tuning to vestibular stimuli, and one-third show multisensory responses. Visual and vestibular direction preferences of multisensory VIP neurons could be congruent or opposite. When visual and vestibular stimuli were combined, VIP responses could be dominated by either input, unlike medial superior temporal area (MSTd) where optic flow tuning typically dominates or the visual posterior sylvian area (VPS) where vestibular tuning dominates. Optic flow selectivity in VIP was weaker than in MSTd but stronger than in VPS. In contrast, vestibular tuning for translation was strongest in VPS, intermediate in VIP, and weakest in MSTd. To characterize response dynamics, direction-time data were fit with a spatiotemporal model in which temporal responses were modeled as weighted sums of velocity, acceleration, and position components. Vestibular responses in VIP reflected balanced contributions of velocity and acceleration, whereas visual responses were dominated by velocity. Timing of vestibular responses in VIP was significantly faster than in MSTd, whereas timing of optic flow responses did not differ significantly among areas. These findings suggest that VIP may be proximal to MSTd in terms of vestibular processing but hierarchically similar to MSTd in terms of optic flow processing. PMID:21849564

Evidence for Non-Opponent Coding of Colour Information in Human Visual Cortex: Selective Loss of "Green" Sensitivity in a Subject with Damaged Ventral Occipito-Temporal Cortex.

PubMed

Rauscher, Franziska G; Plant, Gordon T; James-Galton, Merle; Barbur, John L

2011-01-01

Damage to ventral occipito-temporal extrastriate visual cortex leads to the syndrome of prosopagnosia often with coexisting cerebral achromatopsia. A patient with this syndrome resulting in a left upper homonymous quadrantanopia, prosopagnosia, and incomplete achromatopsia is described. Chromatic sensitivity was assessed at a number of locations in the intact visual field using a dynamic luminance contrast masking technique that isolates the use of colour signals. In normal subjects chromatic detection thresholds form an elliptical contour when plotted in the Commission Internationale d'Eclairage, (x-y), chromaticity diagram. Because the extraction of colour signals in early visual processing involves opponent mechanisms, subjects with Daltonism (congenital red/green loss of sensitivity) show symmetric increase in thresholds towards the long wavelength ("red") and middle wavelength ("green") regions of the spectrum locus. This is also the case with acquired loss of chromatic sensitivity as a result of retinal or optic nerve disease. Our patient's results were an exception to this rule. Whilst his chromatic sensitivity in the central region of the visual field was reduced symmetrically for both "red/green" and "yellow/blue" directions in colour space, the subject's lower left quadrant showed a marked asymmetry in "red/green" thresholds with the greatest loss of sensitivity towards the "green" region of the spectrum locus. This spatially localized asymmetric loss of "green" but not "red" sensitivity has not been reported previously in human vision. Such loss is consistent with selective damage of neural substrates in the visual cortex that process colour information, but are spectrally non-opponent.

Stimulation of subgenual cingulate area decreases limbic top-down effect on ventral visual stream: A DBS-EEG pilot study.

PubMed

Kibleur, Astrid; Polosan, Mircea; Favre, Pauline; Rudrauf, David; Bougerol, Thierry; Chabardès, Stéphan; David, Olivier

2017-02-01

Deep brain stimulation (DBS) of the subgenual cingulate gyrus (area CG25) is beneficial in treatment resistant depression. Though the mechanisms of action of Cg25 DBS remain largely unknown, it is commonly believed that Cg25 DBS modulates limbic activity of large networks to achieve thymic regulation of patients. To investigate how emotional attention is influenced by Cg25 DBS, we assessed behavioral and electroencephalographic (EEG) responses to an emotional Stroop task in 5 patients during ON and OFF stimulation conditions. Using EEG source localization, we found that the main effect of DBS was a reduction of neuronal responses in limbic regions (temporal pole, medial prefrontal and posterior cingulate cortices) and in ventral visual areas involved in face processing. In the dynamic causal modeling (DCM) approach, the changes of the evoked response amplitudes are assumed to be due to changes of long range connectivity induced by Cg25 DBS. Here, using a simplified neural mass model that did not take explicitly into account the cytoarchitecture of the considered brain regions, we showed that the remote action of Cg25 DBS could be explained by a reduced top-down effective connectivity of the amygdalo-temporo-polar complex. Overall, our results thus indicate that Cg25 DBS during the emotional Stroop task causes a decrease of top-down limbic influence on the ventral visual stream itself, rather than a modulation of prefrontal cognitive processes only. Tuning down limbic excitability in relation to sensory processing might be one of the biological mechanisms through which Cg25 DBS produces positive clinical outcome in the treatment of resistant depression. Copyright © 2016 Elsevier Inc. All rights reserved.

Surfing a spike wave down the ventral stream.

PubMed

VanRullen, Rufin; Thorpe, Simon J

2002-10-01

Numerous theories of neural processing, often motivated by experimental observations, have explored the computational properties of neural codes based on the absolute or relative timing of spikes in spike trains. Spiking neuron models and theories however, as well as their experimental counterparts, have generally been limited to the simulation or observation of isolated neurons, isolated spike trains, or reduced neural populations. Such theories would therefore seem inappropriate to capture the properties of a neural code relying on temporal spike patterns distributed across large neuronal populations. Here we report a range of computer simulations and theoretical considerations that were designed to explore the possibilities of one such code and its relevance for visual processing. In a unified framework where the relation between stimulus saliency and spike relative timing plays the central role, we describe how the ventral stream of the visual system could process natural input scenes and extract meaningful information, both rapidly and reliably. The first wave of spikes generated in the retina in response to a visual stimulation carries information explicitly in its spatio-temporal structure: the most salient information is represented by the first spikes over the population. This spike wave, propagating through a hierarchy of visual areas, is regenerated at each processing stage, where its temporal structure can be modified by (i). the selectivity of the cortical neurons, (ii). lateral interactions and (iii). top-down attentional influences from higher order cortical areas. The resulting model could account for the remarkable efficiency and rapidity of processing observed in the primate visual system.

Visuotopic organization of the cebus pulvinar: a double representation the contralateral hemifield.

PubMed

Gattass, R; Oswaldo-Cruz, E; Sousa, A P

1978-08-18

The projection of the visual field in the pulvinar nucleus was studied in 17 Cebus monkeys using electrophysiological techniques. Visual space is represented in two regions of the pulvinar; (1) the ventrolateral group, Pvlg, comprising nuclei P delta, P delta, P gamma, P eta and P mu 1; and (2) P mu. In the first group, which corresponds to the pulvinar inferior and ventral part of the pulvinar lateralis, we observed a greater respresentation of the central part of the visual field. Approximately 58% of the volume of the ventrolateral group is concerned with the visual space within 10 degrees of the fovea. This portion of the visual field is represented at its lateral aspects, mainly close to the level of the caudal pole of the lateral geniculate nucleus (LGN). Projection of the vertical meridian runs along its lateral border while that of the horizontal one is found running from the dorsal third of the LGN's hilus to the medial border of the ventro-lateral group. The lower quadrant is represented at its dorsal portion while the upper quadrant is represented at the ventral one. In Pmu the representation is rotated 90 degrees clockwise around the rostrocaudal axis: the vertical meridian is found at the ventromedial border of this nucleus. Thus, the lower quadrant is represented at the later portion of Pmu and the upper at its medial portion. Both projections are restricted to the contralateral hemifield.

Beyond the visual word form area: the orthography-semantics interface in spelling and reading.

PubMed

Purcell, Jeremy J; Shea, Jennifer; Rapp, Brenda

2014-01-01

Lexical orthographic information provides the basis for recovering the meanings of words in reading and for generating correct word spellings in writing. Research has provided evidence that an area of the left ventral temporal cortex, a subregion of what is often referred to as the visual word form area (VWFA), plays a significant role specifically in lexical orthographic processing. The current investigation goes beyond this previous work by examining the neurotopography of the interface of lexical orthography with semantics. We apply a novel lesion mapping approach with three individuals with acquired dysgraphia and dyslexia who suffered lesions to left ventral temporal cortex. To map cognitive processes to their neural substrates, this lesion mapping approach applies similar logical constraints to those used in cognitive neuropsychological research. Using this approach, this investigation: (a) identifies a region anterior to the VWFA that is important in the interface of orthographic information with semantics for reading and spelling; (b) determines that, within this orthography-semantics interface region (OSIR), access to orthography from semantics (spelling) is topographically distinct from access to semantics from orthography (reading); (c) provides evidence that, within this region, there is modality-specific access to and from lexical semantics for both spoken and written modalities, in both word production and comprehension. Overall, this study contributes to our understanding of the neural architecture at the lexical orthography-semantic-phonological interface within left ventral temporal cortex.

Differential priming effects of color-opponent subliminal stimulation on visual magnetic responses.

PubMed

Hoshiyama, Minoru; Kakigi, Ryusuke; Takeshima, Yasuyuki; Miki, Kensaku; Watanabe, Shoko

2006-10-01

We investigated the effects of subliminal stimulation on visible stimulation to demonstrate the priority of facial discrimination processing, using a unique, indiscernible, color-opponent subliminal (COS) stimulation. We recorded event-related magnetic cortical fields (ERF) by magnetoencephalography (MEG) after the presentation of a face or flower stimulus with COS conditioning using a face, flower, random pattern, and blank. The COS stimulation enhanced the response to visible stimulation when the figure in the COS stimulation was identical to the target visible stimulus, but more so for the face than for the flower stimulus. The ERF component modulated by the COS stimulation was estimated to be located in the ventral temporal cortex. We speculated that the enhancement was caused by an interaction of the responses after subthreshold stimulation by the COS stimulation and the suprathreshold stimulation after target stimulation, such as in the processing for categorization or discrimination. We also speculated that the face was processed with priority at the level of the ventral temporal cortex during visual processing outside of consciousness.

Visual and visuomotor processing of hands and tools as a case study of cross talk between the dorsal and ventral streams.

PubMed

Almeida, Jorge; Amaral, Lénia; Garcea, Frank E; Aguiar de Sousa, Diana; Xu, Shan; Mahon, Bradford Z; Martins, Isabel Pavão

2018-05-24

A major principle of organization of the visual system is between a dorsal stream that processes visuomotor information and a ventral stream that supports object recognition. Most research has focused on dissociating processing across these two streams. Here we focus on how the two streams interact. We tested neurologically-intact and impaired participants in an object categorization task over two classes of objects that depend on processing within both streams-hands and tools. We measured how unconscious processing of images from one of these categories (e.g., tools) affects the recognition of images from the other category (i.e., hands). Our findings with neurologically-intact participants demonstrated that processing an image of a hand hampers the subsequent processing of an image of a tool, and vice versa. These results were not present in apraxic patients (N = 3). These findings suggest local and global inhibitory processes working in tandem to co-register information across the two streams.

Development of the ventral body wall in the human embryo

PubMed Central

Mekonen, Hayelom K; Hikspoors, Jill P J M; Mommen, Greet; Köhler, S Eleonore; Lamers, Wouter H

2015-01-01

Migratory failure of somitic cells is the commonest explanation for ventral body wall defects. However, the embryo increases ∼ 25-fold in volume in the period that the ventral body wall forms, so that differential growth may, instead, account for the observed changes in topography. Human embryos between 4 and 10 weeks of development were studied, using amira® reconstruction and cinema 4D® remodeling software for visualization. Initially, vertebrae and ribs had formed medially, and primordia of sternum and hypaxial flank muscle primordium laterally in the body wall at Carnegie Stage (CS)15 (5.5 weeks). The next week, ribs and muscle primordium expanded in ventrolateral direction only. At CS18 (6.5 weeks), separate intercostal and abdominal wall muscles differentiated, and ribs, sterna, and muscles began to expand ventromedially and caudally, with the bilateral sternal bars fusing in the midline after CS20 (7 weeks) and the rectus muscles reaching the umbilicus at CS23 (8 weeks). The near-constant absolute distance between both rectus muscles and approximately fivefold decline of this distance relative to body circumference between 6 and 10 weeks identified dorsoventral growth in the dorsal body wall as determinant of the ‘closure’ of the ventral body wall. Concomitant with the straightening of the embryonic body axis after the 6th week, the abdominal muscles expanded ventrally and caudally to form the infraumbilical body wall. Our data, therefore, show that the ventral body wall is formed by differential dorsoventral growth in the dorsal part of the body. PMID:26467243

Category-Selectivity in Human Visual Cortex Follows Cortical Topology: A Grouped icEEG Study

PubMed Central

Conner, Christopher Richard; Whaley, Meagan Lee; Baboyan, Vatche George; Tandon, Nitin

2016-01-01

Neuroimaging studies suggest that category-selective regions in higher-order visual cortex are topologically organized around specific anatomical landmarks: the mid-fusiform sulcus (MFS) in the ventral temporal cortex (VTC) and lateral occipital sulcus (LOS) in the lateral occipital cortex (LOC). To derive precise structure-function maps from direct neural signals, we collected intracranial EEG (icEEG) recordings in a large human cohort (n = 26) undergoing implantation of subdural electrodes. A surface-based approach to grouped icEEG analysis was used to overcome challenges from sparse electrode coverage within subjects and variable cortical anatomy across subjects. The topology of category-selectivity in bilateral VTC and LOC was assessed for five classes of visual stimuli—faces, animate non-face (animals/body-parts), places, tools, and words—using correlational and linear mixed effects analyses. In the LOC, selectivity for living (faces and animate non-face) and non-living (places and tools) classes was arranged in a ventral-to-dorsal axis along the LOS. In the VTC, selectivity for living and non-living stimuli was arranged in a latero-medial axis along the MFS. Written word-selectivity was reliably localized to the intersection of the left MFS and the occipito-temporal sulcus. These findings provide direct electrophysiological evidence for topological information structuring of functional representations within higher-order visual cortex. PMID:27272936

Neural Encoding and Decoding with Deep Learning for Dynamic Natural Vision.

