These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Disambiguating the roles of area V1 and the lateral occipital complex (LOC) in contour integration  

PubMed Central

Contour integration, the linking of collinear but disconnected visual elements across space, is an essential facet of object and scene perception. Here, we set out to arbitrate between two previously advanced mechanisms of contour integration: serial facilitative interactions between collinear cells in the primary visual cortex (V1) versus pooling of inputs in higher-order visual areas. To this end, we used high-density electrophysiological recordings to assess the spatio-temporal dynamics of brain activity in response to Gabor contours embedded in Gabor noise (so-called “pathfinder displays”) versus control stimuli. Special care was taken to elicit and detect early activity stemming from the primary visual cortex, as indexed by the C1 component of the visual evoked potential. Arguing against a purely early V1 account, there was no evidence for contour-related modulations within the C1 timeframe (50-100 msecs). Rather, the earliest effects were observed within the timeframe of the N1 component (160-200 msecs) and inverse source analysis pointed to principle generators in the lateral occipital complex (LOC) within the ventral visual stream. Source anlaysis also suggested that it was only during this relatively late processing period that contextual effects emerged in hierarchically early visual regions (i.e. V1/V2), consistent with a more distributed process involving recurrent feedback/feedforward interactions between LOC and early visual sensory regions. The distribution of effects uncovered here is consistent with pooling of information in higher order cortical areas as the initial step in contour integration, and that this pooling occurs relatively late in processing rather than during the initial sensory-processing period. PMID:23201366

Shpaner, Marina; Molholm, Sophie; Forde, Emma-Jane; Foxe, John J.

2013-01-01

2

Involvement of the Superior Temporal Cortex and the Occipital Cortex in Spatial Hearing: Evidence from Repetitive Transcranial Magnetic Stimulation  

Microsoft Academic Search

The processing of auditory spatial information in cortical areas of the human brain outside of the primary auditory cortex remains poorly understood. Here we investigated the role of the superior temporal gyrus (STG) and the occipital cortex (OC) in spatial hearing using repetitive transcranial magnetic stimulation (rTMS). The right STG is known to be of crucial importance for visual spatial

Jörg Lewald; Ingo G. Meister; Jürgen Weidemann; Rudolf Töpper

2004-01-01

3

Mapping hV4 and ventral occipital cortex: The venous eclipse  

E-print Network

occipital (VO) cortex. Much of the interest stems from functional magnetic resonance imaging (fMRI) reports, Lalonde, Wiggs, & Ungerleider, 1995). There also have been several measurements of visual field maps in nearly all subjects. In the experiments we report here, we set out to answer specific questions about one

Wandell, Brian A.

4

The Causal Role of the Occipital Face Area (OFA) and Lateral Occipital (LO) Cortex in Symmetry Perception.  

PubMed

Symmetry is an important cue in face and object perception. Here we used fMRI-guided transcranial magnetic stimulation (TMS) to shed light on the role of the occipital face area (OFA), a key region in face processing, and the lateral occipital (LO) cortex, a key area in object processing, in symmetry detection. In the first experiment, we applied TMS over the rightOFA, its left homolog (leftOFA), rightLO, and vertex (baseline) while participants were discriminating between symmetric and asymmetric dot patterns. Stimulation of rightOFA and rightLO impaired performance, causally implicating these two regions in detection of symmetry in low-level dot configurations. TMS over rightLO but not rightOFA also significantly impaired detection of nonsymmetric shapes defined by collinear Gabor patches, demonstrating that rightOFA responds to symmetry but not to all cues mediating figure-ground segregation. The second experiment showed a causal role for rightOFA but not rightLO in facial symmetry detection. Overall, our results demonstrate that both the rightOFA and rightLO are sensitive to symmetry in dot patterns, whereas only rightOFA is causally involved in facial symmetry detection. PMID:25589766

Bona, Silvia; Cattaneo, Zaira; Silvanto, Juha

2015-01-14

5

Stimulating occipital cortex enhances visual working memory consolidation.  

PubMed

Visual working memory (WM) enables us to store and manipulate visual information for a short duration. Traditionally, prefrontal and parietal regions have been associated with visual WM processing; however recent fMRI studies have shown that visual WM information can be decoded from the visual cortex as well. In this study, we used transcranial direct current stimulation (tDCS) to investigate the role of the visual cortex in retaining visual WM information. All subjects participated in two sessions of sham and active tDCS followed by a standard visual WM task. Two conditions were tested: in short encoding trials, the memory array (6 colored circles) was presented for 200ms whereas in long encoding trials it was presented for 500ms. We hypothesized that if stimulation over visual cortex modulates WM retention, then performance should be enhanced in both encoding conditions. However, if stimulation over visual cortex modulates mainly WM consolidation, then performance should improve only in the short encoding condition. The results supported the latter possibility as stimulation improved performance in the short encoding condition but not in the long encoding condition. Consequently, the robust advantage of the long encoding condition over the short encoding condition after sham stimulation was eliminated after active stimulation. These results suggest that the visual cortex is significant for WM consolidation, while it plays a smaller part in holding visual WM representations. PMID:25205369

Makovski, Tal; Lavidor, Michal

2014-12-15

6

Saccadic Suppression Induces Focal Hypooxygenation in the Occipital Cortex  

Microsoft Academic Search

This study investigated how a decrease in neuronal activity affects cerebral blood oxygenation employing a paradigm of acoustically triggered saccades in complete darkness. Known from behavioral evidence as saccadic suppression, electrophysiologically it has been shown in monkeys that during saccades an attenuation of activity occurs in visual cortex neurons (Duffy and Burchfiel, 1975). In study A, using blood oxygen level-dependent

Petra Wobst; Hauke H. Heekeren; Kenneth K. Kwong; Stephan A. Brandt; Matthias Kohl; Hellmuth Obrig; Ulrich Dirnagl; Arno Villringer; Rüdiger Wenzel

2000-01-01

7

Impact of blindness onset on the functional organization and the connectivity of the occipital cortex.  

PubMed

Contrasting the impact of congenital versus late-onset acquired blindness provides a unique model to probe how experience at different developmental periods shapes the functional organization of the occipital cortex. We used functional magnetic resonance imaging to characterize brain activations of congenitally blind, late-onset blind and two groups of sighted control individuals while they processed either the pitch or the spatial attributes of sounds. Whereas both blind groups recruited occipital regions for sound processing, activity in bilateral cuneus was only apparent in the congenitally blind, highlighting the existence of region-specific critical periods for crossmodal plasticity. Most importantly, the preferential activation of the right dorsal stream (middle occipital gyrus and cuneus) for the spatial processing of sounds was only observed in the congenitally blind. This demonstrates that vision has to be lost during an early sensitive period in order to transfer its functional specialization for space processing toward a non-visual modality. We then used a combination of dynamic causal modelling with Bayesian model selection to demonstrate that auditory-driven activity in primary visual cortex is better explained by direct connections with primary auditory cortex in the congenitally blind whereas it relies more on feedback inputs from parietal regions in the late-onset blind group. Taken together, these results demonstrate the crucial role of the developmental period of visual deprivation in (re)shaping the functional architecture and the connectivity of the occipital cortex. Such findings are clinically important now that a growing number of medical interventions may restore vision after a period of visual deprivation. PMID:23831614

Collignon, Olivier; Dormal, Giulia; Albouy, Geneviève; Vandewalle, Gilles; Voss, Patrice; Phillips, Christophe; Lepore, Franco

2013-09-01

8

Object-Related Activity Revealed by Functional Magnetic Resonance Imaging in Human Occipital Cortex  

Microsoft Academic Search

The stages of integration leading from local feature analysis to object recognition were explored in human visual cortex by using the technique of functional magnetic resonance imaging. Here we report evidence for object-related activation. Such activation was located at the lateral-posterior aspect of the occipital lobe, just abutting the posterior aspect of the motion-sensitive area MT\\/V5, in a region termed

R. Malach; J. B. Reppas; R. R. Benson; K. K. Kwong; H. Jiang; W. A. Kennedy; P. J. Ledden; T. J. Brady; B. R. Rosen; R. B. H. Tootell

1995-01-01

9

MEG reveals a fast pathway from somatosensory cortex to occipital areas via posterior parietal cortex in a blind subject  

PubMed Central

Cross-modal activity in visual cortex of blind subjects has been reported during performance of variety of non-visual tasks. A key unanswered question is through which pathways non-visual inputs are funneled to the visual cortex. Here we used tomographic analysis of single trial magnetoencephalography (MEG) data recorded from one congenitally blind and two sighted subjects after stimulation of the left and right median nerves at three intensities: below sensory threshold, above sensory threshold and above motor threshold; the last sufficient to produce thumb twitching. We identified reproducible brain responses in the primary somatosensory (S1) and motor (M1) cortices at around 20 ms post-stimulus, which were very similar in sighted and blind subjects. Time-frequency analysis revealed strong 45–70 Hz activity at latencies of 20–50 ms in S1 and M1, and posterior parietal cortex Brodmann areas (BA) 7 and 40, which compared to lower frequencies, were substantially more pronounced in the blind than the sighted subjects. Critically, at frequencies from ?-band up to 100 Hz we found clear, strong, and widespread responses in the visual cortex of the blind subject, which increased with the intensity of the somatosensory stimuli. Time-delayed mutual information (MI) revealed that in blind subject the stimulus information is funneled from the early somatosensory to visual cortex through posterior parietal BA 7 and 40, projecting first to visual areas V5 and V3, and eventually V1. The flow of information through this pathway occurred in stages characterized by convergence of activations into specific cortical regions. In sighted subjects, no linked activity was found that led from the somatosensory to the visual cortex through any of the studied brain regions. These results provide the first evidence from MEG that in blind subjects, tactile information is routed from primary somatosensory to occipital cortex via the posterior parietal cortex. PMID:23935576

Ioannides, Andreas A.; Liu, Lichan; Poghosyan, Vahe; Saridis, George A.; Gjedde, Albert; Ptito, Maurice; Kupers, Ron

2013-01-01

10

The Lateral Occipital Cortex in the Face Perception Network: An Effective Connectivity Study  

PubMed Central

The perception of faces involves a large network of cortical areas of the human brain. While several studies tested this network recently, its relationship to the lateral occipital (LO) cortex known to be involved in visual object perception remains largely unknown. We used functional magnetic resonance imaging and dynamic causal modeling (DCM) to test the effective connectivity among the major areas of the face-processing core network and LO. Specifically, we tested how LO is connected to the fusiform face area (FFA) and occipital face area (OFA) and which area provides the major face/object input to the network. We found that LO is connected via significant bidirectional connections to both OFA and FFA, suggesting the existence of a triangular network. In addition, our results also suggest that face- and object-related stimulus inputs are not entirely segregated at these lower level stages of face-processing and enter the network via the LO. These results support the role of LO in face perception, at least at the level of face/non-face stimulus discrimination. PMID:22593748

Nagy, Krisztina; Greenlee, Mark W.; Kovács, Gyula

2012-01-01

11

Repetition suppression for speech processing in the associative occipital and parietal cortex of congenitally blind adults.  

PubMed

In the congenitally blind (CB), sensory deprivation results in cross-modal plasticity, with visual cortical activity observed for various auditory tasks. This reorganization has been associated with enhanced auditory abilities and the recruitment of visual brain areas during sound and language processing. The questions we addressed are whether visual cortical activity might also be observed in CB during passive listening to auditory speech and whether cross-modal plasticity is associated with adaptive differences in neuronal populations compared to sighted individuals (SI). We focused on the neural substrate of vowel processing in CB and SI adults using a repetition suppression (RS) paradigm. RS has been associated with enhanced or accelerated neural processing efficiency and synchronous activity between interacting brain regions. We evaluated whether cortical areas in CB were sensitive to RS during repeated vowel processing and whether there were differences across the two groups. In accordance with previous studies, both groups displayed a RS effect in the posterior temporal cortex. In the blind, however, additional occipital, temporal and parietal cortical regions were associated with predictive processing of repeated vowel sounds. The findings suggest a more expanded role for cross-modal compensatory effects in blind persons during sound and speech processing and a functional transfer of specific adaptive properties across neural regions as a consequence of sensory deprivation at birth. PMID:23717628

Arnaud, Laureline; Sato, Marc; Ménard, Lucie; Gracco, Vincent L

2013-01-01

12

Knockdown of ?2C-adrenoceptors in the occipital cortex rescued long-term potentiation in hidden prenatally malnourished rats.  

PubMed

Moderate reduction in the protein content of the mother's diet calorically compensated by carbohydrates (the so-called "hidden" prenatal malnutrition) leads to increased neocortical expression of the ?(2C)-adrenoceptor subtype, together with decreased cortical release of noradrenaline and impaired long-term potentiation (LTP) and visuospatial memory performance during the rat postnatal life. In order to study whether overexpression of the ?(2C)-adrenoceptor subtype is causally related to the decreased indices of neocortical plasticity found in prenatally malnourished rats, we evaluated the effect of intracortical (occipital cortex) administration of an antisense oligodeoxynucleotide (ODN) raised against the ?(2C)-adrenoceptor mRNA on the LTP elicited in vivo in the occipital cortex of hidden prenatally malnourished rats. In addition, we compare the effect of the antisense ODN to that produced by systemical administration of the subtype-nonselective ?(2)-adrenoceptor antagonist atipamezole. Prenatal protein malnutrition led to impaired occipital cortex LTP together with increased expression of ?(2C)-adrenoceptors (about twice Bmax) in the same cortical region. [(3)H]-rauwolscine binding assay showed that a 7-day intracortical antisense ODN treatment in the malnourished rats resulted in 50% knockdown of ?(2C)-adrenoceptor expression and, in addition, completely rescued the ability of the occipital cortex to develop and maintain long-term potentiation. Atipamezole (0.3 mg/kg i.p.) also led to full recovery of neocortical LTP in malnourished rats. The present results argue in favor of our original hypothesis that the deleterious effect of prenatal malnutrition on neocortical plasticity in the adult progeny is in part consequence of increased neocortical ?(2C)-adrenoceptor expression. This receptor subtype is known to be involved in the presynaptic control of noradrenaline release from central neurons, a neurotransmitter that critically influences LTP and memory formation. PMID:22892388

Barra, Rafael; Soto-Moyano, Rubén; Valladares, Luis; Morgan, Carlos; Pérez, Hernán; Burgos, Héctor; Olivares, Ricardo; Sáez-Briones, Patricio; Laurido, Claudio; Hernández, Alejandro

2012-10-01

13

Gene expression in the rat brain: High similarity but unique differences between frontomedial-, temporal- and occipital cortex  

PubMed Central

Background The six-layered neocortex of the mammalian brain may appear largely homologous, but is in reality a modular structure of anatomically and functionally distinct areas. However, global gene expression seems to be almost identical across the cerebral cortex and only a few genes have so far been reported to show regional enrichment in specific cortical areas. Results In the present study on adult rat brain, we have corroborated the strikingly similar gene expression among cortical areas. However, differential expression analysis has allowed for the identification of 30, 24 and 11 genes enriched in frontomedial -, temporal- or occipital cortex, respectively. A large proportion of these 65 genes appear to be involved in signal transduction, including the ion channel Fxyd6, the neuropeptide Grp and the nuclear receptor Rorb. We also find that the majority of these genes display increased expression levels around birth and show distinct preferences for certain cortical layers and cell types in rodents. Conclusions Since specific patterns of expression often are linked to equally specialised biological functions, we propose that these cortex sub-region enriched genes are important for proper functioning of the cortical regions in question. PMID:21269499

2011-01-01

14

Greater sensitivity to nonaccidental than metric changes in the relations between simple shapes in the lateral occipital cortex.  

PubMed

Behavioral studies and single cell recordings in monkey inferotemporal cortex have documented greater sensitivity to differences in viewpoint invariant or nonaccidental properties (e.g., straight vs. curved), than metric properties (e.g., degree of curvature) of simple shapes. Are we similarly more sensitive to nonaccidental (NAP) than metric (MP) differences of the relations between objects? We addressed this question with sets of scene triplets that could, from a reference or "Base" scene (e.g., a brick slightly separated from a cylinder), undergo a NAP relational change (e.g., the brick attached to the cylinder) or an MP relational change (e.g., the brick further separated from the cylinder). Critically, both relational variations were matched in physical dissimilarity using pixel energy and the Gabor-jet system, a model of V1 similarity. In an adaptive staircase match-to-sample paradigm, subjects required more than double the presentation durations for detecting differences in MP than NAP relations to achieve equivalent levels of accuracy. In two fMRI experiments, NAP changes consistently produced greater responses in the lateral occipital cortex (LO), but not in earlier retinotopic stages, compared to MP changes, implicating LO as the potential neural locus for where the greater detectability of the differences of NAPs than MPs is made explicit. HMAX, a model of cell tuning in higher-level ventral visual areas, did not consistently reflect the marked NAP advantage witnessed in behavioral performance and in LO responses. PMID:22960149

Kim, Jiye G; Biederman, Irving

2012-12-01

15

Retinal abnormalities in human albinism translate into a reduction of grey matter in the occipital cortex  

E-print Network

cell nerve fibres at the optic chiasm. We examined 19 subjects with albinism and 26 control subjects London, UK Keywords: albinism, foveal hypoplasia, visual cortex, voxel-based morphometry Abstract pathway. Normally, ganglion cell axons from nasal retina cross at the optic chiasm and project

Morland, Antony

16

Neural mechanisms of feature conjunction learning: enduring changes in occipital cortex after a week of training.  

PubMed

Most visual activities, whether reading, driving, or playing video games, require rapid detection and identification of learned patterns defined by arbitrary conjunctions of visual features. Initially, such detection is slow and inefficient, but it can become fast and efficient with training. To determine how the brain learns to process conjunctions of visual features efficiently, we trained participants over eight consecutive days to search for a target defined by an arbitrary conjunction of color and location among distractors with a different conjunction of the same features. During each training session, we measured brain activity with functional magnetic resonance imaging (fMRI). The speed of visual search for feature conjunctions improved dramatically within just a few days. These behavioral improvements were correlated with increased neural responses to the stimuli in visual cortex. This suggests that changes in neural processing in visual cortex contribute to the speeding up of visual feature conjunction search. We find evidence that this effect is driven by an increase in the signal-to-noise ratio (SNR) of the BOLD signal for search targets over distractors. In a control condition where target and distractor identities were exchanged after training, learned search efficiency was abolished, suggesting that the primary improvement was perceptual learning for the search stimuli, not task-learning. Moreover, when participants were retested on the original task after nine months without further training, the acquired changes in behavior and brain activity were still present, showing that this can be an enduring form of learning and neural reorganization. PMID:23418123

Frank, Sebastian M; Reavis, Eric A; Tse, Peter U; Greenlee, Mark W

2014-04-01

17

rTMS of medial parieto-occipital cortex interferes with attentional reorienting during attention and reaching tasks.  

PubMed

Unexpected changes in the location of a target for an upcoming action require both attentional reorienting and motor planning update. In both macaque and human brain, the medial posterior parietal cortex is involved in both phenomena but its causal role is still unclear. Here we used on-line rTMS over the putative human V6A (pV6A), a reach-related region in the dorsal part of the anterior bank of the parieto-occipital sulcus, during an attention and a reaching task requiring covert shifts of attention and planning of reaching movements toward cued targets in space. We found that rTMS increased RTs to invalidly cued but not to validly cued targets during both the attention and reaching task. Furthermore, we found that rTMS induced a deviation of reaching endpoints toward visual fixation and that this deviation was larger for invalidly cued targets. The results suggest that reorienting signals are used by human pV6A area to rapidly update the current motor plan or the ongoing action when a behaviorally relevant object unexpectedly occurs in an unattended location. The current findings suggest a direct involvement of the action-related dorso-medial visual stream in attentional reorienting and a more specific role of pV6A area in the dynamic, on-line control of reaching actions. PMID:23647519

Ciavarro, Marco; Ambrosini, Ettore; Tosoni, Annalisa; Committeri, Giorgia; Fattori, Patrizia; Galletti, Claudio

2013-09-01

18

Occipital alpha activity during stimulus processing gates the information flow to object-selective cortex.  

PubMed

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

Zumer, Johanna M; Scheeringa, René; Schoffelen, Jan-Mathijs; Norris, David G; Jensen, Ole

2014-10-01

19

Occipital Alpha Activity during Stimulus Processing Gates the Information Flow to Object-Selective Cortex  

PubMed Central

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

Zumer, Johanna M.; Scheeringa, René; Schoffelen, Jan-Mathijs; Norris, David G.; Jensen, Ole

2014-01-01

20

Size precedes view: developmental emergence of invariant object representations in lateral occipital complex.  

PubMed

Although object perception involves encoding a wide variety of object properties (e.g., size, color, viewpoint), some properties are irrelevant for identifying the object. The key to successful object recognition is having an internal representation of the object identity that is insensitive to these properties while accurately representing important diagnostic features. Behavioral evidence indicates that the formation of these kinds of invariant object representations takes many years to develop. However, little research has investigated the developmental emergence of invariant object representations in the ventral visual processing stream, particularly in the lateral occipital complex (LOC) that is implicated in object processing in adults. Here, we used an fMR adaptation paradigm to evaluate age-related changes in the neural representation of objects within LOC across variations in size and viewpoint from childhood through early adulthood. We found a dissociation between the neural encoding of object size and object viewpoint within LOC: by age of 5-10 years, area LOC demonstrates adaptation across changes in size, but not viewpoint, suggesting that LOC responses are invariant to size variations, but that adaptation across changes in view is observed in LOC much later in development. Furthermore, activation in LOC was correlated with behavioral indicators of view invariance across the entire sample, such that greater adaptation was correlated with better recognition of objects across changes in viewpoint. We did not observe similar developmental differences within early visual cortex. These results indicate that LOC acquires the capacity to compute invariance specific to different sources of information at different time points over the course of development. PMID:25244115

Nishimura, Mayu; Scherf, K Suzanne; Zachariou, Valentinos; Tarr, Michael J; Behrmann, Marlene

2015-03-01

21

S100 immunoreactivity is increased in reactive astrocytes of the visual pathways following a mechanical lesion of the rat occipital cortex.  

PubMed

After demonstration of the paracrine action of glial neurotrophic factors, gliosis has also been considered to be related to neuronal trophism and plasticity rather than solely a repair event following brain injury. S100 is a Ca2+ binding protein, present mainly in astrocytes, that exerts paracrine trophic effects on several neuronal populations. This study analyses the presence of S100 protein by means of immunohistochemistry combined with stereology in the reactive glial cells of the rat visual pathways following a lesion of the visual cortex. Adult male Wistar rats were submitted to a unilateral aspiration of the occipital cortex or to a sham operation. One week later the rats were killed and their brain processed for immunochemistry. Single antibody immunohistochemistry was performed for the visualization of glial fibrillary acidic protein (GFAP, a marker for astrocytes), OX-42 (a marker for microglia) and S100 protein. Double immunofluorescence procedures were applied for co-localization of the S100/GFAP and S100/OX-42. An optical dissector, point interceptors and rotators were used to quantify the degree of glial activation and the changes in the S100 immunoreactivity. We observed an intense microglial and astroglial reaction in addition to an increased S100 immunoreactivity in the occipital cerebral cortex, geniculate nucleus and hippocampus ipsilateral to the lesion. In the ipsilateral superior colliculus, an intense astroglial activation was accompanied by an up-regulation of S100 immunoreactivity. Double-immunofluoresence revealed an increased S100 immunoreactivity in reactive astrocytes, but not in the reactive microglia. Evidence has therefore been obtained that after mechanical trauma, the astroglial S100 protein participates in the trophism and plasticity of the injured visual pathways. PMID:10826771

Cerutti, S M; Chadi, G

2000-01-01

22

[Modulation of the functional activity of the acoustic and visual analyzers under conditions of listening to one's own EEG acoustic image of the temporal and occipital cortex areas].  

PubMed

Investigation into the functional activity of the acoustic and visual analyzer has been carried out before and after procedures of listening to one's own EEG of the temporal and occipital cortex areas. It has been shown, that there is a dependence of the dynamics of latent periods of sensomotor response to modality of stimuli and localization of source of the EEG acoustic image. After listening to acoustic image of the temporal EEG, a reduction of sensomotor reaction latency in the acoustic test has been observed. After listening to acoustic image of the occipital EEC, a reduction of sensomotor reaction latency in the visual test has been observed. In the control session after listening to A. Vivaldi's music, no significant shifts of sensomotor reaction latency have been observed. A conclusion has been made that, under conditions of local EEG-acoustic feedback, there is a selective elevation of functional activity of the brain areas used as the EEG-source for acoustic image forming. PMID:19323448

Konstantinov, K V; Trushina, V N; Iakovlev, N M; Klimenko, V M

2009-01-01

23

Changes in cytochrome-oxidase oxidation in the occipital cortex during visual simulation: improvement in sensitivity by the determination of the wavelength dependence of the differential pathlength  

NASA Astrophysics Data System (ADS)

In this study we assess changes in the hemoglobin oxygenation (oxy-Hb, deoxy-Hb) and the Cytochrome-C-Oxidase redox state (Cyt-ox) in the occipital cortex during visual stimulation by near infrared spectroscopy. For the calculation of changes in oxy-Hb, deoxy-Hb and Cyt-ox from attenuation data via a modified Beer-Lambert equation, the wavelength dependence of the differential pathlength factor (DPF), i.e. the ratio of the mean optical pathlength and the physical light-source-detector separation, has to be taken into account. The wavelength dependence of the DPF determines the crosstalk between the different concentrations and is therefore essential for a high sensitivity. Here a simple method is suggested to estimate the wavelength dependence of the DPF((lambda) ) from pulse induced attenuation changes measured on the head of adult humans. The essence is that the DPF is the ratio of the attenuation changes over absorption coefficient changes and the spectral form of the pulse correlated absorption coefficient change is proportional to the extinction coefficient of blood. Indicators for the validity of the DPF((lambda) ) derived for wavelengths between 700 and 970 nm are the stability of the calculated oxy-Hb, deoxy-Hb and Cyt-ox signals with variations of the wavelength range included for their calculation and its overall agreement with the data available from the literature. The DPF derived from pulse measurements was used for the analysis of attenuation data from cortical stimulations. We show that Cyt-ox in the occipital cortex of human subjects is transiently oxidized during visual stimulation.

Kohl, Matthias; Nolte, Christian; Heekeren, Hauke R.; Horst, Susanne; Scholz, Udo; Obrig, Hellmuth; Villringer, Arno

1997-12-01

24

Changes in cytochrome-oxidase oxidation in the occipital cortex during visual simulation: improvement in sensitivity by the determination of the wavelength dependence of the differential pathlength  

NASA Astrophysics Data System (ADS)

In this study we assess changes in the hemoglobin oxygenation (oxy-Hb, deoxy-Hb) and the Cytochrome-C-Oxidase redox state (Cyt-ox) in the occipital cortex during visual stimulation by near infrared spectroscopy. For the calculation of changes in oxy-Hb, deoxy-Hb and Cyt-ox from attenuation data via a modified Beer-Lambert equation, the wavelength dependence of the differential pathlength factor (DPF), i.e. the ratio of the mean optical pathlength and the physical light-source-detector separation, has to be taken into account. The wavelength dependence of the DPF determines the crosstalk between the different concentrations and is therefore essential for a high sensitivity. Here a simple method is suggested to estimate the wavelength dependence of the DPF((lambda) ) from pulse induced attenuation changes measured on the head of adult humans. The essence is that the DPF is the ratio of the attenuation changes over absorption coefficient changes and the spectral form of the pulse correlated absorption coefficient change is proportional to the extinction coefficient of blood. Indicators for the validity of the DPF((lambda) ) derived for wavelengths between 700 and 970 nm are the stability of the calculated oxy-Hb, deoxy-Hb and Cyt-ox signals with variations of the wavelength range included for their calculation and its overall agreement with the data available from the literature. The DPF derived from pulse measurements was used for the analysis of attenuation data from cortical stimulations. We show that Cyt-ox in the occipital cortex of human subjects is transiently oxidized during visual stimulation.

Kohl-Bareis, Matthias; Nolte, Christian; Heekeren, Hauke R.; Horst, Susanne; Scholz, J.; Obrig, Hellmuth; Villringer, Arno

1998-01-01

25

Evidence for participation by object-selective visual cortex in scene category judgments.  

PubMed

Scene recognition is a core function of the visual system, drawing both on scenes' intrinsic global features, prominently their spatial properties, and on the identities of the objects scenes contain. Neuroimaging and neuropsychological studies have associated spatial property-based scene categorization with parahippocampal cortex, while processing of scene-relevant object information is associated with the lateral occipital complex (LOC), wherein activity patterns distinguish between categories of standalone objects and those embedded in scenes. However, despite the importance of objects to scene categorization and the role of LOC in processing them, damage or disruption to LOC that hampers object recognition has been shown to improve scene categorization. To address this paradox, we used functional magnetic resonance imaging (fMRI) to directly assess the contributions of LOC and the parahippocampal place area (PPA) to category judgments of indoor scenes that were devoid of objective identity signals. Observers were alternately cued to base judgments on scenes' objects or spatial properties. In both LOC and PPA, multivoxel activity patterns better decoded judgments based on their typically associated features: LOC more accurately decoded object-based judgments, while PPA more accurately decoded spatial property-based judgments. The cue contingency of LOC decoding accuracy indicates that it was not an outcome of feedback from judgments and is instead consistent with dependency of judgments on the output of object processing pathways in which LOC participates. PMID:25146577

Linsley, Drew; MacEvoy, Sean P

2014-01-01

26

Fingerprints of Learned Object Recognition Seen in the fMRI Activation Patterns of Lateral Occipital Complex.  

PubMed

One feature of visual processing in the ventral stream is that cortical responses gradually depart from the physical aspects of the visual stimulus and become correlated with perceptual experience. Thus, unlike early retinotopic areas, the responses in the object-related lateral occipital complex (LOC) are typically immune to parameter changes (e.g., contrast, location, etc.) when these do not affect recognition. Here, we use a complementary approach to highlight changes in brain activity following a shift in the perceptual state (in the absence of any alteration in the physical image). Specifically, we focus on LOC and early visual cortex (EVC) and compare their functional magnetic resonance imaging (fMRI) responses to degraded object images, before and after fast perceptual learning that renders initially unrecognized objects identifiable. Using 3 complementary analyses, we find that, in LOC, unlike EVC, learned recognition is associated with a change in the multivoxel response pattern to degraded object images, such that the response becomes significantly more correlated with that evoked by the intact version of the same image. This provides further evidence that the coding in LOC reflects the recognition of visual objects. PMID:24692511

Roth, Zvi N; Zohary, Ehud

2014-03-31

27

Impaired Visual Object Processing Across an Occipital- Frontal-Hippocampal Brain Network in Schizophrenia: An integrated neuroimaging study  

PubMed Central

Background Perceptual closure refers to the ability to identify objects with partial information. Deficits in schizophrenia are indexed by impaired generation of the closure-related negativity (NCL) from ventral stream visual cortex (lateral occipital complex, LOC), as part of a network of brain regions that also includes dorsal stream visual regions, prefrontal cortex (PFC) and hippocampus. This study evaluates network-level interactions during perceptual closure in schizophrenia using parallel ERP, fMRI and neuropsychological assessment. Methods ERP were obtained from 24 patients and 20 healthy volunteers in response to fragmented (closeable) and control scrambled (noncloseable) line drawings. fMRI were obtained from 11 patients and 12 controls. Patterns of between group differences for predefined ERP components and fMRI regions of interest were determined using both analysis of variance and structural equation modeling. Global neuropsychological performance was assessed using elements of the WAIS-III, WMS-III and MATRICS batteries. Results Patients showed impaired visual P1 generation, reflecting dorsal stream dysfunction, along with impaired generation of NCL components over PFC and LOC. In fMRI, patients showed impaired activation of dorsal and ventral visual regions, PFC and hippocampus. Impaired activation of dorsal stream visual regions contributed significantly to impaired PFC activation. Impaired PFC activation contributed significantly to impaired activation of hippocampus and LOC. Impaired LOC and hippocampal activation contributed significantly to deficits on WAIS-III Perceptual Organization Index (POI) and other tests of impaired perceptual processing in schizophrenia. Conclusion Schizophrenia is associated with severe activation deficits across a distributed network of sensory and higher order cognitive regions. Deficit in early visual processing within the dorsal visual stream contributes significantly to impaired frontal activation which, in turn, leads to dysregulation of hippocampus and ventral visual stream. Dysfunction within this network underlies impairment in more traditional measures of neurocognitive dysfunction such as POI, supporting distributed models of brain dysfunction in schizophrenia. PMID:20679585

Sehatpour, Pejman; Dias, Elisa C.; Butler, Pamela D.; Revheim, Nadine; Guilfoyle, David N.; Foxe, John J.; Javitt, Daniel C.

2013-01-01

28

Occipital neuralgia: anatomic considerations.  

PubMed

Occipital neuralgia is a debilitating disorder first described in 1821 as recurrent headaches localized in the occipital region. Other symptoms that have been associated with this condition include paroxysmal burning and aching pain in the distribution of the greater, lesser, or third occipital nerves. Several etiologies have been identified in the cause of occipital neuralgia and include, but are not limited to, trauma, fibrositis, myositis, fracture of the atlas, and compression of the C-2 nerve root, C1-2 arthrosis syndrome, atlantoaxial lateral mass osteoarthritis, hypertrophic cervical pachymeningitis, cervical cord tumor, Chiari malformation, and neurosyphilis. The management of occipital neuralgia can include conservative approaches and/or surgical interventions. Occipital neuralgia is a multifactorial problem where multiple anatomic areas/structures may be involved with this pathology. A review of these etiologies may provide guidance in better understanding occipital neuralgia. PMID:25244129

Cesmebasi, Alper; Muhleman, Mitchel A; Hulsberg, Paul; Gielecki, Jerzy; Matusz, Petru; Tubbs, R Shane; Loukas, Marios

2015-01-01

29

Occipital nerve stimulation.  