PubMed

Wen, Haiguang; Shi, Junxing; Zhang, Yizhen; Lu, Kun-Han; Cao, Jiayue; Liu, Zhongming

2017-10-20

Convolutional neural network (CNN) driven by image recognition has been shown to be able to explain cortical responses to static pictures at ventral-stream areas. Here, we further showed that such CNN could reliably predict and decode functional magnetic resonance imaging data from humans watching natural movies, despite its lack of any mechanism to account for temporal dynamics or feedback processing. Using separate data, encoding and decoding models were developed and evaluated for describing the bi-directional relationships between the CNN and the brain. Through the encoding models, the CNN-predicted areas covered not only the ventral stream, but also the dorsal stream, albeit to a lesser degree; single-voxel response was visualized as the specific pixel pattern that drove the response, revealing the distinct representation of individual cortical location; cortical activation was synthesized from natural images with high-throughput to map category representation, contrast, and selectivity. Through the decoding models, fMRI signals were directly decoded to estimate the feature representations in both visual and semantic spaces, for direct visual reconstruction and semantic categorization, respectively. These results corroborate, generalize, and extend previous findings, and highlight the value of using deep learning, as an all-in-one model of the visual cortex, to understand and decode natural vision. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Diffusion tensor tracking of neuronal fiber pathways in the living human brain

NASA Astrophysics Data System (ADS)

Lori, Nicolas Francisco

2001-11-01

The technique of diffusion tensor tracking (DTT) is described, in which diffusion tensor magnetic resonance imaging (DT-MRI) data are processed to allow the visualization of white matter (WM) tracts in a living human brain. To illustrate the methods, a detailed description is given of the physics of DT-MRI, the structure of the DT-MRI experiment, the computer tools that were developed to visualize WM tracts, the anatomical consistency of the obtained WM tracts, and the accuracy and precision of DTT using computer simulations. When presenting the physics of DT-MRI, a completely quantum-mechanical view of DT-MRI is given where some of the results are new. Examples of anatomical tracts viewed using DTT are presented, including the genu and the splenium of the corpus callosum, the ventral pathway with its amygdala connection highlighted, the geniculo- calcarine tract separated into anterior and posterior parts, the geniculo-calcarine tract defined using functional magnetic resonance imaging (MRI), and U- fibers. In the simulation, synthetic DT-MRI data were constructed that would be obtained for a cylindrical WM tract with a helical trajectory surrounded by gray matter. Noise was then added to the synthetic DT-MRI data, and DTT trajectories were calculated using the noisy data (realistic tracks). Simulated DTT errors were calculated as the vector distance between the realistic tracks and the ideal trajectory. The simulation tested the effects of a comprehensive set of experimental conditions, including voxel size, data sampling, data averaging, type of tract tissue, tract diameter and type of tract trajectory. Simulated DTT accuracy and precision were typically below the voxel dimension, and precision was compatible with the experimental results.

Development of visual cortical function in infant macaques: A BOLD fMRI study

PubMed Central

Meeson, Alan; Munk, Matthias H. J.; Kourtzi, Zoe; Movshon, J. Anthony; Logothetis, Nikos K.; Kiorpes, Lynne

2017-01-01

Functional brain development is not well understood. In the visual system, neurophysiological studies in nonhuman primates show quite mature neuronal properties near birth although visual function is itself quite immature and continues to develop over many months or years after birth. Our goal was to assess the relative development of two main visual processing streams, dorsal and ventral, using BOLD fMRI in an attempt to understand the global mechanisms that support the maturation of visual behavior. Seven infant macaque monkeys (Macaca mulatta) were repeatedly scanned, while anesthetized, over an age range of 102 to 1431 days. Large rotating checkerboard stimuli induced BOLD activation in visual cortices at early ages. Additionally we used static and dynamic Glass pattern stimuli to probe BOLD responses in primary visual cortex and two extrastriate areas: V4 and MT-V5. The resulting activations were analyzed with standard GLM and multivoxel pattern analysis (MVPA) approaches. We analyzed three contrasts: Glass pattern present/absent, static/dynamic Glass pattern presentation, and structured/random Glass pattern form. For both GLM and MVPA approaches, robust coherent BOLD activation appeared relatively late in comparison to the maturation of known neuronal properties and the development of behavioral sensitivity to Glass patterns. Robust differential activity to Glass pattern present/absent and dynamic/static stimulus presentation appeared first in V1, followed by V4 and MT-V5 at older ages; there was no reliable distinction between the two extrastriate areas. A similar pattern of results was obtained with the two analysis methods, although MVPA analysis showed reliable differential responses emerging at later ages than GLM. Although BOLD responses to large visual stimuli are detectable, our results with more refined stimuli indicate that global BOLD activity changes as behavioral performance matures. This reflects an hierarchical development of the visual pathways. Since fMRI BOLD reflects neural activity on a population level, our results indicate that, although individual neurons might be adult-like, a longer maturation process takes place on a population level. PMID:29145469

Cognitive emotion regulation enhances aversive prediction error activity while reducing emotional responses.

PubMed

Mulej Bratec, Satja; Xie, Xiyao; Schmid, Gabriele; Doll, Anselm; Schilbach, Leonhard; Zimmer, Claus; Wohlschläger, Afra; Riedl, Valentin; Sorg, Christian

2015-12-01

Cognitive emotion regulation is a powerful way of modulating emotional responses. However, despite the vital role of emotions in learning, it is unknown whether the effect of cognitive emotion regulation also extends to the modulation of learning. Computational models indicate prediction error activity, typically observed in the striatum and ventral tegmental area, as a critical neural mechanism involved in associative learning. We used model-based fMRI during aversive conditioning with and without cognitive emotion regulation to test the hypothesis that emotion regulation would affect prediction error-related neural activity in the striatum and ventral tegmental area, reflecting an emotion regulation-related modulation of learning. Our results show that cognitive emotion regulation reduced emotion-related brain activity, but increased prediction error-related activity in a network involving ventral tegmental area, hippocampus, insula and ventral striatum. While the reduction of response activity was related to behavioral measures of emotion regulation success, the enhancement of prediction error-related neural activity was related to learning performance. Furthermore, functional connectivity between the ventral tegmental area and ventrolateral prefrontal cortex, an area involved in regulation, was specifically increased during emotion regulation and likewise related to learning performance. Our data, therefore, provide first-time evidence that beyond reducing emotional responses, cognitive emotion regulation affects learning by enhancing prediction error-related activity, potentially via tegmental dopaminergic pathways. Copyright © 2015 Elsevier Inc. All rights reserved.

Loss of PTB or Negative Regulation of Notch mRNA Reveals Distinct Zones of Notch and Actin Protein Accumulation in Drosophila Embryo

PubMed Central

Wesley, Cedric S.; Guo, Heng; Chaudhry, Kanita A.; Thali, Markus J.; Yin, Jerry C.; Clason, Todd; Wesley, Umadevi V.

2011-01-01

Polypyrimidine Tract Binding (PTB) protein is a regulator of mRNA processing and translation. Genetic screens and studies of wing and bristle development during the post-embryonic stages of Drosophila suggest that it is a negative regulator of the Notch pathway. How PTB regulates the Notch pathway is unknown. Our studies of Drosophila embryogenesis indicate that (1) the Notch mRNA is a potential target of PTB, (2) PTB and Notch functions in the dorso-lateral regions of the Drosophila embryo are linked to actin regulation but not their functions in the ventral region, and (3) the actin-related Notch activity in the dorso-lateral regions might require a Notch activity at or near the cell surface that is different from the nuclear Notch activity involved in cell fate specification in the ventral region. These data raise the possibility that the Drosophila embryo is divided into zones of different PTB and Notch activities based on whether or not they are linked to actin regulation. They also provide clues to the almost forgotten role of Notch in cell adhesion and reveal a role for the Notch pathway in cell fusions. PMID:21750738

Distinct requirements of wls, wnt9a, wnt5b and gpc4 in regulating chondrocyte maturation and timing of endochondral ossification

PubMed Central

Ling, Irving TC; Rochard, Lucie; Liao, Eric C.

2017-01-01

Formation of the mandible requires progressive morphologic change, proliferation, differentiation and organization of chondrocytes preceding osteogenesis. The Wnt signaling pathway is involved in regulating bone development and maintenance. Chondrocytes that are fated to become bone require Wnt to polarize and orientate appropriately to initiate the endochondral ossification program. Although the canonical Wnt signaling has been well studied in the context of bone development, the effects of non-canonical Wnt signaling in regulating the timing of cartilage maturation and subsequent bone formation in shaping ventral craniofacial structure is not fully understood.. Here we examined the role of the non-canonical Wnt signaling pathway (wls, gpc4, wnt5b and wnt9a) in regulating zebrafish Meckel’s cartilage maturation to the onset of osteogenic differentiation. We found that disruption of wls resulted in a significant loss of craniofacial bone, whereas lack of gpc4, wnt5b and wnt9a resulted in severely delayed endochondral ossification. This study demonstrates the importance of the non-canonical Wnt pathway in regulating coordinated ventral cartilage morphogenesis and ossification. PMID:27908786

Proteomic analysis of the dorsal and ventral hippocampus of rats maintained on a high fat and refined sugar diet.

PubMed

Francis, Heather M; Mirzaei, Mehdi; Pardey, Margery C; Haynes, Paul A; Cornish, Jennifer L

2013-10-01

The typical Western diet, rich in high saturated fat and refined sugar (HFS), has been shown to increase cognitive decline with aging and Alzheimer's disease, and to affect cognitive functions that are dependent on the hippocampus, including memory processes and reversal learning. To investigate neurophysiological changes underlying these impairments, we employed a proteomic approach to identify differentially expressed proteins in the rat dorsal and ventral hippocampus following maintenance on an HFS diet. Rats maintained on the HFS diet for 8 weeks were impaired on a novel object recognition task that assesses memory and on a Morris Water Maze task assessing reversal learning. Quantitative label-free shotgun proteomic analysis was conducted on biological triplicates for each group. For the dorsal hippocampus, 59 proteins were upregulated and 36 downregulated in the HFS group compared to controls. Pathway ana-lysis revealed changes to proteins involved in molecular transport and cellular and molecular signaling, and changes to signaling pathways including calcium signaling, citrate cycle, and oxidative phosphorylation. For the ventral hippocampus, 25 proteins were upregulated and 27 downregulated in HFS fed rats. Differentially expressed proteins were involved in cell-to-cell signaling and interaction, and cellular and molecular function. Changes to signaling pathways included protein ubiquitination, ubiquinone biosynthesis, oxidative phosphorylation, and mitochondrial dysfunction. This is the first shotgun proteomics study to examine protein changes in the hippocampus following long-term consumption of a HFS diet, identifying changes to a large number of proteins including those involved in synaptic plasticity and energy metabolism. All MS data have been deposited in the ProteomeXchange with identifier PXD000028. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Brain regions mediating α3β4 nicotinic antagonist effects of 18-MC on methamphetamine and sucrose self-administration

PubMed Central

Glick, Stanley D.; Sell, Elizabeth M.; Maisonneuve, Isabelle M.

2008-01-01

The novel iboga alkaloid congener 18-methoxycoronaridine (18-MC) is a putative anti-addictive agent that has been shown, in rats, to decrease the self-administration of several drugs of abuse. Previous work has established that 18-MC is a potent antagonist at α3β4 nicotinic receptors. Because high densities of α3β4 nicotinic receptors occur in the medial habenula and the interpeduncular nucleus and moderate densities occur in the dorsolateral tegmentum, ventral tegmental area, and basolateral amygdala, the present study was conducted to determine if 18-MC could act in these brain areas to modulate methamphetamine self-administration in rats. Local administration of 18-MC into either the medial habenula, the interpeduncular area or the basolateral amygdala decreased methamphetamine self-administration. Similar results were produced by local administration into the same brain areas of two other α3β4 nicotinic antagonists, mecamylamine and α-conotoxin AuIB. Local administration of 18-MC, or the other antagonists, into the dorsolateral tegmentum or the ventral tegmental area had no effect on methamphetamine self-administration. In contrast, local administration of 18-MC and the other antagonists decreased sucrose self-administration when administered into the dorsolateral tegmentum or basolateral amygdala but had no effect when infused into the medial habenula, interpeduncular nucleus, or ventral tegmental area. These data are consistent with the hypothesis that 18-MC decreases methamphetamine self-administration by indirectly modulating the dopaminergic mesolimbic pathway via blockade of α3β4 nicotinic receptors in the habenulo-interpeduncular pathway and the basolateral amygdala. The data also suggest that the basolateral amygdala along with a different pathway involving α3β4 receptors in the dorsolateral tegmentum mediate the effect of 18-MC on sucrose self-administration. PMID:18930043

Tissue interactions in the induction of anterior pituitary: role of the ventral diencephalon, mesenchyme, and notochord.

PubMed

Gleiberman, A S; Fedtsova, N G; Rosenfeld, M G

1999-09-15

Rathke's pouch, the epithelial primordium of the anterior pituitary, differentiates in close topographical and functional association with the ventral diencephalon. It is still not known whether the ventral diencephalon acts as the initial inducer of pituitary development. The roles of the adjacent mesenchyme and notochord, two other tissues located in close proximity to Rathke's pouch, in this process are even less clear. In this report we describe an in vitro experimental system that reproduces the earliest steps of anterior pituitary development. We provide evidence that the ventral diencephalon from 2- to 4-day-old chick embryos is able to function as an inducer of pituitary development and can convert early chick embryonic head ectoderm, which is not involved normally in pituitary development, into typical anterior pituitary tissue. This induction is contact-dependent. In our experimental system, there is a requirement for the supporting action of mesenchyme, which is independent of the mesenchyme source. Transplantation of the notochord into the lateral head region of a six-somite chick embryo induces an epithelial invagination, suggesting that the notochord induces the outpouching of the roof of the stomodeal ectoderm that results in formation of Rathke's pouch and causes the close contact between this ectoderm and the ventral diencephalon. Finally, we demonstrate that the ventral diencephalon from e9.5-e11.5 mouse embryos is also an efficient inducer of anterior pituitary differentiation in chick embryonic lateral head ectoderm, suggesting that the mechanism of anterior pituitary induction is conserved between mammals and birds, using the same, or similar, signaling pathways. Copyright 1999 Academic Press.

Cross-modal representation of spoken and written word meaning in left pars triangularis.

PubMed

Liuzzi, Antonietta Gabriella; Bruffaerts, Rose; Peeters, Ronald; Adamczuk, Katarzyna; Keuleers, Emmanuel; De Deyne, Simon; Storms, Gerrit; Dupont, Patrick; Vandenberghe, Rik

2017-04-15

The correspondence in meaning extracted from written versus spoken input remains to be fully understood neurobiologically. Here, in a total of 38 subjects, the functional anatomy of cross-modal semantic similarity for concrete words was determined based on a dual criterion: First, a voxelwise univariate analysis had to show significant activation during a semantic task (property verification) performed with written and spoken concrete words compared to the perceptually matched control condition. Second, in an independent dataset, in these clusters, the similarity in fMRI response pattern to two distinct entities, one presented as a written and the other as a spoken word, had to correlate with the similarity in meaning between these entities. The left ventral occipitotemporal transition zone and ventromedial temporal cortex, retrosplenial cortex, pars orbitalis bilaterally, and the left pars triangularis were all activated in the univariate contrast. Only the left pars triangularis showed a cross-modal semantic similarity effect. There was no effect of phonological nor orthographic similarity in this region. The cross-modal semantic similarity effect was confirmed by a secondary analysis in the cytoarchitectonically defined BA45. A semantic similarity effect was also present in the ventral occipital regions but only within the visual modality, and in the anterior superior temporal cortex only within the auditory modality. This study provides direct evidence for the coding of word meaning in BA45 and positions its contribution to semantic processing at the confluence of input-modality specific pathways that code for meaning within the respective input modalities. Copyright © 2017 Elsevier Inc. All rights reserved.

Estrogen modulates mesenchyme-epidermis interactions in the adult nipple

PubMed Central

Wu, Hsing-Jung; Oh, Ji Won; Spandau, Dan F.; Tholpady, Sunil; Diaz, Jesus; Schroeder, Laura J.; Offutt, Carlos D.; Glick, Adam B.; Plikus, Maksim V.; Koyama, Sachiko

2017-01-01

Maintenance of specialized epidermis requires signals from the underlying mesenchyme; however, the specific pathways involved remain to be identified. By recombining cells from the ventral skin of the K14-PTHrP transgenic mice [which overexpress parathyroid hormone-related protein (PTHrP) in their developing epidermis and mammary glands] with those from wild type, we show that transgenic stroma is sufficient to reprogram wild-type keratinocytes into nipple-like epidermis. To identify candidate nipple-specific signaling factors, we compared gene expression signatures of sorted Pdgfrα-positive ventral K14-PTHrP and wild-type fibroblasts, identifying differentially expressed transcripts that are involved in WNT, HGF, TGFβ, IGF, BMP, FGF and estrogen signaling. Considering that some of the growth factor pathways are targets for estrogen regulation, we examined the upstream role of this hormone in maintaining the nipple. Ablation of estrogen signaling through ovariectomy produced nipples with abnormally thin epidermis, and we identified TGFβ as a negatively regulated target of estrogen signaling. Estrogen treatment represses Tgfβ1 at the transcript and protein levels in K14-PTHrP fibroblasts in vitro, while ovariectomy increases Tgfb1 levels in K14-PTHrP ventral skin. Moreover, ectopic delivery of Tgfβ1 protein into nipple connective tissue reduced epidermal proliferation. Taken together, these results show that specialized nipple epidermis is maintained by estrogen-induced repression of TGFβ signaling in the local fibroblasts. PMID:28289136

Revealing the dual streams of speech processing.

PubMed

Fridriksson, Julius; Yourganov, Grigori; Bonilha, Leonardo; Basilakos, Alexandra; Den Ouden, Dirk-Bart; Rorden, Christopher

2016-12-27

Several dual route models of human speech processing have been proposed suggesting a large-scale anatomical division between cortical regions that support motor-phonological aspects vs. lexical-semantic aspects of speech processing. However, to date, there is no complete agreement on what areas subserve each route or the nature of interactions across these routes that enables human speech processing. Relying on an extensive behavioral and neuroimaging assessment of a large sample of stroke survivors, we used a data-driven approach using principal components analysis of lesion-symptom mapping to identify brain regions crucial for performance on clusters of behavioral tasks without a priori separation into task types. Distinct anatomical boundaries were revealed between a dorsal frontoparietal stream and a ventral temporal-frontal stream associated with separate components. Collapsing over the tasks primarily supported by these streams, we characterize the dorsal stream as a form-to-articulation pathway and the ventral stream as a form-to-meaning pathway. This characterization of the division in the data reflects both the overlap between tasks supported by the two streams as well as the observation that there is a bias for phonological production tasks supported by the dorsal stream and lexical-semantic comprehension tasks supported by the ventral stream. As such, our findings show a division between two processing routes that underlie human speech processing and provide an empirical foundation for studying potential computational differences that distinguish between the two routes.

Late maturation of visual spatial integration in humans

PubMed Central

Kovács, Ilona; Kozma, Petra; Fehér, Ákos; Benedek, György

1999-01-01

Visual development is thought to be completed at an early age. We suggest that the maturation of the visual brain is not homogeneous: functions with greater need for early availability, such as visuomotor control, mature earlier, and the development of other visual functions may extend well into childhood. We found significant improvement in children between 5 and 14 years in visual spatial integration by using a contour-detection task. The data show that long-range spatial interactions—subserving the integration of orientational information across the visual field—span a shorter spatial range in children than in adults. Performance in the task improves in a cue-specific manner with practice, which indicates the participation of fairly low-level perceptual mechanisms. We interpret our findings in terms of a protracted development of ventral visual-stream function in humans. PMID:10518600

Early development of the circumferential axonal pathway in mouse and chick spinal cord.

PubMed

Holley, J A

1982-03-10

The early development of the circumferential axonal pathway in the brachial and lumbar spinal cord of mouse and chick embryos was studied by scanning and transmission electron microscopy. The cellular processes which comprise this pathway grow in the transverse plane and along the lateral margin of the marginal zone (i.e., circumferentially oriented), as typified by the early embryonic commissural axons. The first formative event observed was in the ventrolateral margin of the primitive spinal cord ventricular zone. Cellular processes were found near the external limiting membrane that appeared to grow a variable distance either dorsally or ventrally. Later in development, presumptive motor column neurons migrated into the ventrolateral region, distal to these early circumferentially oriented processes. Concurrently, other circumferentially oriented perikarya and processes appeared along the dorsolateral margin. Due to their aligned sites of origin and parallel growth, the circumferential processes formed a more or less continuous line or pathway, which in about 10% of the scanned specimens could be followed along the entire lateral margin of the embryonic spinal cord. Several specimens later in development had two sets of aligned circumferential processes in the ventral region. Large numbers of circumferential axons were then found to follow the preformed pathway by fasciculation, after the primitive motor column had become established. Since the earliest circumferential processes appeared to differentiate into axons and were found nearly 24 hours prior to growth of most circumferential axons, their role in guidance as pioneering axons was suggested.

Computational Embryology and Predictive Toxicology of Hypospadias (SOT)

EPA Science Inventory

Hypospadias, one of the most common birth defects in human male infants, is a condition in which the urethral opening is misplaced along ventral aspect of the penis. We developed an Adverse Outcome Pathway (AOP) framework and computer simulation that describes the pathogenesis of...

Evidence for highly selective neuronal tuning to whole words in the "visual word form area".

PubMed

Glezer, Laurie S; Jiang, Xiong; Riesenhuber, Maximilian

2009-04-30

Theories of reading have posited the existence of a neural representation coding for whole real words (i.e., an orthographic lexicon), but experimental support for such a representation has proved elusive. Using fMRI rapid adaptation techniques, we provide evidence that the human left ventral occipitotemporal cortex (specifically the "visual word form area," VWFA) contains a representation based on neurons highly selective for individual real words, in contrast to current theories that posit a sublexical representation in the VWFA.

Loss of Plasticity in the D2-Accumbens Pallidal Pathway Promotes Cocaine Seeking.

PubMed

Heinsbroek, Jasper A; Neuhofer, Daniela N; Griffin, William C; Siegel, Griffin S; Bobadilla, Ana-Clara; Kupchik, Yonatan M; Kalivas, Peter W

2017-01-25

Distinct populations of D1- and D2-dopamine receptor-expressing medium spiny neurons (D1-/D2-MSNs) comprise the nucleus accumbens, and activity in D1-MSNs promotes, whereas activity in D2-MSNs inhibits, motivated behaviors. We used chemogenetics to extend D1-/D2-MSN cell specific regulation to cue-reinstated cocaine seeking in a mouse model of self-administration and relapse, and found that either increasing activity in D1-MSNs or decreasing activity in D2-MSNs augmented cue-induced reinstatement. Both D1- and D2-MSNs provide substantial GABAergic innervation to the ventral pallidum, and chemogenetic inhibition of ventral pallidal neurons blocked the augmented reinstatement elicited by chemogenetic regulation of either D1- or D2-MSNs. Because D1- and D2-MSNs innervate overlapping populations of ventral pallidal neurons, we next used optogenetics to examine whether changes in synaptic plasticity in D1- versus D2-MSN GABAergic synapses in the ventral pallidum could explain the differential regulation of VP activity. In mice trained to self-administer cocaine, GABAergic LTD was abolished in D2-, but not in D1-MSN synapses. A μ opioid receptor antagonist restored GABA currents in D2-, but not D1-MSN synapses of cocaine-trained mice, indicating that increased enkephalin tone on presynaptic μ opioid receptors was responsible for occluding the LTD. These results identify a behavioral function for D1-MSN innervation of the ventral pallidum, and suggest that losing LTD GABA in D2-MSN, but not D1-MSN input to ventral pallidum may promote cue-induced reinstatement of cocaine-seeking. More than 90% of ventral striatum is composed of two cell types, those expressing dopamine D1 or D2 receptors, which exert opposing roles on motivated behavior. Both cell types send GABAergic projections to the ventral pallidum and were found to differentially promote cue-induced reinstatement of cocaine seeking via the ventral pallidum. Furthermore, after cocaine self-administration, synaptic plasticity was selectively lost in D2, but not D1 inputs to the ventral pallidum. The selective impairment in D2 afferents may promote the influence of D1 inputs to drive relapse to cocaine seeking. Copyright © 2017 the authors 0270-6474/17/370757-11$15.00/0.

Loss of Plasticity in the D2-Accumbens Pallidal Pathway Promotes Cocaine Seeking

PubMed Central

Neuhofer, Daniela N.; Griffin, William C.; Siegel, Griffin S.; Bobadilla, Ana-Clara; Kupchik, Yonatan M.

2017-01-01

Distinct populations of D1- and D2-dopamine receptor-expressing medium spiny neurons (D1-/D2-MSNs) comprise the nucleus accumbens, and activity in D1-MSNs promotes, whereas activity in D2-MSNs inhibits, motivated behaviors. We used chemogenetics to extend D1-/D2-MSN cell specific regulation to cue-reinstated cocaine seeking in a mouse model of self-administration and relapse, and found that either increasing activity in D1-MSNs or decreasing activity in D2-MSNs augmented cue-induced reinstatement. Both D1- and D2-MSNs provide substantial GABAergic innervation to the ventral pallidum, and chemogenetic inhibition of ventral pallidal neurons blocked the augmented reinstatement elicited by chemogenetic regulation of either D1- or D2-MSNs. Because D1- and D2-MSNs innervate overlapping populations of ventral pallidal neurons, we next used optogenetics to examine whether changes in synaptic plasticity in D1- versus D2-MSN GABAergic synapses in the ventral pallidum could explain the differential regulation of VP activity. In mice trained to self-administer cocaine, GABAergic LTD was abolished in D2-, but not in D1-MSN synapses. A μ opioid receptor antagonist restored GABA currents in D2-, but not D1-MSN synapses of cocaine-trained mice, indicating that increased enkephalin tone on presynaptic μ opioid receptors was responsible for occluding the LTD. These results identify a behavioral function for D1-MSN innervation of the ventral pallidum, and suggest that losing LTDGABA in D2-MSN, but not D1-MSN input to ventral pallidum may promote cue-induced reinstatement of cocaine-seeking. SIGNIFICANCE STATEMENT More than 90% of ventral striatum is composed of two cell types, those expressing dopamine D1 or D2 receptors, which exert opposing roles on motivated behavior. Both cell types send GABAergic projections to the ventral pallidum and were found to differentially promote cue-induced reinstatement of cocaine seeking via the ventral pallidum. Furthermore, after cocaine self-administration, synaptic plasticity was selectively lost in D2, but not D1 inputs to the ventral pallidum. The selective impairment in D2 afferents may promote the influence of D1 inputs to drive relapse to cocaine seeking. PMID:28123013

The emergence of the visual word form: Longitudinal evolution of category-specific ventral visual areas during reading acquisition

PubMed Central

Monzalvo, Karla; Dehaene, Stanislas

2018-01-01

How does education affect cortical organization? All literate adults possess a region specialized for letter strings, the visual word form area (VWFA), within the mosaic of ventral regions involved in processing other visual categories such as objects, places, faces, or body parts. Therefore, the acquisition of literacy may induce a reorientation of cortical maps towards letters at the expense of other categories such as faces. To test this cortical recycling hypothesis, we studied how the visual cortex of individual children changes during the first months of reading acquisition. Ten 6-year-old children were scanned longitudinally 6 or 7 times with functional magnetic resonance imaging (fMRI) before and throughout the first year of school. Subjects were exposed to a variety of pictures (words, numbers, tools, houses, faces, and bodies) while performing an unrelated target-detection task. Behavioral assessment indicated a sharp rise in grapheme–phoneme knowledge and reading speed in the first trimester of school. Concurrently, voxels specific to written words and digits emerged at the VWFA location. The responses to other categories remained largely stable, although right-hemispheric face-related activity increased in proportion to reading scores. Retrospective examination of the VWFA voxels prior to reading acquisition showed that reading encroaches on voxels that are initially weakly specialized for tools and close to but distinct from those responsive to faces. Remarkably, those voxels appear to keep their initial category selectivity while acquiring an additional and stronger responsivity to words. We propose a revised model of the neuronal recycling process in which new visual categories invade weakly specified cortex while leaving previously stabilized cortical responses unchanged. PMID:29509766

Evidence for Non-Opponent Coding of Colour Information in Human Visual Cortex: Selective Loss of “Green” Sensitivity in a Subject with Damaged Ventral Occipito-Temporal Cortex

PubMed Central

Rauscher, Franziska G.; Plant, Gordon T.; James-Galton, Merle; Barbur, John L.