PubMed

Occipital nerve stimulation (ONS) is a form of neuromodulation therapy aimed at treating intractable headache and craniofacial pain. The therapy utilizes neurostimulating electrodes placed subcutaneously in the occipital region and connected to a permanently implanted programmable pulse generator identical to those used for dorsal column/spinal cord stimulation. The presumed mechanisms of action involve modulation of the trigeminocervical complex, as well as closure of the physiologic pain gate. ONS is a reversible, nondestructive therapy, which can be tailored to a patient's individual needs. Typically, candidates for successful ONS include those patients with migraines, Chiari malformation, or occipital neuralgia. However, recent MRSA infections, unrealistic expectations, and psychiatric comorbidities are generally contraindications. As with any invasive procedure, complications may occur including lead migration, infection, wound erosion, device failure, muscle spasms, and pain. The success of this therapy is dependent on careful patient selection, a preimplantation trial, meticulous implantation technique, programming strategies, and complication avoidance. PMID:25411143

Mammis, Antonios; Agarwal, Nitin; Mogilner, Alon Y

2015-01-01

30

Cortical thinning in cingulate and occipital cortices in first episode schizophrenia Katherine L. Narr, Arthur W. Toga, Philip Szeszko, Paul M. Thompson, Roger P. Woods,  

E-print Network

Cortical thinning in cingulate and occipital cortices in first episode schizophrenia Katherine L maps showed significant cortical thinning within the cingulate cortex bilaterally, with pronounced) in schizophrenia patients compared to controls. Patients also showed cortical thinning in occipital and frontopolar

Thompson, Paul

31

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

PubMed Central

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

Kravitz, Dwight J.; Baker, Chris I.

2013-01-01

32

Downstream targets of methyl CpG binding protein 2 and their abnormal expression in the frontal cortex of the human Rett syndrome brain  

E-print Network

Background: The Rett Syndrome (RTT) brain displays regional histopathology and volumetric reduction, with frontal cortex showing such abnormalities, whereas the occipital cortex is relatively less affected. Results: Using ...

Gibson, Joanne H

33

Acute prefrontal cortex TMS in healthy volunteers: effects on brain 11C-alphaMtrp trapping.  

PubMed

High-frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex (LDLPFC) is a technique with purported efficacy as a treatment for major depression. Here, we assessed in vivo, in healthy volunteers, the effect of acute rTMS of the LDLPFC, relative to the stimulation of the left occipital cortex (LOC), on brain regional serotonin synthesis capacity, using the [(11)C]-alpha-methyl-tryptophan ((11)C-alphaMtrp)/PET method. Ten subjects were studied twice, once following rTMS of the LDLPFC and once following rTMS of the LOC in a randomized counterbalanced order. Three blocks of 15 trains of 10 Hz rTMS were delivered 10 min apart. Behavioural and autonomic measures were recorded before and after each rTMS session. Comparisons of TMS-related changes in regional normalized brain uptake and trapping of (11)C-alphaMtrp (K*) values were carried out using SPM99. Statistically significant regional differences were identified on the basis of an extent threshold of 50 voxels, with a peak threshold of p=0.005 uncorrected. Behavioural and autonomic measures were unaffected by rTMS. Relative to LOC stimulation, LDLPFC rTMS was associated with marked changes in normalized K* in limbic areas, with significantly lower values in the left parahippocampal gyrus (BA 28) and the right insula (BA 13), and higher values in the right cingulate gyrus (BA 31) and cuneus (BA 18). These findings indicate that acute rTMS of the LDLPFC in healthy volunteers modulates aspects of tryptophan/5-HT metabolism in limbic areas. Such adaptive changes may contribute to the mechanism of action of prefrontal rTMS in major depression. PMID:17188517

Sibon, I; Strafella, A P; Gravel, P; Ko, J H; Booij, L; Soucy, J P; Leyton, M; Diksic, M; Benkelfat, C

2007-02-15

34

LocTree3 prediction of localization.  

PubMed

The prediction of protein sub-cellular localization is an important step toward elucidating protein function. For each query protein sequence, LocTree2 applies machine learning (profile kernel SVM) to predict the native sub-cellular localization in 18 classes for eukaryotes, in six for bacteria and in three for archaea. The method outputs a score that reflects the reliability of each prediction. LocTree2 has performed on par with or better than any other state-of-the-art method. Here, we report the availability of LocTree3 as a public web server. The server includes the machine learning-based LocTree2 and improves over it through the addition of homology-based inference. Assessed on sequence-unique data, LocTree3 reached an 18-state accuracy Q18=80±3% for eukaryotes and a six-state accuracy Q6=89±4% for bacteria. The server accepts submissions ranging from single protein sequences to entire proteomes. Response time of the unloaded server is about 90 s for a 300-residue eukaryotic protein and a few hours for an entire eukaryotic proteome not considering the generation of the alignments. For over 1000 entirely sequenced organisms, the predictions are directly available as downloads. The web server is available at http://www.rostlab.org/services/loctree3. PMID:24848019

Goldberg, Tatyana; Hecht, Maximilian; Hamp, Tobias; Karl, Timothy; Yachdav, Guy; Ahmed, Nadeem; Altermann, Uwe; Angerer, Philipp; Ansorge, Sonja; Balasz, Kinga; Bernhofer, Michael; Betz, Alexander; Cizmadija, Laura; Do, Kieu Trinh; Gerke, Julia; Greil, Robert; Joerdens, Vadim; Hastreiter, Maximilian; Hembach, Katharina; Herzog, Max; Kalemanov, Maria; Kluge, Michael; Meier, Alice; Nasir, Hassan; Neumaier, Ulrich; Prade, Verena; Reeb, Jonas; Sorokoumov, Aleksandr; Troshani, Ilira; Vorberg, Susann; Waldraff, Sonja; Zierer, Jonas; Nielsen, Henrik; Rost, Burkhard

2014-07-01

35

Combined diffusion-weighted and functional magnetic resonance imaging reveals a temporal-occipital network involved in auditory-visual object processing  

PubMed Central

Functional magnetic resonance imaging (MRI) showed that the superior temporal and occipital cortex are involved in multisensory integration. Probabilistic fiber tracking based on diffusion-weighted MRI suggests that multisensory processing is supported by white matter connections between auditory cortex and the temporal and occipital lobe. Here, we present a combined functional MRI and probabilistic fiber tracking study that reveals multisensory processing mechanisms that remained undetected by either technique alone. Ten healthy participants passively observed visually presented lip or body movements, heard speech or body action sounds, or were exposed to a combination of both. Bimodal stimulation engaged a temporal-occipital brain network including the multisensory superior temporal sulcus (msSTS), the lateral superior temporal gyrus (lSTG), and the extrastriate body area (EBA). A region-of-interest (ROI) analysis showed multisensory interactions (e.g., subadditive responses to bimodal compared to unimodal stimuli) in the msSTS, the lSTG, and the EBA region. Moreover, sounds elicited responses in the medial occipital cortex. Probabilistic tracking revealed white matter tracts between the auditory cortex and the medial occipital cortex, the inferior occipital cortex (IOC), and the superior temporal sulcus (STS). However, STS terminations of auditory cortex tracts showed limited overlap with the msSTS region. Instead, msSTS was connected to primary sensory regions via intermediate nodes in the temporal and occipital cortex. Similarly, the lSTG and EBA regions showed limited direct white matter connections but instead were connected via intermediate nodes. Our results suggest that multisensory processing in the STS is mediated by separate brain areas that form a distinct network in the lateral temporal and inferior occipital cortex. PMID:23407860

Beer, Anton L.; Plank, Tina; Meyer, Georg; Greenlee, Mark W.

2013-01-01

36

Prenatal Imaging of Occipital Encephaloceles.  

PubMed

Introduction: This retrospective study aims to describe systematically the fetal cerebral MR morphology in cases with occipital meningoencephaloceles using standard and advanced fetal MRI techniques. Material and Methods: The 1.5-tesla MR examinations (T1- and T2-weighted imaging, echo planar imaging, EPI, diffusion-weighted imaging, DWI) of 14 fetuses with occipital/parietal meningoencephaloceles were retrospectively analyzed for the classification of anatomic characteristics. A diffusion tensor sequence was performed in 5 cases. Results: In 9/14 cases the occipital lobes were entirely or partially included in the encephalocele sac. Typical features of Chiari III malformation were seen in 6/14 cases. The displaced brain appeared grossly disorganized in 6/14. The brainstem displayed abnormal 'kinking'/rotation (3/14), a z-shape (1/14) and/or a molar tooth-like configuration of the midbrain (3/14). Tractography revealed the presence and position of sensorimotor tracts in 5/5 and the corpus callosum in 3/5. DWI was helpful in the identification of a displaced brain (in 8/9). EPI visualized the anatomy of draining cerebral veins in 7/9 cases. Clinical (9/14) and MRI (7/14) follow-up data are presented. Discussion: Encephaloceles show a wide range of morphological heterogeneity. Fetal MRI serves as an accurate tool in the visualization of brainstem, white matter pathway and cerebral venous involvement and facilitates the detection of specific underlying syndromes such as ciliopathies. © 2014 S. Karger AG, Basel. PMID:25358260

Kasprian, Gregor J; Paldino, Michael J; Mehollin-Ray, Amy R; Shetty, Anil; Williams, Jennifer L; Lee, Wesley; Cassady, Chris I

2014-10-29

37

Giant occipital osteoid osteoma mimicking calcified meningioma.  

PubMed

Osteoid osteoma is a benign bone tumor, which rarely occurs in the skull, and often causes local pain that is worse at night, characteristically relieved by aspirin. Giant osteoid osteoma in the occipital bone is uncommon. We present a case of a 42-year-old female with an osteoid osteoma of the occipital bone that was totally resected. We discuss the clinical presentation, radiographic findings, and differential diagnosis of occipital osteoid osteoma. PMID:21983381

Erten, Fuat; Hasturk, Askin E; Pak, Isin; Sokmen, Omer

2011-10-01

38

Occipital nerve stimulation for chronic migraine.  

PubMed

Occipital nerve stimulation may be effective in treating chronic migraine. Six studies, including three double-blind studies, were performed, with five showing evidence of benefit. However, of the three randomized, controlled trials, none has met a primary endpoint successfully. A separate study suggested a benefit for combined supraorbital and greater occipital nerve stimulation. PMID:24474153

Young, William B

2014-02-01

39

Individuating Faces and Common Objects Produces Equal Responses in Putative Face-Processing Areas in the Ventral Occipitotemporal Cortex  

PubMed Central

Controversy surrounds the proposal that specific human cortical regions in the ventral occipitotemporal cortex, commonly called the fusiform face area (FFA) and occipital face area (OFA), are specialized for face processing. Here, we present findings from an fMRI study of identity discrimination of faces and objects that demonstrates the FFA and OFA are equally responsive to processing stimuli at the level of individuals (i.e., individuation), be they human faces or non-face objects. The FFA and OFA were defined via a passive viewing task as regions that produced greater activation to faces relative to non-face stimuli within the middle fusiform gyrus and inferior occipital gyrus. In the individuation task, participants judged whether sequentially presented images of faces, diverse objects, or wristwatches depicted the identical or a different exemplar. All three stimulus types produced equivalent BOLD activation within the FFA and OFA; that is, there was no face-specific or face-preferential processing. Critically, individuation processing did not eliminate an object superiority effect relative to faces within a region more closely linked to object processing in the lateral occipital complex (LOC), suggesting that individuation processes are reasonably specific to the FFA and OFA. Taken together, these findings challenge the prevailing view that the FFA and OFA are face-specific processing regions, demonstrating instead that they function to individuate – i.e., identify specific individuals – within a category. These findings have significant implications for understanding the function of brain regions widely believed to play an important role in social cognition. PMID:21206532

Haist, Frank; Lee, Kang; Stiles, Joan

2010-01-01

40

Occipital bending (Yakovlevian torque) in bipolar depression.  

PubMed

Differing levels of occipital lobe asymmetry and enlarged lateral ventricles have been reported within patients with bipolar disorder (BD) compared with healthy controls, suggesting different rates of occipital bending (OB). This may exert pressure on subcortical structures, such as the hippocampus, reduced among psychiatric patients. We investigated OB prevalence in 35 patients with BD and 36 healthy controls, and ventricular and occipital volumes. Prevalence was four times higher among BD patients (12/35 [34.3%]) than in control subjects (3/36 [8.3%]), as well as larger lateral ventricular volumes (LVVs). Furthermore, we found OB to relate to left-to-right ventricular and occipital lobe volume (OLV) ratios. Those with OB also had reduced left-to-right hippocampal volume ratios. The results suggest that OB is more common among BD patients than healthy subjects, and prevalent in both BD Type I and Type II patients. We posit that anomalies in neural pruning or ventricular enlargement may precipitate OB, consequently resulting in one occipital lobe twisting around the other. Although the clinical implications of these results are unclear, the study suggests that asymmetrical ventricular volume matched with a pattern of oppositely asymmetrical occipital volume is related to OB and may be a marker of psychiatric illness. PMID:25480522

Maller, Jerome J; Anderson, Rodney; Thomson, Richard H; Rosenfeld, Jeffrey V; Daskalakis, Zafiris J; Fitzgerald, Paul B

2015-01-30

41

Headache Following Occipital Brain Lesion: A Case of Migraine Triggered by Occipital Spikes?  

PubMed

This study describes the case of an 8-year-old boy who developed a genuine migraine after the surgical excision, from the right occipital lobe, of brain abscesses due to selective infestation of the cerebrum by Entamoeba histolytica. After the surgical treatment, the boy presented daily headaches with typical migraine features, including right-side parieto-temporal pain, nausea, vomiting, and photophobia. Electroencephalography (EEG) showed epileptiform discharges in the right occipital lobe, although he never presented seizures. Clinical and neurophysiological observations were performed, including video-EEG and polygraphic recordings. EEG showed "interictal" epileptiform discharges in the right occipital lobe. A prolonged video-EEG recording performed before, during, and after an acute attack ruled out ictal or postictal migraine. In this boy, an occipital lesion caused occipital epileptiform EEG discharges without seizures, probably prevented by the treatment. We speculate that occipital spikes, in turn, could have caused a chronic headache with features of migraine without aura. Occipital epileptiform discharges, even in absence of seizures, may trigger a genuine migraine, probably by means of either the trigeminovascular or brainstem system. PMID:25406125

Vollono, Catello; Mariotti, Paolo; Losurdo, Anna; Giannantoni, Nadia Mariagrazia; Mazzucchi, Edoardo; Valentini, Piero; De Rose, Paola; Della Marca, Giacomo

2014-11-17

42

Does Shape Discrimination by the Mouth Activate the Parietal and Occipital Lobes? – Near-Infrared Spectroscopy Study  

PubMed Central

A cross-modal association between somatosensory tactile sensation and parietal and occipital activities during Braille reading was initially discovered in tests with blind subjects, with sighted and blindfolded healthy subjects used as controls. However, the neural background of oral stereognosis remains unclear. In the present study, we investigated whether the parietal and occipital cortices are activated during shape discrimination by the mouth using functional near-infrared spectroscopy (fNIRS). Following presentation of the test piece shape, a sham discrimination trial without the test pieces induced posterior parietal lobe (BA7), extrastriate cortex (BA18, BA19), and striate cortex (BA17) activation as compared with the rest session, while shape discrimination of the test pieces markedly activated those areas as compared with the rest session. Furthermore, shape discrimination of the test pieces specifically activated the posterior parietal cortex (precuneus/BA7), extrastriate cortex (BA18, 19), and striate cortex (BA17), as compared with sham sessions without a test piece. We concluded that oral tactile sensation is recognized through tactile/visual cross-modal substrates in the parietal and occipital cortices during shape discrimination by the mouth. PMID:25299397

Kagawa, Tomonori; Narita, Noriyuki; Iwaki, Sunao; Kawasaki, Shingo; Kamiya, Kazunobu; Minakuchi, Shunsuke

2014-01-01

43

Occipital neuralgia secondary to respiratory tract infection.  

PubMed

Occipital neuralgia is an extracranial pain that may be confused with other headaches. It can be attributed to multiple causes. The authors report the case of a 55-year-old woman suffering from right occipital neuralgia secondary to respiratory tract infection that began 6 days before the pain started. The patient suffered from a sharp and burning pain with paroxysms in the right occipital region and at the top of the right ear. Sensation was decreased in the affected area, and hypersensitivity to touch and cold water was also noted. Tinel's sign was present, and local anesthetic block produced pain relief. The combination of gabapentin and amitriptyline did not provide significant pain relief but led to marked adverse effects. Carbamazepine (300 mg/d) was required for pain control. A month later the patient appeared totally pain-free. The treatment was continued for 3 months, and the patient remained pain-free over a subsequent follow-up period of more than 6 months. Thus, in the case of occipital pain, a careful assessment of symptoms and a thorough history are necessary to obtain the correct diagnosis and to choose the appropriate treatment plan. PMID:16106720

Mourouzis, Constantinos; Saranteas, Theodosios; Rallis, George; Anagnostopoulou, Sophia; Tesseromatis, Christina

2005-01-01

44

Autism and visual agnosia in a child with right occipital lobectomy  

PubMed Central

OBJECTIVES—Autistic disorder is a developmental handicap with an unknown neurological basis. Current neuropsychological models for autism suggest an abnormal construction of visual perceptual representation or a deficit in executive functions. These models predict cerebral lesions in the temporo-occipital or frontal regions of autistic patients. The present study aimed at studying the presence of symptoms of autism and visual agnosia in a 13 year old girl who had a right temporo-occipital cortical dysplasia that was surgically removed at the age of 7.?METHODS—Neuropsychological evaluation included Wechsler and Kaufman intelligence scales, a test of word fluency, digit span, Corsi block, California verbal learning, Trail making, Benton facial recognition, Snoodgrass object recognition tests, Rivermead face learning subtest, and developmental test of visual perception. The ADI-R was used to show current and retrospective diagnosis of autistic disorder. Neuroimagery included brain MRI, single photon emission computed tomography (SPECT), and PET.?RESULTS—Brain MRI showed a right occipital defect and an abnormal hyperintensity of the right temporal cortex. PET and SPECT disclosed a left frontal hypometabolism together with the right occipital defect. Neuropsychological testing showed a visual apperceptive agnosia and executive function deficits. Psychiatric study confirmed the diagnosis of autistic disorder.?CONCLUSIONS—Although the possibilty that autism and visual agnosia were dissociable factors in this patient cannot be excluded, the finding of both deficits supports the possibility that occipito-temporal lesions can predispose to the development of autism.?? PMID:9771784

Jambaque, I; Mottron, L; Ponsot, G; Chiron, C

1998-01-01

45

Attentional modulation of oscillatory activity in human visual cortex  

Microsoft Academic Search

The effects of attentional modulation on activity within the human visual cortex were investigated using magnetoencephalography. Chromatic sinusoidal stimuli were used to evoke activity from the occipital cortex, with attention directed either toward or away from the stimulus using a bar-orientation judgment task. For five observers, global magnetic field power was plotted as a function of time from stimulus onset.

Noriko Yamagishi; Daniel E. Callan; Naokazu Goda; Stephen J. Anderson; Yoshikazu Yoshida; Mitsuo Kawatoa

2003-01-01

46

Occipitalized os odontoideum: A case report  

PubMed Central

We report on a 36-year-old man presenting with a sudden onset of motor weakness and numbness in the upper extremities following a fall from a truck bed. Radiological findings demonstrated an os odontoideum and osseous continuity between the occiput and an ossicle, termed an “occipitalized os odontoideum.” The occipitalized ossicle and atlas moved as a functional unit from the body of the axis. He underwent atlantoasxial stabilization with an atlas lateral mass screw and axis pedicle screw. Eighteen months later, he remained free of symptoms and showed solid bone fusion. Atlantoaxial stabilization resulted in an excellent clinical outcome for this condition. Our report provides useful knowledge regarding treatment of extremely rare osseous anomalies in the craniovertebral junction.

Ohya, Junich; Miyoshi, Kota; Kitagawa, Tomoaki; Nakagawa, Shogo

2014-01-01

47

Occipitalized os odontoideum: A case report.  

PubMed

We report on a 36-year-old man presenting with a sudden onset of motor weakness and numbness in the upper extremities following a fall from a truck bed. Radiological findings demonstrated an os odontoideum and osseous continuity between the occiput and an ossicle, termed an "occipitalized os odontoideum." The occipitalized ossicle and atlas moved as a functional unit from the body of the axis. He underwent atlantoasxial stabilization with an atlas lateral mass screw and axis pedicle screw. Eighteen months later, he remained free of symptoms and showed solid bone fusion. Atlantoaxial stabilization resulted in an excellent clinical outcome for this condition. Our report provides useful knowledge regarding treatment of extremely rare osseous anomalies in the craniovertebral junction. PMID:25558149

Ohya, Junich; Miyoshi, Kota; Kitagawa, Tomoaki; Nakagawa, Shogo

2014-10-01

48

The timing of spheno-occipital fusion in hominoids.  

PubMed

The degree of spheno-occipital fusion has been used to assign a relative age to dentally mature hominoid cranial specimens. However, a recent study of captive individuals (Poe: Am J Phys Anthropol 144 (2011) 162–165) concluded that fusion of the spheno-occipital suture in great ape taxa is of little utility for aging dentally mature individuals. In this contribution, I use dentally mature samples of extant hominoid taxa (Homo sapiens, Pan troglodytes schweinfurthii, Gorilla gorilla gorilla, Pongo pygmaeus pygmaeus and Hylobates lar) to investigate a) the temporal relationship between spheno-occipital fusion and dental maturity, b) whether there is an association between the degree of spheno-occipital fusion and relative age, c) whether there are differences in relative timing of spheno-occipital fusion between taxa, and d) whether there are sex differences in the relative timing of spheno-occipital fusion. Results suggest that a) a substantial proportion of dentally mature wild-shot chimpanzee, gorilla and orang-utans have unfused or partially fused spheno-occipital synchondoses, b) there is an association between the degree of spheno-occipital fusion and age, c) there are interspecific differences in the timing of spheno-occipital fusion, and d) there are significant sex differences in spheno-occipital fusion in chimpanzees, orang-utans and gibbons. Thus, contrary to previous work, degree of spheno-occipital fusion is a potentially useful indicator of relative maturity, especially in great ape taxa. PMID:25293964

Balolia, Katharine L

2015-01-01

49

Q-Ball of Inferior Fronto-Occipital Fasciculus and Beyond  

PubMed Central

The inferior fronto-occipital fasciculus (IFOF) is historically described as the longest associative bundle in the human brain and it connects various parts of the occipital cortex, temporo-basal area and the superior parietal lobule to the frontal lobe through the external/extreme capsule complex. The exact functional role and the detailed anatomical definition of the IFOF are still under debate within the scientific community. In this study we present a fiber tracking dissection of the right and left IFOF by using a q-ball residual-bootstrap reconstruction of High-Angular Resolution Diffusion Imaging (HARDI) data sets in 20 healthy subjects. By defining a single seed region of interest on the coronal fractional anisotropy (FA) color map of each subject, we investigated all the pathways connecting the parietal, occipital and posterior temporal cortices to the frontal lobe through the external/extreme capsule. In line with recent post-mortem dissection studies we found more extended anterior-posterior association connections than the “classical” fronto-occipital representation of the IFOF. In particular the pathways we evidenced showed: a) diffuse projections in the frontal lobe, b) fronto-parietal lobes connections trough the external capsule in almost all the subjects and c) widespread connections in the posterior regions. Our study represents the first consistent in vivo demonstration across a large group of individuals of these novel anterior and posterior terminations of the IFOF detailed described only by post-mortem anatomical dissection. Furthermore our work establishes the feasibility of consistent in vivo mapping of this architecture with independent in vivo methodologies. In conclusion q-ball tractography dissection supports a more complex definition of IFOF, which includes several subcomponents likely underlying specific function. PMID:24945305

Amirbekian, Bagrat; Berger, Mitchel S.; Henry, Roland G.

2014-01-01

50

Coherent Activity in Bilateral Parieto-Occipital Cortices during P300-BCI Operation.  

PubMed

The visual P300 brain-computer interface (BCI), a popular system for electroencephalography (EEG)-based BCI, uses the P300 event-related potential to select an icon arranged in a flicker matrix. In earlier studies, we used green/blue (GB) luminance and chromatic changes in the P300-BCI system and reported that this luminance and chromatic flicker matrix was associated with better performance and greater subject comfort compared with the conventional white/gray (WG) luminance flicker matrix. To highlight areas involved in improved P300-BCI performance, we used simultaneous EEG-fMRI recordings and showed enhanced activities in bilateral and right lateralized parieto-occipital areas. Here, to capture coherent activities of the areas during P300-BCI, we collected whole-head 306-channel magnetoencephalography data. When comparing functional connectivity between the right and left parieto-occipital channels, significantly greater functional connectivity in the alpha band was observed under the GB flicker matrix condition than under the WG flicker matrix condition. Current sources were estimated with a narrow-band adaptive spatial filter, and mean imaginary coherence was computed in the alpha band. Significantly greater coherence was observed in the right posterior parietal cortex under the GB than under the WG condition. Re-analysis of previous EEG-based P300-BCI data showed significant correlations between the power of the coherence of the bilateral parieto-occipital cortices and their performance accuracy. These results suggest that coherent activity in the bilateral parieto-occipital cortices plays a significant role in effectively driving the P300-BCI. PMID:24860546

Takano, Kouji; Ora, Hiroki; Sekihara, Kensuke; Iwaki, Sunao; Kansaku, Kenji

2014-01-01

51

LEARNING AND ORGANIZATIONAL CHANGE (LOC) The Learning and Organizational Change concentration helps you explore how  

E-print Network

-based systems, involving people, technology and organizational structures and culture are a particular strength Culture and Cognition · LOC 306 Studies in Organizational Change · LOC 310 Learning OrganizationsLEARNING AND ORGANIZATIONAL CHANGE (LOC) CURRICULUM The Learning and Organizational Change

Shahriar, Selim

52

[Panic attacks simulated by occipital lobe seizures].  

PubMed

Eleven-year-old Stephanie was admitted to a child and adolescent psychiatry day hospital with symptoms of an anxiety and panic disorder, and compulsive and self-harmful behavior. The patient described detailed threatening scenic sequences that caused her to feel panicky. They symptoms could be classified as epilepsy with visually dominated seizures of the occipital lobe. In addition to pharmacological treatment with oxcabazepine, extensive multimodal interventions as part of the child and adolescent psychiatric day hospital treatment program helped all family members to understand and handle the seizures. Eight weeks after initiation of treatment, Stephanie was seizure-free. Complex partial epilepsy can be mistaken for primary child-psychiatric disorder. PMID:19415605

Stolle, Martin; Sieben, Claudia; Püst, Burkhard

2009-05-01

53

Greater occipital nerve block in chronic migraine.  

PubMed

Headache syndromes often involve occipital and neck symptoms suggesting a functional connectivity between nociceptive trigeminal and cervical afferents. Several studies have suggested that pain relief in migraine and other types of headache can be achieved by local injections of steroids, local anaesthetics or a mixture of both in the area of greater occipital nerve (GON). Usually greater occipital nerve block (GONB) is performed by using local anaesthetics alone or with steroid. The rationale of performing a GONB for the treatment of chronic headache states is on the anatomical connections between trigeminal and upper cervical sensory fibres at the level of the trigeminal nucleus caudalis. However, the reason for the improvement after GONB in primary headache is unknown. The objective of this study is to determine whether adding triamcinolone to local anaesthetics increased the efficacy of GONB and trigger point injections (TPIs) for chronic migraine (TM). Patients with TM were randomized to receive GONB and TPIs using lidocaine 2% and bupivacaine 0.5% + either saline or triamcinolone 40 mg. Particularly, a 10-ml syringe containing 4.5 ml of lidocaine 2%, 4.5 ml of bupivacaine 0.5% and 1 ml of either saline (group A) or triamcinolone 40 mg/ml (group B) was prepared for each patients. Patients were given bilateral GONB and TPIs in the cervical paraspinal and trapezius muscles bilaterally. 2 ml were injected into each GON at the medial third of the distance between the occipital protuberance and the mastoid process. In addition, 0.5 ml was injected into each of the 12 trigger points. The total injected volume was 10 ml. The primary outcome measure was the change in mean headache severity from before injection to 20 min after in the two groups. Secondary outcome measures were the change in mean neck pain, photophobia and phonofobia severity from before injection to 20 min after in the two groups. Patients documented headache and severity of associated symptoms for 4 weeks after injection. Changes in symptom severity were compared between the two groups. Thirty-seven patients were included. Twenty minutes after injection, mean headache severity decreased by 3.2 points in group A (p < 0.01) and by 3.1 points in group B (p < 0.01). Mean neck pain severity decreased by 1.5 points in group A (p < 0.01) and by 1.7 points in group B (p < 0.01). Mean duration of being headache-free was 2.7 +/- 3.8 days in group A and 1.0 +/- 1.1 days in group B (p = 0.67). None of the outcome measures differed significantly between the two groups. Both treatments were full tolerated. In our study, adding triamcinolone to local anaesthetic when performing GONB and TPIs was not associated with improved outcome in the sample of patients with TM. In both groups, the procedure resulted in significant and rapid relief of headache, neck pain, photophobia and phonofobia. PMID:20464617

Saracco, Maria Gabriella; Valfrè, W; Cavallini, M; Aguggia, M

2010-06-01

54

Occipital neurostimulation in primary headaches: update.  

PubMed

A subset of headache patients are chronic and results refractory to standard medical treatments, they are unsatisfied or unable to tolerate the side effects of medications. In the lack of more effective prophylactic treatment, there is need of alternative approach. Migraine is conceptualized as a chronic and potentially progressive disorder. It is conceivable that more aggressive therapeutic efforts could be warranted in drug-refractory chronic migraine. In this prospective, the new, device-based therapies that allow to affect brain function in less invasive ways may represent a therapeutic opportunity. Peripheral occipital neurostimulation resulted in several trials and case reports to be beneficial in a large variety of headache and craniofacial pain disorders, with chronic primary headache the most studied. We comment on our experience in the application of ONS in drug-refractory chronic cluster headache and chronic migraine patients. PMID:23695057

Proietti Cecchini, A; Leone, M; Tullo, V; Curone, M; Di Fiore, P; Bussone, G

2013-05-01

55

Cooled Radiofrequency Ablation for Bilateral Greater Occipital Neuralgia  

PubMed Central

This report describes a case of bilateral greater occipital neuralgia treated with cooled radiofrequency ablation. The case is considered in relation to a review of greater occipital neuralgia, continuous thermal and pulsed radiofrequency ablation, and current medical literature on cooled radiofrequency ablation. In this case, a 35-year-old female with a 2.5-year history of chronic suboccipital bilateral headaches, described as constant, burning, and pulsating pain that started at the suboccipital region and radiated into her vertex. She was diagnosed with bilateral greater occipital neuralgia. She underwent cooled radiofrequency ablation of bilateral greater occipital nerves with minimal side effects and 75% pain reduction. Cooled radiofrequency ablation of the greater occipital nerve in challenging cases is an alternative to pulsed and continuous RFA to alleviate pain with less side effects and potential for long-term efficacy. PMID:24716017

Chhatre, Akhil

2014-01-01

56

Mirror Focus in a Patient with Intractable Occipital Lobe Epilepsy  

PubMed Central

Mirror focus is one of the evidence of progression in epilepsy, and also has practical points for curative resective epilepsy surgery. The mirror foci are related to the kindling phenomena that occur through interhemispheric callosal or commissural connections. A mirror focus means the secondary epileptogenic foci develop in the contralateral hemispheric homotopic area. Thus mirror foci are mostly reported in patients with temporal or frontal lobe epilepsy, but not in occipital lobe epilepsy. We have observed occipital lobe epilepsy with mirror focus. Before epilepsy surgery, the subject’s seizure onset zone was observed in the left occipital area by ictal studies. Her seizures abated for 10 months after the resection of left occipital epileptogenic focus, but recurred then. The recurred seizures were originated from the right occipital area which was in the homotopic contralateral area. This case can be an evidence that occipital lobe epilepsy may have mirror foci, even though each occipital lobe has any direct interhemispheric callosal connections between them. PMID:24977131

Kim, Jiyoung; Shin, Hae kyung; Hwang, Kyoung Jin; Choi, Su Jung; Joo, Eun Yeon; Hong, Seung Bong; Hong, Seung Chul; Seo, Dae-Won

2014-01-01

57

PBF LOCA test LOC-6 fuel-behavior report. [PWR  

SciTech Connect

This report presents the results of Loss-of-Coolant (LOC) Test LOC-6, conducted in the Power Burst Facility at the Idaho National Engineering Laboratory by EG and G Idaho, Inc., for the US Nuclear Regulatory Commission. Postirradiation examination results are included, together with the results of thermal-hydraulic and fuel behavior calculations using the RELAP4 and FRAP-T6/BALON-2 computer codes. Two of the four light water reactor type fuel rods ballooned and ruptured during the test. Peak cladding temperatures at the rupture locations were high in the alpha phase (1066 and 1098/sup 0/K). The effects of initial rod internal prepressurization and prior irradiation were investigated during the experiment. The effect of rod prepressurization was found to be significant, and, for burnups of about 17,000 MWd/t, prior irradiation increased cladding circumferential strains at failure.