2011-01-01

Damage to ventral occipito-temporal extrastriate visual cortex leads to the syndrome of prosopagnosia often with coexisting cerebral achromatopsia. A patient with this syndrome resulting in a left upper homonymous quadrantanopia, prosopagnosia, and incomplete achromatopsia is described. Chromatic sensitivity was assessed at a number of locations in the intact visual field using a dynamic luminance contrast masking technique that isolates the use of colour signals. In normal subjects chromatic detection thresholds form an elliptical contour when plotted in the Commission Internationale d’Eclairage, (x-y), chromaticity diagram. Because the extraction of colour signals in early visual processing involves opponent mechanisms, subjects with Daltonism (congenital red/green loss of sensitivity) show symmetric increase in thresholds towards the long wavelength (“red”) and middle wavelength (“green”) regions of the spectrum locus. This is also the case with acquired loss of chromatic sensitivity as a result of retinal or optic nerve disease. Our patient’s results were an exception to this rule. Whilst his chromatic sensitivity in the central region of the visual field was reduced symmetrically for both “red/green” and “yellow/blue” directions in colour space, the subject’s lower left quadrant showed a marked asymmetry in “red/green” thresholds with the greatest loss of sensitivity towards the “green” region of the spectrum locus. This spatially localized asymmetric loss of “green” but not “red” sensitivity has not been reported previously in human vision. Such loss is consistent with selective damage of neural substrates in the visual cortex that process colour information, but are spectrally non-opponent. PMID:27956924

The emergence of the visual word form: Longitudinal evolution of category-specific ventral visual areas during reading acquisition.

PubMed

Dehaene-Lambertz, Ghislaine; Monzalvo, Karla; Dehaene, Stanislas

2018-03-01

How does education affect cortical organization? All literate adults possess a region specialized for letter strings, the visual word form area (VWFA), within the mosaic of ventral regions involved in processing other visual categories such as objects, places, faces, or body parts. Therefore, the acquisition of literacy may induce a reorientation of cortical maps towards letters at the expense of other categories such as faces. To test this cortical recycling hypothesis, we studied how the visual cortex of individual children changes during the first months of reading acquisition. Ten 6-year-old children were scanned longitudinally 6 or 7 times with functional magnetic resonance imaging (fMRI) before and throughout the first year of school. Subjects were exposed to a variety of pictures (words, numbers, tools, houses, faces, and bodies) while performing an unrelated target-detection task. Behavioral assessment indicated a sharp rise in grapheme-phoneme knowledge and reading speed in the first trimester of school. Concurrently, voxels specific to written words and digits emerged at the VWFA location. The responses to other categories remained largely stable, although right-hemispheric face-related activity increased in proportion to reading scores. Retrospective examination of the VWFA voxels prior to reading acquisition showed that reading encroaches on voxels that are initially weakly specialized for tools and close to but distinct from those responsive to faces. Remarkably, those voxels appear to keep their initial category selectivity while acquiring an additional and stronger responsivity to words. We propose a revised model of the neuronal recycling process in which new visual categories invade weakly specified cortex while leaving previously stabilized cortical responses unchanged.

Neural Encoding of Relative Position

ERIC Educational Resources Information Center

Hayworth, Kenneth J.; Lescroart, Mark D.; Biederman, Irving

2011-01-01

Late ventral visual areas generally consist of cells having a significant degree of translation invariance. Such a "bag of features" representation is useful for the recognition of individual objects; however, it seems unable to explain our ability to parse a scene into multiple objects and to understand their spatial relationships. We…

Preparation for the Implantation of an Intracortical Visual Prosthesis in a Human

DTIC Science & Technology

2015-12-01

cluster of the WFMA. Electrode current flows between the micro-(working) electrode and a longer large-area counter electrode, using either...Biomed Eng 44(10):931-9. McCreery DB, Yuen TGH, Agnew, WF, Bullara LA (2000). Chronic microstimulation in the feline ventral cochlear nucleus

Insights from event-related potentials into the temporal and hierarchical organization of the ventral and dorsal streams of the visual system in selective attention.

PubMed

Martín-Loeches, M; Hinojosa, J A; Rubia, F J

1999-11-01

The temporal and hierarchical relationships between the dorsal and the ventral streams in selective attention are known only in relation to the use of spatial location as the attentional cue mediated by the dorsal stream. To improve this state of affairs, event-related brain potentials were recorded while subjects attended simultaneously to motion direction (mediated by the dorsal stream) and to a property mediated by the ventral stream (color or shape). At about the same time, a selection positivity (SP) started for attention mediated by both streams. However, the SP for color and shape peaked about 60 ms later than motion SP. Subsequently, a selection negativity (SN) followed by a late positive component (LPC) were found simultaneously for attention mediated by both streams. A hierarchical relationship between the two streams was not observed, but neither SN nor LPC for one property was completely insensitive to the values of the other property.

Neuroimaging reveals dual routes to reading in simultaneous proficient readers of two orthographies

PubMed Central

Das, T.; Padakannaya, P.; Pugh, K. R.; Singh, N. C.

2012-01-01

Orthographic differences across languages impose differential weighting on distinct component processes, and consequently on different pathways during word-reading tasks. Readers of transparent orthographies such as Italian and Hindi are thought to rely on spelling-to-sound assembly and show increased activation in phonologically-tuned areas along the dorsal pathway, whereas reading an opaque orthography such as English is thought to rely more on lexically-mediated processing associated with increased activation of semantically-tuned regions along the ventral pathway. To test if biliterate Hindi/English readers exhibit orthography-specific reading pathways, we used behavioural measures and functional neuroimaging. Reaction times and activation patterns of monolingual English and Hindi readers were compared to two groups of adult biliterates; 14 simultaneous readers who learnt to read both languages at age 5 and 10 sequential readers who learnt Hindi at 5 and English at 10. Simultaneous, but not sequential readers demonstrated relative activation differences of dorsal and ventral areas in the two languages. Similar to native counterparts, simultaneous readers preferentially activated the left inferior temporal gyrus for English and left inferior parietal lobule (L-IPL) for Hindi, whereas, sequential readers showed higher activation along the L-IPL for reading both languages. We suggest that early simultaneous exposure to reading distinct orthographies results in orthography-specific plasticity that persists through adulthood. PMID:20854914

Expectation and Surprise Determine Neural Population Responses in the Ventral Visual Stream

PubMed Central

Egner, Tobias; Monti, Jim M.; Summerfield, Christopher

2014-01-01

Visual cortex is traditionally viewed as a hierarchy of neural feature detectors, with neural population responses being driven by bottom-up stimulus features. Conversely, “predictive coding” models propose that each stage of the visual hierarchy harbors two computationally distinct classes of processing unit: representational units that encode the conditional probability of a stimulus and provide predictions to the next lower level; and error units that encode the mismatch between predictions and bottom-up evidence, and forward prediction error to the next higher level. Predictive coding therefore suggests that neural population responses in category-selective visual regions, like the fusiform face area (FFA), reflect a summation of activity related to prediction (“face expectation”) and prediction error (“face surprise”), rather than a homogenous feature detection response. We tested the rival hypotheses of the feature detection and predictive coding models by collecting functional magnetic resonance imaging data from the FFA while independently varying both stimulus features (faces vs houses) and subjects’ perceptual expectations regarding those features (low vs medium vs high face expectation). The effects of stimulus and expectation factors interacted, whereby FFA activity elicited by face and house stimuli was indistinguishable under high face expectation and maximally differentiated under low face expectation. Using computational modeling, we show that these data can be explained by predictive coding but not by feature detection models, even when the latter are augmented with attentional mechanisms. Thus, population responses in the ventral visual stream appear to be determined by feature expectation and surprise rather than by stimulus features per se. PMID:21147999

Noun and knowledge retrieval for biological and non-biological entities following right occipitotemporal lesions.

PubMed

Bruffaerts, Rose; De Weer, An-Sofie; De Grauwe, Sophie; Thys, Miek; Dries, Eva; Thijs, Vincent; Sunaert, Stefan; Vandenbulcke, Mathieu; De Deyne, Simon; Storms, Gerrit; Vandenberghe, Rik

2014-09-01

We investigated the critical contribution of right ventral occipitotemporal cortex to knowledge of visual and functional-associative attributes of biological and non-biological entities and how this relates to category-specificity during confrontation naming. In a consecutive series of 7 patients with lesions confined to right ventral occipitotemporal cortex, we conducted an extensive assessment of oral generation of visual-sensory and functional-associative features in response to the names of biological and nonbiological entities. Subjects also performed a confrontation naming task for these categories. Our main novel finding related to a unique case with a small lesion confined to right medial fusiform gyrus who showed disproportionate naming impairment for nonbiological versus biological entities, specifically for tools. Generation of visual and functional-associative features was preserved for biological and non-biological entities. In two other cases, who had a relatively small posterior lesion restricted to primary visual and posterior fusiform cortex, retrieval of visual attributes was disproportionately impaired compared to functional-associative attributes, in particular for biological entities. However, these cases did not show a category-specific naming deficit. Two final cases with the largest lesions showed a classical dissociation between biological versus nonbiological entities during naming, with normal feature generation performance. This is the first lesion-based evidence of a critical contribution of the right medial fusiform cortex to tool naming. Second, dissociations along the dimension of attribute type during feature generation do not co-occur with category-specificity during naming in the current patient sample. Copyright © 2014 Elsevier Ltd. All rights reserved.

Why people see things that are not there: a novel Perception and Attention Deficit model for recurrent complex visual hallucinations.

PubMed

Collerton, Daniel; Perry, Elaine; McKeith, Ian

2005-12-01

As many as two million people in the United Kingdom repeatedly see people, animals, and objects that have no objective reality. Hallucinations on the border of sleep, dementing illnesses, delirium, eye disease, and schizophrenia account for 90% of these. The remainder have rarer disorders. We review existing models of recurrent complex visual hallucinations (RCVH) in the awake person, including cortical irritation, cortical hyperexcitability and cortical release, top-down activation, misperception, dream intrusion, and interactive models. We provide evidence that these can neither fully account for the phenomenology of RCVH, nor for variations in the frequency of RCVH in different disorders. We propose a novel Perception and Attention Deficit (PAD) model for RCVH. A combination of impaired attentional binding and poor sensory activation of a correct proto-object, in conjunction with a relatively intact scene representation, bias perception to allow the intrusion of a hallucinatory proto-object into a scene perception. Incorporation of this image into a context-specific hallucinatory scene representation accounts for repetitive hallucinations. We suggest that these impairments are underpinned by disturbances in a lateral frontal cortex-ventral visual stream system. We show how the frequency of RCVH in different diseases is related to the coexistence of attentional and visual perceptual impairments; how attentional and perceptual processes can account for their phenomenology; and that diseases and other states with high rates of RCVH have cholinergic dysfunction in both frontal cortex and the ventral visual stream. Several tests of the model are indicated, together with a number of treatment options that it generates.

Yawed-Landing Investigation of a Model of the Convair Y2-2 Airplane, TED No. NACA DE 363

NASA Technical Reports Server (NTRS)

Hoffman, Edward L.; Fisher, Lloyd J.

1950-01-01

A model of the Convair Y2-2 airplane was tested in Langley tank no. 2 to determine whether satisfactory stability in yawed landings was possible with a certain ventral fin. Free-body landings were made in smooth and rough water at two speeds and two rates of descent with the model yawed 15deg. The behavior of the model was determined by visual observations and from motion-picture re.cords. It was concluded that satisfactory stability was possible with the ventral fin as tested but that the characteristics of the model shock absorbers and the settings of the elevon control surfaces had an appreciable influence on behavior.

Focal and Ambient Processing of Built Environments: Intellectual and Atmospheric Experiences of Architecture

PubMed Central

Rooney, Kevin K.; Condia, Robert J.; Loschky, Lester C.

2017-01-01

Neuroscience has well established that human vision divides into the central and peripheral fields of view. Central vision extends from the point of gaze (where we are looking) out to about 5° of visual angle (the width of one’s fist at arm’s length), while peripheral vision is the vast remainder of the visual field. These visual fields project to the parvo and magno ganglion cells, which process distinctly different types of information from the world around us and project that information to the ventral and dorsal visual streams, respectively. Building on the dorsal/ventral stream dichotomy, we can further distinguish between focal processing of central vision, and ambient processing of peripheral vision. Thus, our visual processing of and attention to objects and scenes depends on how and where these stimuli fall on the retina. The built environment is no exception to these dependencies, specifically in terms of how focal object perception and ambient spatial perception create different types of experiences we have with built environments. We argue that these foundational mechanisms of the eye and the visual stream are limiting parameters of architectural experience. We hypothesize that people experience architecture in two basic ways based on these visual limitations; by intellectually assessing architecture consciously through focal object processing and assessing architecture in terms of atmosphere through pre-conscious ambient spatial processing. Furthermore, these separate ways of processing architectural stimuli operate in parallel throughout the visual perceptual system. Thus, a more comprehensive understanding of architecture must take into account that built environments are stimuli that are treated differently by focal and ambient vision, which enable intellectual analysis of architectural experience versus the experience of architectural atmosphere, respectively. We offer this theoretical model to help advance a more precise understanding of the experience of architecture, which can be tested through future experimentation. (298 words) PMID:28360867

Focal and Ambient Processing of Built Environments: Intellectual and Atmospheric Experiences of Architecture.

PubMed

Rooney, Kevin K; Condia, Robert J; Loschky, Lester C

2017-01-01

Neuroscience has well established that human vision divides into the central and peripheral fields of view. Central vision extends from the point of gaze (where we are looking) out to about 5° of visual angle (the width of one's fist at arm's length), while peripheral vision is the vast remainder of the visual field. These visual fields project to the parvo and magno ganglion cells, which process distinctly different types of information from the world around us and project that information to the ventral and dorsal visual streams, respectively. Building on the dorsal/ventral stream dichotomy, we can further distinguish between focal processing of central vision, and ambient processing of peripheral vision. Thus, our visual processing of and attention to objects and scenes depends on how and where these stimuli fall on the retina. The built environment is no exception to these dependencies, specifically in terms of how focal object perception and ambient spatial perception create different types of experiences we have with built environments. We argue that these foundational mechanisms of the eye and the visual stream are limiting parameters of architectural experience. We hypothesize that people experience architecture in two basic ways based on these visual limitations; by intellectually assessing architecture consciously through focal object processing and assessing architecture in terms of atmosphere through pre-conscious ambient spatial processing. Furthermore, these separate ways of processing architectural stimuli operate in parallel throughout the visual perceptual system. Thus, a more comprehensive understanding of architecture must take into account that built environments are stimuli that are treated differently by focal and ambient vision, which enable intellectual analysis of architectural experience versus the experience of architectural atmosphere, respectively. We offer this theoretical model to help advance a more precise understanding of the experience of architecture, which can be tested through future experimentation. (298 words).

Person perception involves functional integration between the extrastriate body area and temporal pole.

PubMed

Greven, Inez M; Ramsey, Richard

2017-02-01

The majority of human neuroscience research has focussed on understanding functional organisation within segregated patches of cortex. The ventral visual stream has been associated with the detection of physical features such as faces and body parts, whereas the theory-of-mind network has been associated with making inferences about mental states and underlying character, such as whether someone is friendly, selfish, or generous. To date, however, it is largely unknown how such distinct processing components integrate neural signals. Using functional magnetic resonance imaging and connectivity analyses, we investigated the contribution of functional integration to social perception. During scanning, participants observed bodies that had previously been associated with trait-based or neutral information. Additionally, we independently localised the body perception and theory-of-mind networks. We demonstrate that when observing someone who cues the recall of stored social knowledge compared to non-social knowledge, a node in the ventral visual stream (extrastriate body area) shows greater coupling with part of the theory-of-mind network (temporal pole). These results show that functional connections provide an interface between perceptual and inferential processing components, thus providing neurobiological evidence that supports the view that understanding the visual environment involves interplay between conceptual knowledge and perceptual processing. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Towards a Computational Comparative Neuroprimatology: Framing the language-ready brain.

PubMed

Arbib, Michael A

2016-03-01

We make the case for developing a Computational Comparative Neuroprimatology to inform the analysis of the function and evolution of the human brain. First, we update the mirror system hypothesis on the evolution of the language-ready brain by (i) modeling action and action recognition and opportunistic scheduling of macaque brains to hypothesize the nature of the last common ancestor of macaque and human (LCA-m); and then we (ii) introduce dynamic brain modeling to show how apes could acquire gesture through ontogenetic ritualization, hypothesizing the nature of evolution from LCA-m to the last common ancestor of chimpanzee and human (LCA-c). We then (iii) hypothesize the role of imitation, pantomime, protosign and protospeech in biological and cultural evolution from LCA-c to Homo sapiens with a language-ready brain. Second, we suggest how cultural evolution in Homo sapiens led from protolanguages to full languages with grammar and compositional semantics. Third, we assess the similarities and differences between the dorsal and ventral streams in audition and vision as the basis for presenting and comparing two models of language processing in the human brain: A model of (i) the auditory dorsal and ventral streams in sentence comprehension; and (ii) the visual dorsal and ventral streams in defining "what language is about" in both production and perception of utterances related to visual scenes provide the basis for (iii) a first step towards a synthesis and a look at challenges for further research. Copyright © 2015 Elsevier B.V. All rights reserved.

Towards a Computational Comparative Neuroprimatology: Framing the language-ready brain

NASA Astrophysics Data System (ADS)

Arbib, Michael A.

2016-03-01

We make the case for developing a Computational Comparative Neuroprimatology to inform the analysis of the function and evolution of the human brain. First, we update the mirror system hypothesis on the evolution of the language-ready brain by (i) modeling action and action recognition and opportunistic scheduling of macaque brains to hypothesize the nature of the last common ancestor of macaque and human (LCA-m); and then we (ii) introduce dynamic brain modeling to show how apes could acquire gesture through ontogenetic ritualization, hypothesizing the nature of evolution from LCA-m to the last common ancestor of chimpanzee and human (LCA-c). We then (iii) hypothesize the role of imitation, pantomime, protosign and protospeech in biological and cultural evolution from LCA-c to Homo sapiens with a language-ready brain. Second, we suggest how cultural evolution in Homo sapiens led from protolanguages to full languages with grammar and compositional semantics. Third, we assess the similarities and differences between the dorsal and ventral streams in audition and vision as the basis for presenting and comparing two models of language processing in the human brain: A model of (i) the auditory dorsal and ventral streams in sentence comprehension; and (ii) the visual dorsal and ventral streams in defining ;what language is about; in both production and perception of utterances related to visual scenes provide the basis for (iii) a first step towards a synthesis and a look at challenges for further research.

Metabolic Pathways Visualization Skills Development by Undergraduate Students

ERIC Educational Resources Information Center

dos Santos, Vanessa J. S. V.; Galembeck, Eduardo

2015-01-01

We have developed a metabolic pathways visualization skill test (MPVST) to gain greater insight into our students' abilities to comprehend the visual information presented in metabolic pathways diagrams. The test is able to discriminate students' visualization ability with respect to six specific visualization skills that we identified as key to…

Amygdala-ventral striatum circuit activation decreases long-term fear

PubMed Central

Correia, Susana S; McGrath, Anna G; Lee, Allison; Graybiel, Ann M; Goosens, Ki A

2016-01-01

In humans, activation of the ventral striatum, a region associated with reward processing, is associated with the extinction of fear, a goal in the treatment of fear-related disorders. This evidence suggests that extinction of aversive memories engages reward-related circuits, but a causal relationship between activity in a reward circuit and fear extinction has not been demonstrated. Here, we identify a basolateral amygdala (BLA)-ventral striatum (NAc) pathway that is activated by extinction training. Enhanced recruitment of this circuit during extinction learning, either by pairing reward with fear extinction training or by optogenetic stimulation of this circuit during fear extinction, reduces the return of fear that normally follows extinction training. Our findings thus identify a specific BLA-NAc reward circuit that can regulate the persistence of fear extinction and point toward a potential therapeutic target for disorders in which the return of fear following extinction therapy is an obstacle to treatment. DOI: http://dx.doi.org/10.7554/eLife.12669.001 PMID:27671733

Self-Affirmation Activates the Ventral Striatum: A Possible Reward-Related Mechanism for Self-Affirmation.

PubMed

Dutcher, Janine M; Creswell, J David; Pacilio, Laura E; Harris, Peter R; Klein, William M P; Levine, John M; Bower, Julienne E; Muscatell, Keely A; Eisenberger, Naomi I

2016-04-01

Self-affirmation (reflecting on important personal values) has been shown to have a range of positive effects; however, the neural basis of self-affirmation is not known. Building on studies showing that thinking about self-preferences activates neural reward pathways, we hypothesized that self-affirmation would activate brain reward circuitry during functional MRI (fMRI) studies. In Study 1, with college students, making judgments about important personal values during self-affirmation activated neural reward regions (i.e., ventral striatum), whereas making preference judgments that were not self-relevant did not. Study 2 replicated these results in a community sample, again showing that self-affirmation activated the ventral striatum. These are among the first fMRI studies to identify neural processes during self-affirmation. The findings extend theory by showing that self-affirmation may be rewarding and may provide a first step toward identifying a neural mechanism by which self-affirmation may produce a wide range of beneficial effects. © The Author(s) 2016.

HDAC I inhibition in the dorsal and ventral hippocampus differentially modulates predator-odor fear learning and generalization.

PubMed

Yuan, Robin K; Hebert, Jenna C; Thomas, Arthur S; Wann, Ellen G; Muzzio, Isabel A

2015-01-01

Although predator odors are ethologically relevant stimuli for rodents, the molecular pathways and contribution of some brain regions involved in predator odor conditioning remain elusive. Inhibition of histone deacetylases (HDACs) in the dorsal hippocampus has been shown to enhance shock-induced contextual fear learning, but it is unknown if HDACs have differential effects along the dorso-ventral hippocampal axis during predator odor fear learning. We injected MS-275, a class I HDAC inhibitor, bilaterally in the dorsal or ventral hippocampus of mice and found that it had no effects on innate anxiety in either region. We then assessed the effects of MS-275 at different stages of fear learning along the longitudinal hippocampal axis. Animals were injected with MS-275 or vehicle after context pre-exposure (pre-conditioning injections), when a representation of the context is first formed, or after exposure to coyote urine (post-conditioning injections), when the context becomes associated with predator odor. When MS-275 was administered after context pre-exposure, dorsally injected animals showed enhanced fear in the training context but were able to discriminate it from a neutral environment. Conversely, ventrally injected animals did not display enhanced learning in the training context but generalized the fear response to a neutral context. However, when MS-275 was administered after conditioning, there were no differences between the MS-275 and vehicle control groups in either the dorsal or ventral hippocampus. Surprisingly, all groups displayed generalization to a neutral context, suggesting that predator odor exposure followed by a mild stressor such as restraint leads to fear generalization. These results may elucidate distinct functions of the dorsal and ventral hippocampus in predator odor-induced fear conditioning as well as some of the molecular mechanisms underlying fear generalization.

Genetic Analysis of Hedgehog Signaling in Ventral Body Wall Development and the Onset of Omphalocele Formation

PubMed Central

Matsumaru, Daisuke; Haraguchi, Ryuma; Miyagawa, Shinichi; Motoyama, Jun; Nakagata, Naomi; Meijlink, Frits; Yamada, Gen

2011-01-01

Background An omphalocele is one of the major ventral body wall malformations and is characterized by abnormally herniated viscera from the body trunk. It has been frequently found to be associated with other structural malformations, such as genitourinary malformations and digit abnormalities. In spite of its clinical importance, the etiology of omphalocele formation is still controversial. Hedgehog (Hh) signaling is one of the essential growth factor signaling pathways involved in the formation of the limbs and urogenital system. However, the relationship between Hh signaling and ventral body wall formation remains unclear. Methodology/Principal Findings To gain insight into the roles of Hh signaling in ventral body wall formation and its malformation, we analyzed phenotypes of mouse mutants of Sonic hedgehog (Shh), GLI-Kruppel family member 3 (Gli3) and Aristaless-like homeobox 4 (Alx4). Introduction of additional Alx4Lst mutations into the Gli3Xt/Xt background resulted in various degrees of severe omphalocele and pubic diastasis. In addition, loss of a single Shh allele restored the omphalocele and pubic symphysis of Gli3Xt/+; Alx4Lst/Lst embryos. We also observed ectopic Hh activity in the ventral body wall region of Gli3Xt/Xt embryos. Moreover, tamoxifen-inducible gain-of-function experiments to induce ectopic Hh signaling revealed Hh signal dose-dependent formation of omphaloceles. Conclusions/Significance We suggest that one of the possible causes of omphalocele and pubic diastasis is ectopically-induced Hh signaling. To our knowledge, this would be the first demonstration of the involvement of Hh signaling in ventral body wall malformation and the genetic rescue of omphalocele phenotypes. PMID:21283718

Cortical networks involved in visual awareness independent of visual attention.

PubMed

Webb, Taylor W; Igelström, Kajsa M; Schurger, Aaron; Graziano, Michael S A

2016-11-29

It is now well established that visual attention, as measured with standard spatial attention tasks, and visual awareness, as measured by report, can be dissociated. It is possible to attend to a stimulus with no reported awareness of the stimulus. We used a behavioral paradigm in which people were aware of a stimulus in one condition and unaware of it in another condition, but the stimulus drew a similar amount of spatial attention in both conditions. The paradigm allowed us to test for brain regions active in association with awareness independent of level of attention. Participants performed the task in an MRI scanner. We looked for brain regions that were more active in the aware than the unaware trials. The largest cluster of activity was obtained in the temporoparietal junction (TPJ) bilaterally. Local independent component analysis (ICA) revealed that this activity contained three distinct, but overlapping, components: a bilateral, anterior component; a left dorsal component; and a right dorsal component. These components had brain-wide functional connectivity that partially overlapped the ventral attention network and the frontoparietal control network. In contrast, no significant activity in association with awareness was found in the banks of the intraparietal sulcus, a region connected to the dorsal attention network and traditionally associated with attention control. These results show the importance of separating awareness and attention when testing for cortical substrates. They are also consistent with a recent proposal that awareness is associated with ventral attention areas, especially in the TPJ.

Structural and functional analyses of human cerebral cortex using a surface-based atlas

NASA Technical Reports Server (NTRS)

Van Essen, D. C.; Drury, H. A.

1997-01-01

We have analyzed the geometry, geography, and functional organization of human cerebral cortex using surface reconstructions and cortical flat maps of the left and right hemispheres generated from a digital atlas (the Visible Man). The total surface area of the reconstructed Visible Man neocortex is 1570 cm2 (both hemispheres), approximately 70% of which is buried in sulci. By linking the Visible Man cerebrum to the Talairach stereotaxic coordinate space, the locations of activation foci reported in neuroimaging studies can be readily visualized in relation to the cortical surface. The associated spatial uncertainty was empirically shown to have a radius in three dimensions of approximately 10 mm. Application of this approach to studies of visual cortex reveals the overall patterns of activation associated with different aspects of visual function and the relationship of these patterns to topographically organized visual areas. Our analysis supports a distinction between an anterior region in ventral occipito-temporal cortex that is selectively involved in form processing and a more posterior region (in or near areas VP and V4v) involved in both form and color processing. Foci associated with motion processing are mainly concentrated in a region along the occipito-temporal junction, the ventral portion of which overlaps with foci also implicated in form processing. Comparisons between flat maps of human and macaque monkey cerebral cortex indicate significant differences as well as many similarities in the relative sizes and positions of cortical regions known or suspected to be homologous in the two species.

What Role Does "Elongation" Play in "Tool-Specific" Activation and Connectivity in the Dorsal and Ventral Visual Streams?

PubMed

Chen, Juan; Snow, Jacqueline C; Culham, Jody C; Goodale, Melvyn A

2018-04-01

Images of tools induce stronger activation than images of nontools in a left-lateralized network that includes ventral-stream areas implicated in tool identification and dorsal-stream areas implicated in tool manipulation. Importantly, however, graspable tools tend to be elongated rather than stubby, and so the tool-selective responses in some of these areas may, to some extent, reflect sensitivity to elongation rather than "toolness" per se. Using functional magnetic resonance imaging, we investigated the role of elongation in driving tool-specific activation in the 2 streams and their interconnections. We showed that in some "tool-selective" areas, the coding of toolness and elongation coexisted, but in others, elongation and toolness were coded independently. Psychophysiological interaction analysis revealed that toolness, but not elongation, had a strong modulation of the connectivity between the ventral and dorsal streams. Dynamic causal modeling revealed that viewing tools (either elongated or stubby) increased the connectivity from the ventral- to the dorsal-stream tool-selective areas, but only viewing elongated tools increased the reciprocal connectivity between these areas. Overall, these data disentangle how toolness and elongation affect the activation and connectivity of the tool network and help to resolve recent controversies regarding the relative contribution of "toolness" versus elongation in driving dorsal-stream "tool-selective" areas.