Broughton, T.M.; Vinjamuri, K.; Hagrman, D.L.; Golden, D.W.; MacDonald, P.E.

1983-04-01

58

Anton's Syndrome due to Bilateral Ischemic Occipital Lobe Strokes  

PubMed Central

We present a case of a patient with Anton's syndrome (i.e., visual anosognosia with confabulations), who developed bilateral occipital lobe infarct. Bilateral occipital brain damage results in blindness, and patients start to confabulate to fill in the missing sensory input. In addition, the patient occasionally becomes agitated and talks to himself, which indicates that, besides Anton's syndrome, he might have had Charles Bonnet syndrome, characterized by both visual loss and hallucinations. Anton syndrome, is not so frequent condition and is most commonly caused by ischemic stroke. In this particular case, the patient had successive bilateral occipital ischemia as a result of massive stenoses of head and neck arteries. PMID:25530893

Zuki?, Sanela; Sinanovi?, Osman; Hodži?, Renata; Mujagi?, Svjetlana; Smajlovi?, Edina

2014-01-01

59

Peripheral occipital nerve stimulation to treat chronic refractory migraine.  

PubMed

Peripheral nerve stimulation of the occipital nerve has a favourable efficacy to safety profile for chronic migraine, which is notoriously difficult to treat. This article covers the rationale, surgical procedure and clinical data for this treatment option. PMID:23411977

Ashkan, Keyoumars; Dowson, Andrew

2013-02-01

60

A computed tomography morphometric study of occipital bone and C2 pedicle anatomy for occipital-cervical fusion  

PubMed Central

Background: Occipital-cervical fusion (OCF) has been used to treat instability of the occipito-cervical junction and to provide biomechanical stability after decompressive surgery. The specific areas that require detailed morphologic knowledge to prevent technical failures are the thickness of the occipital bone and diameter of the C2 pedicle, as the occipital midline bone and the C2 pedicle have structurally the strongest bone to provide the biomechanical purchase for cranio-cervical instrumentation. The aim of this study was to perform a quantitative morphometric analysis using computed tomography (CT) to determine the variability of the occipital bone thickness and C2 pedicle thickness to optimize screw placement for OCF in a South East Asian population. Methods: Thirty patients undergoing cranio-cervical junction instrumentation during the period 2008-2010 were included. The thickness of the occipital bone and the length and diameter of the C2 pedicle were measured based on CT. Results: The thickest point on the occipital bone was in the midline with a maximum thickness below the external occipital protuberance of 16.2 mm (±3.0 mm), which was thicker than in the Western population. The average C2 pedicle diameter was 5.3 mm (±2.0 mm). This was smaller than Western population pedicle diameters. The average length of the both pedicles to the midpoint of the C2 vertebral body was 23.5 mm (±3.3 mm on the left and ±2.3 mm on the right). Conclusions: The results of this first study in the South East Asian population should help guide and improve the safety in occipito-cervical region instrumentation. Thus reducing the risk of technical failures and neuro-vascular injury. PMID:25289166

King, Nicolas K. K.; Rajendra, Tiruchelvarayan; Ng, Ivan; Ng, Wai Hoe

2014-01-01

61

3.2 "Lab-on-a-Chip" A Lab-on-a-Chip (LOC) device, also known as a micro-total-analytical system  

E-print Network

shows an example of an LOC device that was tested on the International Space Station in 2007. Figure 28: LOC device tested on the International Space Station in 2007 At the heart of LOC devices are "chips

62

Grievous temporal and occipital injury caused by a bear attack.  

PubMed

Bear attacks are reported from nearly every part of the world. The chance of a human encountering a bear increases as the remote bear territory diminishes. The sloth bear is one of the three species of bears found in India, which inhabits the forests of India and its neighboring countries. Here we describe a teenager who came to us with a critical injury involving the face, temporal and occipital bones inflicted by a sloth bear attack. He underwent a temporal exploration, facial nerve decompression, pinna reconstruction, and occipital bone repair to save him from fatality. PMID:24396623

Prasad, Sampath Chandra; Thada, Nikhil Dinaker; Rao, Pallavi; Thada, Smitha Rani; Prasad, Kishore Chandra

2013-01-01

63

Occipital Nerve Stimulation Using a Medtronic Resume II? Electrode Array  

Microsoft Academic Search

II?,peripheral nerve \\/ spinal cord stimulator electrode for causing peripheral stimulation of the occipital nerve in the suboccipital re- gion. Initial results suggest improved stim- ulation with lower power requirements us- ing this larger electrode. The larger contact size might lessen the effect of scar forma-

Rodney L. Jones

64

Refractory headaches treated with bilateral occipital and temporal region stimulation  

PubMed Central

Objectives To describe use of bilateral temporal and occipital stimulator leads for a refractory headache disorder. Materials and methods A 31-year-old female had a 10-year history of chronic, severe occipital and temporal region headaches. The patient underwent permanent implant of an occipital stimulator system that resulted in sustained, compete resolution of her occipital pain. However, she continued to suffer disabling (10/10) temporal region headaches and was bedbound most days of the week. Therefore, bilateral temporal stimulator leads were implanted and tunneled to her internal pulse generator. Results At 12-month follow-up, the patient enjoyed sustained improvement in her pain scores (8/10) and marked increase in her level of functioning. Taking into account increased activity level, she rated her overall improvement at 50%. Unfortunately, infection and erosion of her right temporal lead necessitated temporal stimulator removal. Conclusion Headache disorders may require stimulation of all painful cephalic regions. However, our success in this case must be considered in light of the technical challenges and expense of placing stimulator leads subcutaneously around the head and neck, including the risk of infection, lead breakage, erosion, and migration. PMID:24707189

Zach, Kelly J; Trentman, Terrence L; Zimmerman, Richard S; Dodick, David W

2014-01-01

65

Conservative management of a large occipital extradural haematoma.  

PubMed

A 26-year-old male presented with a mild confusion and hemianopsia after traumatic brain injury. Cerebral CT-scan revealed a 62.5 cm(3) left occipital extradural haematoma (EDH). Although conventional neurosurgical management would have been to evacuate the haematoma, a conservative strategy was preferred, and the patient made a total recovery. PMID:23428147

Chauvet, D; Reina, V; Clarencon, F; Bitar, A; Cornu, P

2013-08-01

66

RESEARCH REPORT Occipital gamma activation during Vipassana meditation  

E-print Network

RESEARCH REPORT Occipital gamma activation during Vipassana meditation B. Rael Cahn · Arnaud Long-term Vipassana meditators sat in medi- tation vs. a control rest (mind-wandering) state for 21 min in a counterbalanced design with spontaneous EEG recor- ded. Meditation state dynamics were measured with spec- tral

67

RESEARCH REPORT Occipital gamma activation during Vipassana meditation  

E-print Network

RESEARCH REPORT Occipital gamma activation during Vipassana meditation B. Rael Cahn · Arnaud. This article is published with open access at Springerlink.com Abstract Long-term Vipassana meditators sat with spontaneous EEG recor- ded. Meditation state dynamics were measured with spec- tral decomposition of the last

Delorme, Arnaud

68

Occipital Horn syndrome in a 2-year-old boy.  

PubMed

The clinical presentation of Occipital Horn syndrome, a rare X-linked recessive condition, in a 2-year-old boy is described. This is the youngest patient reported so far. The major clinical, pathophysiological and molecular aspects of this condition are summarized. PMID:10457850

De Paepe, A; Loeys, B; Devriendt, K; Fryns, J P

1999-07-01

69

Enhanced effective connectivity in mild occipital stroke patients with hemianopia.  

PubMed

Plasticity-based spontaneous recovery and rehabilitation intervention of stroke-induced hemianopia have drawn great attention in recent years. However, the underlying neural mechanism remains unknown. This study aims to investigate brain network disruption and reorganization in hemianopia patients due to mild occipital stroke. Resting-state networks were constructed from 12 hemianopia patients with right occipital infarct by partial directed coherence analysis of multi-channel electroencephalograms. Compared with control subjects, the patients presented enhanced connectivity owing to newly formed connections. Compensational connections mostly originated from the peri-infarct area and targeted contralesional frontal, central, and parietal cortices. These new ipsilesional-to-contralesional inter-hemispheric connections coordinately presented significant correlation with the extent of vision loss. The enhancement of connectivity might be the neural substrate for brain plasticity in stroke-induced hemianopia and may shed light on plasticity-based recovery or rehabilitation. PMID:24876132

Guo, Xiaoli; Jin, Zheng; Feng, Xinyang; Tong, Shanbao

2014-11-01

70

Idiopathic photosensitive occipital epilepsy: clinical and electroencephalographic (EEG) features.  

PubMed

Idiopathic photosensitive occipital lobe epilepsy is a reflex, age- and localization-related syndrome. We describe the clinical and electroencephalographic features, therapy, and outcome of 16 children/adolescents with this syndrome. The cohort included 2 sets of siblings and 7 patients with other first- or second-degree relatives with a seizure history. All patients had occipital onset seizures and 15 had secondarily generalized tonic-clonic seizures. Seizure frequency was relatively low in all patients but one. Myoclonic seizures later developed in 2 patients with juvenile myoclonic epilepsy. Eight patients achieved full seizure control with monotherapy, and 5 required a second drug; 3 patients had rare seizures and were not treated with antiepileptics. Seven patients required special education or developmental assistance. This interesting syndrome sheds light on the pathophysiology and genetic etiology of common phenomena such as photosensitivity and headache. Further large prospective studies are required to better define this unique syndrome and its implications. PMID:23334080

Politi-Elishkevich, Keren; Kivity, Sara; Shuper, Avinoam; Levine, Hagit; Goldberg-Stern, Hadassa

2014-03-01

71

The Involvement of Occipital and Inferior Frontal Cortex in the Phonological Learning of Chinese Characters  

ERIC Educational Resources Information Center

Neural changes related to the learning of the pronunciation of Chinese characters in English speakers were examined using fMRI. We examined the item-specific learning effects for trained characters and the generalization of phonetic knowledge to novel transfer characters that shared a phonetic radical (part of a character that gives a clue to the…

Deng, Yuan; Chou, Tai-li; Ding, Guo-sheng; Peng, Dan-ling; Booth, James R.

2011-01-01

72

Dopamine in the visual cortex of the cat  

Microsoft Academic Search

Summary The endogenous content of noradrenaline (NA) and dopamine (DA) was determined by radioenzymatic assays in three different areas of the occipital (visual) cortex, in normal cats as well as in DA-deafferented animals. The use of HPLC methodology enabled us to detect and measure in addition two metabolites of DA: 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), thus confirming the

T. A. Reader; L. F. Quesney

1986-01-01

73

Expression of long non-coding RNA LOC285194 and its prognostic significance in human pancreatic ductal adenocarcinoma  

PubMed Central

Introduction: Dysregulation of long non-coding RNAs (lncRNAs) plays critical roles in tumor progression. lncRNA LOC285194 was previously shown to be correlated with aggressive clinicopathological features and poor prognosis in several cancers. The aim of this study was to investigate relationship between LOC285194 expression and clinical outcomes in human pancreatic ductal adenocarcinoma (PDAC). Methods: Quantitative real-time PCR (qRT-PCR) assay was performed to detect the expression of lncRNA LOC285194 in human PDAC cells and tissue samples. The association of LOC285194 expression with clinicopathologic features was analyzed. Kaplan-Meier analyses were used to assess survival of patients. Univariate and multivariate analyses were performed using the Cox proportional hazards model to analyze the prognostic significance of LOC285194 expression. Results: Our data showed that the relative level of LOC285194 in PDAC cells was significantly lower than that in normal human pancreatic duct epithelial cell line. Also, the expression of LOC285194 in PDAC tissues was significantly lower than that in adjacent non-tumor tissues. By statistical analyses, low LOC285194 expression was observed to be closely correlated with clinical stage, lymphnode metastasis and liver metastasis. Kaplan-Meier survival analysis revealed that patients with low LOC285194 expression had a poor overall survival compared with the high LOC285194 group (P < 0.05). Univariate and multivariate analyses showed that low LOC285194 expression was an independent poor prognostic factor for PDAC patients. Conclusions: Our data provided the first evidence that reduced LOC285194 in PDAC tissues was correlated with tumor progression, and lncRNA LOC285194 might be a potential molecular biomarker for predicting the prognosis of patients.

Ding, Yue-Chao; Yu, Wei; Ma, Chao; Wang, Qian; Huang, Chang-Shan; Huang, Tao

2014-01-01

74

Occipital peripheral nerve stimulation in the management of chronic intractable occipital neuralgia in a patient with neurofibromatosis type 1: a case report  

PubMed Central

Introduction Occipital peripheral nerve stimulation is an interventional pain management therapy that provides beneficial results in the treatment of refractory chronic occipital neuralgia. Herein we present a first-of-its-kind case study of a patient with neurofibromatosis type 1 and bilateral occipital neuralgia treated with occipital peripheral nerve stimulation. Case presentation A 42-year-old Caucasian woman presented with bilateral occipital neuralgia refractory to various conventional treatments, and she was referred for possible treatment with occipital peripheral nerve stimulation. She was found to be a suitable candidate for the procedure, and she underwent implantation of two octapolar stimulating leads and a rechargeable, programmable, implantable generator. The intensity, severity, and frequency of her symptoms resolved by more than 80%, but an infection developed at the implantation site two months after the procedure that required explantation and reimplantation of new stimulating leads three months later. To date she continues to experience symptom resolution of more than 60%. Conclusion These results demonstrate the significance of peripheral nerve stimulation in the management of refractory occipital neuralgias in patients with neurofibromatosis type 1 and the possible role of neurofibromata in the development of occipital neuralgia in these patients. PMID:21569290

2011-01-01

75

Monoclonal antibody VC1.1 selectively stains a population of GABAergic neurons containing the calcium-binding protein parvalbumin in the rat cerebral cortex  

Microsoft Academic Search

Monoclonal antibody VC1.1 is shown to stain selectively a subpopulation of GABAergic neurons in the rat cerebral cortex. Almost all VC1.1 immunoreactive cells were also GABA-like immunoreactive (GABA-LI) and parvalbumin (PV) immunoreactive, whereas they were about 30% and 65% of GABA-LI and PV-positive cells in the parietal cortex and about 13% and 32% in the occipital cortex, respectively. Although a

T. Kosaka; C. W. Heizmann; C. J. Barnstable

1989-01-01

76

Peritrigonal and temporo-occipital heterotopia with corpus callosum and cerebellar dysgenesis  

PubMed Central

Objective: To describe a homogeneous subtype of periventricular nodular heterotopia (PNH) as part of a newly defined malformation complex. Methods: Observational study including review of brain MRI and clinical findings of a cohort of 50 patients with PNH in the temporo-occipital horns and trigones, mutation analysis of the FLNA gene, and anatomopathologic study of a fetal brain. Results: There were 28 females and 22 males. All were sporadic with the exception of an affected mother and son. Epilepsy occurred in 62%, cerebellar signs in 56%, cognitive impairment in 56%, and autism in 12%. Seventy percent were referred within the 3rd year of life. Imaging revealed a normal cerebral cortex in 76% and abnormal cortical folding in 24%. In all patients the hippocampi were under-rotated and in 10% they merged with the heterotopia. Cerebellar dysgenesis was observed in 84% and a hypoplastic corpus callosum in 60%. There was no gender bias or uneven gender distribution of clinical and anatomic severity. No mutations of FLNA occurred in 33 individuals examined. Heterotopia in the fetal brain revealed cytoarchitectonic characteristics similar to those associated with FLNA mutations; cortical pathology was not typical of polymicrogyria. Cerebellar involvement was more severe and the hippocampi appeared simple and under-rotated. Conclusions: This series delineates a malformation complex in which PNH in the trigones and occipito-temporal horns is associated with hippocampal, corpus callosum, and cerebellar dysgenesis. This subtype of PNH is distinct from classic PNH caused by FLNA mutations. PMID:22914838

Pisano, Tiziana; Barkovich, A. James; Leventer, Richard J.; Squier, Waney; Scheffer, Ingrid E.; Parrini, Elena; Blaser, Susan; Marini, Carla; Robertson, Stephen; Tortorella, Gaetano; Rosenow, Felix; Thomas, Pierre; McGillivray, George; Andermann, Eva; Andermann, Frederick; Berkovic, Samuel F.; Dobyns, William B.

2012-01-01

77

Occipital Neuralgia after Hair Transplantation and Its Treatment  

PubMed Central

While undergoing full thickness tissue harvest from the posterior scalp, a 72-year-old man experienced immediate severe pain in the right occiput and was unable to complete the procedure. The pain was constant “sharp” and “shocking” with numbness in the distribution of the lesser occipital nerve, exacerbated by physical activity, and local anesthetic blocks provided temporary complete relief. After numerous treatments over several years, including oral analgesics, botulinum toxin injections, and acupuncture, proved ineffective, pulsed radiofrequency neuromodulation provided greater than 80% relief for 5 months.

Siefferman, Jason; Khelemsky, Yury

2015-01-01

78

The Intramuscular Course of the Greater Occipital Nerve: Novel Findings with Potential Implications for Operative Interventions and Occipital Neuralgia  

PubMed Central

Background: A better understanding of the etiologies of occipital neuralgia would help the clinician treat patients with this debilitating condition. Since few studies have examined the muscular course of the greater occipital nerve (GON), this study was performed. Methods: Thirty adult cadaveric sides underwent dissection of the posterior occiput with special attention to the intramuscular course of the GON. Nerves were typed based on their muscular course. Results: The GON traveled through the trapezius (type I; n = 5, 16.7%) or its aponeurosis (type II; n = 15, 83.3%) to become subcutaneous. Variations in the subtrapezius muscular course were found in 10 (33%) sides. In two (6.7%) sides, the GON traveled through the lower edge of the inferior capitis oblique muscle (subtype a). On five (16.7%) sides, the GON coursed through a tendinous band of the semispinalis capitis, not through its muscular fibers (subtype b). On three (10%) sides the GON bypassed the semispinalis capitis muscle to travel between its most medial fibers and the nuchal ligament (subtype c). For subtypes, eight were type II courses (through the aponeurosis of the trapezius), and two were type I courses (through the trapezius muscle). The authors identified two type IIa courses, four type IIb courses, and two type IIc courses. Type I courses included one type Ib and one type Ic courses. Conclusions: Variations in the muscular course of the GON were common. Future studies correlating these findings with the anatomy in patients with occipital neuralgia may elucidate nerve courses vulnerable to nerve compression. This enhanced classification scheme describes the morphology in this region and allows more specific communications about GON variations. PMID:25422783

Tubbs, R. Shane; Watanabe, Koichi; Loukas, Marios; Cohen-Gadol, Aaron A.

2014-01-01

79

Differential Contribution of Right and Left Parietal Cortex to the Control of Spatial Attention: A Simultaneous EEG–rTMS Study  

PubMed Central

We have recently shown that interference with repetitive transcranial magnetic stimulation (rTMS) of right posterior intraparietal sulcus (IPS) cortex during the allocation of spatial attention leads to abnormal desynchronization of anticipatory (pretarget) electroencephalographic alpha rhythms (8–12 Hz) in occipital–parietal cortex and the detection of subsequently presented visual targets (Capotosto et al. 2009). Since lesion data suggest that lesions of the right frontoparietal cortices produce more severe and long-lasting deficits of visual spatial attention than lesions of the left hemisphere, here, we used the mentioned rTMS-electroencephalographic procedure to test if the control of anticipatory alpha rhythms by IPS is asymmetrically organized in the 2 hemispheres. Results showed that interference with either left or right IPS during covert spatial attention equally disrupted the normally lateralized anticipatory modulation of occipital visual cortex, with stronger alpha desynchronization contralaterally to the attended visual field. In contrast, only interference with right IPS induced a paradoxical pretarget synchronization of alpha rhythms and bilateral deficits of target identification. These results suggest that the control of spatial topography of anticipatory alpha rhythms in occipital–parietal cortex is shared between left and right IPS cortex, but that right IPS uniquely contributes to a bilateral prestimulus activation of occipital visual cortex. PMID:21666126

Babiloni, Claudio; Romani, Gian Luca; Corbetta, Maurizio

2012-01-01

80

Early Electrophysiological Indices Of Illusory Contour Processing Within The Lateral Occipital Complex Are Virtually Impervious To Manipulations Of Illusion Strength  

PubMed Central

The visual system can automatically interpolate or “fill-in” the boundaries of objects when inputs are fragmented or incomplete. A canonical class of visual stimuli known as illusory-contour (IC) stimuli have been extensively used to study this contour interpolation process. Visual evoked potential (VEP) studies have identified a neural signature of these boundary completion processes, the so-called IC-effect, which typically onsets at 90–110ms and is generated within the lateral occipital complex (LOC). Here we set out to determine the delimiting factors of automatic boundary completion with the use of illusory contour stimuli and high-density scalp recordings of brain activity. Retinal eccentricity, ratio of real to illusory contours (i.e. support ratio), and inducer diameter were each varied parametrically, and any resulting effects on the amplitude and latency of the IC-effect were examined. Somewhat surprisingly, the amplitude of the IC-effect was found to be impervious to all changes in these stimulus parameters, manipulations that are known to impact perceived illusion strength. Thus, this automatic stage of object processing appears to be a binary process in which, so-long as minimal conditions are met, contours are automatically completed. At the same time, the latency of the IC-effect was found to vary inversely with support ratio, likely reflecting the additional time necessary to interpolate across the relatively longer induced boundaries of the implied object. These data are interpreted in the context of a two stage object-recognition model that parses processing into an early automatic perceptual stage that is followed by a more effortful conceptual processing stage. PMID:22037001

Altschuler, Ted S.; Molholm, Sophie; Russo, Natalie N.; Snyder, Adam C.; Brandwein, Alice B.; Blanco, Daniella; Foxe, John J.

2011-01-01

81

Responses to interocular disparity correlation in the human cerebral cortex  

PubMed Central

Purpose Perceiving binocular depth relies on the ability of our visual system to precisely match corresponding features in the left and right eyes. Yet how the human brain extracts interocular disparity correlation is poorly understood. Methods We used functional magnetic resonance imaging (fMRI) to characterize brain regions involved in processing interocular disparity correlation. By varying the amount of interocular correlation of a disparity-defined random-dot-stereogram, we concomitantly controlled the perception of binocular depth and measured the percent Blood-Oxygenation-Level-Dependent (%BOLD)-signal in multiple regions-of-interest in the human occipital cortex and along the intra-parietal sulcus. Results A linear support vector machine classification analysis applied to cortical responses showed patterns of activation that represented different disparity correlation levels within regions-of-interest in the visual cortex. These also revealed a positive trend between the difference in disparity correlation and classification accuracy in V1, V3 and lateral occipital cortex. Classifier performance was significantly related to behavioural performance in dorsal visual area V3. Cortical responses to random-dot-stereogram stimuli were greater in the right compared to the left hemisphere. Conclusions Our results show that multiple regions in the cerebral cortex are sensitive to changes in interocular disparity correlation, and that dorsal area V3 may play an important role in the early transformation of binocular disparity to depth perception. PMID:24588533

Ip, Ifan Betina; Minini, Loredana; Dow, James; Parker, Andrew J; Bridge, Holly

2014-01-01

82

Charged-coupled device (CCD) detectors for Lab-on-a Chip (LOC) optical analysis.  

PubMed

A critical element of any Lab-on-a-Chip (LOC) is a detector; among the many detection approaches, optical detection is very widely used for biodetection. One challenge for advancing the development of LOC for biodetection has been to enhance the portability and lower the cost for Point-of-Care diagnostics, which has the potential to enhance the quality of healthcare delivery for underserved populations and for global health. We describe a simple and relatively low cost charged-coupled device (CCD)-based detector that can be integrated with a conventional microtiter plate or a portable LOC assay for various optical detection modalities including fluorescence, chemiluminescence, densitometry, and colorimetric assays. In general, the portable battery-operated CCD-based detection system consists of four modules: (1) a cooled CCD digital camera to monitor light emission, (2) a LOC or microtiter plate to perform assays, (3) a light source to illuminate the assay (such as electroluminescence (EL) or light emitting diode (LED)), and (4) a portable computer to acquire and analyze images. The configuration of the fluorescence detector presented here was designed to measure fluorogenic excitation at 490 nm and to monitor emission at 523 nm used for FITC detection.The LOC used for this detection system was fabricated with laminated object manufacturing (LOM) technology, and was designed to detection activity of botulinum neurotoxin serotype A (BoNT-A) using a fluorogenic peptide substrate (SNAP-25) for botulinum neurotoxin serotype A (BoNT-A) labeled with FITC. The limit of detection (LOD) for the CCD detector is 0.5 nM (25 ng/ml). The portable system is small and is powered by a 12 V source. The modular detector was designed with easily interchangeable LEDs, ELs, filters, lenses, and LOC, and can be used and adapted for a wide variety of densitometry, florescence and colorimetric assays. PMID:23329454

Rasooly, Avraham; Kostov, Yordan; Bruck, Hugh A

2013-01-01

83

PLATE 1 Color-coded maps of visual cortex produced by optical imaging of the brain of a subject (a  

E-print Network

PLATE 1 Color-coded maps of visual cortex produced by optical imaging of the brain of a subject (a regions, based on results of fMRI experiments, show key centers of the visual system. LO lateral occipital area; MT middle temporal visual. PLATE 4 See page 234. A creature in the picture is difficult to see

Blake, Randolph

84

Management of hydrocephalus associated with occipital encephalocoele using endoscopic third ventriculostomy: report of two cases  

Microsoft Academic Search

BACKGROUNDOccipital encephalocoele is the most common cranial dysraphism in the western hemisphere and is often complicated by hydrocephalus. Management of hydrocephalus and reducing the CSF pressure is crucial in preventing dehiscence at the site of the encephalocoele repair.METHODSTwo female patients had presented with occipital encephalocoeles. The first patient (aged 42 days) had undergone repair of the occipital encephalocoele and then

Ranjith K Moorthy; Vedantam Rajshekhar

2002-01-01

85

Juvenile myoclonic epilepsy and idiopathic photosensitive occipital lobe epilepsy: is there overlap?  

Microsoft Academic Search

Summary Although epileptic photosensitivity is well known, its genetics and syndromic associations are incompletely understood. Seizures triggered by photic stimulation are usually a manifestation of the idiopathic generalized epilepsies, especially juvenile myoclonic epilepsy (JME), or of the occipital epilepsies. Idiopathic photosensitive occipital epilepsy (IPOE) is a focal epilepsy with colourful elementary visual auras, often with conscious tonic head and eye

Isabella Taylor; Carla Marini; Michael R. Johnson; Samantha Turner; Samuel F. Berkovic; Ingrid E. Scheffer

2004-01-01

86

Occipital seizures and subcortical T2 hypointensity in the setting of hyperglycemia  

PubMed Central

Introduction Occipital lobe seizures are a recognized manifestation of diabetic nonketotic hyperglycemia, though not as common as focal motor seizures. Occipital lobe white matter T2 hypointensity may suggest this diagnosis. Methods We present a case of a 66-year-old man with hyperglycemia-related occipital lobe seizures who presented with confusion, intermittent visual hallucinations, and homonymous hemianopia. Results Magnetic resonance imaging showed subcortical T2 hypointensity within the left occipital lobe with adjacent leptomeningeal enhancement. These findings were transient with disappearance in a follow-up MRI. The EEG captured frequent seizures originating in the left occipital region. HbA1c level was 13.4% on presentation, and finger stick blood glucose level was 400 mg/dl. Conclusion Hyperglycemia should be considered in the etiology of differential diagnosis of patients with visual abnormalities suspicious for seizures, especially when the MRI shows focal subcortical T2 hypointensity with or without leptomeningeal enhancement.

Putta, Swapna L.; Weisholtz, Daniel; Milligan, Tracey A.

2014-01-01

87

PAPER www.rsc.org/loc | Lab on a Chip Laser-induced cavitation based micropump  

E-print Network

of cavitation in microfluidics, for example in microfluidic phase- change heat-exchangers.6 Yet, in the authorsPAPER www.rsc.org/loc | Lab on a Chip Laser-induced cavitation based micropump Rory Dijkinka as versatile and robust pumping techniques. Here, we present a cavitation based technique, which is able

Ohl, Claus-Dieter

88

Compatible immuno-NASBA LOC device for quantitative detection of waterborne pathogens: design and validation.  

PubMed

Waterborne pathogens usually pose a global threat to animals and human beings. There has been a growing demand for convenient and sensitive tools to detect the potential emerging pathogens in water. In this study, a lab-on-a-chip (LOC) device based on the real-time immuno-NASBA (immuno-nucleic acid sequence-based amplification) assay was designed, fabricated and verified. The disposable immuno-NASBA chip is modelled on a 96-well ELISA microplate, which contains 43 reaction chambers inside the bionic channel networks. All valves are designed outside the chip and are reusable. The sample and reagent solutions were pushed into each chamber in turn, which was controlled by the valve system. Notably, the immuno-NASBA chip is completely compatible with common microplate readers in a biological laboratory, and can distinguish multiple waterborne pathogens in water samples quantitatively and simultaneously. The performance of the LOC device was demonstrated by detecting the presence of a synthetic peptide, ACTH (adrenocorticotropic hormone) and two common waterborne pathogens, Escherichia coli (E. coli) and rotavirus, in artificial samples. The results indicated that the LOC device has the potential to quantify traces of waterborne pathogens at femtomolar levels with high specificity, although the detection process was still subject to some factors, such as ribonuclease (RNase) contamination and non-specific adsorption. As an ultra-sensitive tool to quantify waterborne pathogens, the LOC device can be used to monitor water quality in the drinking water system. Furthermore, a series of compatible high-throughput LOC devices for monitoring waterborne pathogens could be derived from this prototype with the same design idea, which may render the complicated immuno-NASBA assays convenient to common users without special training. PMID:22146918

Zhao, Xinyan; Dong, Tao; Yang, Zhaochu; Pires, Nuno; Høivik, Nils

2012-02-01

89

Facial expression recognition takes longer in the posterior superior temporal sulcus than in the occipital face area.  

PubMed

Neuroimaging studies have identified a face-selective region in the right posterior superior temporal sulcus (rpSTS) that responds more strongly during facial expression recognition tasks than during facial identity recognition tasks, but precisely when the rpSTS begins to causally contribute to expression recognition is unclear. The present study addressed this issue using transcranial magnetic stimulation (TMS). In Experiment 1, repetitive TMS delivered over the rpSTS of human participants, at a frequency of 10 Hz for 500 ms, selectively impaired a facial expression task but had no effect on a matched facial identity task. In Experiment 2, participants performed the expression task only while double-pulse TMS (dTMS) was delivered over the rpSTS or over the right occipital face area (rOFA), a face-selective region in lateral occipital cortex, at different latencies up to 210 ms after stimulus onset. Task performance was selectively impaired when dTMS was delivered over the rpSTS at 60-100 ms and 100-140 ms. dTMS delivered over the rOFA impaired task performance at 60-100 ms only. These results demonstrate that the rpSTS causally contributes to expression recognition and that it does so over a longer time-scale than the rOFA. This difference in the length of the TMS induced impairment between the rpSTS and the rOFA suggests that the neural computations that contribute to facial expression recognition in each region are functionally distinct. PMID:24990937

Pitcher, David

2014-07-01

90

Two-Layer Lab-on-a-Chip (LOC) with Passive Capillary Valves for mHealth Medical Diagnostics.  

PubMed

There is a new potential to address needs for medical diagnostics in Point-of-Care (PoC) applications using mHealth (Mobile computing, medical sensors, and communications technologies for health care), a mHealth based lab test will require a LOC to perform clinical analysis. In this work, we describe the design of a simple Lab-on-a-chip (LOC) platform for mHealth medical diagnostics. The LOC utilizes a passive capillary valve with no moving parts for fluid control using channels with very low aspect ratios cross sections (i.e., channel width???height) achieved through transitions in the channel geometry via that arrest capillary flow. Using a CO2 laser in raster engraving mode, we have designed and fabricated an eight-channel LOC for fluorescence signal detection fabricated by engraving and combining just two polymer layers. Each of the LOC channels is capable of mixing two reagents (e.g., enzyme and substrate) for various assays. For mHealth detection, we used a mobile CCD detector equipped with LED multispectral illumination in the red, green, blue, and white range. This technology enables the development of low-cost LOC platforms for mHealth whose fabrication is compatible with standard industrial plastic fabrication processes to enable mass production of mHealth diagnostic devices, which may broaden the use of LOCs in PoC applications, especially in global health settings. PMID:25626544

Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

2015-01-01

91

Sensitivity to syntax in visual cortex.  