Tectonigral Projections in the Primate: A Pathway for Pre-Attentive Sensory Input to Midbrain Dopaminergic Neurons

PubMed Central

May, Paul J.; McHaffie, John G.; Stanford, Terrence R.; Jiang, Huai; Costello, M. Gabriela; Coizet, Veronique; Hayes, Lauren M.; Haber, Suzanne N.; Redgrave, Peter

2010-01-01

Much of the evidence linking the short-latency phasic signaling of midbrain dopaminergic neurons with reward-prediction errors used in learning and habit formation comes from recording the visual responses of monkey dopaminergic neurons. However, the information encoded by dopaminergic neuron activity is constrained by the qualities of the afferent visual signals made available to these cells. Recent evidence from rats and cats indicates the primary source of this visual input originates subcortically, via a direct tectonigral projection. The present anatomical study sought to establish whether a direct tectonigral projection is a significant feature of the primate brain. Injections of anterograde tracers into the superior colliculus of macaque monkeys labelled terminal arbors throughout the substantia nigra, with the densest terminations in the dorsal tier. Labelled boutons were found in close association (possibly indicative of synaptic contact) with ventral midbrain neurons staining positively for the dopaminergic marker tyrosine hydroxylase. Injections of retrograde tracer confined to the macaque substantia nigra retrogradely labelled small to medium sized neurons in the intermediate and deep layers of the superior colliculus. Together, these data indicate that a direct tectonigral projection is also a feature of the monkey brain, and therefore likely to have been conserved throughout mammalian evolution. Insofar as the superior colliculus is configured to detect unpredicted, biologically salient, sensory events, it may be safer to regard the phasic responses of midbrain dopaminergic neurons as ‘sensory prediction errors’ rather than ‘reward prediction errors’, in which case, dopamine-based theories of reinforcement learning will require revision. PMID:19175405

Inactivation of Primate Prefrontal Cortex Impairs Auditory and Audiovisual Working Memory.

PubMed

Plakke, Bethany; Hwang, Jaewon; Romanski, Lizabeth M

2015-07-01

The prefrontal cortex is associated with cognitive functions that include planning, reasoning, decision-making, working memory, and communication. Neurophysiology and neuropsychology studies have established that dorsolateral prefrontal cortex is essential in spatial working memory while the ventral frontal lobe processes language and communication signals. Single-unit recordings in nonhuman primates has shown that ventral prefrontal (VLPFC) neurons integrate face and vocal information and are active during audiovisual working memory. However, whether VLPFC is essential in remembering face and voice information is unknown. We therefore trained nonhuman primates in an audiovisual working memory paradigm using naturalistic face-vocalization movies as memoranda. We inactivated VLPFC, with reversible cortical cooling, and examined performance when faces, vocalizations or both faces and vocalization had to be remembered. We found that VLPFC inactivation impaired subjects' performance in audiovisual and auditory-alone versions of the task. In contrast, VLPFC inactivation did not disrupt visual working memory. Our studies demonstrate the importance of VLPFC in auditory and audiovisual working memory for social stimuli but suggest a different role for VLPFC in unimodal visual processing. The ventral frontal lobe, or inferior frontal gyrus, plays an important role in audiovisual communication in the human brain. Studies with nonhuman primates have found that neurons within ventral prefrontal cortex (VLPFC) encode both faces and vocalizations and that VLPFC is active when animals need to remember these social stimuli. In the present study, we temporarily inactivated VLPFC by cooling the cortex while nonhuman primates performed a working memory task. This impaired the ability of subjects to remember a face and vocalization pair or just the vocalization alone. Our work highlights the importance of the primate VLPFC in the processing of faces and vocalizations in a manner that is similar to the inferior frontal gyrus in the human brain. Copyright © 2015 the authors 0270-6474/15/359666-10$15.00/0.

Thalamic alterations in preterm neonates and its relation to ventral striatum disturbances revealed by a combined shape and pose analysis

PubMed Central

Lao, Yi; Wang, Yalin; Shi, Jie; Ceschin, Rafael; Nelson, Marvin D.; Panigrahy, Ashok; Leporé, Natasha

2015-01-01

Finding the neuroanatomical correlates of prematurity is vital to understanding which structures are affected, and design efficient prevention andtreatment strategy. Converging results reveal that thalamic abnormalities are important indicators of prematurity. However, little is known about the localization of the disturbance within the subnuclei of the thalamus, or on the association of altered thalamic development with other deep gray matter disturbances. Here, using brain structural magnetic resonance imaging (MRI), we perform a novel combined shape and pose analysis of the thalamus and ventral striatum between 17 preterm and 19 term-born neonates. We detect statistically significant surface deformations and pose changes on the thalamus andventral striatum, successfully locating the alterations on specific regions such as the anterior and ventral-anterior thalamic nuclei, and for the first time, demonstrating the feasibility of using relative pose parameters as indicators for prematurity in neonates. We also perform a set of correlation analyses between the thalamus and the ventral striatum, based on the surface and pose results. Our methods show that regional abnormalities of the thalamus are associated with alterations of the ventral striatum, possibly due to disturbed development of sharedpre-frontal connectivity. More specifically, the significantly correlated regions in these two structures point to frontal-subcortical pathways including the dorsolateral prefrontal-subcortical circuit, the lateral orbitofrontal-subcortical circuit, the motor circuit, and the oculomotor circuit. These findings reveal new insight into potential subcortical structural covariatesfor poor neurodevelopmental outcomes in the preterm population. PMID:25366970

Molecular signatures that correlate with induction of lens regeneration in newts: lessons from proteomic analysis.

PubMed

Sousounis, Konstantinos; Bhavsar, Rital; Looso, Mario; Krüger, Marcus; Beebe, Jessica; Braun, Thomas; Tsonis, Panagiotis A

2014-12-11

Amphibians have the remarkable ability to regenerate missing body parts. After complete removal of the eye lens, the dorsal but not the ventral iris will transdifferentiate to regenerate an exact replica of the lost lens. We used reverse-phase nano-liquid chromatography followed by mass spectrometry to detect protein concentrations in dorsal and ventral iris 0, 4, and 8 days post-lentectomy. We performed gene expression comparisons between regeneration and intact timepoints as well as between dorsal and ventral iris. Our analysis revealed gene expression patterns associated with the ability of the dorsal iris for transdifferentiation and lens regeneration. Proteins regulating gene expression and various metabolic processes were enriched in regeneration timepoints. Proteins involved in extracellular matrix, gene expression, and DNA-associated functions like DNA repair formed a regeneration-related protein network and were all up-regulated in the dorsal iris. In addition, we investigated protein concentrations in cultured dorsal (transdifferentiation-competent) and ventral (transdifferentiation-incompetent) iris pigmented epithelial (IPE) cells. Our comparative analysis revealed that the ability of dorsal IPE cells to keep memory of their tissue of origin and transdifferentiation is associated with the expression of proteins that specify the dorso-ventral axis of the eye as well as with proteins found highly expressed in regeneration timepoints, especially 8 days post-lentectomy. The study deepens our understanding in the mechanism of regeneration by providing protein networks and pathways that participate in the process.

Identification of neuroanatomic circuits from spinal cord to stomach in mouse: retrograde transneuronal viral tracing study.

PubMed

Ye, Da-Wei; Liu, Cheng; Tian, Xue-Bi; Xiang, Hong-Bing

2014-01-01

To determine the spinal innervation and neuronal connections is important for studying gastric carbohydrate metabolism and motor responses. Neurons involved in the efferent control of the stomach were identified following visualization of pseudorabies virus (PRV)-614 retrograde tracing. PRV-614 was injected into the ventral stomach wall in 13 adult C57BL/6J strain male mice. On the fifth day postinjection, animals were humanely sacrificed, and spinal cords were removed and sectioned, and processed for PRV visualization. The virus injected into the ventral stomach wall was specifically transported to the thoracic spinal cord. At 5 d after injection of the PRV-614, stomach enlargement and tissue edema were found, and PRV-614 positive cells were found in the intermediolateral cell column, the intercalates nucleus or the central autonomic nucleus of spinal cord segments T3 to L1, and major PRV-614 labeled cells were focused in the T6-10 segment. Our results revealed neuroanatomical circuits between stomach and the spinal intermediolateral cell column neurons.

Learning and recall of form discriminations during reversible cooling deactivation of ventral-posterior suprasylvian cortex in the cat.

PubMed Central

Lomber, S G; Payne, B R; Cornwell, P

1996-01-01

Extrastriate visual cortex of the ventral-posterior suprasylvian gyrus (vPS cortex) of freely behaving cats was reversibly deactivated with cooling to determine its role in performance on a battery of simple or masked two-dimensional pattern discriminations, and three-dimensional object discriminations. Deactivation of vPS cortex by cooling profoundly impaired the ability of the cats to recall the difference between all previously learned pattern and object discriminations. However, the cats' ability to learn or relearn pattern and object discriminations while vPS was deactivated depended upon the nature of the pattern or object and the cats' prior level of exposure to them. During cooling of vPS cortex, the cats could neither learn the novel object discriminations nor relearn a highly familiar masked or partially occluded pattern discrimination, although they could relearn both the highly familiar object and simple pattern discriminations. These cooling-induced deficits resemble those induced by cooling of the topologically equivalent inferotemporal cortex of monkeys and provides evidence that the equivalent regions contribute to visual processing in similar ways. Images Fig. 1 Fig. 3 PMID:8643686

Heterogeneity across the dorso-ventral axis in zebrafish EVL is regulated by a novel module consisting of sox, snail1a and max genes.

PubMed

Chen, Yi-Yen; Harris, Matthew P; Levesque, Mitchell P; Nüsslein-Volhard, Christiane; Sonawane, Mahendra

2012-01-01

In vertebrates, the dorso-ventral (DV) axis is defined by the combinatorial action of localised Wnt, FGF and Nodal signalling along with the antagonizing activities of Chordin and BMP pathways. Our knowledge of the factors that may act in concert with these core pathways to regulate early embryonic patterning is far from complete. Furthermore, while all three germ layers respond to these patterning cues, it is not clear whether in zebrafish the outermost protective epithelium, the enveloping layer (EVL), is also patterned along the DV axis. Here, we have identified a transgenic line driving GFP under a crestin promoter, which specifically labels the dorsal domain of the EVL suggesting heterogeneity in the EVL across the DV axis. Our attempts to understand how the expression from this promoter fragment is regulated specifically in the dorsal domain, have unravelled potential novel players involved in early EVL and embryonic patterning. We show that along with Nodal signalling components, four proteins Sox11b, Sox19b, Snail1a and Max are involved in regulating the size of this EVL domain. However, Chordin-BMP signalling might be dispensable for the dorso-ventral patterning of the EVL. For the first time, this transgenic line unravels the heterogeneity in the EVL and will serve as an important tool in understanding the molecular basis of the DV patterning of the EVL. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Chronic corticosterone administration facilitates aversive memory retrieval and increases GR/NOS immunoreactivity.

PubMed

Santos, Thays B; Céspedes, Isabel C; Viana, Milena B

2014-07-01

Glucocorticoids are stress hormones that mediate the organism's reaction to stress. It has been previously proposed that the facilitation of emotional aversive conditioning induced by these hormones may involve nitric oxide-pathways. The purpose of the present study was to address this question. For that, male Wistar rats were surgically implanted with slow-release corticosterone (CORT) pellets (21 days) and tested in a step-down inhibitory avoidance task. Additional groups of animals were also submitted to the same treatment conditions and on the 21st day of treatment assayed for GR (glucocorticoid receptors)-nNOS (neuronal nitric oxide synthase) immunoreactivity (GRi-nNOSi) or measurements of plasma CORT. Results showed that CORT treatment induced facilitation of step-down inhibitory avoidance. This same treatment also significantly increased CORT plasma levels and GRi in the medial, basolateral and basomedial amygdala, in the paraventricular hypothalamic nucleus (PVN), in the ventral and dorsal dentate gyrus, in the ventral CA1 region and in the dorsal CA1 and CA3 regions. Furthermore, nNOSi and GRi-nNOSi were significantly increased by CORT treatment in the medial amygdala and basolateral amygdaloid complex, in the PVN, subiculum, in the dorsal CA3 region and in the ventral CA1 and CA3 regions. These results indicate that the facilitation of aversive conditioning induced by CORT involves GR-nNOS pathways activation, what may be of relevance for a better understanding of stress-related psychiatric conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Gene expression changes in the ventral hippocampus and medial prefrontal cortex of adolescent alcohol-preferring (P) rats following binge-like alcohol drinking.

PubMed

McClintick, Jeanette N; McBride, William J; Bell, Richard L; Ding, Zheng-Ming; Liu, Yunlong; Xuei, Xiaoling; Edenberg, Howard J

2018-05-01

Binge drinking of alcohol during adolescence is a serious public health concern with long-term consequences, including decreased hippocampal and prefrontal cortex volume and deficits in memory. We used RNA sequencing to assess the effects of adolescent binge drinking on gene expression in these regions. Male adolescent alcohol-preferring (P) rats were exposed to repeated binge drinking (three 1-h sessions/day during the dark/cycle, 5 days/week for 3 weeks starting at 28 days of age; ethanol intakes of 2.5-3 g/kg/session). Ethanol significantly altered the expression of 416 of 11,727 genes expressed in the ventral hippocampus. Genes and pathways involved in neurogenesis, long-term potentiation, and axonal guidance were decreased, which could relate to the impaired memory function found in subjects with adolescent alcohol binge-like exposure. The decreased expression of myelin and cholesterol genes and apparent decrease in oligodendrocytes in P rats could result in decreased myelination. In the medial prefrontal cortex, 638 of 11,579 genes were altered; genes in cellular stress and inflammatory pathways were increased, as were genes involved in oxidative phosphorylation. Overall, the results of this study suggest that adolescent binge-like alcohol drinking may alter the development of the ventral hippocampus and medial prefrontal cortex and produce long-term consequences on learning and memory, and on control of impulsive behaviors. Copyright © 2017 Elsevier Inc. All rights reserved.

Ventral and dorsal streams for choosing word order during sentence production

PubMed Central

Thothathiri, Malathi; Rattinger, Michelle

2015-01-01

Proficient language use requires speakers to vary word order and choose between different ways of expressing the same meaning. Prior statistical associations between individual verbs and different word orders are known to influence speakers’ choices, but the underlying neural mechanisms are unknown. Here we show that distinct neural pathways are used for verbs with different statistical associations. We manipulated statistical experience by training participants in a language containing novel verbs and two alternative word orders (agent-before-patient, AP; patient-before-agent, PA). Some verbs appeared exclusively in AP, others exclusively in PA, and yet others in both orders. Subsequently, we used sparse sampling neuroimaging to examine the neural substrates as participants generated new sentences in the scanner. Behaviorally, participants showed an overall preference for AP order, but also increased PA order for verbs experienced in that order, reflecting statistical learning. Functional activation and connectivity analyses revealed distinct networks underlying the increased PA production. Verbs experienced in both orders during training preferentially recruited a ventral stream, indicating the use of conceptual processing for mapping meaning to word order. In contrast, verbs experienced solely in PA order recruited dorsal pathways, indicating the use of selective attention and sensorimotor integration for choosing words in the right order. These results show that the brain tracks the structural associations of individual verbs and that the same structural output may be achieved via ventral or dorsal streams, depending on the type of regularities in the input. PMID:26621706

Clinical implications of parallel visual pathways.

PubMed

Bassi, C J; Lehmkuhle, S

1990-02-01

Visual information travels from the retina to visual cortical areas along at least two parallel pathways. In this paper, anatomical and physiological evidence is presented to demonstrate the existence of, and trace these two pathways throughout the visual systems of the cat, primate, and human. Physiological and behavioral experiments are discussed which establish that these two pathways are differentially sensitive to stimuli that vary in spatial and temporal frequency. One pathway (M-pathway) is more sensitive to coarse visual form that is modulated or moving at fast rates, whereas the other pathway (P-pathway) is more sensitive to spatial detail that is stationary or moving at slow rates. This difference between the M- and P-pathways is related to some spatial and temporal effects observed in humans. Furthermore, evidence is presented that certain diseases selectively comprise the functioning of M- or P-pathways (i.e., glaucoma, Alzheimer's disease, and anisometropic amblyopia), and some of the spatial and temporal deficits observed in these patients are presented within the context of the dysfunction of the M- or P-pathway.

Monoclonal L-citrulline immunostaining reveals nitric oxide-producing vestibular neurons

NASA Technical Reports Server (NTRS)

Holstein, G. R.; Friedrich, V. L. Jr; Martinelli, G. P.

2001-01-01

Nitric oxide is an unstable free radical that serves as a novel messenger molecule in the central nervous system (CNS). In order to understand the interplay between classic and novel chemical communication systems in vestibular pathways, the staining obtained using a monoclonal antibody directed against L-citrulline was compared with the labeling observed using more traditional markers for the presence of nitric oxide. Brainstem tissue from adult rats was processed for immunocytochemistry employing a monoclonal antibody directed against L-citrulline, a polyclonal antiserum against neuronal nitric oxide synthase, and/or NADPH-diaphorase histochemistry. Our findings demonstrate that L-citrulline can be fixed in situ by vascular perfusion, and can be visualized in fixed CNS tissue sections by immunocytochemistry. Further, the same vestibular regions and cell types are labeled by NADPH-diaphorase histochemistry, by the neuronal nitric oxide synthase antiserum, and by our anti-L-citrulline antibody. Clusters of L-citrulline-immunoreactive neurons are present in subregions of the vestibular nuclei, including the caudal portion of the inferior vestibular nucleus, the magnocellular portion of the medial vestibular nucleus, and the large cells in the ventral tier of the lateral vestibular nucleus. NADPH-diaphorase histochemical staining of these neurons clearly demonstrated their multipolar, fusiform and globular somata and long varicose dendritic processes. These results provide support for the suggestion that nitric oxide serves key roles in both vestibulo-autonomic and vestibulo-spinal pathways.

Bladder volume-dependent excitatory and inhibitory influence of lumbosacral dorsal and ventral roots on bladder activity in rats

PubMed Central

Sugaya, Kimio; de Groat, William C.

2011-01-01

This study was undertaken to examine the role of the afferent and efferent pathways of the lumbosacral spinal nerve roots in the tonic control of bladder activity. Changes of isovolumetric bladder activity were recorded in 21 sympathectomized female rats under urethane anesthesia following transection of the dorsal (DRT) and ventral (VRT) lumbosacral spinal roots, and after intraperitoneal administration of hexamethonium. DRT altered the baseline intravesical pressure in a bladder volume-dependent manner in each animal. The percent change of baseline pressure after VRT following DRT was also dependent upon bladder volume. The percent change of baseline pressure after VRT alone was similarly dependent on bladder volume, but not after VRT followed by DRT. The percent change of baseline intravesical pressure (y)(−9 to +8 cm H2O, −56 to +46%) after DRT and VRT depended upon bladder volume (x)(y = 44.7 x −40.4) in all rats. Hexamethonium increased the amplitude of small myogenic bladder contractions after DRT and VRT. In conclusion, the bladder is tonically excited or inhibited by a local reflex pathway and by a parasympathetic reflex pathway that depends on connections with the lumbosacral spinal cord and the pelvic nerves. Both reflex mechanisms are influenced by bladder volume. PMID:17878597

Resolving the organization of the third tier visual cortex in primates: a hypothesis-based approach.

PubMed

Angelucci, Alessandra; Rosa, Marcello G P

2015-01-01

As highlighted by several contributions to this special issue, there is still ongoing debate about the number, exact location, and boundaries of the visual areas located in cortex immediately rostral to the second visual area (V2), i.e., the "third tier" visual cortex, in primates. In this review, we provide a historical overview of the main ideas that have led to four models of third tier cortex organization, which are at the center of today's debate. We formulate specific predictions of these models, and compare these predictions with experimental evidence obtained primarily in New World primates. From this analysis, we conclude that only one of these models (the "multiple-areas" model) can accommodate the breadth of available experimental evidence. According to this model, most of the third tier cortex in New World primates is occupied by two distinct areas, both representing the full contralateral visual quadrant: the dorsomedial area (DM), restricted to the dorsal half of the third visual complex, and the ventrolateral posterior area (VLP), occupying its ventral half and a substantial fraction of its dorsal half. DM belongs to the dorsal stream of visual processing, and overlaps with macaque parietooccipital (PO) area (or V6), whereas VLP belongs to the ventral stream and overlaps considerably with area V3 proposed by others. In contrast, there is substantial evidence that is inconsistent with the concept of a single elongated area V3 lining much of V2. We also review the experimental evidence from macaque monkey and humans, and propose that, once the data are interpreted within an evolutionary-developmental context, these species share a homologous (but not necessarily identical) organization of the third tier cortex as that observed in New World monkeys. Finally, we identify outstanding issues, and propose experiments to resolve them, highlighting in particular the need for more extensive, hypothesis-driven investigations in macaque and humans.

Altered white matter in early visual pathways of humans with amblyopia.

PubMed

Allen, Brian; Spiegel, Daniel P; Thompson, Benjamin; Pestilli, Franco; Rokers, Bas

2015-09-01

Amblyopia is a visual disorder caused by poorly coordinated binocular input during development. Little is known about the impact of amblyopia on the white matter within the visual system. We studied the properties of six major visual white-matter pathways in a group of adults with amblyopia (n=10) and matched controls (n=10) using diffusion weighted imaging (DWI) and fiber tractography. While we did not find significant differences in diffusion properties in cortico-cortical pathways, patients with amblyopia exhibited increased mean diffusivity in thalamo-cortical visual pathways. These findings suggest that amblyopia may systematically alter the white matter properties of early visual pathways. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spatiotemporal oscillatory dynamics of visual selective attention during a flanker task.

PubMed

McDermott, Timothy J; Wiesman, Alex I; Proskovec, Amy L; Heinrichs-Graham, Elizabeth; Wilson, Tony W

2017-08-01

The flanker task is a test of visual selective attention that has been widely used to probe error monitoring, response conflict, and related constructs. However, to date, few studies have focused on the selective attention component of this task and imaged the underlying oscillatory dynamics serving task performance. In this study, 21 healthy adults successfully completed an arrow-based version of the Eriksen flanker task during magnetoencephalography (MEG). All MEG data were pre-processed and transformed into the time-frequency domain. Significant oscillatory brain responses were imaged using a beamforming approach, and voxel time series were extracted from the peak responses to identify the temporal dynamics. Across both congruent and incongruent flanker conditions, our results indicated robust decreases in alpha (9-12Hz) activity in medial and lateral occipital regions, bilateral parietal cortices, and cerebellar areas during task performance. In parallel, increases in theta (3-7Hz) oscillatory activity were detected in dorsal and ventral frontal regions, and the anterior cingulate. As per conditional effects, stronger alpha responses (i.e., greater desynchronization) were observed in parietal, occipital, and cerebellar cortices during incongruent relative to congruent trials, whereas the opposite pattern emerged for theta responses (i.e., synchronization) in the anterior cingulate, left dorsolateral prefrontal, and ventral prefrontal cortices. Interestingly, the peak latency of theta responses in these latter brain regions was significantly correlated with reaction time, and may partially explain the amplitude difference observed between congruent and incongruent trials. Lastly, whole-brain exploratory analyses implicated the frontal eye fields, right temporoparietal junction, and premotor cortices. These findings suggest that regions of both the dorsal and ventral attention networks contribute to visual selective attention processes during incongruent trials, and that such differential processes are transient and fully completed shortly after the behavioral response in most trials. Copyright © 2017 Elsevier Inc. All rights reserved.

Similarities in neural activations of face and Chinese character discrimination.

PubMed

Liu, Jiangang; Tian, Jie; Li, Jun; Gong, Qiyong; Lee, Kang

2009-02-18

This study compared Chinese participants' visual discrimination of Chinese faces with that of Chinese characters, which are highly similar to faces on a variety of dimensions. Both Chinese faces and characters activated the bilateral middle fusiform with high levels of correlations. These findings suggest that although the expertise systems for faces and written symbols are known to be anatomically differentiated at the later stages of processing to serve face processing or written-symbol-specific processing purposes, they may share similar neural structures in the ventral occipitotemporal cortex at the stages of visual processing.

Sensory and motor properties of the cerebellar uvula and modulus

NASA Technical Reports Server (NTRS)

Robinson, F. R.

1985-01-01

The uvula and nodulus (vermal lobules 9 and 10) of the vestibulocerebellum are implicated by behavioral evidence in the control of eye and head movements and in the production of motion sickness. The uvula and nodulus could play a role in these functions through known output pathways. Purkinje cells in both structures project via the fastigial and vestibular nuceli to the ventral horn of the cervical spin cord, to oculomotor neurons, and to the emetic region of the reticular formation (ablation of which abolishes susceptability to motion sickness). Uvula and nodulus Purkinje cells will be analyzed in cats trained to make controlled head movements. The activity of these neurons is expected to modulate well during head and/or eye movements because the uvula and nodulus receive heavy projections from sources of visual, vestibular and neck proprioceptive information. How neuron activity contributes to movement and how different sensory inputs converge to influence this contribution may be determined by characterizing movement related properties of these neurons. A population of neurons that modulates powerfully to the conflict between different head movement signals that can cause motion sickness may be identified.

Psychophysical and neuroimaging responses to moving stimuli in a patient with the Riddoch phenomenon due to bilateral visual cortex lesions.

PubMed

Arcaro, Michael J; Thaler, Lore; Quinlan, Derek J; Monaco, Simona; Khan, Sarah; Valyear, Kenneth F; Goebel, Rainer; Dutton, Gordon N; Goodale, Melvyn A; Kastner, Sabine; Culham, Jody C

2018-05-09

Patients with injury to early visual cortex or its inputs can display the Riddoch phenomenon: preserved awareness for moving but not stationary stimuli. We provide a detailed case report of a patient with the Riddoch phenomenon, MC. MC has extensive bilateral lesions to occipitotemporal cortex that include most early visual cortex and complete blindness in visual field perimetry testing with static targets. Nevertheless, she shows a remarkably robust preserved ability to perceive motion, enabling her to navigate through cluttered environments and perform actions like catching moving balls. Comparisons of MC's structural magnetic resonance imaging (MRI) data to a probabilistic atlas based on controls reveals that MC's lesions encompass the posterior, lateral, and ventral early visual cortex bilaterally (V1, V2, V3A/B, LO1/2, TO1/2, hV4 and VO1 in both hemispheres) as well as more extensive damage to right parietal (inferior parietal lobule) and left ventral occipitotemporal cortex (VO1, PHC1/2). She shows some sparing of anterior occipital cortex, which may account for her ability to see moving targets beyond ~15 degrees eccentricity during perimetry. Most strikingly, functional and structural MRI revealed robust and reliable spared functionality of the middle temporal motion complex (MT+) bilaterally. Moreover, consistent with her preserved ability to discriminate motion direction in psychophysical testing, MC also shows direction-selective adaptation in MT+. A variety of tests did not enable us to discern whether input to MT+ was driven by her spared anterior occipital cortex or subcortical inputs. Nevertheless, MC shows rich motion perception despite profoundly impaired static and form vision, combined with clear preservation of activation in MT+, thus supporting the role of MT+ in the Riddoch phenomenon. Copyright © 2018 Elsevier Ltd. All rights reserved.

On the organization of the perisylvian cortex: Insights from the electrophysiology of language. Comment on "Towards a Computational Comparative Neuroprimatology: Framing the language-ready brain" by M.A. Arbib

NASA Astrophysics Data System (ADS)

Brouwer, Harm; Crocker, Matthew W.

2016-03-01

The Mirror System Hypothesis (MSH) on the evolution of the language-ready brain draws upon the parallel dorsal-ventral stream architecture for vision [1]. The dorsal ;how; stream provides a mapping of parietally-mediated affordances onto the motor system (supporting preshape), whereas the ventral ;what; stream engages in object recognition and visual scene analysis (supporting pantomime and verbal description). Arbib attempts to integrate this MSH perspective with a recent conceptual dorsal-ventral stream model of auditory language comprehension [5] (henceforth, the B&S model). In the B&S model, the dorsal stream engages in time-dependent combinatorial processing, which subserves syntactic structuring and linkage to action, whereas the ventral stream performs time-independent unification of conceptual schemata. These streams are integrated in the left Inferior Frontal Gyrus (lIFG), which is assumed to subserve cognitive control, and no linguistic processing functions. Arbib criticizes the B&S model on two grounds: (i) the time-independence of the semantic processing in the ventral stream (by arguing that semantic processing is just as time-dependent as syntactic processing), and (ii) the absence of linguistic processing in the lIFG (reconciling syntactic and semantic representations is very much linguistic processing proper). Here, we provide further support for these two points of criticism on the basis of insights from the electrophysiology of language. In the course of our argument, we also sketch the contours of an alternative model that may prove better suited for integration with the MSH.