PubMed

One of the most intriguing findings on language comprehension is that violations of syntactic predictions can affect event-related potentials as early as 120 ms, in the same time-window as early sensory processing. This effect, the so-called early left-anterior negativity (ELAN), has been argued to reflect word category access and initial syntactic structure building (Friederici, 2002). In two experiments, we used magnetoencephalography to investigate whether (a) rapid word category identification relies on overt category-marking closed-class morphemes and (b) whether violations of word category predictions affect modality-specific sensory responses. Participants read sentences containing violations of word category predictions. Unexpected items varied in whether or not their word category was marked by an overt function morpheme. In Experiment 1, the amplitude of the visual evoked M100 component was increased for unexpected items, but only when word category was overtly marked by a function morpheme. Dipole modeling localized the generator of this effect to the occipital cortex. Experiment 2 replicated the main results of Experiment 1 and eliminated two non-morphology-related explanations of the M100 contrast we observed between targets containing overt category-marking and targets that lacked such morphology. Our results show that during reading, syntactically relevant cues in the input can affect activity in occipital regions at around 125 ms, a finding that may shed new light on the remarkable rapidity of language processing. PMID:19121826

Dikker, Suzanne; Rabagliati, Hugh; Pylkkänen, Liina

2009-03-01

92

Collet-Sicard Syndrome Associated with Occipital Condyle Fracture and Epidural Hematoma  

PubMed Central

A 31-year-old male was presented with a very rare case of ipsilateral palsies of the nerves IX through XII (Collet-Sicard syndrome) after a closed head injury. An occipital condyle fracture that was associated with epidural hematoma was diagnosed by computed tomography. The patient was conservatively managed, and following the treatment, partial neurological recovery ensued. The phenomenon of occipital condyle fracture involving the last four cranial nerve palsies is relatively rare. Although 3 cases of Collet-Sicard syndrome that were caused by an occipital condyle fracture has been reported, the association between condyle fracture and epidural hematoma has never been described before. PMID:17326254

Topsakal, Cahide; Kaplan, Metin; Y?ld?r?m, Hanifi; Ozveren, Mehmet Faik

2007-01-01

93

The sub-occipital transtentorial approach revisited base on our own experience.  

PubMed

The surgical experience of the sub-occipital approach for treatment of pineal gland and pineal region tumors is reported. This approach was originally proposed by Jamieson and modified by Lapras who by changing the shape of the bone flap obtained the elevation of the occipital lobe which consequently resulted in a better exposition of this deep region. The reason why this approach became the basis for their treatment is particularly related to the personal experience of Lapras who reported his fantastic experience of surgery in this deep area and demonstrated the advantages of the sub-occipital transtentorial approach. PMID:24856312

Mottolese, C; Szathmari, A; Ricci-Franchi, A C; Beuriat, P A; Grassiot, B

2014-05-20

94

Frontal and occipital perfusion changes in dissociative identity disorder.  

PubMed

The aim of the study was to investigate if there were any characteristics of regional cerebral blood flow (rCBF) in dissociative identity disorder. Twenty-one drug-free patients with dissociative identity disorder and nine healthy volunteers participated in the study. In addition to a clinical evaluation, dissociative psychopathology was assessed using the Structured Clinical Interview for DSM-IV Dissociative Disorders, the Dissociative Experiences Scale and the Clinician-Administered Dissociative States Scale. A semi-structured interview for borderline personality disorder, the Hamilton Depression Rating Scale, and the Childhood Trauma Questionnaire were also administered to all patients. Normal controls had to be without a history of childhood trauma and without any depressive or dissociative disorder. Regional cerebral blood flow (rCBF) was studied with single photon emission computed tomography (SPECT) with Tc99m-hexamethylpropylenamine (HMPAO) as a tracer. Compared with findings in the control group, the rCBF ratio was decreased among patients with dissociative identity disorder in the orbitofrontal region bilaterally. It was increased in median and superior frontal regions and occipital regions bilaterally. There was no significant correlation between rCBF ratios of the regions of interest and any of the psychopathology scale scores. An explanation for the neurophysiology of dissociative psychopathology has to invoke a comprehensive model of interaction between anterior and posterior brain regions. PMID:17961993

Sar, Vedat; Unal, Seher N; Ozturk, Erdinc

2007-12-15

95

Tecto-Cerebellar Dysraphia Manifesting as Occipital Meningocoele Associated with Congenital Melanocytic Nevi and Pectus Excavatum  

PubMed Central

Background Only few reported cases of tectocerebellar dysraphia with occipital encephalocele have been reported in the literature. Case Presentation Three month baby boy, the first child of healthy, consanguineous parents presented with a small swelling over the occipital region since birth. The child also used to have apneic spells without cyanosis and spontaneous recovery. CT scan showed absence of the cerebellar vermis, absence of tectum and the 4th ventricle communicating with the occipital menigocoele sac and an occipital bone defect. The excision of the encephalocoele sac was performed, however the child continued to have apneic spells and did not do well. Conclusion In our child irregular respiration probably was the manifestation of the tecto-cerebellar dysraphia syndrome complex and associated shunt malfunction followed by seizures decompensated the physiology of the child leading to fatal outcome. PMID:23056693

Agrawal, Amit; Joharapurkar, Sudhakar Ratanlal; Khan, Ata-Ullah

2010-01-01

96

Neuropsychologia xxx (2004) xxxxxx Segregation and persistence of form in the lateral occipital complex  

E-print Network

Neuropsychologia xxx (2004) xxx­xxx Segregation and persistence of form in the lateral occipital.neuropsychologia.2004.06.020 #12;2 S. Ferber et al. / Neuropsychologia xxx (2004) xxx­xxx in this area regardless

Vilis, Tutis

97

Vascular Compression as a Potential Cause of Occipital Neuralgia: A Case Report  

Microsoft Academic Search

Vascular compression is a well-established cause of cranial nerve neuralgic syndromes. A unique case is presented that demonstrates that vascular compression may be a possible cause of occipital neuralgia. A 48-year-old woman with refractory left occipital neuralgia revealed on magnetic resonance imaging and computed tomographic imaging of the upper cervical spine an atypically low loop of the left posterior inferior

JB White; PP Atkinson; HJ Cloft; JLD Atkinson

2008-01-01

98

Occipital spine of Orthacanthus (Xenacanthidae, Elasmobranchii): structure and growth.  

PubMed

The morphology of 16 occipital spines of the xenacanthid Orthacanthus from Upper Carboniferous deposits of Robinson (Kansas, USA), Nýran (Czech Republic) and Puertollano (Spain) is described. The nonreplaced spines reveal the growth pattern of the shark. Moreover, the relationship between growth and paleoenvironmental conditions can be used to determine paleoecological conditions. Both external and internal morphology indicate that the spine was superficially inserted in the skin. During growth, the spine moved from a deep position in the dermis, in which trabecular dentine is formed, to a more superficial location in which centrifugally growing lamellar dentine was formed. Centripetally growing lamellar dentine was deposited more slowly than the centrifugally growing dentine; it obliterated the pulp cavity. The denticles are independent dermal elements formed by a dermal papilla and secondarily attached by dentine to the spine proper. The number of denticles per annual cycle and the density of denticulation vary with the growth rate. Moreover, the ratio of length of denticulated region to total length of the spine changes throughout ontogeny. In consequence, those features cannot be used for systematic purposes without a careful analysis of the variability. Centrifugally growing lamellar dentine in spines from Robinson shows a regular alternation of layers, suggesting tidal conditions in the environment in which the sharks lived. Monthly and seasonal cycles also occur. Tidal (lunar) cyclicity is also observed in the denticles: size and distance between denticles increase and decrease gradually, forming waves that are considered seasonal and yearly cycles. The observed regularity could be related to the variation in calcium phosphate deposition following the cyclical changes in water temperature produced in the tidal zone. Monthly and seasonal cycles are the result of the interaction of the solar and tidal (lunar) cycles. The cyclical pattern of growth is used to determine the age and growth rates. Orthacanthus was a fast-growing shark like the Recent sharks Isurus, Mustelus, and Negaprion. PMID:10493780

Soler-Gijón, R

1999-10-01

99

dLocAuth: a dynamic multifactor authentication scheme for mCommerce applications using independent location-based obfuscation  

NASA Astrophysics Data System (ADS)

This paper proposes a new technique to obfuscate an authentication-challenge program (named LocProg) using randomly generated data together with a client's current location in real-time. LocProg can be used to enable any handsetapplication on mobile-devices (e.g. mCommerce on Smartphones) that requires authentication with a remote authenticator (e.g. bank). The motivation of this novel technique is to a) enhance the security against replay attacks, which is currently based on using real-time nonce(s), and b) add a new security factor, which is location verified by two independent sources, to challenge / response methods for authentication. To assure a secure-live transaction, thus reducing the possibility of replay and other remote attacks, the authors have devised a novel technique to obtain the client's location from two independent sources of GPS on the client's side and the cellular network on authenticator's side. The algorithm of LocProg is based on obfuscating "random elements plus a client's data" with a location-based key, generated on the bank side. LocProg is then sent to the client and is designed so it will automatically integrate into the target application on the client's handset. The client can then de-obfuscate LocProg if s/he is within a certain range around the location calculated by the bank and if the correct personal data is supplied. LocProg also has features to protect against trial/error attacks. Analysis of LocAuth's security (trust, threat and system models) and trials based on a prototype implementation (on Android platform) prove the viability and novelty of LocAuth.

Kuseler, Torben; Lami, Ihsan A.

2012-06-01

100

Frontoparietal cortex controls spatial attention through modulation of anticipatory alpha rhythms.  

PubMed

A dorsal frontoparietal network, including regions in intraparietal sulcus (IPS) and frontal eye field (FEF), has been hypothesized to control the allocation of spatial attention to environmental stimuli. One putative mechanism of control is the desynchronization of electroencephalography (EEG) alpha rhythms (approximately 8-12 Hz) in visual cortex in anticipation of a visual target. We show that brief interference by repetitive transcranial magnetic stimulation (rTMS) with preparatory activity in right IPS or right FEF while subjects attend to a spatial location impairs identification of target visual stimuli approximately 2 s later. This behavioral effect is associated with the disruption of anticipatory (prestimulus) alpha desynchronization and its spatially selective topography in parieto-occipital cortex. Finally, the disruption of anticipatory alpha rhythms in occipital cortex after right IPS- or right FEF-rTMS correlates with deficits of visual identification. These results support the causal role of the dorsal frontoparietal network in the control of visuospatial attention, and suggest that this is partly exerted through the synchronization of occipital visual neurons. PMID:19420253

Capotosto, Paolo; Babiloni, Claudio; Romani, Gian Luca; Corbetta, Maurizio

2009-05-01

101

LocZ Is a New Cell Division Protein Involved in Proper Septum Placement in Streptococcus pneumoniae  

PubMed Central

ABSTRACT How bacteria control proper septum placement at midcell, to guarantee the generation of identical daughter cells, is still largely unknown. Although different systems involved in the selection of the division site have been described in selected species, these do not appear to be widely conserved. Here, we report that LocZ (Spr0334), a newly identified cell division protein, is involved in proper septum placement in Streptococcus pneumoniae. We show that locZ is not essential but that its deletion results in cell division defects and shape deformation, causing cells to divide asymmetrically and generate unequally sized, occasionally anucleated, daughter cells. LocZ has a unique localization profile. It arrives early at midcell, before FtsZ and FtsA, and leaves the septum early, apparently moving along with the equatorial rings that mark the future division sites. Consistently, cells lacking LocZ also show misplacement of the Z-ring, suggesting that it could act as a positive regulator to determine septum placement. LocZ was identified as a substrate of the Ser/Thr protein kinase StkP, which regulates cell division in S. pneumoniae. Interestingly, homologues of LocZ are found only in streptococci, lactococci, and enterococci, indicating that this close phylogenetically related group of bacteria evolved a specific solution to spatially regulate cell division. PMID:25550321

Hole?ková, Nela; Molle, Virginie; Buriánková, Karolína; Benada, Old?ich; Kofro?ová, Olga; Ulrych, Aleš; Branny, Pavel

2014-01-01

102

Changes in Cerebral Cortex of Children Treated for Medulloblastoma  

SciTech Connect

Purpose: Children with medulloblastoma undergo surgery, radiotherapy, and chemotherapy. After treatment, these children have numerous structural abnormalities. Using high-resolution magnetic resonance imaging, we measured the thickness of the cerebral cortex in a group of medulloblastoma patients and a group of normally developing children. Methods and Materials: We obtained magnetic resonance imaging scans and measured the cortical thickness in 9 children after treatment of medulloblastoma. The measurements from these children were compared with the measurements from age- and gender-matched normally developing children previously scanned. For additional comparison, the pattern of thickness change was compared with the cortical thickness maps from a larger group of 65 normally developing children. Results: In the left hemisphere, relatively thinner cortex was found in the perirolandic region and the parieto-occipital lobe. In the right hemisphere, relatively thinner cortex was found in the parietal lobe, posterior superior temporal gyrus, and lateral temporal lobe. These regions of cortical thinning overlapped with the regions of cortex that undergo normal age-related thinning. Conclusion: The spatial distribution of cortical thinning suggested that the areas of cortex that are undergoing development are more sensitive to the effects of treatment of medulloblastoma. Such quantitative methods may improve our understanding of the biologic effects that treatment has on the cerebral development and their neuropsychological implications.

Liu, Arthur K. [Harvard Combined Radiation Oncology Program, Harvard Medical School, Boston, MA (United States)]. E-mail: aliu1@partners.org; Marcus, Karen J. [Department of Radiation Oncology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Department of Radiation Oncology, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Department of Radiation Oncology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (United States); Fischl, Bruce [Athinoula A. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA (United States); Department of Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Division of Health Sciences and Technology, Cambridge, MA (United States); Grant, P. Ellen [Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Young Poussaint, Tina [Department of Radiology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Rivkin, Michael J. [Departments of Neurology, Psychiatry, and Radiology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Davis, Peter [Departments of Neurology, Psychiatry, and Radiology, Children's Hospital Boston, Harvard Medical School, Boston, MA (United States); Tarbell, Nancy J. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Yock, Torunn I. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States)

2007-07-15

103

The cortex is in overall control of 'voluntary' eye movement.  

PubMed

The neural circuits that control eye movements are complex and distributed in brainstem, basal ganglia, cerebellum, and multiple areas of cortex. The anatomical function of the substrates implicated in eye movements has been studied for decades in numerous countries, laboratories, and clinics. The modest goal of this brief review is twofold. (1) To present a focused overview of the knowledge about the role of the cerebral cortex in voluntary control of eye movements. (2) To very briefly mention two findings showing that the accepted hierarchy between the frontal and the occipital sensory areas involved in sensory-motor transformation might not be so trivial to reconcile, and to interpret in the context of eye movement command. This presentation has been part of the 44th Cambridge Ophthalmological Symposium, on ocular motility, 3 September 2014 to 5 November 2014.Eye advance online publication, 5 December 2014; doi:10.1038/eye.2014.284. PMID:25475239

Pouget, P

2014-12-01

104

The role of transverse occipital sulcus in scene perception and its relationship to object individuation in inferior intraparietal sulcus  

PubMed Central

The parietal cortex has been functionally divided into various subregions; however, very little is known about how these areas relate to each other. Two such regions are the transverse occipital sulcus (TOS) scene area and inferior intraparietal sulcus (IPS). TOS exhibits similar activation patterns to the scene selective parahippocampal place area (PPA), suggesting its role in scene perception. Inferior IPS, in contrast, has been shown to participate in object individuation and selection via location. Interestingly, both regions have been localized to the same general area of the brain. If these two were actually the same brain region, it would have important implications regarding these regions’ role in cognition. To explore this, we first localized TOS and inferior IPS in individual participants and examined the degree of overlap between these regions in each participant. We found that TOS showed only a minor degree of overlap with inferior IPS (?10%). We then directly explored the role of TOS and inferior IPS in object individuation and scene perception by examining their responses to furnished rooms, empty rooms, isolated furniture, and multiple isolated objects. If TOS and inferior IPS were the same region, we would expect to see similar response patterns in both. Instead, the response of TOS was predominantly scene selective, while activity in inferior IPS was primarily driven by the number of objects present in the display, regardless of scene context. These results show that TOS and inferior IPS are nearby, but distinct regions, with different functional roles in visual cognition. PMID:23662863

Bettencourt, Katherine C.; Xu, Yaoda

2013-01-01

105

Neural responses in parietal and occipital areas in response to visual events are modulated by prior multisensory stimuli.  

PubMed

The effect of multi-modal vs uni-modal prior stimuli on the subsequent processing of a simple flash stimulus was studied in the context of the audio-visual 'flash-beep' illusion, in which the number of flashes a person sees is influenced by accompanying beep stimuli. EEG recordings were made while combinations of simple visual and audio-visual stimuli were presented. The experiments found that the electric field strength related to a flash stimulus was stronger when it was preceded by a multi-modal flash/beep stimulus, compared to when it was preceded by another uni-modal flash stimulus. This difference was found to be significant in two distinct timeframes--an early timeframe, from 130-160 ms, and a late timeframe, from 300-320 ms. Source localisation analysis found that the increased activity in the early interval was localised to an area centred on the inferior and superior parietal lobes, whereas the later increase was associated with stronger activity in an area centred on primary and secondary visual cortex, in the occipital lobe. The results suggest that processing of a visual stimulus can be affected by the presence of an immediately prior multisensory event. Relatively long-lasting interactions generated by the initial auditory and visual stimuli altered the processing of a subsequent visual stimulus. PMID:24391939

Innes-Brown, Hamish; Barutchu, Ayla; Crewther, David P

2013-01-01

106

Occipital sharp waves in idiopathic partial epilepsies--clinical and genetic aspects.  

PubMed

In order to gain new insight into the pathogenesis and nosography of benign partial epilepsy with occipital paroxysms (BEOP) we retrospectively analysed cases with benign focal sharp waves (SHW) of different localisations, in which analogous EEG changes had been found in at least one first degree relative. Fifty-six families were evaluated. Nineteen cases with occipital SHW (group A) were compared with 37 cases without (group B). There was a broad spectrum of symptomatology with large overlaps between the two groups. However, a number of striking differences, yielding a characteristic picture of early childhood epilepsy with occipital foci were identified: (1) Age of onset under 5 years; (2) a larger proportion of febrile convulsions (FC 47 vs. 19%); (3) a trend towards a higher rate of typical early childhood occipital seizures (26 vs. 5%); (4) a higher rate of frontal and generalizing SHW foci (32 vs. 5%; 37 vs. 11%); (5) a higher rate of generalized spikes and waves (SW) (46 vs. 14%); (6) a trend towards a higher rate of photoparoxysmal response (PPR) (57 vs. 32%). The high prevalence of independent genetic traits favours a multifactorial pathogenesis. The predisposition to FC with characteristic early seizure onset and varying patterns of generalized genetic EEG traits plays a crucial role within the complex pathogenetic network. The early-onset benign childhood occipital seizure susceptibility syndrome of Panayiotopoulos (Benign Childhood Partial Seizures and Related Epileptic Syndromes, John Libbey & Company Ltd., London (1999)) cannot be regarded as the sole representative of occipital spikes in early childhood but as an important even though rare form of occipital epilepsy. PMID:11823116

Doose, Hermann; Petersen, Birgit; Neubauer, Bernd Axel

2002-01-01

107

Bridging the gap: global disparity processing in the human visual cortex  

PubMed Central

The human stereoscopic system is remarkable in its ability to utilize widely separated features as references to support fine depth discrimination. In a search for possible neural substrates of this ability, we recorded high-density EEG and used a distributed inverse technique to estimate population-level disparity responses in five regions of interest (ROIs): V1, V3A, hMT+, V4, and lateral occipital complex (LOC). The stimulus was a central modulating disk surrounded by a correlated “reference” annulus presented in the fixation plane. We varied a gap separating the disk from the annulus parametrically from 0 to 5.5° as a test of long-range disparity integration. In the V1, LOC, and hMT+ ROIs, the responses with gaps >0.5° were equal to those obtained in a control condition where the surround was composed of uncorrelated noise (no reference). By contrast, in the V4 and V3A ROIs, responses with gaps as large as 5.5° were still significantly higher than the control. As a test of the spatial distribution of the disparity reference information, we manipulated the properties of the stimulus by placing noise between the center and the surround or throughout the surround. The V3A ROI was particularly sensitive to disparity noise between the center and annulus regions, suggesting an important contribution of disparity edge detectors in this ROI. PMID:22323636

McKee, Suzanne P.; Norcia, Anthony M.

2012-01-01

108

Preferential effect of isoflurane on top-down vs. bottom-up pathways in sensory cortex  

PubMed Central

The mechanism of loss of consciousness (LOC) under anesthesia is unknown. Because consciousness depends on activity in the cortico-thalamic network, anesthetic actions on this network are likely critical for LOC. Competing theories stress the importance of anesthetic actions on bottom-up “core” thalamo-cortical (TC) vs. top-down cortico-cortical (CC) and matrix TC connections. We tested these models using laminar recordings in rat auditory cortex in vivo and murine brain slices. We selectively activated bottom-up vs. top-down afferent pathways using sensory stimuli in vivo and electrical stimulation in brain slices, and compared effects of isoflurane on responses evoked via the two pathways. Auditory stimuli in vivo and core TC afferent stimulation in brain slices evoked short latency current sinks in middle layers, consistent with activation of core TC afferents. By contrast, visual stimuli in vivo and stimulation of CC and matrix TC afferents in brain slices evoked responses mainly in superficial and deep layers, consistent with projection patterns of top-down afferents that carry visual information to auditory cortex. Responses to auditory stimuli in vivo and core TC afferents in brain slices were significantly less affected by isoflurane compared to responses triggered by visual stimuli in vivo and CC/matrix TC afferents in slices. At a just-hypnotic dose in vivo, auditory responses were enhanced by isoflurane, whereas visual responses were dramatically reduced. At a comparable concentration in slices, isoflurane suppressed both core TC and CC/matrix TC responses, but the effect on the latter responses was far greater than on core TC responses, indicating that at least part of the differential effects observed in vivo were due to local actions of isoflurane in auditory cortex. These data support a model in which disruption of top-down connectivity contributes to anesthesia-induced LOC, and have implications for understanding the neural basis of consciousness. PMID:25339873

Raz, Aeyal; Grady, Sean M.; Krause, Bryan M.; Uhlrich, Daniel J.; Manning, Karen A.; Banks, Matthew I.

2014-01-01

109

When the left brain is not right the right brain may be left: report of personal experience of occipital hemianopia  

PubMed Central

OBJECTIVES—To make a personal report of a hemianopia due to an occipital infarct, sustained by a professor of neurology.?METHODS—Verbatim observation of neurological phenomena recorded during the acute illness.?RESULTS—Hemianopia, visual hallucinations, and non-occipital deficits without extraoccipital lesions on MRI, are described and discussed.?CONCLUSIONS—Hemianopia, due to an occipital infarct, without alexia, is not a disability which precludes a normal professional career. Neurorehabilitation has not been necessary.?? PMID:10406983

Cole, M.

1999-01-01

110

Sounds activate visual cortex and improve visual discrimination.  

PubMed

A recent study in humans (McDonald et al., 2013) found that peripheral, task-irrelevant sounds activated contralateral visual cortex automatically as revealed by an auditory-evoked contralateral occipital positivity (ACOP) recorded from the scalp. The present study investigated the functional significance of this cross-modal activation of visual cortex, in particular whether the sound-evoked ACOP is predictive of improved perceptual processing of a subsequent visual target. A trial-by-trial analysis showed that the ACOP amplitude was markedly larger preceding correct than incorrect pattern discriminations of visual targets that were colocalized with the preceding sound. Dipole modeling of the scalp topography of the ACOP localized its neural generators to the ventrolateral extrastriate visual cortex. These results provide direct evidence that the cross-modal activation of contralateral visual cortex by a spatially nonpredictive but salient sound facilitates the discriminative processing of a subsequent visual target event at the location of the sound. Recordings of event-related potentials to the targets support the hypothesis that the ACOP is a neural consequence of the automatic orienting of visual attention to the location of the sound. PMID:25031419

Feng, Wenfeng; Störmer, Viola S; Martinez, Antigona; McDonald, John J; Hillyard, Steven A

2014-07-16

111

Anticipatory Biasing of Visuospatial Attention Indexed by Retinotopically Specific a-Band Electroencephalography Increases over Occipital Cortex  

Microsoft Academic Search

a-Band (8-14 Hz) oscillatory EEG activity was examined with high-density scalp electrical recording during the cue-stimulus interval of an endogenous spatial cueing paradigm. In different blocks, cued spatial locations (left or right) were in either the upper or lower visual field, and attended stimuli were either oriented Ts or moving dots. Distractor stimuli were equally likely in the uncued hemifield.

Michael S. Worden; John J. Foxe; Norman Wang; Gregory V. Simpson

2000-01-01

112

Evidence of diffuse damage in frontal and occipital cortex in the brain of patients with post-traumatic stress disorder  

Microsoft Academic Search

A number of MRI studies have shown focal or diffuse cortical gray matter (GM) abnormalities in patients with post-traumatic\\u000a stress disorder (PTSD). However, the results of these studies are unclear regarding the cortical regions involved in this\\u000a condition, perhaps due to the heterogeneity of the PTSD population included or to the differences in the methodology used\\u000a for the quantification of

Maricla TavantiMarco; Marco Battaglini; Federico Borgogni; Letizia Bossini; Sara Calossi; Daniela Marino; Gianpaolo Vatti; Fulvio Pieraccini; Antonio Federico; Paolo Castrogiovanni; Nicola De Stefano

113

Economic evaluation of "pulse dose" radiofrequency in the treatment of occipital neuralgia headache.  

PubMed

Headache occipital neuralgia is an example of pain-disease for which treatment both pharmacological protocols and invasive methods are used. Among the latter, the RF (Radiofrequency) pulse-dose has been of interest for the prospects of analgesic efficacy, safety and patient compliance, although at the moment only data concerning the pulsed RF and not the RF pulse-dose, that represents its evolution, are discussed in scientific literature. The purpose of this study is a "simple" economic evaluation of this method in headache occipital neuralgia. PMID:23905049

Giovannini, Vittoria; Pusateri, Rachele; Russo, Viera; Viscardi, Daniela; Palomba, Rosa

2012-05-01

114

Fatal Airbag-Mediated Atlanto-Occipital Dislocation in a Child  

PubMed Central

An atlanto-occipital dislocation is a rare airbag-induced injury in trauma patients. We report a case of an atlanto-occipital dislocation in a 6-year-old patient who was an unrestrained passenger in the front seat of a vehicle involved in a low-speed motor vehicle accident. This case illustrates the fatal threat of airbag deployment to the child passenger travelling in the vehicle front seat even in a low-speed collision, and supports the recommendation that children under 12 years of age travelling in vehicles with dual airbag systems should be seated in the back. PMID:22135564

Hassan, Radhiana; Mohd Yusof, Mubarak; Kamarudin, Norie Azilah

2010-01-01

115

Allocentric versus egocentric representation of remembered reach targets in human cortex.  

PubMed

The location of a remembered reach target can be encoded in egocentric and/or allocentric reference frames. Cortical mechanisms for egocentric reach are relatively well described, but the corresponding allocentric representations are essentially unknown. Here, we used an event-related fMRI design to distinguish human brain areas involved in these two types of representation. Our paradigm consisted of three tasks with identical stimulus display but different instructions: egocentric reach (remember absolute target location), allocentric reach (remember target location relative to a visual landmark), and a nonspatial control, color report (report color of target). During the delay phase (when only target location was specified), the egocentric and allocentric tasks elicited widely overlapping regions of cortical activity (relative to the control), but with higher activation in parietofrontal cortex for egocentric task and higher activation in early visual cortex for allocentric tasks. In addition, egocentric directional selectivity (target relative to gaze) was observed in the superior occipital gyrus and the inferior occipital gyrus, whereas allocentric directional selectivity (target relative to a visual landmark) was observed in the inferior temporal gyrus and inferior occipital gyrus. During the response phase (after movement direction had been specified either by reappearance of the visual landmark or a pro-/anti-reach instruction), the parietofrontal network resumed egocentric directional selectivity, showing higher activation for contralateral than ipsilateral reaches. These results show that allocentric and egocentric reach mechanisms use partially overlapping but different cortical substrates and that directional specification is different for target memory versus reach response. PMID:25209289

Chen, Ying; Monaco, Simona; Byrne, Patrick; Yan, Xiaogang; Henriques, Denise Y P; Crawford, J Douglas

2014-09-10

116

Abnormal visual field maps in human cortex: a mini-review and a case report.  

PubMed

Human visual cortex contains maps of the visual field. Much research has been dedicated to answering whether and when these visual field maps change if critical components of the visual circuitry are damaged. Here, we first provide a focused mini-review of the functional magnetic resonance imaging (fMRI) studies that have evaluated the human cortical visual field maps in the face of retinal lesions, brain injury, and atypical retinocortical projections. We find that there is a fair body of research that has found abnormal fMRI activity, but also that this abnormal activity does not necessarily stem from cortical remapping. The abnormal fMRI activity can often be explained in terms of task effects and/or the uncovering of normally hidden system dynamics. We then present the case of a 16-year-old patient who lost the entire left cerebral hemisphere at age three for treatment of chronic focal encephalitis (Rasmussen syndrome) and intractable epilepsy. Using an fMRI retinotopic mapping procedure and population receptive field (pRF) modeling, we found that (1) despite the long period since the hemispherectomy, the retinotopic organization of early visual cortex remained unaffected by the removal of an entire cerebral hemisphere, and (2) the intact lateral occipital cortex contained an exceptionally large representation of the center of the visual field. The same method also indicates that the neuronal receptive fields in these lateral occipital brain regions are extraordinarily small. These features are clearly abnormal, but again they do not necessarily stem from cortical remapping. For example, the abnormal features can also be explained by the notion that the hemispherectomy took place during a critical period in the development of the lateral occipital cortex and therefore arrested its normal development. Thus, caution should be exercised when interpreting abnormal fMRI activity as a marker of cortical remapping; there are often other explanations. PMID:23347557

Haak, Koen V; Langers, Dave R M; Renken, Remco; van Dijk, Pim; Borgstein, Johannes; Cornelissen, Frans W

2014-07-01

117

The white matter of the human cerebrum: Part I The occipital lobe by Heinrich Sachs  

PubMed Central

This is the first complete translation of Heinrich Sachs' outstanding white matter atlas dedicated to the occipital lobe. This work is accompanied by a prologue by Prof Carl Wernicke who for many years was Sachs' mentor in Breslau and enthusiastically supported his work. PMID:25527430

Forkel, Stephanie J.; Mahmood, Sajedha; Vergani, Francesco; Catani, Marco

2015-01-01

118

Skeleton page 1 bones of the calvaria -occipital, parietal, frontal, temporal, sphenoid, ethmoid  

E-print Network

articulation) · frontal bone - glabella, nasion (frontal:nasal) · sutures of the calvaria - coronal suture (frontal:parietal), sagittal suture (parietal:parietal), lambdoid suture (parietal:occipital), bregma foramen (branches of maxillary artery and nV2; really part of face) · features of the cranial cavity

Houde, Peter

119

The white matter of the human cerebrum: Part I The occipital lobe by Heinrich Sachs.  

PubMed

This is the first complete translation of Heinrich Sachs' outstanding white matter atlas dedicated to the occipital lobe. This work is accompanied by a prologue by Prof Carl Wernicke who for many years was Sachs' mentor in Breslau and enthusiastically supported his work. PMID:25527430

Forkel, Stephanie J; Mahmood, Sajedha; Vergani, Francesco; Catani, Marco

2015-01-01

120

MEG and EEG sensitivity in a case of medial occipital epilepsy.  

PubMed

Interictal or ictal events in partial epilepsies may project on scalp EEG contralaterally to the side of the epileptogenic lesion. Such paradoxical lateralization can be observed in case of para-sagittal generators, and is likely due to the spatial orientation of the generator, presenting an oblique projection towards the midline. We present here a case of medial occipital epilepsy investigated using EEG, MEG and stereoelectroencephalography (SEEG). MRI displayed a focal cortical dysplasia in the superior margin of the right calcarine fissure. SEEG demonstrated bilateral medial occipital interictal spikes, with an inversion of polarity at the level of the lesion and a contralateral propagation occurring in 10 ms. Interictal iterative EEG cartographies showed a large posterior field, with a maximum contralateral to the initial generator (EEG paradoxical lateralization). With the same number of channels, interictal iterative MEG cartographies were more precise and more complex than EEG ones, indicating an onset accurately lateralized. A few milliseconds later, MEG cartographies were quadripolar, thus indicating two homotopic active generators. These MEG and EEG cartographies have been reproduced using BESA dipole simulator. Relative merits of MEG and EEG are still debated. With 151 channels, MEG source localizations indicated the right medial occipital area, as demonstrated by SEEG. An investigation with a corresponding number of EEG channels was not performed. After a down sampling to 64 sensors, this precision was lost. MEG and EEG source localization results, both with 64 channels, were quite comparable, indicating both medial occipital areas. However, a careful analysis of MEG/EEG iterative cartographies, performed with the same number of channels in both modalities, demonstrated that, in this configuration, MEG sensitivity was superior to the EEG one, allowing separating two medial occipital sources, characterized in SEEG by a time delay of 10 ms. PMID:24005334

Gavaret, Martine; Badier, Jean-Michel; Bartolomei, Fabrice; Bénar, Christian-Georges; Chauvel, Patrick

2014-01-01

121

Graphical Analysis of Electromagnetic Coupling on B-737 and B-757 Aircraft for VOR and LOC IPL Data  

NASA Technical Reports Server (NTRS)

Electromagnetic coupling measurements were performed from numerous passenger cabin locations to aircraft instrument landing system localizer (LOC) and VHF Omni-Ranging (VOR) systems. This paper presents and compares the data for B-757 and B-737 airplanes, and provides a basis for fuzzy modeling of coupling patterns in different types of airplanes and airplanes with different antenna locations.

Jafri, Madiha; Ely, Jay; Vahala, Linda

2005-01-01

122

Freiburg RNA Tools: a web server integrating IntaRNA, ExpaRNA and LocARNA  

E-print Network

The Freiburg RNA tools web server integrates three tools for the advanced analysis of RNA in a common web-based user interface. The tools IntaRNA, ExpaRNA and LocARNA support the prediction of RNA–RNA interaction, exact ...

Smith, Cameron

123

TECHNICAL NOTE www.rsc.org/loc | Lab on a Chip Neutravidin micropatterning by deep UV irradiation  

E-print Network

TECHNICAL NOTE www.rsc.org/loc | Lab on a Chip Neutravidin micropatterning by deep UV irradiation February 2008, Accepted 16th June 2008 First published as an Advance Article on the web 13th August 2008 by exposure to deep UV irradiation. Neutravidin is physically absorbed onto the glass or quartz substrate

Hancock, William O.

124

PAPER www.rsc.org/loc | Lab on a Chip Teflon films for chemically-inert microfluidic valves and pumps  

E-print Network

PAPER www.rsc.org/loc | Lab on a Chip Teflon films for chemically-inert microfluidic valves800600h We present a simple method for fabricating chemically-inert Teflon microfluidic valves and pumps for microfluidic devices. Previous work has shown that spin-coated amorphous fluoropolymers and Teflon

Manalis, Scott

125

Conceptual object representations in human anterior temporal cortex.  

PubMed

Interaction with everyday objects requires the representation of conceptual object properties, such as where and how an object is used. What are the neural mechanisms that support this knowledge? While research on semantic dementia has provided evidence for a critical role of the anterior temporal lobes (ATLs) in object knowledge, fMRI studies using univariate analysis have primarily implicated regions outside the ATL. In the present human fMRI study we used multivoxel pattern analysis to test whether activity patterns in ATLs carry information about conceptual object properties. Participants viewed objects that differed on two dimensions: where the object is typically found (in the kitchen or the garage) and how the object is commonly used (with a rotate or a squeeze movement). Anatomical region-of-interest analyses covering the ventral visual stream revealed that information about the location and action dimensions increased from posterior to anterior ventral temporal cortex, peaking in the temporal pole. Whole-brain multivoxel searchlight analysis confirmed these results, revealing highly significant and regionally specific information about the location and action dimensions in the anterior temporal lobes bilaterally. In contrast to conceptual object properties, perceptual and low-level visual properties of the objects were reflected in activity patterns in posterior lateral occipitotemporal cortex and occipital cortex, respectively. These results provide fMRI evidence that object representations in the anterior temporal lobes are abstracted away from perceptual properties, categorizing objects in semantically meaningful groups to support conceptual object knowledge. PMID:23136412

Peelen, Marius V; Caramazza, Alfonso

2012-11-01

126

Suture material for flexor tendon repair: 3–0 V-Loc versus 3–0 Stratafix in a biomechanical comparison ex vivo  

PubMed Central

Background Barbed suture material offers the possibility of knotless flexor tendon repair, as suggested in an increasing number of biomechanical studies. There are currently two different absorbable barbed suture products available, V-Loc™ and Stratafix™, and both have not been compared to each other with regard to flexor tendon repair. The purpose of this study was to evaluate both suture materials for primary stability under static and cyclic loading in a biomechanical ex vivo model. Methods Forty fresh porcine flexor digitorum profundus tendons were randomized in two groups. A four-strand modified Kessler suture technique was used to repair the tendon either with a 3–0 V-Loc™ or 3–0 Stratafix™ without a knot. Parameters of interest were mode of failure, 2-mm gap formation force, displacement, stiffness and maximum load under static and cyclic testing. Results The maximum load was 42.3?±?7.2 for the Stratafix™ group and 50.7?±?8.8 N for the V-Loc™ group. Thus, the ultimate tensile strength was significantly higher for V-Loc™ (p?Loc™ group (n.s.). Displacement was 2.65?±?0.56 mm in the V-Loc™ group and 2.71?±?0.59 mm in the Stratafix™ group (n.s.). Stiffness was 4.24?±?0.68 (N/mm) in the V-Loc™ group and 3.85?±?0.55 (N/mm) the Stratafix™ group (n.s.). Those measured differences were not significant. Conclusion V-Loc™ demonstrates a higher maximum load in tendon reconstruction. The differences in 2-mm gap formation force, displacement and stiffness were not significant. Hereby, the V-Loc™ has an advantage when used as unidirectional barbed suture for knotless flexor tendon repair. PMID:25205062

2014-01-01

127

Neurofibromatosis Type 1: Transcatheter Arterial Embolization for Ruptured Occipital Arterial Aneurysms  

SciTech Connect

Two cases of ruptured aneurysms in the posterior cervical regions associated with type-1 neurofibromatosis treated by transcatheter embolization are reported. Patients presented with acute onset of swelling and pain in the affected areas. Emergently performed contrast-enhanced CT demonstrated aneurysms and large hematomas widespread in the posterior cervical regions. Angiography revealed aneurysms and extravasations of the occipital artery. Patients were successfully treated by percutaneous transcatheter arterial microcoil embolization. Transcatheter arterial embolization therapy was found to be an effective method for treating aneurysmal rupture in the posterior cervical regions occurring in association with type-1 neurofibromatosis. A literature review revealed that rupture of an occipital arterial aneurysm, in the setting of neurofibromatosis type 1, has not been reported previously.

Kanematsu, Masayuki; Kato, Hiroki; Kondo, Hiroshi; Goshima, Satoshi; Tsuge, Yusuke; Kojima, Toshiaki; Watanabe, Haruo [Gifu University Hospital, Department of Radiology (Japan)

2011-02-15

128

Giant cell tumor of the occipital bone: A case report and review of the literature  

PubMed Central

Giant cell tumors (GCTs) are usually found in the epiphysis of the long bones, and represent ~5% of all bone tumors. Only <1% of GCTs are localized in the cranium. When localized in the cranium, GCTs are commonly observed in the sphenoid or temporal bones, and rarely in the parietal or frontal bones. Occipital bone posterior fossa involvement is an extremely rare occurrence. The current study presents a 22-year-old female patient was admitted to the Department of Radiation Oncology (Karadeniz Technical University, Faculty of Medicine, Trabzon, Turkey) with complaints of neck pain and headache. The patients cranial magnetic resonance images showed a 2.5 6-cm mass in the occipital bone, which was subtotally excised. The patient was treated with radiotherapy following the surgery. At present, the patient has shown no progression after 20 months of follow-up. PMID:24959236

USLU, GONCA HANEDAN; CANYILMAZ, EMINE; YÖNEY, ADNAN; AYDIN, SEVDEGÜL; ?AHBAZ, ASLI; SARI, AHMET

2014-01-01

129

Prenatal ultrasound and MRI findings of temporal and occipital lobe dysplasia in a twin with achondroplasia.  

PubMed

Thanatophoric dysplasia, hypochondroplasia and achondroplasia are all caused by FGFR3 (fibroblast growth factor receptor 3) mutations. Neuropathological findings of temporal lobe dysplasia are found in thanatophoric dysplasia, and temporal and occipital lobe abnormalities have been described recently in brain imaging studies of children with hypochondroplasia. We describe twins discordant for achondroplasia, in one of whom the prenatal diagnosis was based on ultrasound and fetal MRI documentation of temporal and occipital lobe abnormalities characteristic of hypochondroplasia, in addition to the finding of short long bones. Despite the intracranial findings suggestive of hypochondroplasia, achondroplasia was confirmed following postnatal clinical and genetic testing. These intracranial abnormalities have not been previously described in a fetus with achondroplasia. PMID:24616001

Pugash, D; Lehman, A M; Langlois, S

2014-09-01

130

Homonymous Ganglion Cell Layer Thinning After Isolated Occipital Lesion: Macular OCT Demonstrates Transsynaptic Retrograde Retinal Degeneration.  

PubMed

: A 48-year-old man was examined 24 months after medial and surgical treatment of an isolated well-circumscribed right occipital lobe abscess. An asymptomatic residual left homonymous inferior scotoma was present. Fundus examination revealed temporal pallor of both optic discs, and optical coherence tomography (OCT) revealed mild temporal loss of retinal nerve fiber layer in both eyes. No relative afferent pupillary defect was present. Assessment of the retinal ganglion cell layer demonstrated homonymous thinning in a pattern corresponding to the homonymous visual field loss. There were no abnormalities of the lateral geniculate nuclei or optic tracts on review of the initial brain computed tomography and follow-up magnetic resonance imaging. We believe our patient showed evidence of transsynaptic retrograde degeneration after an isolated right occipital lobe lesion, and the homonymous neuronal loss was detected on OCT by assessing the retinal ganglion cell layer. PMID:25285723

Meier, Paolo G; Maeder, Philippe; Kardon, Randy H; Borruat, François-Xavier

2014-11-01

131

Different Cellular Types in Mesopontine Cholinergic Nuclei Related to Ponto-Geniculo-Occipital Waves  

Microsoft Academic Search

The only mesopontine neurons previously described as in- volved in the transfer of ponto-geniculo-occipital (PGO) waves from the brain stem to the thalamus were termed PGO-on bursting cells. We have studied, in chronically implanted cats, neuronal activities in brain-stem peribrachial (PB) and laterodorsal tegmental (LDT) cholinergic nuclei in relation to PGO waves recorded from the lateral geniculate (LG) tha- lamic

M. Steriade; S. Datta; G. Oakson; R. Curt

1990-01-01

132

Pulsatile tinnitus from reversal of flow in an aberrant occipital artery: resolved after carotid artery stenting.  

PubMed

Carotid artery stent placement, performed for correction of an asymptomatic severe stenosis, leads to the resolution of persistent and troublesome pulsatile tinnitus. Tinnitus has been reported as a consequence of severe carotid stenoses on previous occasions. This case highlights how an aberrant occipital artery originating above a carotid artery stenosis can result in flow reversal and be a mechanism by which tinnitus may develop. PMID:19435946

Cowley, P O; Jones, R; Tuch, P; McAuliffe, W

2009-05-01

133

Metric sex determination from the basal region of the occipital bone in a documented french sample  

Microsoft Academic Search

\\u000a Abstract  The determination of sex from human skeletal remains is of fundamental importance in both medicolegal and bioarchaeological\\u000a investigations. In the present study, the basal region of the occipital bone in a documented French collection was analyzed\\u000a for sex differences using standard osteometric techniques. The results demonstrated that a low level of sexual dimorphism\\u000a is present in the cranial base of

P. J. Macaluso Jr

2011-01-01

134

Occipital nerve stimulation for chronic headache--long-term safety and efficacy.  

PubMed

The aim of this study was to examine the safety and efficacy of occipital nerve stimulation for medically intractable headache. Electrical stimulation of large sensory afferents has an antinociceptive effect. Occipital nerve stimulation may be effective for the treatment of medically intractable headache. Retrospective analysis was performed of 15 patients with medically refractory headache who underwent implantation of an occipital nerve stimulator. Pre- and postimplant data regarding headache frequency, severity, disability, depression and poststimulator complications were collected. Twelve patients were female and three male. Ages ranged from 21 to 52 years (mean 39 years). Eight patients had chronic migraine, three chronic cluster, two hemicrania continua and two had post-traumatic headache. Eight patients underwent bilateral and seven had unilateral lead placement. Patients were measured after 5-42 months (mean 19). All six mean headache measures improved significantly from baseline (P < 0.03). Headache frequency per 90 days improved by 25 days from a baseline of 89 days; headache severity (0-10) improved 2.4 points from a baseline of 7.1 points; MIDAS disability improved 70 points from a baseline of 179 points; HIT-6 scores improved 11 points from a baseline of 71 points; BDI-II improved eight points from a baseline of 20 points; and the mean subjective percent change in pain was 52%. Most patients (60%) required lead revision within 1 year. One patient required generator revision. Occipital nerve stimulation may be effective in some patients with intractable headache. Surgical revisions may be commonly required. Safety and efficacy results from prospective, randomized, sham-controlled studies in patients with medically refractory headache are needed. PMID:17257236

Schwedt, T J; Dodick, D W; Hentz, J; Trentman, T L; Zimmerman, R S

2007-02-01

135

Retropharyngeal pseudomeningocele formation as a traumatic atlanto-occipital dislocation complication: case report and review  

PubMed Central

Retropharyngeal pseudomeningocele after atlanto-occipital dislocation is a rare complication, with only five cases described in the literature. It develops when a traumatic dural tear occurs allowing cerebrospinal fluid outflow, and it often appears associated with hydrocephalus. We present a case of a 29-year-old female who suffered a motor vehicle accident causing severe brain trauma and spinal cord injury. At hospital arrival the patient scored three points in the Glasgow Coma Scale. Admission computed tomography of the head and neck demonstrated subarachnoid hemorrhage and atlanto-occipital dislocation. Three weeks later, when impossibility to disconnect her from mechanical ventilation was noticed, a magnetic resonance imaging of the neck showed a large retropharyngeal pseudomeningocele. No radiological evidence of hydrocephalus was documented. Given the poor neurological status of the patient, with spastic quadriplegia and disability to breathe spontaneously due to bulbar-medullar injury, no invasive measure was performed to treat the pseudomeningocele. Retropharyngeal pseudomeningocele after atlanto-occipital dislocation should be managed by means of radiological brain study in order to assess for the presence of hydrocephalus, since these two pathologies often appear associated. If allowed by neurological condition of the patient, shunting procedures such as ventriculo-peritoneal or lumbo-peritoneal shunt placement may be helpful for the treatment of the pseudomeningocele, regardless of craniocervical junction management. PMID:17973127

Boto, Gregorio R.; Pérez-Zamarrón, Álvaro; Rivero-Garvía, Mónica

2007-01-01

136

Aesthetic sideburn reconstruction with an expanded reversed temporoparieto-occipital scalp flap.  

PubMed

The sideburn is an important feature of the facial profile in both women and men. Scars in the area around the sideburn and temple are difficult to conceal. Sideburn reconstruction is an especially challenging procedure for plastic surgeons because of the difficulty involved in acquiring high-quality tissue and achieving proper hair direction for a satisfactory appearance. This article describes how to utilize an expanded temporoparieto-occipital scalp flap for sideburn reconstruction, which results in satisfactory hair direction, inconspicuous scars in both the donor and recipient areas, and few complications. From August 2011 to April 2012, 11 patients underwent sideburn reconstruction treatments that involved the use of an expanded temporoparieto-occipital scalp flap. The likeness of hair color and density in the sideburn area was achieved, and the scars at the donor site were hidden in the post-auricular hairline. All of the patients were shown a satisfactory appearance, with few complications both on the recipient and donor site. An expanded temporoparieto-occipital scalp flap is an ideal flap to utilize in sideburn reconstructions because it results in satisfactory hair direction, inconspicuous scars at both the donor and recipient areas, and few complications. PMID:25006889

Yang, Zengjie; Fan, Jincai; Tian, Jia; Liu, Liqiang; Gan, Cheng; Chen, Wenlin; Yin, Zhuming

2014-07-01

137

Multiple Occipital, Parietal, Temporal, and Frontal Foramina: A Variant of Enlarged Parietal Foramina in an Infant  

PubMed Central

Background: Calvarial lesions are often detected incidentally in routine radiology. Most lytic lesions of the skull are benign. Enlarged parietal foramina are benign lesions caused by deficient intramembranous ossification. Case Report: An 11 month-old female patient was admitted with a mass on the right of the back of the head. Physical examination showed a soft 5 cm mass area with no palpable bone in the right occipital. The family history revealed a similar mass in a maternal cousin that resolved over time. Craniography showed lytic lesions, and there were no other pathologies on a complete skeletal X-ray. Computed tomography (CT) showed regular-shaped defects in the bilateral temporal bones, right parietal bone, bilateral frontal bones in the upper-medial orbital wall, and particularly in the occipital bone. The well-defined contours, absence of a soft tissue component, and normal structure and density of the adjacent calvarial bones all pointed to a congenital defect. No change in the lesions was observed during a three-year ultrasound follow-up period. Conclusion: To the best of our knowledge, this is the first described case of multiple occipital, parietal, temporal, and frontal foramina in the cranium. A diagnosis of enlarged parietal foramina variant should be considered after ruling out the differential diagnosis in patients with multiple calvarial lesions. CT may provide valuable findings for the differential diagnosis, and sonography may be used for follow-up.

Y?lmaz, Erdem; Yetim, Aylin; Erol, O?uz Bülent; Pekcan, Melih; Yekeler, Ensar

2014-01-01

138

Occipital hypoperfusion in Parkinson's disease without dementia: correlation to impaired cortical visual processing  

PubMed Central

Objective: The purpose of this study was to analyse changes in regional cerebral blood flow (rCBF) in Parkinson's disease (PD) without dementia. Methods: Twenty eight non-demented patients with PD and 17 age matched normal subjects underwent single photon emission computed tomography with N-isopropyl-p-[123I]iodoamphetamine to measure rCBF. The statistical parametric mapping 96 programme was used for statistical analysis. Results: The PD patients showed significantly reduced rCBF in the bilateral occipital and posterior parietal cortices (p<0.01, corrected for multiple comparison p<0.05), when compared with the control subjects. There was a strong positive correlation between the score of Raven's coloured progressive matrices (RCPM) and the rCBF in the right visual association area (p<0.01, corrected for multiple comparison p<0.05) among the PD patients. Conclusions: This study showed occipital and posterior parietal hypoperfusion in PD patients without dementia. Furthermore, it was demonstrated that occipital hypoperfusion is likely to underlie impairment of visual cognition according to the RCPM test, which is not related to motor impairment. PMID:12640053

Abe, Y; Kachi, T; Kato, T; Arahata, Y; Yamada, T; Washimi, Y; Iwai, K; Ito, K; Yanagisawa, N; Sobue, G

2003-01-01

139

Dopamine D sub 2 receptors in the cerebral cortex: Distribution and pharmacological characterization with ( sup 3 H)raclopride  

SciTech Connect

An apparent involvement of dopamine in the regulation of cognitive functions and the recognition of a widespread dopaminergic innervation of the cortex have focused attention on the identity of cortical dopamine receptors. However, only the presence and distribution of dopamine D{sub 1} receptors in the cortex have been well documented. Comparable information on cortical D{sub 2} sites is lacking. The authors report here the results of binding studied in the cortex and neostriatum of rat and monkey using the D{sub 2} selective antagonist ({sup 3}H)raclopride. In both structures ({sup 3}H)raclopride bound in a sodium-dependent and saturable manner to a single population of sites with pharmacological profiles of dopamine D{sub 2} receptors. D{sub 2} sites were present in all regions of the cortex, although their density was much lower than in the neostriatum. The density of these sites in both monkey and, to a lesser extent, rat cortex displayed a rostral-caudal gradient with highest concentrations in the prefrontal and lowest concentrations in the occipital cortex, corresponding to dopamine levels in these areas. Thus, the present study established the presence and widespread distribution of dopamine D{sub 2} receptors in the cortex.

Lidow, M.S.; Goldman-Rakic, P.S.; Rakic, P.; Innis, R.B. (Yale Univ., New Haven, CT (USA))

1989-08-01

140

Enhanced Awareness Followed Reversible Inhibition of Human Visual Cortex: A Combined TMS, MRS and MEG Study  

PubMed Central

This series of experiments investigated the neural basis of conscious vision in humans using a form of transcranial magnetic stimulation (TMS) known as continuous theta burst stimulation (cTBS). Previous studies have shown that occipital TMS, when time-locked to the onset of visual stimuli, can induce a phenomenon analogous to blindsight in which conscious detection is impaired while the ability to discriminate ‘unseen’ stimuli is preserved above chance. Here we sought to reproduce this phenomenon using offline occipital cTBS, which has been shown to induce an inhibitory cortical aftereffect lasting 45–60 minutes. Contrary to expectations, our first experiment revealed the opposite effect: cTBS enhanced conscious vision relative to a sham control. We then sought to replicate this cTBS-induced potentiation of consciousness in conjunction with magnetoencephalography (MEG) and undertook additional experiments to assess its relationship to visual cortical excitability and levels of the inhibitory neurotransmitter ?-aminobutyric acid (GABA; via magnetic resonance spectroscopy, MRS). Occipital cTBS decreased cortical excitability and increased regional GABA concentration. No significant effects of cTBS on MEG measures were observed, although the results provided weak evidence for potentiation of event related desynchronisation in the ? band. Collectively these experiments suggest that, through the suppression of noise, cTBS can increase the signal-to-noise ratio of neural activity underlying conscious vision. We speculate that gating-by-inhibition in the visual cortex may provide a key foundation of consciousness. PMID:24956195

Allen, Christopher P. G.; Dunkley, Benjamin T.; Muthukumaraswamy, Suresh D.; Edden, Richard; Evans, C. John; Sumner, Petroc; Singh, Krish D.; Chambers, Christopher D.

2014-01-01

141

Enhanced awareness followed reversible inhibition of human visual cortex: a combined TMS, MRS and MEG study.  

PubMed

This series of experiments investigated the neural basis of conscious vision in humans using a form of transcranial magnetic stimulation (TMS) known as continuous theta burst stimulation (cTBS). Previous studies have shown that occipital TMS, when time-locked to the onset of visual stimuli, can induce a phenomenon analogous to blindsight in which conscious detection is impaired while the ability to discriminate 'unseen' stimuli is preserved above chance. Here we sought to reproduce this phenomenon using offline occipital cTBS, which has been shown to induce an inhibitory cortical aftereffect lasting 45-60 minutes. Contrary to expectations, our first experiment revealed the opposite effect: cTBS enhanced conscious vision relative to a sham control. We then sought to replicate this cTBS-induced potentiation of consciousness in conjunction with magnetoencephalography (MEG) and undertook additional experiments to assess its relationship to visual cortical excitability and levels of the inhibitory neurotransmitter ?-aminobutyric acid (GABA; via magnetic resonance spectroscopy, MRS). Occipital cTBS decreased cortical excitability and increased regional GABA concentration. No significant effects of cTBS on MEG measures were observed, although the results provided weak evidence for potentiation of event related desynchronisation in the ? band. Collectively these experiments suggest that, through the suppression of noise, cTBS can increase the signal-to-noise ratio of neural activity underlying conscious vision. We speculate that gating-by-inhibition in the visual cortex may provide a key foundation of consciousness. PMID:24956195

Allen, Christopher P G; Dunkley, Benjamin T; Muthukumaraswamy, Suresh D; Edden, Richard; Evans, C John; Sumner, Petroc; Singh, Krish D; Chambers, Christopher D

2014-01-01

142

Occipital Neuralgia  

MedlinePLUS

... of headache characterized by piercing, throbbing, or electric-shock-like chronic pain in the upper neck, back ... condition. Many individuals will improve with therapy involving heat, rest, anti-inflammatory medications, and muscle relaxants. Recovery ...

143

Effects of Visual Cortex Activation on the Nociceptive Blink Reflex in Healthy Subjects  

PubMed Central

Bright light can cause excessive visual discomfort, referred to as photophobia. The precise mechanisms linking luminance to the trigeminal nociceptive system supposed to mediate this discomfort are not known. To address this issue in healthy human subjects we modulated differentially visual cortex activity by repetitive transcranial magnetic stimulation (rTMS) or flash light stimulation, and studied the effect on supraorbital pain thresholds and the nociceptive-specific blink reflex (nBR). Low frequency rTMS that inhibits the underlying cortex, significantly decreased pain thresholds, increased the 1st nBR block ipsi- and contralaterally and potentiated habituation contralaterally. After high frequency or sham rTMS over the visual cortex, and rMS over the right greater occipital nerve we found no significant change. By contrast, excitatory flash light stimulation increased pain thresholds, decreased the 1st nBR block of ipsi- and contralaterally and increased habituation contralaterally. Our data demonstrate in healthy subjects a functional relation between the visual cortex and the trigeminal nociceptive system, as assessed by the nociceptive blink reflex. The results argue in favour of a top-down inhibitory pathway from the visual areas to trigemino-cervical nociceptors. We postulate that in normal conditions this visuo-trigeminal inhibitory pathway may avoid disturbance of vision by too frequent blinking and that hypoactivity of the visual cortex for pathological reasons may promote headache and photophobia. PMID:24936654

Sava, Simona L.; de Pasqua, Victor; Magis, Delphine; Schoenen, Jean

2014-01-01

144

Vestibular function in the temporal and parietal cortex: distinct velocity and inertial processing pathways.  

PubMed

A number of behavioral and neuroimaging studies have reported converging data in favor of a cortical network for vestibular function, distributed between the temporo-parietal cortex and the prefrontal cortex in the primate. In this review, we focus on the role of the cerebral cortex in visuo-vestibular integration including the motion sensitive temporo-occipital areas i.e., the middle superior temporal area (MST) and the parietal cortex. Indeed, these two neighboring cortical regions, though they both receive combined vestibular and visual information, have distinct implications in vestibular function. In sum, this review of the literature leads to the idea of two separate cortical vestibular sub-systems forming (1) a velocity pathway including MST and direct descending pathways on vestibular nuclei. As it receives well-defined visual and vestibular velocity signals, this pathway is likely involved in heading perception and rapid top-down regulation of eye/head coordination and (2) an inertial processing pathway involving the parietal cortex in connection with the subcortical vestibular nuclei complex responsible for velocity storage integration. This vestibular cortical pathway would be implicated in high-order multimodal integration and cognitive functions, including world space and self-referential processing. PMID:25071481

Ventre-Dominey, Jocelyne

2014-01-01

145

Vestibular function in the temporal and parietal cortex: distinct velocity and inertial processing pathways  

PubMed Central

A number of behavioral and neuroimaging studies have reported converging data in favor of a cortical network for vestibular function, distributed between the temporo-parietal cortex and the prefrontal cortex in the primate. In this review, we focus on the role of the cerebral cortex in visuo-vestibular integration including the motion sensitive temporo-occipital areas i.e., the middle superior temporal area (MST) and the parietal cortex. Indeed, these two neighboring cortical regions, though they both receive combined vestibular and visual information, have distinct implications in vestibular function. In sum, this review of the literature leads to the idea of two separate cortical vestibular sub-systems forming (1) a velocity pathway including MST and direct descending pathways on vestibular nuclei. As it receives well-defined visual and vestibular velocity signals, this pathway is likely involved in heading perception and rapid top-down regulation of eye/head coordination and (2) an inertial processing pathway involving the parietal cortex in connection with the subcortical vestibular nuclei complex responsible for velocity storage integration. This vestibular cortical pathway would be implicated in high-order multimodal integration and cognitive functions, including world space and self-referential processing. PMID:25071481

Ventre-Dominey, Jocelyne

2014-01-01

146

Incidence of neuropathic pain after radiofrequency denervation of the third occipital nerve  

PubMed Central

The purpose of this study was to identify the incidence of neuropathic pain occurring after radiofrequency neurotomy of the third occipital nerve (TON). This study was conducted at a teaching hospital from January 1, 2008, to March 31, 2010. With institutional review board approval, Current Procedural Terminology codes were used to identify patients who received radiofrequency ablation (RFA) of the nerves supplying the C2-3 facet joint and the TON. The C3 dorsal ramus provides innervation to the C2-3 facet joint and the suboccipital cutaneous region, and procedures that included ablation to this region were reviewed for complications. Postprocedural data were collected by reviewing follow-up appointment notes and telephone calls. Included were patients who had new neuropathic pain in the distribution of the TON after RFA. They described what they were feeling as burning, tingling, or numbness. All patients who presented with complaints had normal neurologic findings and no secondary cause for their symptoms. The included patient medical records were then reviewed for severity and duration of symptoms and the need for treatment with pain medication. Sixty-four patients underwent C2-3 RFA or TON RFA, and 12 patients were identified as experiencing ablation-induced third occipital neuralgia, an incidence rate of 19%. This finding suggests that patients undergoing RFA of the nerves supplying the C2-3 joint or TON are at risk for postprocedural third occipital neuralgia. This possibility may affect providing informed consent as well as anticipating and managing postprocedural pain. PMID:24748815

Gazelka, Halena M; Knievel, Sarah; Mauck, William D; Moeschler, Susan M; Pingree, Matthew J; Rho, Richard H; Lamer, Tim J

2014-01-01

147

Increased Visual Stimulation Systematically Decreases Activity in Lateral Intermediate Cortex.  

PubMed

Previous studies have attributed multiple diverse roles to the posterior superior temporal cortex (STC), both visually driven and cognitive, including part of the default mode network (DMN). Here, we demonstrate a unifying property across this multimodal region. Specifically, the lateral intermediate (LIM) portion of STC showed an unexpected feature: a progressively decreasing fMRI response to increases in visual stimulus size (or number). Such responses are reversed in sign, relative to well-known responses in classic occipital temporal visual cortex. In LIM, this "reversed" size function was present across multiple object categories and retinotopic eccentricities. Moreover, we found a significant interaction between the LIM size function and the distribution of subjects' attention. These findings suggest that LIM serves as a part of the DMN. Further analysis of functional connectivity, plus a meta-analysis of previous fMRI results, suggests that LIM is a heterogeneous area including different subdivisions. Surprisingly, analogous fMRI tests in macaque monkeys did not reveal a clear homolog of LIM. This interspecies discrepancy supports the idea that self-referential thinking and theory of mind are more prominent in humans, compared with monkeys. PMID:25480358

Nasr, Shahin; Stemmann, Heiko; Vanduffel, Wim; Tootell, Roger B H

2014-12-01

148

Electrochemical dissolved oxygen removal from microfluidic streams for LOC sample pretreatment.  

PubMed

Current water quality monitoring for heavy metal contaminants largely results in analytical snapshots at a particular time and place. Therefore, we have been interested in miniaturized and inexpensive sensors suitable for long-term, real-time monitoring of the drinking water distribution grid, industrial wastewater effluents, and even rivers and lakes. Among the biggest challenges for such sensors are the issues of in-field device calibration and sample pretreatment. Previously, we have demonstrated use of coulometric stripping analysis for calibration-free determination of copper and mercury. For more negatively reduced metals, O2 reduction interferes with stripping analysis; hence, most electroanalysis techniques rely on pretreatments to remove dissolved oxygen (DO). Current strategies for portable DO removal offer limited practicality, because of their complexity, and often cause inadvertent sample alterations. Therefore, we have designed an indirect in-line electrochemical DO removal device (EDOR), utilizing a silver cathode to reduce DO in a chamber that is fluidically isolated from the sample stream by an O2-permeable membrane. The resulting concentration gradient supports passive DO diffusion from the sample stream into the deoxygenation chamber. The DO levels in the sample stream were determined by cyclic voltammetry (CV) and amperometry at a custom thin-layer cell (TLC) detector. Results show removal of 98% of the DO in a test sample at flow rates approaching 50 ?L/min and power consumption as low as 165 mW h L(-1) at steady state. Besides our specific stripping application, this device is well-suited for LOC applications where miniaturized DO removal and/or regulation are desirable. PMID:25082792

Marei, Mohamed M; Roussel, Thomas J; Keynton, Robert S; Baldwin, Richard P

2014-09-01

149

Coarse-to-fine categorization of visual scenes in scene-selective cortex.  

PubMed

Neurophysiological, behavioral, and computational data indicate that visual analysis may start with the parallel extraction of different elementary attributes at different spatial frequencies and follows a predominantly coarse-to-fine (CtF) processing sequence (low spatial frequencies [LSF] are extracted first, followed by high spatial frequencies [HSF]). Evidence for CtF processing within scene-selective cortical regions is, however, still lacking. In the present fMRI study, we tested whether such processing occurs in three scene-selective cortical regions: the parahippocampal place area (PPA), the retrosplenial cortex, and the occipital place area. Fourteen participants were subjected to functional scans during which they performed a categorization task of indoor versus outdoor scenes using dynamic scene stimuli. Dynamic scenes were composed of six filtered images of the same scene, from LSF to HSF or from HSF to LSF, allowing us to mimic a CtF or the reverse fine-to-coarse (FtC) sequence. Results showed that only the PPA was more activated for CtF than FtC sequences. Equivalent activations were observed for both sequences in the retrosplenial cortex and occipital place area. This study suggests for the first time that CtF sequence processing constitutes the predominant strategy for scene categorization in the PPA. PMID:24738768

Musel, Benoit; Kauffmann, Louise; Ramanoël, Stephen; Giavarini, Coralie; Guyader, Nathalie; Chauvin, Alan; Peyrin, Carole

2014-10-01

150

Multiple occipital defects caused by arachnoid granulations: Emphasis on T2 mapping  

PubMed Central

A 56-year-old man presented with a 6-mo history of headache. Although neurological and laboratory examinations were normal, computed tomography (CT) scan was performed which revealed multiple occipital osteolytic lesions, which were suspected to be multiple myeloma. Subsequently nuclear magnetic resonance imaging (MRI) showed that these lesions presented with a cerebrospinal fluid (CSF)-like signal intensity, no diffusional restriction and intrinsic mass-like enhancement on conventional sequences were seen. T2 relaxation time was similar to that of CSF in the ventricles and adjacent subarachnoid space on T2-mapping. Single photon emission CT with 99mTc-Methyl diphosphonate was performed which revealed no increased radiotracing accumulation. Finally, these lesions were diagnosed as mutiple arachnoid granulations (AGs). The headache was treated symptomatically with medical therapy. On follow up examination after 6 mo no evidence of tumor was detected. This report aimed to illustrate the appearance and differentiation of occipital defects caused by multiple AGs on CT and MRI, with emphasis on the findings from T2 mapping. PMID:22900137

Lu, Chao-Xuan; Du, Yong; Xu, Xiao-Xue; Li, Yang; Yang, Han-Feng; Deng, Shao-Qiang; Xiao, Dong-Mei; Li, Bing; Tian, Yun-Hong

2012-01-01

151

Multiple occipital defects caused by arachnoid granulations: Emphasis on T2 mapping.  