Salient sounds activate human visual cortex automatically.

PubMed

McDonald, John J; Störmer, Viola S; Martinez, Antigona; Feng, Wenfeng; Hillyard, Steven A

2013-05-22

Sudden changes in the acoustic environment enhance perceptual processing of subsequent visual stimuli that appear in close spatial proximity. Little is known, however, about the neural mechanisms by which salient sounds affect visual processing. In particular, it is unclear whether such sounds automatically activate visual cortex. To shed light on this issue, this study examined event-related brain potentials (ERPs) that were triggered either by peripheral sounds that preceded task-relevant visual targets (Experiment 1) or were presented during purely auditory tasks (Experiments 2-4). In all experiments the sounds elicited a contralateral ERP over the occipital scalp that was localized to neural generators in extrastriate visual cortex of the ventral occipital lobe. The amplitude of this cross-modal ERP was predictive of perceptual judgments about the contrast of colocalized visual targets. These findings demonstrate that sudden, intrusive sounds reflexively activate human visual cortex in a spatially specific manner, even during purely auditory tasks when the sounds are not relevant to the ongoing task.

Salient sounds activate human visual cortex automatically

PubMed Central

McDonald, John J.; Störmer, Viola S.; Martinez, Antigona; Feng, Wenfeng; Hillyard, Steven A.

2013-01-01

Sudden changes in the acoustic environment enhance perceptual processing of subsequent visual stimuli that appear in close spatial proximity. Little is known, however, about the neural mechanisms by which salient sounds affect visual processing. In particular, it is unclear whether such sounds automatically activate visual cortex. To shed light on this issue, the present study examined event-related brain potentials (ERPs) that were triggered either by peripheral sounds that preceded task-relevant visual targets (Experiment 1) or were presented during purely auditory tasks (Experiments 2, 3, and 4). In all experiments the sounds elicited a contralateral ERP over the occipital scalp that was localized to neural generators in extrastriate visual cortex of the ventral occipital lobe. The amplitude of this cross-modal ERP was predictive of perceptual judgments about the contrast of co-localized visual targets. These findings demonstrate that sudden, intrusive sounds reflexively activate human visual cortex in a spatially specific manner, even during purely auditory tasks when the sounds are not relevant to the ongoing task. PMID:23699530

A task-dependent causal role for low-level visual processes in spoken word comprehension.

PubMed

Ostarek, Markus; Huettig, Falk

2017-08-01

It is well established that the comprehension of spoken words referring to object concepts relies on high-level visual areas in the ventral stream that build increasingly abstract representations. It is much less clear whether basic low-level visual representations are also involved. Here we asked in what task situations low-level visual representations contribute functionally to concrete word comprehension using an interference paradigm. We interfered with basic visual processing while participants performed a concreteness task (Experiment 1), a lexical-decision task (Experiment 2), and a word class judgment task (Experiment 3). We found that visual noise interfered more with concrete versus abstract word processing, but only when the task required visual information to be accessed. This suggests that basic visual processes can be causally involved in language comprehension, but that their recruitment is not automatic and rather depends on the type of information that is required in a given task situation. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

How the Ventral Pathway Got Lost--And What Its Recovery Might Mean

ERIC Educational Resources Information Center

Weiller, Cornelius; Bormann, Tobias; Saur, Dorothee; Musso, Mariachristina; Rijntjes, Michel

2011-01-01

Textbooks dealing with the anatomical representation of language in the human brain display two language-related zones, Broca's area and Wernicke's area, connected by a single dorsal fiber tract, the arcuate fascicle. This classical model is incomplete. Modern imaging techniques have identified a second long association tract between the temporal…

New approaches to the management of schizophrenia: focus on aberrant hippocampal drive of dopamine pathways

PubMed Central

Perez, Stephanie M; Lodge, Daniel J

2014-01-01

Schizophrenia is a disease affecting up to 1% of the population. Current therapies are based on the efficacy of chlorpromazine, discovered over 50 years ago. These drugs block dopamine D2-like receptors and are effective at primarily treating positive symptoms in a subset of patients. Unfortunately, current therapies are far from adequate, and novel treatments require a better understanding of disease pathophysiology. Here we review the dopamine, gamma-aminobutyric acid (GABA), and glutamate hypotheses of schizophrenia and describe a pathway whereby a loss of inhibitory signaling in ventral regions of the hippocampus actually drives a dopamine hyperfunction. Moreover, we discuss novel therapeutic approaches aimed at attenuating ventral hippocampal activity in a preclinical model of schizophrenia, namely the MAM GD17 rat. Specifically, pharmacological (allosteric modulators of the α5 GABAA receptor), neurosurgical (deep brain stimulation), and cell-based (GABAergic precursor transplants) therapies are discussed. By better understanding the underlying circuit level dysfunctions in schizophrenia, novel treatments can be advanced that may provide better efficacy and a superior side effect profile to conventional antipsychotic medications. PMID:25061280

New approaches to the management of schizophrenia: focus on aberrant hippocampal drive of dopamine pathways.

PubMed

Perez, Stephanie M; Lodge, Daniel J

2014-01-01

Schizophrenia is a disease affecting up to 1% of the population. Current therapies are based on the efficacy of chlorpromazine, discovered over 50 years ago. These drugs block dopamine D2-like receptors and are effective at primarily treating positive symptoms in a subset of patients. Unfortunately, current therapies are far from adequate, and novel treatments require a better understanding of disease pathophysiology. Here we review the dopamine, gamma-aminobutyric acid (GABA), and glutamate hypotheses of schizophrenia and describe a pathway whereby a loss of inhibitory signaling in ventral regions of the hippocampus actually drives a dopamine hyperfunction. Moreover, we discuss novel therapeutic approaches aimed at attenuating ventral hippocampal activity in a preclinical model of schizophrenia, namely the MAM GD17 rat. Specifically, pharmacological (allosteric modulators of the α5 GABAA receptor), neurosurgical (deep brain stimulation), and cell-based (GABAergic precursor transplants) therapies are discussed. By better understanding the underlying circuit level dysfunctions in schizophrenia, novel treatments can be advanced that may provide better efficacy and a superior side effect profile to conventional antipsychotic medications.

Network Interactions Explain Sensitivity to Dynamic Faces in the Superior Temporal Sulcus.

PubMed

Furl, Nicholas; Henson, Richard N; Friston, Karl J; Calder, Andrew J

2015-09-01

The superior temporal sulcus (STS) in the human and monkey is sensitive to the motion of complex forms such as facial and bodily actions. We used functional magnetic resonance imaging (fMRI) to explore network-level explanations for how the form and motion information in dynamic facial expressions might be combined in the human STS. Ventral occipitotemporal areas selective for facial form were localized in occipital and fusiform face areas (OFA and FFA), and motion sensitivity was localized in the more dorsal temporal area V5. We then tested various connectivity models that modeled communication between the ventral form and dorsal motion pathways. We show that facial form information modulated transmission of motion information from V5 to the STS, and that this face-selective modulation likely originated in OFA. This finding shows that form-selective motion sensitivity in the STS can be explained in terms of modulation of gain control on information flow in the motion pathway, and provides a substantial constraint for theories of the perception of faces and biological motion. © The Author 2014. Published by Oxford University Press.

Beyond the FFA: The Role of the Ventral Anterior Temporal Lobes in Face Processing

PubMed Central

Collins, Jessica A.; Olson, Ingrid R.

2014-01-01

Extensive research has supported the existence of a specialized face-processing network that is distinct from the visual processing areas used for general object recognition. The majority of this work has been aimed at characterizing the response properties of the fusiform face area (FFA) and the occipital face area (OFA), which together are thought to constitute the core network of brain areas responsible for facial identification. Although accruing evidence has shown that face-selective patches in the ventral anterior temporal lobes (vATLs) are interconnected with the FFA and OFA, and that they play a role in facial identification, the relative contribution of these brain areas to the core face-processing network has remained unarticulated. Here we review recent research critically implicating the vATLs in face perception and memory. We propose that current models of face processing should be revised such that the ventral anterior temporal lobes serve a centralized role in the visual face-processing network. We speculate that a hierarchically organized system of face processing areas extends bilaterally from the inferior occipital gyri to the vATLs, with facial representations becoming increasingly complex and abstracted from low-level perceptual features as they move forward along this network. The anterior temporal face areas may serve as the apex of this hierarchy, instantiating the final stages of face recognition. We further argue that the anterior temporal face areas are ideally suited to serve as an interface between face perception and face memory, linking perceptual representations of individual identity with person-specific semantic knowledge. PMID:24937188

Ventral striatal dysfunction in cocaine dependence - difference mapping for subregional resting state functional connectivity.

PubMed

Zhang, Sheng; Li, Chiang-Shan R

2018-06-18

Research of dopaminergic deficits has focused on the ventral striatum (VS) with many studies elucidating altered resting state functional connectivity (rsFC) in individuals with cocaine dependence (CD). The VS comprises functional subregions and delineation of subregional changes in rsFC requires careful consideration of the differences between addicted and healthy populations. In the current study, we parcellated the VS using whole-brain rsFC differences between CD and non-drug-using controls (HC). Voxels with similar rsFC changes formed functional clusters. The results showed that the VS was divided into 3 subclusters, in the area of the dorsal-anterior VS (daVS), dorsal posterior VS (dpVS), and ventral VS (vVS), each in association with different patterns of rsFC. The three subregions shared reduced rsFC with bilateral hippocampal/parahippocampal gyri (HG/PHG) but also showed distinct changes, including reduced vVS rsFC with ventromedial prefrontal cortex (vmPFC) and increased daVS rsFC with visual cortex in CD as compared to HC. Across CD, daVS visual cortical connectivity was positively correlated with amount of prior-month cocaine use and cocaine craving, and vVS vmPFC connectivity was negatively correlated with the extent of depression and anxiety. These findings suggest a distinct pattern of altered VS subregional rsFC in cocaine dependence, and some of the changes have eluded analyses using the whole VS as a seed region. The findings may provide new insight to delineating VS circuit deficits in cocaine dependence and provide an alternative analytical framework to address functional dysconnectivity in other mental illnesses.

Effect of emotional valence on retrieval-related recapitulation of encoding activity in the ventral visual stream

PubMed Central

Kark, Sarah M.; Kensinger, Elizabeth A.

2015-01-01

While prior work has shown greater retrieval-related reactivation in the ventral visual stream for emotional stimuli compared to neutral stimuli, the effects of valence on retrieval-related recapitulation of successful encoding processes (Dm effects) have yet to be investigated. Here, seventeen participants (aged 19–35) studied line drawings of negative, positive, or neutral images followed immediately by the complete photo. After a 20-minute delay, participants performed a challenging recognition memory test, distinguishing the studied line drawing outlines from novel ones. First, results replicated earlier work by demonstrating that negative and positive hits elicited greater ventral occipito-temporal cortex (VOTC) activity than neutral hits during both encoding and retrieval. Moreover, the amount of activation in portions of the VOTC correlated with the magnitude of participants’ emotional memory enhancement. Second, results revealed significant retrieval-related recapitulation of Dm effects (Hits > Misses) in VOTC (anterior inferior temporal gyri) only for negative stimuli. Third, connectivity between the amygdala and fusiform gyrus during the encoding of negative stimuli increased the likelihood of fusiform activation during successful retrieval. Together, these results suggest that recapitulation in posterior VOTC reflects memory for the affective dimension of the stimuli (Emotional Hits > Neutral Hits) and the magnitude of activation in some of these regions is related to superior emotional memory. Moreover, for negative stimuli, recapitulation in more anterior portions of the VOTC is greater for remembered than forgotten items. The current study offers new evidence for effects of emotion on recapitulation of activity and functional connectivity in support of memory. PMID:26459096

Effect of emotional valence on retrieval-related recapitulation of encoding activity in the ventral visual stream.

PubMed

Kark, Sarah M; Kensinger, Elizabeth A

2015-11-01

While prior work has shown greater retrieval-related reactivation in the ventral visual stream for emotional stimuli compared to neutral stimuli, the effects of valence on retrieval-related recapitulation of successful encoding processes (Dm effects) have yet to be investigated. Here, seventeen participants (aged 19-35) studied line drawings of negative, positive, or neutral images followed immediately by the complete photo. After a 20-min delay, participants performed a challenging recognition memory test, distinguishing the studied line drawing outlines from novel ones. First, results replicated earlier work by demonstrating that negative and positive hits elicited greater ventral occipito-temporal cortex (VOTC) activity than neutral hits during both encoding and retrieval. Moreover, the amount of activation in portions of the VOTC correlated with the magnitude of participants' emotional memory enhancement. Second, results revealed significant retrieval-related recapitulation of Dm effects (Hits>Misses) in VOTC (anterior inferior temporal gyri) only for negative stimuli. Third, connectivity between the amygdala and fusiform gyrus during the encoding of negative stimuli increased the likelihood of fusiform activation during successful retrieval. Together, these results suggest that recapitulation in posterior VOTC reflects memory for the affective dimension of the stimuli (Emotional Hits>Neutral Hits) and the magnitude of activation in some of these regions is related to superior emotional memory. Moreover, for negative stimuli, recapitulation in more anterior portions of the VOTC is greater for remembered than forgotten items. The current study offers new evidence for effects of emotion on recapitulation of activity and functional connectivity in support of memory. Copyright © 2015 Elsevier Ltd. All rights reserved.

Investigating Occipito-Temporal Contributions to Reading with TMS

ERIC Educational Resources Information Center

Duncan, Keith J.; Pattamadilok, Chotiga; Devlin, Joseph T.

2010-01-01

The debate regarding the role of ventral occipito-temporal cortex (vOTC) in visual word recognition arises, in part, from difficulty delineating the functional contributions of vOTC as separate from other areas of the reading network. Here, we investigated the feasibility of using TMS to interfere with vOTC processing in order to explore its…