PubMed

A 56-year-old man presented with a 6-mo history of headache. Although neurological and laboratory examinations were normal, computed tomography (CT) scan was performed which revealed multiple occipital osteolytic lesions, which were suspected to be multiple myeloma. Subsequently nuclear magnetic resonance imaging (MRI) showed that these lesions presented with a cerebrospinal fluid (CSF)-like signal intensity, no diffusional restriction and intrinsic mass-like enhancement on conventional sequences were seen. T2 relaxation time was similar to that of CSF in the ventricles and adjacent subarachnoid space on T2-mapping. Single photon emission CT with (99m)Tc-Methyl diphosphonate was performed which revealed no increased radiotracing accumulation. Finally, these lesions were diagnosed as mutiple arachnoid granulations (AGs). The headache was treated symptomatically with medical therapy. On follow up examination after 6 mo no evidence of tumor was detected. This report aimed to illustrate the appearance and differentiation of occipital defects caused by multiple AGs on CT and MRI, with emphasis on the findings from T2 mapping. PMID:22900137

Lu, Chao-Xuan; Du, Yong; Xu, Xiao-Xue; Li, Yang; Yang, Han-Feng; Deng, Shao-Qiang; Xiao, Dong-Mei; Li, Bing; Tian, Yun-Hong

2012-07-28

152

Radiation-induced malignant fibrous histiocytoma of the occipital: a case report  

PubMed Central

Malignant fibrous histiocytoma (MFH) is a rare neoplasm exhibiting a propensity for aggressive clinical behavior. Effective treatment modality is surgical resection with wide margins, but its rate of recurrence and metastasis is still high. Early detection and complete excision of the tumor is necessary. A MFH of the occipital developed in a 51-year-old woman eight years after surgery and radiation for medulloblastoma of the cerebellar vermis. The secondary neoplasm arose at the site of tumor resection within the irradiated field, and was resected. The development of sarcomas is a recognized complication of radiation therapy. The final diagnosis after the operation was MFH. Radiation-induced sarcoma (RIS) is well known, but radiation-induced MFH is relatively rare in the head and neck region, especially in the occipital. The imaging findings are not diagnosis specific, but strict follow-up within the radiation field by computerized tomography (CT) and magnetic resonance imaging (MRI) and appreciation of the expected latency period may help in providing the diagnosis of RIS. PMID:24742094

2014-01-01

153

Distinctive Menkes disease variant with occipital horns: Delineation of natural history and clinical phenotype  

SciTech Connect

To delineate further the clinical spectrum of Menkes disease, an X-linked recessive disorder of copper transport, we studied 4 related males, ranging in age from 4-38 years, with a unique phenotype that combines manifestations of classical and mild Menkes disease and occipital horn syndrome (OHS). The propositus, an 18-year-old man, was evaluated following an intracerebral hemorrhage at age 15 years and was noted to have marked hypotonia, motor delay with mental retardation, bladder diverticula, failure to thrive, and diarrhea from infancy; seizures from age 3 years; and abnormal hair (pili torti) and face, cutis laxa, and multiple joint dislocations. Radiographic abnormalities included occipital exostoses, tortuous cerebral blood vessels with multiple branch occlusions, and hammer-shaped clavicles. Biochemical studies demonstrated reduced copper and ceruloplasmin levels in serum, and abnormal plasma catecholamine ratios. We reported previously the molecular defect in this family, a splice-site mutation that predicts formation of approximately 20% of the normal Menkes gene product. Here, we detail the clinical course and physical features and radiographic findings in these 4 individuals, and compare their phenotype with classical and mild Menkes and OHS. Unusual Menkes disease variants such as this may escape recognition due to anomalies that appear inconsistent with the diagnosis, particularly prolonged survival and later onset of seizures. Males with mental retardation and connective tissue abnormalities should be evaluated for biochemical evidence of defective copper transport. 28 refs., 8 figs.

Proud, V.K.; Mussell, H.G.; Percy, A.K. [Univ. of Alabama School of Medicine, Birmingham, AL (United States)] [and others] [Univ. of Alabama School of Medicine, Birmingham, AL (United States); and others

1996-10-02

154

Non-holistic coding of objects in lateral occipital complex with and without attention.  

PubMed

A fundamental issue in visual cognition is whether high-level visual areas code objects in a part-based or a view-based (holistic) format. Previous behavioral and neuroimaging studies that examined the viewpoint invariance of object recognition have yielded ambiguous results, providing evidence for either type of representational format. A critical factor distinguishing the two formats could be the availability of attentional resources, as a number of priming studies have found greater viewpoint invariance for attended compared to unattended objects. It has therefore been suggested that the activation of part-based representations requires attention, whereas the activation of holistic representations occurs automatically irrespective of attention. Using functional magnetic resonance imaging in combination with a novel multivariate pattern analysis approach, the present study probed the format of object representations in human lateral occipital complex and its dependence on attention. We presented human participants with intact and half-split versions of objects that were either attended or unattended. Cross-classifying between intact and split objects, we found that the object-related information coded in activation patterns of intact objects is fully preserved in the patterns of split objects and vice versa. Importantly, the generalization between intact and split objects did not depend on attention. We conclude that lateral occipital complex codes objects in a non-holistic format, both in the presence and absence of attention. PMID:25512039

Guggenmos, Matthias; Thoma, Volker; Cichy, Radoslaw Martin; Haynes, John-Dylan; Sterzer, Philipp; Richardson-Klavehn, Alan

2015-02-15

155

Occipital nerve stimulation for the treatment of intractable chronic migraine headache: ONSTIM feasibility study  

PubMed Central

Background: Medically intractable chronic migraine (CM) is a disabling illness characterized by headache ?15 days per month. Methods: A multicenter, randomized, blinded, controlled feasibility study was conducted to obtain preliminary safety and efficacy data on occipital nerve stimulation (ONS) in CM. Eligible subjects received an occipital nerve block, and responders were randomized to adjustable stimulation (AS), preset stimulation (PS) or medical management (MM) groups. Results: Seventy-five of 110 subjects were assigned to a treatment group; complete diary data were available for 66. A responder was defined as a subject who achieved a 50% or greater reduction in number of headache days per month or a three-point or greater reduction in average overall pain intensity compared with baseline. Three-month responder rates were 39% for AS, 6% for PS and 0% for MM. No unanticipated adverse device events occurred. Lead migration occurred in 12 of 51 (24%) subjects. Conclusion: The results of this feasibility study offer promise and should prompt further controlled studies of ONS in CM. PMID:20861241

Saper, Joel R; Dodick, David W; Silberstein, Stephen D; McCarville, Sally; Sun, Mark; Goadsby, Peter J

2011-01-01

156

Natural evolution from idiopathic photosensitive occipital lobe epilepsy to idiopathic generalized epilepsy in an untreated young patient.  

PubMed

Idiopathic photosensitive occipital lobe epilepsy (IPOE) is an idiopathic localization-related epilepsy characterized by age-related onset, specific mode of precipitation, occipital photic-induced seizures--frequently consisting of visual symptoms--and good prognosis. This uncommon epilepsy, which usually starts in childhood or adolescence, has rarely been observed in families in which idiopathic generalized epilepsy also affects other members. We describe a nuclear family in which the proband showed electro-clinical features of idiopathic photosensitive occipital lobe epilepsy in childhood, which subsequently evolved into absences and a single generalized tonico-clonic seizure in early adolescence. His mother had features suggestive of juvenile myoclonic epilepsy. This case illustrates a continuum between focal and generalized entities in the spectrum of the so-called idiopathic (genetically determined) epileptic syndromes. PMID:23815968

Bonini, Francesca; Egeo, Gabriella; Fattouch, Jinan; Fanella, Martina; Morano, Alessandra; Giallonardo, Anna Teresa; di Bonaventura, Carlo

2014-04-01

157

The auditory cortex  

Microsoft Academic Search

The division of the auditory cortex into various fields, functional aspects of these fields, and neuronal coding in the primary\\u000a auditory cortical field (AI) are reviewed with stress on features that may be common to mammals. On the basis of 14 topographies\\u000a and clustered distributions of neuronal response characteristics in the primary auditory cortical field, a hypothesis is developed\\u000a of

G. Ehret

1997-01-01

158

A BOLD signature of eyeblinks in the visual cortex.  

PubMed

We are usually unaware of the brief but large illumination changes caused by blinks, presumably because of blink suppression mechanisms. In fMRI however, increase of the BOLD signal was reported in the visual cortex, e.g. during blocks of voluntary blinks (Bristow, Frith and Rees, 2005) or after spontaneous blinks recorded during the prolonged fixation of a static stimulus (Tse, Baumgartner and Greenlee, 2010). We tested whether such activation, possibly related to illumination changes, was also present during standard fMRI retinotopic and visual experiments and was large enough to contaminate the BOLD signal we are interested in. We monitored in a 3T scanner the eyeblinks of 14 subjects who observed three different types of visual stimuli, including periodic rotating wedges and contracting/expanding rings, event-related Mondrians and graphemes, while fixating. We performed event-related analyses on the set of detected spontaneous blinks. We observed large and widespread BOLD responses related to blinks in the visual cortex of every subject and whatever the visual stimulus. The magnitude of the modulation was comparable to visual stimulation. However, blink-related activations lay mostly in the anterior parts of retinotopic visual areas, coding the periphery of the visual field well beyond the extent of our stimuli. Blinks therefore represent an important source of BOLD variations in the visual cortex and a troublesome source of noise since any correlation, even weak, between the distribution of blinks and a tested protocol could trigger artifactual activities. However, the typical signature of blinks along the anterior calcarine and the parieto-occipital sulcus allows identifying, even in the absence of eyetracking, fMRI protocols possibly contaminated by a heterogeneous distribution of blinks. PMID:22426351

Hupé, Jean-Michel; Bordier, Cécile; Dojat, Michel

2012-05-15

159

The functional organization of human extrastriate cortex: a PET-rCBF study of selective attention to faces and locations.  

PubMed

The functional dissociation of human extrastriate cortical processing streams for the perception of face identity and location was investigated in healthy men by measuring visual task-related changes in regional cerebral blood flow (rCBF) with positron emission tomography (PET) and H2(15)O. Separate scans were obtained while subjects performed face matching, location matching, or sensorimotor control tasks. The matching tasks used identical stimuli for some scans and stimuli of equivalent visual complexity for others. Face matching was associated with selective rCBF increases in the fusiform gyrus in occipital and occipitotemporal cortex bilaterally and in a right prefrontal area in the inferior frontal gyrus. Location matching was associated with selective rCBF increases in dorsal occipital, superior parietal, and intraparietal sulcus cortex bilaterally and in dorsal right premotor cortex. Decreases in rCBF, relative to the sensorimotor control task, were observed for both matching tasks in auditory, auditory association, somatosensory, and midcingulate cortex. These results suggest that, within a sensory modality, selective attention is associated with increased activity in those cortical areas that process the attended information but is not associated with decreased activity in areas that process unattended visual information. Selective attention to one sensory modality, on the other hand, is associated with decreased activity in cortical areas dedicated to processing input from other sensory modalities. Direct comparison of our results with those from other PET-rCBF studies of extrastriate cortex demonstrates agreement in the localization of cortical areas mediating face and location perception and dissociations between these areas and those mediating the perception of color and motion. PMID:7965040

Haxby, J V; Horwitz, B; Ungerleider, L G; Maisog, J M; Pietrini, P; Grady, C L

1994-11-01

160

Sensing with the Motor Cortex  

PubMed Central

The primary motor cortex is a critical node in the network of brain regions responsible for voluntary motor behavior. It has been less appreciated, however, that the motor cortex exhibits sensory responses in a variety of modalities including vision and somatosensation. We review current work that emphasizes the heterogeneity in sensori-motor responses in the motor cortex and focus on its implications for cortical control of movement as well as for brain-machine interface development. PMID:22078507

Hatsopoulos, Nicholas G.; Suminski, Aaron J.

2011-01-01

161

An Anatomical Variation of the Lesser Occipital Nerve in the "Carefree part" of the Posterior Triangle.  

PubMed

The occurrence of the lesser occipital nerve (LON) at an anomalous location in the "carefree part" within the posterior triangle has been seldom reported in the literature. We are reporting a rare case of location of the LON in the "carefree part" of the posterior triangle, in a 55-year-old formalin embalmed male cadaver. LON, after emerging from the posterior margin of the sternomastoid muscle (SM), ran obliquely towards the trapezius muscle. Here, it hooked around the unusual separated muscle fasciculus of the trapezius, 7.5 cm below the superior nuchal line. Further, LON gave contributions to spinal accessory nerve (SAN); one deep into the SM and another one in the posterior triangle. The knowledge on the unusual location and course of the LON and its contribution to the SAN is significantly important while an anaesthetic blockade is being performed for the management of a cervicogenic headache and a super selective radical neck dissection. PMID:24959430

Ravindra S, Swamy; Sirasanagandla, Srinivasa Rao; Nayak, Satheesha B; Rao Kg, Mohandas; Patil, Jyothsna

2014-04-01

162

Impairment of gaze-centered updating of reach targets in bilateral parietal-occipital damaged patients.  

PubMed

Recent studies have suggested that internal updating of visuospatial targets in humans occurs in gaze-centered coordinates and takes place in the parietal and extrastriate cortices. We explored how information for reaching is updated in two patients with bilateral lesions in these areas. Subjects performed two visuomotor tasks: (i) a fixation reaching task, which began with the appearance of one of five fixation positions (varying eye positions) followed by a central reaching target. Subjects reached to the target while fixating on the presented fixation position (relative to gaze the target was always presented in the periphery); and (ii) a saccade reaching task, in which subjects foveated on the central reaching target, then made a saccade to the presented fixation position before reaching to the central target. In both tasks, subjects reached to targets after a 500 or 5000 ms delay. Gaze-centered updating predicts similarities in reaching errors between fixation and saccade trials. Control subjects showed evidence for gaze-centered updating during both 500 and 5000 ms delay conditions. In contrast, patient AT, who had extensive occipital-parietal damage, only showed signs of gaze-centered representation after 5 s. Patient IG, with a more focal lesion in the parietal cortices, showed partial updating in gaze-centered coordinates when reaching with the small memory delay but recovered a complete gaze-centered representation after the longer delay. This suggests that patients with bilateral occipital-parietal lesions may rely on non-gaze-centered frames to store immediate target locations in reaching space but, given enough time, this information may be rerouted to access other gaze-centered motor cortical mechanisms. PMID:15746004

Khan, Aarlenne Z; Pisella, Laure; Rossetti, Yves; Vighetto, Alain; Crawford, J Douglas

2005-10-01

163

Visual cortex in aging and Alzheimer's disease: changes in visual field maps and population receptive fields  

PubMed Central

Although several studies have suggested that cortical alterations underlie such age-related visual deficits as decreased acuity, little is known about what changes actually occur in visual cortex during healthy aging. Two recent studies showed changes in primary visual cortex (V1) during normal aging; however, no studies have characterized the effects of aging on visual cortex beyond V1, important measurements both for understanding the aging process and for comparison to changes in age-related diseases. Similarly, there is almost no information about changes in visual cortex in Alzheimer's disease (AD), the most common form of dementia. Because visual deficits are often reported as one of the first symptoms of AD, measurements of such changes in the visual cortex of AD patients might improve our understanding of how the visual system is affected by neurodegeneration as well as aid early detection, accurate diagnosis and timely treatment of AD. Here we use fMRI to first compare the visual field map (VFM) organization and population receptive fields (pRFs) between young adults and healthy aging subjects for occipital VFMs V1, V2, V3, and hV4. Healthy aging subjects do not show major VFM organizational deficits, but do have reduced surface area and increased pRF sizes in the foveal representations of V1, V2, and hV4 relative to healthy young control subjects. These measurements are consistent with behavioral deficits seen in healthy aging. We then demonstrate the feasibility and first characterization of these measurements in two patients with mild AD, which reveal potential changes in visual cortex as part of the pathophysiology of AD. Our data aid in our understanding of the changes in the visual processing pathways in normal aging and provide the foundation for future research into earlier and more definitive detection of AD. PMID:24570669

Brewer, Alyssa A.; Barton, Brian

2012-01-01

164

Retinotopic maps in human prestriate visual cortex: the demarcation of areas V2 and V3.  

PubMed

We have used PET (positron emission tomography) to chart the mapping of the retina in human occipital visual cortex and hence to locate the secondary and tertiary visual areas, V2 and V3. A group of four non-selected male volunteers was presented with dynamic stimuli that were aligned with either the vertical or the right horizontal meridians (VM or HM) from 0 degree to 29 degrees eccentricity; the vertical stimuli were restricted to either the inferior or the superior hemifields. PET scans were performed using intravenous infusion of H215O and a Siemens-CTI 953B PET scanner with 3D data acquisition. Subjects received 18 scans, divided equally among the right HM, the superior VM, and the inferior VM. Data were analyzed with SPM software. The group average result confirmed our experimental hypothesis that human occipital visual cortex has retinotopic maps similar to those of the macaque monkey. Thus human areas V2 and V3 can be defined on the basis that the border between them is formed by the HM and that the outer border of V3 is demarcated by a second representation of the VM that runs approximately parallel to the primary representation of the VM at the V1/V2 border. Furthermore, as in many mammals, the extrastriate representation of the HM is "split", such that the superior contralateral quadrant is mapped in lower V2 and V3, occupying the ventral surface of human cortex, and the inferior contralateral quadrant is mapped in upper V2 and V3, which extend over the lateral and medial surfaces of each hemisphere. After stereotaxic normalization, the position of V3 defined by retinal topography was found to correspond to that surmised from our previous PET studies employing moving stimuli. PMID:9343595

Shipp, S; Watson, J D; Frackowiak, R S; Zeki, S

1995-06-01

165

Variations in the squamous part of the occipital bone in medieval and contemporary cranial series from Bulgaria.  

PubMed

The squamous part of the occipital bone is a place of many different variations. They are a result of faulty ossification in the occipital squama or due to the presence of sutural bones in the lambda region. As their differentiation is intricate because of the various criteria used, the issue of their recognition in the adult skull still remains difficult even though they can be clearly distinguished at a younger age. The aim of the present study was to compare the frequency of interparietal, preinterparietal and sutural bones in the lambda region in medieval male and female cranial series as well as between medieval and contemporary male series from Bulgaria. We also discuss the development of the occipital squama in order to set clearer criteria for further differentiation of such variations in the adult skull. In the reviewed 3 cranial series, the variations in the squamous portion of the occipital bone were observed with a low frequency. The incidence of preinterparietal bones was more common than the interparietal ones. The sutural bones in the lambda region were numerous in the series. No statistically significant sex or intergroup differences were established. So even if these anatomical variations are relatively rare, the understanding of them is of significance for many disciplines like anthropology, comparative and developmental anatomy, clinical and forensic medicine. PMID:25448900

Nikolova, S; Toneva, D; Yordanov, Y; Lazarov, N

2014-11-01

166

Conceptual priming in perceptual identification for patients with Alzheimer's disease and a patient with right occipital lobectomy  

Microsoft Academic Search

Two experiments examined explicit recognition memory and perceptual and conceptual contribu- tions to implicit perceptual-identification repetition priming for patients with Alzheimer's disease (AD) and Patient M.S. with right-occipital lobectomy. Participants read words (perceptual encoding) and generated words (conceptual encoding) from a definition and letter cue (e.g., \\

Debra A. Fleischman; John D. E. Gabrieli; Sheryl Reminger; Julie Rinaldi

1995-01-01

167

Occipital sources of resting-state alpha rhythms are related to local gray matter density in subjects with amnesic mild cognitive impairment and Alzheimer's disease.  

PubMed

Occipital sources of resting-state electroencephalographic (EEG) alpha rhythms are abnormal, at the group level, in patients with amnesic mild cognitive impairment (MCI) and Alzheimer's disease (AD). Here, we evaluated the hypothesis that amplitude of these occipital sources is related to neurodegeneration in occipital lobe as measured by magnetic resonance imaging. Resting-state eyes-closed EEG rhythms were recorded in 45 healthy elderly (Nold), 100 MCI, and 90 AD subjects. Neurodegeneration of occipital lobe was indexed by weighted averages of gray matter density, estimated from structural MRIs. EEG rhythms of interest were alpha 1 (8-10.5 Hz) and alpha 2 (10.5-13 Hz). EEG cortical sources were estimated by low-resolution brain electromagnetic tomography. Results showed a positive correlation between occipital gray matter density and amplitude of occipital alpha 1 sources in Nold, MCI, and AD subjects as a whole group (r = 0.3, p = 0.000004, N = 235). Furthermore, there was a positive correlation between the amplitude of occipital alpha 1 sources and cognitive status as revealed by Mini Mental State Examination score across all subjects (r = 0.38, p = 0.000001, N = 235). Finally, amplitude of occipital alpha 1 sources allowed a moderate classification of individual Nold and AD subjects (sensitivity: 87.8%; specificity: 66.7%; area under the receiver operating characteristic curve: 0.81). These results suggest that the amplitude of occipital sources of resting-state alpha rhythms is related to AD neurodegeneration in occipital lobe along pathologic aging. PMID:25442118

Babiloni, Claudio; Del Percio, Claudio; Boccardi, Marina; Lizio, Roberta; Lopez, Susanna; Carducci, Filippo; Marzano, Nicola; Soricelli, Andrea; Ferri, Raffaele; Triggiani, Antonio Ivano; Prestia, Annapaola; Salinari, Serenella; Rasser, Paul E; Basar, Erol; Famà, Francesco; Nobili, Flavio; Yener, Görsev; Emek-Sava?, Derya Durusu; Gesualdo, Loreto; Mundi, Ciro; Thompson, Paul M; Rossini, Paolo M; Frisoni, Giovanni B

2015-02-01

168

Title/Loc/Date: gen tran poly/AMS montrea/ May 2002 Slide # 1 Jo EllisMonaghan, UVM and SMC  

E-print Network

Title/Loc/Date: gen tran poly/AMS montrea/ May 2002 Slide # 1 Jo Ellis­Monaghan, UVM and SMC Irasema Sarmiento, CINVESTAV e­mail: joellis@emba.uvm.edu website: http://academics.smcvt.edu/jellis­monaghan

Ellis-Monaghan, Joanna

169

Evaluation of the thermal-hydraulic response and fuel rod thermal and mechanical deformation behavior during the power burst facility test LOC-3. [PWR  

Microsoft Academic Search

An evaluation of the results from the LOC-3 nuclear blowdown test conducted in the Power Burst Facility is presented. The test objective was to examine fuel and cladding behavior during a postulated cold leg break accident in a pressurized water reactor (PWR). Separate effects of rod internal pressure and the degree of irradiation were investigated in the four-rod test. Extensive

T. R. Yackle; P. E. MacDonald; J. M. Broughton

1980-01-01

170

PAPER www.rsc.org/loc | Lab on a Chip Programmable assembly of a metabolic pathway enzyme in a pre-packaged  

E-print Network

PAPER www.rsc.org/loc | Lab on a Chip Programmable assembly of a metabolic pathway enzyme in a pre report a biofunctionalization strategy for the assembly of catalytically active enzymes within and temporally defined sites. The enzyme of a bacterial metabolic pathway, S-adenosylhomocysteine nucleosidase

Rubloff, Gary W.

171

HybridGO-Loc: mining hybrid features on gene ontology for predicting subcellular localization of multi-location proteins.  

PubMed

Protein subcellular localization prediction, as an essential step to elucidate the functions in vivo of proteins and identify drugs targets, has been extensively studied in previous decades. Instead of only determining subcellular localization of single-label proteins, recent studies have focused on predicting both single- and multi-location proteins. Computational methods based on Gene Ontology (GO) have been demonstrated to be superior to methods based on other features. However, existing GO-based methods focus on the occurrences of GO terms and disregard their relationships. This paper proposes a multi-label subcellular-localization predictor, namely HybridGO-Loc, that leverages not only the GO term occurrences but also the inter-term relationships. This is achieved by hybridizing the GO frequencies of occurrences and the semantic similarity between GO terms. Given a protein, a set of GO terms are retrieved by searching against the gene ontology database, using the accession numbers of homologous proteins obtained via BLAST search as the keys. The frequency of GO occurrences and semantic similarity (SS) between GO terms are used to formulate frequency vectors and semantic similarity vectors, respectively, which are subsequently hybridized to construct fusion vectors. An adaptive-decision based multi-label support vector machine (SVM) classifier is proposed to classify the fusion vectors. Experimental results based on recent benchmark datasets and a new dataset containing novel proteins show that the proposed hybrid-feature predictor significantly outperforms predictors based on individual GO features as well as other state-of-the-art predictors. For readers' convenience, the HybridGO-Loc server, which is for predicting virus or plant proteins, is available online at http://bioinfo.eie.polyu.edu.hk/HybridGoServer/. PMID:24647341

Wan, Shibiao; Mak, Man-Wai; Kung, Sun-Yuan

2014-01-01

172

Retinotopically defined primary visual cortex in Williams syndrome.  

PubMed

Williams syndrome, caused by a hemizygous microdeletion on chromosome 7q11.23, is characterized by severe impairment in visuospatial construction. To examine potential contributions of early visual processing to this cognitive problem, we functionally mapped the size and neuroanatomical variability of primary visual cortex (V1) in high-functioning adults with Williams syndrome and age- and IQ-matched control participants from the general population by using fMRI-based retinotopic mapping and cortical surface models generated from high-resolution structural MRI. Visual stimulation, consisting of rotating hemicircles and expanding rings, was used to retinotopically define early visual processing areas. V1 boundaries based on computed phase and field sign maps were used to calculate the functional area of V1. Neuroanatomical variability was assessed by computing overlap maps of V1 location for each group on standardized cortical surfaces, and non-parametric permutation test methods were used for statistical inference. V1 did not differ in size between groups, although its anatomical boundaries were more variable in the group with Williams syndrome. V1 overlap maps showed that the average centres of gravity for the two groups were similarly located near the fundus of the calcarine fissure, approximately 25 mm away from the most posterior aspect of the occipital lobe. In summary, our functional definition of V1 size and location indicates that recruitment of primary visual cortex is grossly normal in Williams syndrome, consistent with the notion that neural abnormalities underlying visuospatial construction arise at later stages in the visual processing hierarchy. PMID:19255058

Olsen, Rosanna K; Kippenhan, J Shane; Japee, Shruti; Kohn, Philip; Mervis, Carolyn B; Saad, Ziad S; Morris, Colleen A; Meyer-Lindenberg, Andreas; Berman, Karen Faith

2009-03-01

173

Binding 3-D object perception in the human visual cortex.  

PubMed

How do visual luminance, shape, motion, and depth bind together in the brain to represent the coherent percept of a 3-D object within hundreds of milliseconds (msec)? We provide evidence from simultaneous magnetoencephalographic (MEG) and electroencephalographic (EEG) data that perception of 3-D objects defined by luminance or motion elicits sequential activity in human visual cortices within 500 msec. Following activation of the primary visual cortex around 100 msec, 3-D objects elicited sequential activity with only little overlap (dynamic 3-D shapes: MT-LO-Temp; stationary 3-D shapes: LO-Temp). A delay of 80 msec, both in MEG/EEG responses and in reaction times (RTs), was found when additional motion information was processed. We also found significant positive correlations between RT, and MEG and EEG responses in the right temporal location. After about 400 msec, long-lasting activity was observed in the parietal cortex and concurrently in previously activated regions. Novel time-frequency analyses indicate that the activity in the lateral occipital (LO) complex is associated with an increase of induced power in the gamma band, a hallmark of binding. The close correspondence of an induced gamma response with concurrent sources located in the LO in both experimental conditions at different points in time ( approximately 200 msec for luminance and approximately 300 msec for dynamic cues) strongly suggests that the LO is the key region for the assembly of object features. The assembly is fed forward to achieve coherent perception of a 3-D object within 500 msec. PMID:18052779

Jiang, Yang; Boehler, C N; Nönnig, Nina; Düzel, Emrah; Hopf, Jens-Max; Heinze, Hans-Jochen; Schoenfeld, Mircea Ariel

2008-04-01

174

Reading without the left ventral occipito-temporal cortex  

PubMed Central

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

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

175

Occipital Artery Function during the Development of 2-Kidney, 1-Clip Hypertension in Rats  

PubMed Central

This study compared the contractile responses elicited by angiotensin II (AII), arginine vasopressin (AVP), and 5-hydroxytryptamine (5-HT) in isolated occipital arteries (OAs) from sham-operated (SHAM) and 2-kidney, 1-clip (2K-1C) hypertensive rats. OAs were isolated and bisected into proximal segments (closer to the common carotid artery) and distal segments (closer to the nodose ganglion) and mounted separately on myographs. On day 9, 2K-1C rats had higher mean arterial blood pressures, heart rates, and plasma renin concentrations than SHAM rats. The contractile responses to AII were markedly diminished in both proximal and distal segments of OAs from 2K-1C rats as compared to those from SHAM rats. The responses elicited by AVP were substantially greater in distal than in proximal segments of OAs from SHAM rats and that AVP elicited similar responses in OA segments from 2K-1C rats. The responses elicited by 5-HT were similar in proximal and distal segments from SHAM and 2K-1C rats. These results demonstrate that continued exposure to circulating AII and AVP in 2K-1C rats reduces the contractile efficacy of AII but not AVP or 5-HT. The diminished responsiveness to AII may alter the physiological status of OAs in vivo. PMID:25140254

Chelko, Stephen P.; Schmiedt, Chad W.; Lewis, Tristan H.; Robertson, Tom P.; Lewis, Stephen J.

2014-01-01

176

Ultrasound-guided atlanto-occipital puncture for cerebrospinal fluid analysis on the standing horse.  

PubMed

The atlanto-occipital site (AO) is convenient for retrieving an adequate volume and quality of cerebrospinal fluid (CSF) in the diagnosis of neurological disease in horses. However, general anaesthesia is not always possible for horses displaying severe neurological signs, or for economical reasons. The objectives of the present work were to determine the feasibility and safety of ultrasound-guided CSF puncture at the AO site on the standing horse. Seven horses (six healthy and one mildly ataxic) were sedated with acepromazine (0.02 mg/kg bodyweight intravenously or 0.04 mg/kg bodyweight intramuscularly) and detomidine (0.01 mg/kg bodyweight intravenously), and placed in stocks or in a recovery stall with the head kept on a headstand. Puncture was performed by ultrasonographic guidance with a parasagittal technique, as previously described, using a 20 g, 3.5 inch spinal needle. In all horses, no adverse reaction was observed when crossing the dura mater and 20 ml of CSF was rapidly retrieved without any blood contamination. Ultrasound-guided CSF puncture can be performed easily at the AO site on a healthy standing horse. Regarding the potential risk of this procedure, safety measures and close observation are essential. Further studies on a larger amount of ataxic horses are also required before considering this technique as an alternative option for CSF puncture. PMID:24225443

Depecker, M; Bizon-Mercier, C; Couroucé-Malblanc, A

2014-01-11

177

Successful Treatment of Occipital Neuralgia with Implantable Peripheral Nerve Stimulation in a Pacemaker-Dependent Patient  

PubMed Central

Background Peripheral nerve stimulation has been used to treat patients with occipital nerve–related chronic headaches who have been unsuccessful with less invasive therapeutic approaches. Patients with pacemaker-dependent cardiac conduction abnormalities require unique consideration prior to the implantation of peripheral nerve stimulators because the placement of the devices may lead to failure of the systems secondary to electromagnetic interference or crosstalk between the devices. Case Report An 86-year-old female who suffered from chronic right-sided cervicogenic headaches and neck pain had received only temporary relief from previous treatments. Additional comorbidities included longstanding pacemaker-dependent atrioventricular node conduction disease. Because the extent to which nerve stimulators electrically interact with pacemakers is unclear, we tunneled the leads to the lumbar region of the back and placed the generator on the contralateral side to the pacemaker to minimize the chance that the 2 devices would interfere. The patient has remained pain free for 1 year since implantation. Conclusion Although no current published trials evaluate the degree of interference between medical devices, case reports increasingly suggest that simultaneous implantation of a spinal cord stimulator and pacemaker is safe as long as precautions are taken and the devices are checked periodically, particularly when the devices are adjusted. PMID:24688344

Chaiban, Gassan; Tolba, Reda; Eissa, Hazem; Lirette, Lesley Smallwood; Almualim, Mohammed; Malaty, Adham; Atallah, Joseph

2014-01-01

178

Transcallosal inhibition dampens neural responses to high contrast stimuli in human visual cortex.  

PubMed

Visual cortical areas in the two hemispheres interact via the corpus callosum, but the precise role of the callosal pathway in visual processing remains controversial. Here we have investigated the function of transcallosal projections in human primary visual cortex (V1). Visual evoked potentials (VEPs) triggered by grating stimuli of different contrasts were recorded before and after functional inactivation of the occipital cortex of one hemisphere via off-line low-frequency repetitive transcranial magnetic stimulation (rTMS; 0.5 Hz stimulation for 20 min). VEPs were recorded in V1 before (T0), immediately after (T1) and 45' following the completion of rTMS (T2). We found that low-frequency rTMS had an inhibitory effect on VEPs amplitudes at all contrasts in the treated side. Remarkably, reduction of VEP amplitudes in the inhibited hemisphere at T1 was accompanied by an increase in VEP amplitudes in the contralateral side only at mid-high contrasts (50-90%). This disinhibitory effect was observed with both central and hemifield stimulation. No changes in VEP amplitudes were observed when rTMS was applied to a cortical site more anterior with respect to V1. These data provide the first evidence that a mechanism of transcallosal inhibition dampens neural responses at high contrasts in human visual cortex. PMID:21557988

Bocci, T; Caleo, M; Giorli, E; Barloscio, D; Maffei, L; Rossi, S; Sartucci, F

2011-07-28

179

Voxel-based analysis of MRI detects abnormal visual cortex in children and adults with amblyopia.  

PubMed

Amblyopia, sometimes called "lazy eye," is a relatively common developmental visual disorder well characterized behaviorally; however, the neural substrates associated with amblyopia in humans remain unclear. We hypothesized that abnormalities in the cerebral cortex of subjects with amblyopia exist, possibly as a result of experience-dependent neuronal plasticity. Anatomic magnetic resonance imaging (MRI) and psychophysical vision testing was carried out on 74 subjects divided into two age ranges, 7-12 years and 18-35 years, and three diagnoses, strabismic amblyopia, anisometropic amblyopia, and normal vision. We report a behavioral impairment in contrast sensitivity for subjects with amblyopia, consistent with previous reports. When the high-resolution MRI brain images were analyzed quantitatively with optimized voxel-based morphometry, results indicated that adults and children with amblyopia have decreased gray matter volume in visual cortical regions, including the calcarine sulcus, known to contain primary visual cortex. This finding was confirmed with a separate region-of-interest analysis. For the children with amblyopia, additional gray matter reductions in parietal-occipital areas and ventral temporal cortex were detected, consistent with recent reports that amblyopia can result in spatial location and object processing deficits. These data are the first to provide possible neuroanatomic bases for the loss of binocularity and visual sensitivity in children and adults with amblyopia. PMID:15846772

Mendola, Janine D; Conner, Ian P; Roy, Anjali; Chan, Suk-Tak; Schwartz, Terry L; Odom, J Vernon; Kwong, Kenneth K

2005-06-01

180

Inter-Subject Synchronization of Prefrontal Cortex Hemodynamic Activity During Natural Viewing  

PubMed Central

Hemodynamic activity in occipital, temporal, and parietal cortical areas were recently shown to correlate across subjects during viewing of a 30-minute movie clip. However, most of the frontal cortex lacked between-subject correlations. Here we presented 12 healthy naïve volunteers with the first 72 minutes of a movie (“Crash”, 2005, Lions Gate Films) outside of the fMRI scanner to involve the subjects in the plot of the movie, followed by presentation of the last 36 minutes during fMRI scanning. We observed significant between-subjects correlation of fMRI activity in especially right hemisphere frontal cortical areas, in addition to the correlation of activity in temporal, occipital, and parietal areas. It is possible that this resulted from the subjects following the plot of the movie and being emotionally engaged in the movie during fMRI scanning. We further show that probabilistic independent component analysis (ICA) reveals meaningful activations in individual subjects during natural viewing. PMID:19018313

Jääskeläinen, Iiro P; Koskentalo, Katri; Balk, Marja H; Autti, Taina; Kauramäki, Jaakko; Pomren, Cajus; Sams, Mikko

2008-01-01

181

MRI volumetry of prefrontal cortex  

NASA Astrophysics Data System (ADS)

Prefrontal cortex volumetry by brain magnetic resonance (MR) is required to estimate changes postulated to occur in certain psychiatric and neurologic disorders. A semiautomated method with quantitative characterization of its performance is sought to reliably distinguish small prefrontal cortex volume changes within individuals and between groups. Stereological methods were tested by a blinded comparison of measurements applied to 3D MR scans obtained using an MPRAGE protocol. Fixed grid stereologic methods were used to estimate prefrontal cortex volumes on a graphic workstation, after the images are scaled from 16 to 8 bits using a histogram method. In addition images were resliced into coronal sections perpendicular to the bicommissural plane. Prefrontal cortex volumes were defined as all sections of the frontal lobe anterior to the anterior commissure. Ventricular volumes were excluded. Stereological measurement yielded high repeatability and precision, and was time efficient for the raters. The coefficient of error was cortex boundaries on 3D images was critical to obtaining accurate measurements. MR prefrontal cortex volumetry by stereology can yield accurate and repeatable measurements. Small frontal lobe volume reductions in patients with brain disorders such as depression and schizophrenia can be efficiently assessed using this method.

Sheline, Yvette I.; Black, Kevin J.; Lin, Daniel Y.; Pimmel, Joseph; Wang, Po; Haller, John W.; Csernansky, John G.; Gado, Mokhtar; Walkup, Ronald K.; Brunsden, Barry S.; Vannier, Michael W.

1995-05-01

182

A comparative study between the effects of side-lying sacroiliac adjustments and Sacro Occipital Technic on the muscle strength of the gastrocnemius muscle in asymptomatic adult males .  

E-print Network

??This unblinded, non-randomised pilot study was conducted in order to determine if diversified chiropractic manipulation and/or sacro occipital technic adjustments of the sacroiliac (SI) joint… (more)

Pretorius, Grant

2008-01-01

183

Retinotopic and lateralized processing of spatial frequencies in human visual cortex during scene categorization.  

PubMed

Using large natural scenes filtered in spatial frequencies, we aimed to demonstrate that spatial frequency processing could not only be retinotopically mapped but could also be lateralized in both hemispheres. For this purpose, participants performed a categorization task using large black and white photographs of natural scenes (indoors vs. outdoors, with a visual angle of 24° × 18°) filtered in low spatial frequencies (LSF), high spatial frequencies (HSF), and nonfiltered scenes, in block-designed fMRI recording sessions. At the group level, the comparison between the spatial frequency content of scenes revealed first that, compared with HSF, LSF scene categorization elicited activation in the anterior half of the calcarine fissures linked to the peripheral visual field, whereas, compared with LSF, HSF scene categorization elicited activation in the posterior part of the occipital lobes, which are linked to the fovea, according to the retinotopic property of visual areas. At the individual level, functional activations projected on retinotopic maps revealed that LSF processing was mapped in the anterior part of V1, whereas HSF processing was mapped in the posterior and ventral part of V2, V3, and V4. Moreover, at the group level, direct interhemispheric comparisons performed on the same fMRI data highlighted a right-sided occipito-temporal predominance for LSF processing and a left-sided temporal cortex predominance for HSF processing, in accordance with hemispheric specialization theories. By using suitable method of analysis on the same data, our results enabled us to demonstrate for the first time that spatial frequencies processing is mapped retinotopically and lateralized in human occipital cortex. PMID:23574583

Musel, Benoit; Bordier, Cécile; Dojat, Michel; Pichat, Cédric; Chokron, Sylvie; Le Bas, Jean-François; Peyrin, Carole

2013-08-01

184

Increased glutamate levels observed upon functional activation in the anterior cingulate cortex using the Stroop Task and functional spectroscopy.  

PubMed

It has been shown in recent studies that it is possible to detect changes in the main excitatory neurotransmitter, glutamate, upon functional activation with visual and motor paradigms using a 7?T MRI and functional magnetic resonance spectroscopy. A cognitive task would be desirable for this technique because it could then be used to examine psychiatric disorders that have cognitive deficiencies. The aim of the work presented here was to use functional magnetic resonance spectroscopy with a 7?T MRI to show that increases in glutamate can be observed within the anterior cingulate cortex using the Stroop Task as the activation paradigm in healthy controls. Significant glutamate increases (0.24±0.09?µmol/g, P<0.025), comparable with what has been reported in the studies of the occipital cortex and motor cortex, were observed when the participants (n=7) performed the task, followed by a trend toward returning to baseline in the post-task recovery period (-0.23±0.13?µmol/g). This method would be ideal for the study of neuropsychiatric disorders that have been shown to have abnormal resting glutamate levels and cognitive deficiencies in the anterior cingulate cortex, such as schizophrenia. This exploratory study is the first to demonstrate functional magnetic resonance spectroscopy in the anterior cingulate with a cognitive task using a 7?T MRI. PMID:25536234

Taylor, Reggie; Schaefer, Betsy; Densmore, Maria; Neufeld, Richard W J; Rajakumar, Nagalingam; Williamson, Peter C; Théberge, Jean

2015-02-11

185

Increased glutamate levels observed upon functional activation in the anterior cingulate cortex using the Stroop Task and functional spectroscopy  

PubMed Central

It has been shown in recent studies that it is possible to detect changes in the main excitatory neurotransmitter, glutamate, upon functional activation with visual and motor paradigms using a 7?T MRI and functional magnetic resonance spectroscopy. A cognitive task would be desirable for this technique because it could then be used to examine psychiatric disorders that have cognitive deficiencies. The aim of the work presented here was to use functional magnetic resonance spectroscopy with a 7?T MRI to show that increases in glutamate can be observed within the anterior cingulate cortex using the Stroop Task as the activation paradigm in healthy controls. Significant glutamate increases (0.24±0.09?µmol/g, P<0.025), comparable with what has been reported in the studies of the occipital cortex and motor cortex, were observed when the participants (n=7) performed the task, followed by a trend toward returning to baseline in the post-task recovery period (?0.23±0.13?µmol/g). This method would be ideal for the study of neuropsychiatric disorders that have been shown to have abnormal resting glutamate levels and cognitive deficiencies in the anterior cingulate cortex, such as schizophrenia. This exploratory study is the first to demonstrate functional magnetic resonance spectroscopy in the anterior cingulate with a cognitive task using a 7?T MRI. PMID:25536234

Schaefer, Betsy; Densmore, Maria; Neufeld, Richard W.J.; Rajakumar, Nagalingam; Williamson, Peter C.; Théberge, Jean

2015-01-01

186

Quantitative assessment of diffuse optical tomography sensitivity to the cerebral cortex using a whole-head probe  

NASA Astrophysics Data System (ADS)

We quantify the variability in diffuse optical tomography (DOT) sensitivity over the cortical surface in eight young adult subjects. We use the 10/5 electroencephalography system as a basis for our whole-head optical high-density probe design. The contrast-to-noise ratio (CNR) is calculated along with the percentage of the cortex that is above a CNR = 0 dB threshold. We also quantify the effect of including vasculature on the forward model and list our assumptions that allow us to estimate light penetration depth in the head. We show that using the 10/5 system for the optical probe design allows for the measurement of 37% of the cortical surface on average, with a mean CNR in the visible region of 5.5 dB. Certain anatomical regions, such as the lateral occipital cortex, had a very high percentage above the CNR threshold, while other regions such as the cingulate cortex were not measurable. Vasculature blocked optical sensitivity over 1% of the cortex. Cortical coverage was positively correlated with intracranial volume and relative cerebrospinal fluid volume, and negatively correlated with relative scalp volume and skull volume. These contributions allow experimenters to understand how anatomical variation in a subject population may impact DOT or functional near-infrared spectroscopy measurements.

Perdue, Katherine L.; Fang, Qianqian; Diamond, Solomon G.

2012-05-01

187

Pre- and postnatal development of the primary visual cortex of the common marmoset. I. A changing space for synaptogenesis.  

PubMed

The primary visual cortex of Callithrix jacchus occupies a large portion of the occipital neocortex and can be safely delineated from fetal stages onwards. In 20 animals ranging in age from fetal to adult age the morphological development of area 17 was evaluated and compared with the growth of whole brain, skull, and head size. Cortical thickness, surface area, and volume of the area were determined in addition to predominant growth directions. The volume of area 17 approximately doubles between birth (241 mm3) and three months of age (506 mm3). This maximum value marks an overshoot in growth (volume: 180%, surface area: 150%, thickness: 122%), which is followed by a considerable reduction before adult values (100%) are reached. Although these values seem to indicate that the overall reduction in size is fairly isometric, growth and regression are locally anisometric. For example, layers II-IVc contribute disproportionately to the overshoot; thickening is less pronounced than tangential growth and follows a slightly different time course. These data suggest that the developing visual cortex represents a highly dynamic distribution space for the developing synaptic junctions which should be taken into account in studies on synaptogenesis. By comparison it is suggested that this growth dynamic is not restricted to area 17 but also occurs in some other parts of the cerebral cortex. In contrast, most subcortical brain regions apparently do not undergo overshoot growth. Structural changes of the skull compensate the overshoot in cortex growth, so that head size increases steadily. PMID:8340495

Missler, M; Eins, S; Merker, H J; Rothe, H; Wolff, J R

1993-07-01

188

Probabilistic and single-subject retinotopic maps reveal the topographic organization of face patches in the macaque cortex.  

PubMed

Face perception is crucial to survival among social primates. It has been suggested that a group of extrastriate cortical regions responding more strongly to faces than to nonface objects is critical for face processing in primates. It is generally assumed that these regions are not retinotopically organized, as with human face-processing areas, showing foveal bias but lacking any organization with respect to polar angle. Despite many electrophysiological studies targeting monkey face patches, the retinotopic organization of these patches remains largely unclear. We have examined the relationship between cortical face patches and the topographic organization of extrastriate cortex using biologically relevant, phase-encoded retinotopic mapping stimuli in macaques. Single-subject fMRI results indicated a gradual shift from highly retinotopic to no topographic organization from posterior to anterior face patches in inferotemporal cortex. We also constructed a probabilistic retinotopic atlas of occipital and ventral extrastriate visual cortex. By comparing this probabilistic map to the locations of face patches at the group level, we showed that a previously identified posterior lateral temporal face patch (PL) is located within the posterior inferotemporal dorsal (PITd) retinotopic area. Furthermore, we identified a novel face patch posterior PL, which is located in retinotopically organized transitional area V4 (V4t). Previously published coordinates of human PITd coincide with the group-level occipital face area (OFA), according to a probabilistic map derived from a large population, implying a potential correspondence between monkey PL/PITd and human OFA/PITd. Furthermore, the monkey middle lateral temporal face patch (ML) shows consistent foveal biases but no obvious polar-angle structure. In contrast, middle fundus temporal (MF), anterior temporal and prefrontal monkey face patches lacked topographic organization. PMID:25080579

Janssens, Thomas; Zhu, Qi; Popivanov, Ivo D; Vanduffel, Wim

2014-07-30

189

Changes in visual cortex excitability in blind subjects as demonstrated by transcranial magnetic stimulation.  

PubMed

Any attempt to restore visual functions in blind subjects with pregeniculate lesions provokes the question of the extent to which deafferented visual cortex is still able to generate conscious visual experience. As a simple approach to assessing activation of the visual cortex, subjects can be asked to report conscious subjective light sensations (phosphenes) elicited by focal transcranial magnetic stimulation (TMS) over the occiput. We hypothesized that such induction of phosphenes can be used as an indicator of residual function of the visual cortex and studied 35 registered blind subjects after partial or complete long-term (>10 years) deafferentation of the visual cortex due to pregeniculate lesions. TMS was applied over the visual cortex in 10 blind subjects with some residual vision (visual acuity <20/400; Group 1), 15 blind subjects with very poor residual vision (only perception of movement or light; Group 2), 10 blind subjects without any residual vision (Group 3) and 10 healthy controls. A stimulation mapping procedure was performed on a 1 x 1 cm skull surface grid with 130 stimulation points overlying the occipital skull. We analysed the occurrence of phosphenes at each stimulation point with regard to frequency and location of phosphenes in the visual field. Previous experiments have shown that repetitive TMS reliably elicits brief flashes of white or coloured patches of light. Therefore, stimulation was performed with short trains of seven consecutive 15 Hz stimuli applied with an intensity of 1.3 times the motor threshold. Under such conditions, phosphenes occurred in 100% of subjects in Group 1, in 60% of Group 2 and in 20% of Group 3. Phosphene thresholds were normal, but the number of effective stimulation sites was significantly reduced in Groups 2 and 3. The results indicate that in blind subjects there is alteration in TMS-induced activation of the deafferented visual cortex or processes engaged in bringing the artificial cortex input to consciousness. The ability to elicit phosphenes is reduced in subjects with a high degree of visual deafferentation, especially in those without previous visual experience. PMID:11872606

Gothe, Janna; Brandt, Stephan A; Irlbacher, Kerstin; Röricht, Simone; Sabel, Bernhard A; Meyer, Bernd-Ulrich

2002-03-01

190

Attention modulates spatial priority maps in the human occipital, parietal and frontal cortices  

PubMed Central

Computational theories propose that attention modulates the topographical landscape of spatial ‘priority’ maps in regions of visual cortex so that the location of an important object is associated with higher activation levels. While single-unit recording studies have demonstrated attention-related increases in the gain of neural responses and changes in the size of spatial receptive fields, the net effect of these modulations on the topography of region-level priority maps has not been investigated. Here, we used fMRI and a multivariate encoding model to reconstruct spatial representations of attended and ignored stimuli using activation patterns across entire visual areas. These reconstructed spatial representations reveal the influence of attention on the amplitude and size of stimulus representations within putative priority maps across the visual hierarchy. Our results suggest that attention increases the amplitude of stimulus representations in these spatial maps, particularly in higher visual areas, but does not substantively change their size. PMID:24212672

Sprague, Thomas C.; Serences, John T.

2014-01-01

191

Sensory-specific anomic aphasia following left occipital lesions: data from free oral descriptions of concrete word meanings.  

PubMed

The present study investigated hierarchical lexical semantic structure in oral descriptions of concrete word meanings produced by a subject (ZZ) diagnosed with anomic aphasia due to left occipital lesions. The focus of the analysis was production of a) nouns at different levels of semantic specificity (e.g., "robin"-"bird"-"animal") and b) words describing sensory or motor experiences (e.g., "blue," "soft," "fly"). Results show that in contrast to healthy and aphasic controls, who produced words at all levels of specificity and mainly vision-related sensory information, ZZ produced almost exclusively nouns at the most non-specific levels and words associated with sound and movement. PMID:23425233

Mårtensson, F; Roll, M; Lindgren, M; Apt, P; Horne, M

2014-04-01

192

An unusual case of isolated hypoglossal nerve palsy secondary to osteophytic projection from the atlanto-occipital joint.  

PubMed

We describe an unusual and rare case of isolated left hypoglossal nerve palsy secondary to compression from a prominent degenerative osteophyte from the left atlanto-occipital joint. The hypoglossal nerve is a purely motor cranial nerve innervating the tongue musculature. Palsy of the hypoglossal nerve is frequently associated with other cranial nerve palsies and can be related to vascular, neoplastic, infectious or traumatic conditions. Isolated hypoglossal nerve palsy is quite rare and very few cases have been reported in the literature to date. PMID:24976205

Patro, Satya Narayana; Torres, Carlos; Riascos, Roy

2014-06-01

193

The Functions of the Orbitofrontal Cortex  

ERIC Educational Resources Information Center

The orbitofrontal cortex contains the secondary taste cortex, in which the reward value of taste is represented. It also contains the secondary and tertiary olfactory cortical areas, in which information about the identity and also about the reward value of odours is represented. The orbitofrontal cortex also receives information about the sight…

Rolls, Edmund T.

2004-01-01

194

The insular cortex: a review.  

PubMed

The human insular cortex forms a distinct, but entirely hidden lobe, situated in the depth of the Sylvian fissure. Here, we first review the recent literature on the connectivity and the functions of this structure. It appears that this small lobe, taking up less than 2% of the total cortical surface area, receives afferents from some sensory thalamic nuclei, is (mostly reciprocally) connected with the amygdala and with many limbic and association cortical areas, and is implicated in an astonishingly large number of widely different functions, ranging from pain perception and speech production to the processing of social emotions. Next, we embark on a long, adventurous journey through the voluminous literature on the structural organization of the insular cortex. This journey yielded the following take-home messages: (1) The meticulous, but mostly neglected publications of Rose (1928) and Brockhaus (1940) are still invaluable for our understanding of the architecture of the mammalian insular cortex. (2) The relation of the insular cortex to the adjacent claustrum is neither ontogenetical nor functional, but purely topographical. (3) The insular cortex has passed through a spectacular progressive differentiation during hominoid evolution, but the assumption of Craig (2009) that the human anterior insula has no homologue in the rhesus monkey is untenable. (4) The concept of Mesulam and Mufson (1985), that the primate insula is essentially composed of three concentrically arranged zones, agranular, dysgranular, and granular, is presumably correct, but there is at present much confusion concerning the more detailed architecture of the anterior insular cortex. (5) The large spindle-shaped cells in the fifth layer of the insular cortex, currently known as von Economo neurons (VENs), are not only confined to large-brained mammals, such as whales, elephants, apes, and humans, but also occur in monkeys and prosimians, as well as in the pygmy hippopotamus, the Atlantic walrus, and Florida manatee. Finally, we point out that the human insula presents a unique opportunity for performing an in-depth comparative analysis of the relations between structure and function in a typical sensory and a typical cognitive cortical domain. PMID:22230626

Nieuwenhuys, Rudolf

2012-01-01

195

Training transfers the limits on perception from parietal to ventral cortex.  

PubMed

Visually guided behavior depends on (1) extracting and (2) discriminating signals from complex retinal inputs, and these perceptual skills improve with practice. For instance, training on aerial reconnaissance facilitated World War II Allied military operations; analysts pored over stereoscopic photographs, becoming expert at (1) segmenting pictures into meaningful items to break camouflage from (noisy) backgrounds, and (2) discriminating fine details to distinguish V-weapons from innocuous pylons. Training is understood to optimize neural circuits that process scene features (e.g., orientation) for particular purposes (e.g., judging position). Yet learning is most beneficial when it generalizes to other settings and is critical in recovery after adversity, challenging understanding of the circuitry involved. Here we used repetitive transcranial magnetic stimulation (rTMS) to infer the functional organization supporting learning generalization in the human brain. First, we show dissociable contributions of the posterior parietal cortex (PPC) versus lateral occipital (LO) circuits: extracting targets from noise is disrupted by PPC stimulation, in contrast to judging feature differences, which is affected by LO rTMS. Then, we demonstrate that training causes striking changes in this circuit: after feature training, identifying a target in noise is not disrupted by PPC stimulation but instead by LO stimulation. This indicates that training shifts the limits on perception from parietal to ventral brain regions and identifies a critical neural circuit for visual learning. We suggest that generalization is implemented by supplanting dynamic processing conducted in the PPC with specific feature templates stored in the ventral cortex. PMID:25283780

Chang, Dorita H F; Mevorach, Carmel; Kourtzi, Zoe; Welchman, Andrew E

2014-10-20

196

Human vestibular cortex as identified with caloric stimulation in functional magnetic resonance imaging.  

PubMed

Anatomic and electrophysiological studies in monkeys have yielded a detailed map of cortex areas receiving vestibular afferents. In contrast, comparatively little is known about the cortical representation of the human vestibular system. In this study we applied caloric stimulation and fMRI to further characterize human cortical vestibular areas and to test for hemispheric dominance of vestibular information processing. For caloric vestibular stimulation we used cold nitrogen to avoid susceptibility artifacts induced by water calorics. Right and left side vestibular stimulation was repetitively performed inducing a nystagmus for at least 90 s after the end of the stimulation in all subjects. Only the first 60 s of this nystagmus period was included for statistical analysis and compared with the baseline condition. Activation maps revealed a cortical network with right hemispheric dominance, which in all subjects comprised the temporoparietal junction extending into the posterior insula and, furthermore, the anterior insula, pre- and postcentral gyrus, areas in the parietal lobe, the ventrolateral portion of the occipital lobe, and the inferior frontal gyrus extending into the inferior part of the precentral sulcus. In conclusion, caloric stimulation in fMRI reveals a widespread cortical network involved in vestibular signal processing corresponding to the findings from animal experiments and previous functional imaging studies in humans. Furthermore, this study demonstrates a strong right hemispheric dominance of vestibular cortex areas regardless of the stimulated side, consistent with the current view of a rightward asymmetrical cortical network for spatial orientation. PMID:12414278

Fasold, Oliver; von Brevern, Michael; Kuhberg, Marc; Ploner, Christoph J; Villringer, Arno; Lempert, Thomas; Wenzel, Rüdiger

2002-11-01

197

Specific EEG Sleep Pattern in the Prefrontal Cortex in Primary Insomnia  

PubMed Central

Objective To assess the specific prefrontal activity in comparison to those in the other main cortical areas in primary insomnia patients and in good sleepers. Methods Fourteen primary insomnia patients and 11 good sleepers were included in the analysis. Participants completed one night of polysomnography in the sleep lab. Power spectra were calculated during the NREM (Non-rapid eyes movements) and the REM (Rapid eyes movements) sleep periods at prefrontal, occipital, temporal and central electrode positions. Results During the NREM sleep, the power spectra did not differ between groups in the prefrontal cortex; while primary insomnia patients exhibited a higher beta power spectrum and a lower delta power spectrum compared to good sleepers in other areas. During the REM sleep, the beta1 power spectrum was lower in the prefrontal cortex in primary insomnia patients compared to good sleepers; while no significant difference between groups was obtained for the other areas. Conclusions The present study shows a specific prefrontal sleep pattern during the whole sleep period. In addition, we suggest that primary insomnia patients displayed a dysfunction in the reactivation of the limbic system during the REM sleep and we give additional arguments in favor of a sleep-protection mechanism displayed by primary insomnia patients. PMID:25611059

Perrier, Joy; Clochon, Patrice; Bertran, Françoise; Couque, Colette; Bulla, Jan; Denise, Pierre; Bocca, Marie-Laure

2015-01-01

198

Different neural mechanisms within occipitotemporal cortex underlie repetition suppression across same and different-size faces.  

PubMed

Repetition suppression (RS) (or functional magnetic resonance imaging adaptation) refers to the reduction in blood oxygen level-dependent signal following repeated presentation of a stimulus. RS is frequently used to investigate the role of face-selective regions in human visual cortex and is commonly thought to be a "localized" effect, reflecting fatigue of a neuronal population representing a given stimulus. In contrast, predictive coding theories characterize RS as a consequence of "top-down" changes in between-region modulation. Differentiating between these accounts is crucial for the correct interpretation of RS effects in the face-processing network. Here, dynamic causal modeling revealed that different mechanisms underlie different forms of RS to faces in occipitotemporal cortex. For both familiar and unfamiliar faces, repetition of identical face images (same size) was associated with changes in "forward" connectivity between the occipital face area (OFA) and the fusiform face area (FFA) (OFA-to-FFA). In contrast, RS across image size was characterized by altered "backward" connectivity (FFA-to-OFA). In addition, evidence was higher for models in which information projected directly into both OFA and FFA, challenging the role of OFA as the input stage of the face-processing network. These findings suggest "size-invariant" RS to faces is a consequence of interactions between regions rather than being a localized effect. PMID:22510534

Ewbank, Michael P; Henson, Richard N; Rowe, James B; Stoyanova, Raliza S; Calder, Andrew J

2013-05-01

199

Functional mapping of face-selective regions in the extrastriate visual cortex of the marmoset.  

PubMed

The cerebral cortex of humans and macaques has specialized regions for processing faces and other visual stimulus categories. It is unknown whether a similar functional organization exists in New World monkeys, such as the common marmoset (Callithrix jacchus), a species of growing interest as a primate model in neuroscience. To address this question, we measured selective neural responses in the brain of four awake marmosets trained to fix their gaze upon images of faces, bodies, objects, and control patterns. In two of the subjects, we measured high gamma-range field potentials from electrocorticography arrays implanted over a large portion of the occipital and inferotemporal cortex. In the other two subjects, we measured BOLD fMRI responses across the entire brain. Both techniques revealed robust, regionally specific patterns of category-selective neural responses. We report that at least six face-selective patches mark the occipitotemporal pathway of the marmoset, with the most anterior patches showing the strongest preference for faces over other stimuli. The similar appearance of these patches to previous findings in macaques and humans, including their apparent arrangement in two parallel pathways, suggests that core elements of the face processing network were present in the common anthropoid primate ancestor living ?35 million years ago. The findings also identify the marmoset as a viable animal model system for studying specialized neural mechanisms related to high-level social visual perception in humans. PMID:25609630

Hung, Chia-Chun; Yen, Cecil C; Ciuchta, Jennifer L; Papoti, Daniel; Bock, Nicholas A; Leopold, David A; Silva, Afonso C

2015-01-21

200

A cardinal orientation bias in scene-selective visual cortex  

PubMed Central

It has long been known that human vision is more sensitive to contours at cardinal (horizontal and vertical) orientations, compared to oblique orientations; this is the ‘oblique effect’. However, the real-world relevance of the oblique effect is not well understood. Experiments here suggest that this effect is to linked to scene perception, via a common bias in the image statistics of scenes. This statistical bias for cardinal orientations is found in many ‘carpentered environments’, such as buildings and indoor scenes, and some natural scenes. In experiment 1, we confirmed the presence of a perceptual oblique effect in a specific set of scene stimuli. Using those scenes, we found that a well-known ‘scene-selective’ visual cortical area (the Parahippocampal Place Area; PPA) showed distinctively higher fMRI activity to cardinal versus oblique orientations. This fMRI-based ‘oblique effect’ was not observed in other cortical areas (including scene-selective areas Transverse Occipital Sulcus (TOS) and Retro-Splenial Cortex (RSC)), although all three scene-selective areas showed the expected inversion effect to scenes. Experiments 2 and 3 tested for an analogous selectivity for cardinal orientations using computer-generated arrays of simple squares and line segments, respectively. The results confirmed the preference for cardinal orientations in PPA, thus demonstrating that the ‘oblique effect’ can also be produced in PPA by simple geometrical images, with statistics similar to those in scenes. Thus, PPA shows distinctive fMRI selectivity for cardinal orientations across a broad range of stimuli, which may reflect a perceptual oblique effect. PMID:23100415

Nasr, Shahin; Tootell, Roger BH

2012-01-01

201

The role of the right prefrontal cortex in self-evaluation of the face: a functional magnetic resonance imaging study.  

PubMed

Individuals can experience negative emotions (e.g., embarrassment) accompanying self-evaluation immediately after recognizing their own facial image, especially if it deviates strongly from their mental representation of ideals or standards. The aim of this study was to identify the cortical regions involved in self-recognition and self-evaluation along with self-conscious emotions. To increase the range of emotions accompanying self-evaluation, we used facial feedback images chosen from a video recording, some of which deviated significantly from normal images. In total, 19 participants were asked to rate images of their own face (SELF) and those of others (OTHERS) according to how photogenic they appeared to be. After scanning the images, the participants rated how embarrassed they felt upon viewing each face. As the photogenic scores decreased, the embarrassment ratings dramatically increased for the participant's own face compared with those of others. The SELF versus OTHERS contrast significantly increased the activation of the right prefrontal cortex, bilateral insular cortex, anterior cingulate cortex, and bilateral occipital cortex. Within the right prefrontal cortex, activity in the right precentral gyrus reflected the trait of awareness of observable aspects of the self; this provided strong evidence that the right precentral gyrus is specifically involved in self-face recognition. By contrast, activity in the anterior region, which is located in the right middle inferior frontal gyrus, was modulated by the extent of embarrassment. This finding suggests that the right middle inferior frontal gyrus is engaged in self-evaluation preceded by self-face recognition based on the relevance to a standard self. PMID:18275339

Morita, Tomoyo; Itakura, Shoji; Saito, Daisuke N; Nakashita, Satoshi; Harada, Tokiko; Kochiyama, Takanori; Sadato, Norihiro

2008-02-01

202

Temporal and spatial pattern of expression of cyclic nucleotide-gated channels in developing rat visual cortex.  

PubMed

Cyclic nucleotide-gated channels, ligand-gated and highly permeable to calcium, are good candidates for transducing signals received by migrating cells, growth cones and developing synapses. The level of calcium in growth cones is important for axon guidance. Further, cyclic nucleotides, whose levels can be altered by nitric oxide and other transmitters, are known to alter growth cone motility. We use rat visual cortex as a model in our semi-quantitative RT-PCR and in situ hybridization studies to determine the developmental time course and localization of all three CNG family members (rod, olfactory and cone/testis). We demonstrate that in the cortex, the three channel subtypes are each expressed in a distinct temporal and spatial pattern in only sensorimotor and occipital regions of the cortex. Specifically, the rod and olfactory subtypes are present at the time of migration and rapid dendritic outgrowth, and the cone/testis subtype is highly expressed after eye opening. These results suggest CNG channels may play a role in both early and late events in visual cortical development. PMID:10426413

Samanta Roy, D R; Barnstable, C J

1999-06-01

203

A model of cerebral cortex formation during fetal development using reaction-diffusion-convection equations with Turing space parameters.  

PubMed

The cerebral cortex is a gray lamina formed by bodies of neurons covering the cerebral hemispheres, varying in thickness from 1.25 mm in the occipital lobe to 4mm in the anterior lobe. The brain's surface is about 30 times greater that of the skull because of its many folds; such folds form the gyri, sulci and fissures and mark out areas having specific functions, divided into five lobes. Convolution formation may vary between individuals and is an important feature of brain formation; such patterns can be mathematically represented as Turing patterns. This article describes how a phenomenological model was developed by describing the formation pattern for the gyri occurring in the cerebral cortex by reaction diffusion equations with Turing space parameters. Numerical examples for simplified geometries of a brain were solved to study pattern formation. The finite element method was used for the numerical solution, in conjunction with the Newton-Raphson method. The numerical examples showed that the model can represent cerebral cortex fold formation and reproduce pathologies related to gyri formation, such as polymicrogyria and lissencephaly. PMID:21784547

Garzón-Alvarado, Diego Alexander; Martinez, Angelica Maria Ramirez; Segrera, Dorian Luis Linero

2011-12-01

204

Increased Amygdala and Visual Cortex Activity and Functional Connectivity towards Stimulus Novelty Is Associated with State Anxiety  

PubMed Central

Novel stimuli often require a rapid reallocation of sensory processing resources to determine the significance of the event, and the appropriate behavioral response. Both the amygdala and the visual cortex are central elements of the neural circuitry responding to novelty, demonstrating increased activity to new as compared to highly familiarized stimuli. Further, these brain areas are intimately connected, and thus the amygdala may be a key region for directing sensory processing resources to novel events. Although knowledge regarding the neurocircuit of novelty detection is gradually increasing, we still lack a basic understanding of the conditions that are necessary and sufficient for novelty-specific responses in human amygdala and the visual cortices, and if these brain areas interact during detection of novelty. In the present study, we investigated the response of amygdala and the visual cortex to novelty, by comparing functional MRI activity between 1st and 2nd time presentation of a series of emotional faces in an event-related task. We observed a significant decrease in amygdala and visual cortex activity already after a single stimulus exposure. Interestingly, this decrease in responsiveness was less for subjects with a high score on state anxiety. Further, novel faces stimuli were associated with a relative increase in the functional coupling between the amygdala and the inferior occipital gyrus (BA 18). Thus, we suggest that amygdala is involved in fast sensory boosting that may be important for attention reallocation to novel events, and that the strength of this response depends on individual state anxiety. PMID:24755617

Ousdal, Olga T.; Andreassen, Ole A.; Server, Andres; Jensen, Jimmy

2014-01-01

205

The selective role of premotor cortex in speech perception: a contribution to phoneme judgements but not speech comprehension.  

PubMed

Several accounts of speech perception propose that the areas involved in producing language are also involved in perceiving it. In line with this view, neuroimaging studies show activation of premotor cortex (PMC) during phoneme judgment tasks; however, there is debate about whether speech perception necessarily involves motor processes, across all task contexts, or whether the contribution of PMC is restricted to tasks requiring explicit phoneme awareness. Some aspects of speech processing, such as mapping sounds onto meaning, may proceed without the involvement of motor speech areas if PMC specifically contributes to the manipulation and categorical perception of phonemes. We applied TMS to three sites-PMC, posterior superior temporal gyrus, and occipital pole-and for the first time within the TMS literature, directly contrasted two speech perception tasks that required explicit phoneme decisions and mapping of speech sounds onto semantic categories, respectively. TMS to PMC disrupted explicit phonological judgments but not access to meaning for the same speech stimuli. TMS to two further sites confirmed that this pattern was site specific and did not reflect a generic difference in the susceptibility of our experimental tasks to TMS: stimulation of pSTG, a site involved in auditory processing, disrupted performance in both language tasks, whereas stimulation of occipital pole had no effect on performance in either task. These findings demonstrate that, although PMC is important for explicit phonological judgments, crucially, PMC is not necessary for mapping speech onto meanings. PMID:23937689

Krieger-Redwood, Katya; Gaskell, M Gareth; Lindsay, Shane; Jefferies, Elizabeth

2013-12-01

206

R3P-Loc: a compact multi-label predictor using ridge regression and random projection for protein subcellular localization.  

PubMed

Locating proteins within cellular contexts is of paramount significance in elucidating their biological functions. Computational methods based on knowledge databases (such as gene ontology annotation (GOA) database) are known to be more efficient than sequence-based methods. However, the predominant scenarios of knowledge-based methods are that (1) knowledge databases typically have enormous size and are growing exponentially, (2) knowledge databases contain redundant information, and (3) the number of extracted features from knowledge databases is much larger than the number of data samples with ground-truth labels. These properties render the extracted features liable to redundant or irrelevant information, causing the prediction systems suffer from overfitting. To address these problems, this paper proposes an efficient multi-label predictor, namely R3P-Loc, which uses two compact databases for feature extraction and applies random projection (RP) to reduce the feature dimensions of an ensemble ridge regression (RR) classifier. Two new compact databases are created from Swiss-Prot and GOA databases. These databases possess almost the same amount of information as their full-size counterparts but with much smaller size. Experimental results on two recent datasets (eukaryote and plant) suggest that R3P-Loc can reduce the dimensions by seven-folds and significantly outperforms state-of-the-art predictors. This paper also demonstrates that the compact databases reduce the memory consumption by 39 times without causing degradation in prediction accuracy. For readers? convenience, the R3P-Loc server is available online at url:http://bioinfo.eie.polyu.edu.hk/R3PLocServer/. PMID:24997236

Wan, Shibiao; Mak, Man-Wai; Kung, Sun-Yuan

2014-11-01

207

Nuclear Shuttling of She2p Couples ASH1 mRNA Localization to its Translational Repression by Recruiting Loc1p and Puf6p  

PubMed Central

The transport and localization of mRNAs results in the asymmetric synthesis of specific proteins. In yeast, the nucleocytoplasmic shuttling protein She2 binds the ASH1 mRNA and targets it for localization at the bud tip by recruiting the She3p–Myo4p complex. Although the cytoplasmic role of She2p in mRNA localization is well characterized, its nuclear function is still unclear. Here, we show that She2p contains a nonclassical nuclear localization signal (NLS) that is essential for its nuclear import via the importin ? Srp1p. Exclusion of She2p from the nucleus by mutagenesis of its NLS leads to defective ASH1 mRNA localization and Ash1p sorting. Interestingly, these phenotypes mimic knockouts of LOC1 and PUF6, which encode for nuclear RNA-binding proteins that bind the ASH1 mRNA and control its translation. We find that She2p interacts with both Loc1p and Puf6p and that excluding She2p from the nucleus decreases this interaction. Absence of nuclear She2p disrupts the binding of Loc1p and Puf6p to the ASH1 mRNA, suggesting that nuclear import of She2p is necessary to recruit both factors to the ASH1 transcript. This study reveals that a direct coupling between localization and translation regulation factors in the nucleus is required for proper cytoplasmic localization of mRNAs. PMID:19244342

Shen, Zhifa; Paquin, Nicolas; Forget, Amélie

2009-01-01

208

Frontal Eye Fields Control Attentional Modulation of Alpha and Gamma Oscillations in Contralateral Occipitoparietal Cortex  

PubMed Central

Covertly directing visuospatial attention produces a frequency-specific modulation of neuronal oscillations in occipital and parietal cortices: anticipatory alpha (8–12 Hz) power decreases contralateral and increases ipsilateral to attention, whereas stimulus-induced gamma (>40 Hz) power is boosted contralaterally and attenuated ipsilaterally. These modulations must be under top-down control; however, the control mechanisms are not yet fully understood. Here we investigated the causal contribution of the human frontal eye field (FEF) by combining repetitive transcranial magnetic stimulation (TMS) with subsequent magnetoencephalography. Following inhibitory theta burst stimulation to the left FEF, right FEF, or vertex, participants performed a visual discrimination task requiring covert attention to either visual hemifield. Both left and right FEF TMS caused marked attenuation of alpha modulation in the occipitoparietal cortex. Notably, alpha modulation was consistently reduced in the hemisphere contralateral to stimulation, leaving the ipsilateral hemisphere relatively unaffected. Additionally, right FEF TMS enhanced gamma modulation in left visual cortex. Behaviorally, TMS caused a relative slowing of response times to targets contralateral to stimulation during the early task period. Our results suggest that left and right FEF are causally involved in the attentional top-down control of anticipatory alpha power in the contralateral visual system, whereas a right-hemispheric dominance seems to exist for control of stimulus-induced gamma power. These findings contrast the assumption of primarily intrahemispheric connectivity between FEF and parietal cortex, emphasizing the relevance of interhemispheric interactions. The contralaterality of effects may result from a transient functional reorganization of the dorsal attention network after inhibition of either FEF. PMID:25632139

O'Shea, Jacinta; Jensen, Ole; Bergmann, Til O.

2015-01-01

209

An analysis of von Economo neurons in the cerebral cortex of cetaceans, artiodactyls, and perissodactyls.  

PubMed

Von Economo neurons (VENs) are specialized projection neurons with a characteristic spindle-shaped soma and thick basal and apical dendrites. VENs have been described in restricted cortical regions, with their most frequent appearance in layers III and V of the anterior cingulate cortex, anterior insula, and frontopolar cortex of humans, great apes, macaque monkeys, elephants, and some cetaceans. Recently, a ubiquitous distribution of VENs was reported in various cortical areas in the pygmy hippopotamus, one of the closest living relatives of cetaceans. That finding suggested that VENs might not be unique to only a few species that possess enlarged brains. In the present analysis, we assessed the phylogenetic distribution of VENs within species representative of the superordinal clade that includes cetartiodactyls and perissodactyls, as well as afrotherians. In addition, the distribution of fork cells that are often found in close proximity to VENs was also assessed. Nissl-stained sections from the frontal pole, anterior cingulate cortex, anterior insula, and occipital pole of bowhead whale, cow, sheep, deer, horse, pig, rock hyrax, and human were examined using stereologic methods to quantify VENs and fork cells within layer V of all four cortical regions. VENs and fork cells were found in each of the species examined here with species-specific differences in distributions and densities. The present results demonstrated that VENs and fork cells were not restricted to highly encephalized or socially complex species, and their repeated emergence among distantly related species seems to represent convergent evolution of specialized pyramidal neurons. The widespread phylogenetic presence of VENs and fork cells indicates that these neuron morphologies readily emerged in response to selective forces,whose variety and nature are yet to be identified. PMID:24852852

Raghanti, Mary Ann; Spurlock, Linda B; Robert Treichler, F; Weigel, Sara E; Stimmelmayr, Raphaela; Butti, Camilla; Hans Thewissen, J G M; Hof, Patrick R

2014-05-23

210

Frontal eye fields control attentional modulation of alpha and gamma oscillations in contralateral occipitoparietal cortex.  

PubMed

Covertly directing visuospatial attention produces a frequency-specific modulation of neuronal oscillations in occipital and parietal cortices: anticipatory alpha (8-12 Hz) power decreases contralateral and increases ipsilateral to attention, whereas stimulus-induced gamma (>40 Hz) power is boosted contralaterally and attenuated ipsilaterally. These modulations must be under top-down control; however, the control mechanisms are not yet fully understood. Here we investigated the causal contribution of the human frontal eye field (FEF) by combining repetitive transcranial magnetic stimulation (TMS) with subsequent magnetoencephalography. Following inhibitory theta burst stimulation to the left FEF, right FEF, or vertex, participants performed a visual discrimination task requiring covert attention to either visual hemifield. Both left and right FEF TMS caused marked attenuation of alpha modulation in the occipitoparietal cortex. Notably, alpha modulation was consistently reduced in the hemisphere contralateral to stimulation, leaving the ipsilateral hemisphere relatively unaffected. Additionally, right FEF TMS enhanced gamma modulation in left visual cortex. Behaviorally, TMS caused a relative slowing of response times to targets contralateral to stimulation during the early task period. Our results suggest that left and right FEF are causally involved in the attentional top-down control of anticipatory alpha power in the contralateral visual system, whereas a right-hemispheric dominance seems to exist for control of stimulus-induced gamma power. These findings contrast the assumption of primarily intrahemispheric connectivity between FEF and parietal cortex, emphasizing the relevance of interhemispheric interactions. The contralaterality of effects may result from a transient functional reorganization of the dorsal attention network after inhibition of either FEF. PMID:25632139

Marshall, Tom R; O'Shea, Jacinta; Jensen, Ole; Bergmann, Til O

2015-01-28

211

Evaluation of the thermal-hydraulic response and fuel rod thermal and mechanical deformation behavior during the power burst facility test LOC-3. [PWR  

SciTech Connect

An evaluation of the results from the LOC-3 nuclear blowdown test conducted in the Power Burst Facility is presented. The test objective was to examine fuel and cladding behavior during a postulated cold leg break accident in a pressurized water reactor (PWR). Separate effects of rod internal pressure and the degree of irradiation were investigated in the four-rod test. Extensive cladding deformation (ballooning) and failure occurred during blowdown. The deformation of the low and high pressure rods was similar; however, the previously irradiated test rod deformed to a greater extent than a similar fresh rod exposed to identical system conditions.

Yackle, T.R.; MacDonald, P.E.; Broughton, J.M.

1980-01-01

212

[Atlanto-axial, Atlanto-occipital dislocations, developmental cervical canal stenosis in the Ehlers-Danlos syndrome (author's transl)].  

PubMed

Clinical, biological, histopathological and laboratory data are reported on a 13-year-old male with atlanto-axial, atlanto-occipital hypermobilities, cervical canal stenosis, hypoplastic atlas and hypoplastic first rib in the Ehlers-Danlos syndrome. He developed frequent attacks of sudden tetraplegia or tetraparesis and numbness below C2 due to trivial neck injuries. Examination revealed marked hypermobilities of all joints the cutis elastica (Fig. 1), spastic tetraparesis and fasciculation of the tongue. Occipito-atlantal hypermobility measured by Wiesel and Rhothmans' method revealed 5 mm horizontal translation (Fig. 2). Anterior and lateral dislocations of atlanto-axial joints were marked due to laxicity of the joint. Posterior decompression of C1, laminotomy of C2,3, occipito-C2 fixation with autogenous iliac "board (3 X 6 cm, rectangular board) graft" yielded favorable results with 15 months follow-up. To our knowledge, this is the first patient reported with this unusual combinations. PMID:7242840

Nagashima, C; Tsuji, R; Kubota, S; Tajima, K

1981-04-01

213

Occipital Artery Arising from the Anterior Aspect of the Internal Carotid Artery Identified by Three-Dimensional Computed Tomography Angiography  

PubMed Central

Variation of the branches of the external carotid artery (ECA) is well known, but it is extremely rare for the occipital artery (OA) to arise from the internal carotid artery (ICA). A 87-year-old man was found to have this anatomical variation on the right side by threedimensional computed tomography angiography for vascular mapping of the carotid arteries before superselective intra-arterial catheterization for advanced tongue cancer. Imaging showed the OA arose from the anterior aspect of the right ICA with the origin located 8.8 mm distal from the carotid bifurcation. The inner diameter of the origin of the OA was 2.1 mm and the angle between the OA and the ICA was 62 degrees. It is important to recognize this anatomic variation of the branches of the ECA before head and neck microsurgical reconstruction or superselective intra-arterial chemotherapy for oral cancer. PMID:23329973

Iwai, Toshinori; Izumi, Toshiharu; Inoue, Tomio; Maegawa, Jiro; Fuwa, Nobukazu; Mitsudo, Kenji; Tohnai, Iwai

2012-01-01

214

Prenatal diagnosis of occipital encephalocele, mega-cisterna magna, mesomelic shortening, and clubfeet associated with pure tetrasomy 20p.  

PubMed

We present the first case of a fetus with pure tetrasomy 20p proven by cord-blood sampling at 24 weeks of gestation. This case was diagnosed in utero with multiple congenital anomalies including occipital encephalocele, mega-cisterna magna, mesomelic shortening, and clubfeet. An analysis of GTG-banded chromosomes of 20 metaphase cells was performed. Female karyotype [47,XX, +i(20)(p10)] was revealed in all cells. Pure tetrasomy 20p was confirmed using fluorescent in situ hybridization (FISH) with a telomere probe for chromosome 20p in all seven metaphase cells. The pregnancy was terminated because of associated multiple anomalies and severe oligohydramnios. The postmortem examination confirmed the prenatal diagnosis. PMID:12575018

Wu, Yi-Cheng; Fang, Jye Siung; Lee, Kuei-Fang; Estipona, Judy; Yang, Man-Li; Yuan, Chiou-Chung

2003-02-01

215

Dynamic Representation of Eye Position in the Parieto-Occipital Sulcus K. NAKAMURA, H. H. CHUNG, M.S.A. GRAZIANO, AND C. G. GROSS  

E-print Network

Dynamic Representation of Eye Position in the Parieto-Occipital Sulcus K. NAKAMURA, H. H. CHUNG, M 08544 Nakamura, K., H. H. Chung, M.S.A. Graziano, and C. G. Gross. Dynamic representation of eye stimulation and to the position and movement of the eyes. We examined the effects of eye position and eye

Graziano, Michael

216

Frontal cortex TMS for tinnitus.  

PubMed

Both invasive and non-invasive neuromodulation of the dorsolateral prefrontal cortex (DLPFC) are capable of suppressing tinnitus loudness. Repetitive transcranial magnetic stimulation (rTMS) of the DLPFC has an add-on effect for auditory cortex (AC) rTMS in improving tinnitus-related distress. We aimed to investigate whether TMS and rTMS of the DLPFC is capable of reducing tinnitus loudness and what mechanism might be involved. Two TMS studies targeting the right DLPFC were performed. Study 1 investigated 44 tinnitus patients who underwent either 1 or 10 Hz real or sham TMS (200 pulses at 80% motor threshold). In Study 2 we performed rTMS (10 sessions of 600 pulses) in responders of study 1. Changes on the visual analog scale (VAS) loudness were evaluated. All patients underwent a pre-TMS electroencephalography: differences in functional connectivity between responders and non-responders were evaluated using sLORETA. Only 1 Hz TMS was capable of significantly reducing tinnitus loudness for 11 patients with a mean suppression of 39.23%. RTMS for these 11 patients yielded a 21% improvement in VAS loudness, and in 7 of 11 rTMS was successful, with, a mean suppression of 27.13%. The responders were characterized by a difference in lagged linear connectivity in the theta band among the DLPFC, anterior cingulate cortex (ACC), parahippocampus and AC. In summary, 1 H, TMS and rTMS of the right DLPFC can transiently reduce the perceived tinnitus loudness mediated via functional connections between the DLPFC and a network consisting of the ACC, parahippocampus and AC. PMID:22853891

De Ridder, Dirk; Song, Jae-Jin; Vanneste, Sven

2013-05-01

217

Chromosome 11: Ubiquilin 3 and LOC genes affecting smell, 3D animation with no audioSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

DNAi location: Genome>Tour>flyover>Ubiquilin and olfactory receptor cluster The intergenic region is followed by two adjacent ubiquilin genes, which are involved in key cell processes, from replication to \\"programmed\\" death. Ubiquilin 3 is expressed specifically in the testis, where it is believed to help regulate sperm development. These are followed by a cluster of gene locations (LOC) thought to encode olfactory receptors, which receive stimuli in the nose to allow us to detect smells. At 31,110 nucleotides long, the first gene in this cluster, LOC120009, is the longest we will encounter on our journey. Its 11 coding exons are indicated in red, but most of its bulk comes from its yellow introns and 29 blue and purple transposons. However, the majority of olfactory receptors are short. The next four gene locations are more typical of olfactory receptors in having only one or two coding exons. About 60% of our smell receptors are nonfunctional. Presumably, humans have less need for smell in locating food and interacting socially. The mutations that inactivate many receptors vary among people, meaning that there is a DNA basis for the observation that some people can smell better than others! It also suggests that the loss of smelling acuity has occurred very recently in human evolution and is still ongoing.

2008-10-06

218

The multifunctional application of microfluidic lab-on-a-chip surface enhanced Raman spectroscopy (LOC-SERS) within the field of bioanalytics  

NASA Astrophysics Data System (ADS)

This contribution will present a variety of applications of lab-on-a-chip surface enhanced Raman spectroscopy in the field of bioanalytic. Beside the quantification and online monitoring of drugs and pharmaceuticals, determination of enzyme activity and discrimination of bacteria are successfully carried out utilizing LOC-SERS. The online-monitoring of drugs using SERS in a microfluidic device is demonstrated for nicotine. The enzyme activity of thiopurine methyltransferase (TPMT) in lysed red blood cells is determined by SERS in a lab-on-a-chip device. To analyse the activity of TPMT the metabolism of 6-mercaptopurine to 6-methylmercaptopurine is investigated. The discrimination of bacteria on strain level is carried out with different E. coli strains. For the investigations, the bacteria are busted by ultra sonic to achieve a high information output. This sample preparation provides the possibility to detect SERS spectra containing information of the bacterial cell walls as well as of the cytoplasm. This contribution demonstrates the great potential of LOC-SERS in the field of bioanalytics.

März, Anne; Mönch, Bettina; Walter, Angela; Bocklitz, Thomas; Schumacher, Wilm; Rösch, Petra; Kiehntopf, Michael; Popp, Jürgen

2011-07-01

219

Organization of the Posterior Parietal Cortex in Galagos: II. Ipsilateral Cortical Connections of Physiologically Identified Zones Within Anterior Sensorimotor Region  

PubMed Central

We studied cortical connections of functionally distinct movement zones of the posterior parietal cortex (PPC) in galagos identified by intracortical microstimulation with long stimulus trains (~500 msec). All these zones were in the anterior half of PPC, and each of them had a different pattern of connections with premotor (PM) and motor (M1) areas of the frontal lobe and with other areas of parietal and occipital cortex. The most rostral PPC zone has major connections with motor and visuomotor areas of frontal cortex as well as with somatosensory areas 3a and 1-2 and higher order somatosensory areas in the lateral sulcus. The dorsal part of anterior PPC region representing hand-to-mouth movements is connected mostly to the forelimb representation in PM, M1, 3a, 1-2, and somatosensory areas in the lateral sulcus and on the medial wall. The more posterior defensive and reaching zones have additional connections with nonprimary visual areas (V2, V3, DL, DM, MST). Ventral aggressive and defensive face zones have reciprocal connections with each other as well as connections with mostly face, but also forelimb representations of premotor areas and M1 as well as prefrontal cortex, FEF, and somatosensory areas in the lateral sulcus and areas on the medial surface of the hemisphere. Whereas the defensive face zone is additionally connected to nonprimary visual cortical areas, the aggressive face zone is not. These differences in connections are consistent with our functional parcellation of PPC based on intracortical long-train microstimulation, and they identify parts of cortical networks that mediate different motor behaviors. PMID:19844952

STEPNIEWSKA, IWONA; CERKEVICH, CHRISTINA M.; FANG, PEI-CHUN Y.; KAAS, JON H.

2013-01-01

220

Attention: control in the visual cortex.  

PubMed

A recent study in which the human visual cortex was directly stimulated to create visual percepts has shown that visual spatial attention can act directly on neural activity in sensory cortex without involving attentional modulation of subcortical visual inputs. PMID:17339016

Mangun, George R; Fannon, Sean P

2007-03-01

221

Dynamic Neuroplasticity after Human Prefrontal Cortex Damage  

E-print Network

. Damage to the human prefrontal cortex (PFC) results in attention (Barcelo´ et al., 2000; Rossi et al in activity in homologous cortical regions in the nonlesioned hemisphere and in perilesion cortex (Ward et al., 2007; Johansen-Berg et al., 2002; Blasi et al., 2002; Corbetta et al., 2005; He et al., 2007; Nudo

Oregon, University of

222

Subspecialization in the human posterior medial cortex.  

PubMed

The posterior medial cortex (PMC) is particularly poorly understood. Its neural activity changes have been related to highly disparate mental processes. We therefore investigated PMC properties with a data-driven exploratory approach. First, we subdivided the PMC by whole-brain coactivation profiles. Second, functional connectivity of the ensuing PMC regions was compared by task-constrained meta-analytic coactivation mapping (MACM) and task-unconstrained resting-state correlations (RSFC). Third, PMC regions were functionally described by forward/reverse functional inference. A precuneal cluster was mostly connected to the intraparietal sulcus, frontal eye fields, and right temporo-parietal junction; associated with attention and motor tasks. A ventral posterior cingulate cortex (PCC) cluster was mostly connected to the ventromedial prefrontal cortex and middle left inferior parietal cortex (IPC); associated with facial appraisal and language tasks. A dorsal PCC cluster was mostly connected to the dorsomedial prefrontal cortex, anterior/posterior IPC, posterior midcingulate cortex, and left dorsolateral prefrontal cortex; associated with delay discounting. A cluster in the retrosplenial cortex was mostly connected to the anterior thalamus and hippocampus. Furthermore, all PMC clusters were congruently coupled with the default mode network according to task-unconstrained but not task-constrained connectivity. We thus identified distinct regions in the PMC and characterized their neural networks and functional implications. PMID:25462801

Bzdok, Danilo; Heeger, Adrian; Langner, Robert; Laird, Angela R; Fox, Peter T; Palomero-Gallagher, Nicola; Vogt, Brent A; Zilles, Karl; Eickhoff, Simon B

2015-02-01

223

4 Adaptation and Decorrelation in the Cortex  

Microsoft Academic Search

Summary Any small region of the cortex receives input through a large number of afferent fibres, and transmits efferent output to other regions of the brain. If the units interact according to an anti-Hebbian rule, the outputs define a coordinate system in which there are no correlations even when the input fibres show strong correlations. The idea that cortex performs

Horace Barlow; Peter Fddi

1989-01-01

224

Mapping Prefrontal Cortex Functions in Human Infancy  

ERIC Educational Resources Information Center

It has long been thought that the prefrontal cortex, as the seat of most higher brain functions, is functionally silent during most of infancy. This review highlights recent work concerned with the precise mapping (localization) of brain activation in human infants, providing evidence that prefrontal cortex exhibits functional activation much…

Grossmann, Tobias

2013-01-01

225

Auditory Neuroscience: Activating the Cortex without Sound  

E-print Network

. In a recent neuroimaging study of auditory attention, Voisin and colleagues [2] asked subjects to indicateAuditory Neuroscience: Activating the Cortex without Sound Sensory brain areas are usually that activation of auditory cortex occurs spontaneously and can be induced during silence by stimulus expectancy

Oxford, University of

226

The similarities between the hallucinations associated with the partial epileptic seizures of the occipital lobe and ball lightning observations  

NASA Astrophysics Data System (ADS)

Ball Lightning was seen and described since antiquity and recorded in many places. Ball lightning is usually observed during thunderstorms but large number of ball lightning observations is also reported during fine weather without any connection to thunderstorms or lightning. However, so far no one has managed to generate them in the laboratory. It is photographed very rarely and in many cases the authenticity of them is questionable. It is possible that many different phenomena are grouped together and categorized simply as ball lightning. Indeed, the visual hallucinations associated with simple partial epileptic seizures, during which the patient remains conscious, may also be categorized by a patient unaware of his or her condition as ball lightning observation. Such visual hallucinations may occur as a result of an epileptic seizure in the occipital, temporo-occipital or temporal lobes of the cerebrum [1,2,3]. In some cases the hallucination is perceived as a coloured ball moving horizontally from the periphery to the centre of the vision. The ball may appear to be rotating or spinning. The colour of the ball can be red, yellow, blue or green. Sometimes, the ball may appear to have a solid structure surrounded by a thin glow or in other cases the ball appears to generate spark like phenomena. When the ball is moving towards the centre of the vision it may increase its intensity and when it reaches the centre it can 'explode' illuminating the whole field of vision. During the hallucinations the vision is obscured only in the area occupied by the apparent object. The hallucinations may last for 5 to 30 seconds and rarely up to a minute. Occipital seizures may spread into other regions of the brain giving auditory, olfactory and sensory sensations. These sensations could be buzzing sounds, the smell of burning rubber, pain with thermal perception especially in the arms and the face, and numbness and tingling sensation. In some cases a person may experience only one seizure during lifetime and may not be aware of the reason for the experience. Being of good health otherwise, the person may categorize the experience as a ball lightning encounter. If, as described above, the seizure spread into other regions of the brain the resulting experience may appear as electrical effects (the smell, heat sensation, tingling feeling etc.) of ball lightning. Epileptic seizures are a common and important medical problem, with about one in eleven persons experiencing at least one seizure at some point. Thus some of the ball lightning encounters presented in the literature could very well be associated with the experiences of persons who had an epileptic seizure with visual hallucinations. [1] Blom, S. et al., Epilepsy, Neurology, Edited by S-M Aquilonius and J. Fagius, Liber, 2000. [2] Panayiotopoulos, C. P., J. Neorl. Neurosurg. Psychiatry, 66, 536-540, 1999. [3] Bien et al, Brain,123, 244-253, 2000.

Cooray, G. K.; Cooray, V.

2007-12-01

227

Useful signals from motor cortex  

PubMed Central

Historically, the motor cortical function has been explained as a funnel to muscle activation. This invokes the idea that motor cortical neurons, or ‘upper motoneurons’, directly cause muscle contraction just like spinal motoneurons. Thus, the motor cortex and muscle activity are inextricably entwined like a puppet master and his marionette. Recently, this concept has been challenged by current experimentation showing that many behavioural aspects of action are represented in motor cortical activity. Although this activity may still be related to muscle activation, the relation between the two is likely to be indirect and complex, whereas the relation between cortical activity and kinematic parameters is simple and robust. These findings show how to extract useful signals that help explain the underlying process that generates behaviour and to harness these signals for potentially therapeutic applications. PMID:17255162

Schwartz, Andrew B

2007-01-01

228

Impulsive Reconnection Dynamics: From the Laboratory to the Loc... http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verb... 1 of 1 3/10/05 11:33 AM  

E-print Network

Impulsive Reconnection Dynamics: From the Laboratory to the Loc... http://wwwD-01 TI: Impulsive Reconnection Dynamics: From the Laboratory to the Local Cosmos AU-steady. Most often, it is impulsive or bursty. Impulsive reconnection is characterized not only by a fast

Ng, Chung-Sang

229

Foramen magnum meningiomas: To drill or not to drill the occipital condyle? A series of 12 patients  

PubMed Central

Background: Despite the development of microsurgery and cranial base techniques, the surgical management of Foramen Magnum Meningiomas (FMM) continues to be a technical challenge to neurosurgeons. Controversy concerning the utility of systematic condyle drilling for approaching FMM has been raised. Our aim was to describe the surgical technique, analyze its safety, and the postoperative outcome in 12 consecutive FMM patients. Methods: From 1986 to 2011, 12 patients with FMM underwent operations in the Department of Neurosurgery at Servidores do Estado Hospital and in a private clinic. All patients were operated using a standard suboccipital craniectomy, preserving the occipital condyle, opening of the Foramen Magnum, and ipsilateral removal of the posterior arch of C1. Results: There was no operative mortality, nine patients achieved Glasgow Outcome Scale 4 or 5. Condylar resection was not deemed necessary in any case. Gross total resection was achieved in nine patients. After surgery, four patients developed lower cranial nerve weakness. There was no significant postoperative complication in the remaining patients. The average follow-up is 8.2 years. Conclusion The vast majority of FMM can be safely removed with a retrocondylar lateral suboccipital approach without condylar resection, using meticulous microsurgical techniques. PMID:23776759

Lynch, Jose Carlos; Temponi, Vicente; Emmerich, João Cláudio; Pereira, Celestino Esteves; Gonçalves, Mariangela Barbi

2013-01-01

230

Effect of Visual Feedback on the Occipital-Parietal-Motor Network in Parkinson’s Disease with Freezing of Gait  

PubMed Central

Freezing of gait (FOG) is an elusive phenomenon that debilitates a large number of Parkinson’s disease (PD) patients regardless of stage of disease, medication status, or deep brain stimulation implantation. Sensory feedback cues, especially visual feedback cues, have been shown to alleviate FOG episodes or even prevent episodes from occurring. Here, we examine cortical information flow between occipital, parietal, and motor areas during the pre-movement stage of gait in a PD-with-FOG patient that had a strong positive behavioral response to visual cues, one PD-with-FOG patient without any behavioral response to visual cues, and age-matched healthy controls, before and after training with visual feedback. Results for this case study show differences in cortical information flow between the responding PD-with-FOG patient and the other two subject types, notably, an increased information flow in the beta range. Tentatively suggesting the formation of an alternative cortical sensory-motor pathway during training with visual feedback, these results are proposed as subject for further verification employing larger cohorts of patients. PMID:24409167

Velu, Priya D.; Mullen, Tim; Noh, Eunho; Valdivia, Matthew C.; Poizner, Howard; Baram, Yoram; de Sa, Virginia R.

2014-01-01

231

Pressure-volume index-based volume calculation of contrast medium for atlanto-occipital myelography in dogs.  

PubMed

Subarachnoid pressure recordings were made during atlanto-occipital myelography in 45 dogs with clinical signs of spinal disease. Iohexol was injected at a dosage of 0.3 ml/kg body weight and simultaneous pressure values were recorded in the cerebellomedullary cistern. The mean subarachnoid pressure was 9 ± 3 mmHg before and 70 ± 32 mmHg at the end of administration. From the pressure change induced by the volume load, the pressure-volume index (PVI) of the subarachnoid space was calculated and found to be in close correlation with body weight and the crown-rump length (r = 0.94 and 0.87). Using the estimated PVI values, the appropriate volume of contrast medium can be calculated for an animal according to body weight. Dogs of a large body size require relatively less contrast medium than small-sized dogs (range 0.17-0.35 ml/kg). This calculated volume is unlikely to increase the subarachnoid pressure above 40 mmHg as a specific pressure limit. Using these data, simplified recommendations for the choice of contrast medium volumes have been generated. PMID:22548310

Arany-Tóth, Attila; Csébi, Péter; Reiczigel, Jen?; Németh, Tibor

2012-01-01

232

Dual occipital and supraorbital nerve stimulation for chronic migraine: a single-center experience, review of literature, and surgical considerations.  

PubMed

Occipital nerve stimulation (ONS) has been studied in a few clinical trials for the treatment of chronic migraine (CM) with failure to prove sufficient efficacy. To date, peripheral nerve stimulation for the treatment of primary headache is limited to off-label use only. The authors report their institutional experience in CM therapy with combined ONS and supraorbital nerve stimulation (SONS). Fourteen patients treated with dual ONS and SONS for CM were studied with follow-up ranging from 3 to 60 months. Seventy-one percent achieved successful stimulation as defined by a 50% or greater decrease in pain severity. The mean reduction in headache-related visual analog scale (VAS) score was 3.92 ± 2.4. Half of the patients also had resolution of migraine-associated neurological symptoms and returned to normal functional capacity. The main adverse events included lead migration (42.8%), supraorbital lead allodynia (21.4%), and infection (14.2%) with a resulting high reoperation rate (35.7%). The authors' stimulation efficacy was superior to the combined 33% positive response rates (? 50% pain reduction) in the published studies of ONS for CM. This is likely due to the fact that topographical paresthesia induced by combined ONS and SONS covers the area of migraine pain better than ONS alone. The authors also discuss effective surgical techniques to prevent patient morbidity. PMID:23991822

Hann, Shannon; Sharan, Ashwini

2013-09-01

233

Effect of visual feedback on the occipital-parietal-motor network in Parkinson's disease with freezing of gait.  

PubMed

Freezing of gait (FOG) is an elusive phenomenon that debilitates a large number of Parkinson's disease (PD) patients regardless of stage of disease, medication status, or deep brain stimulation implantation. Sensory feedback cues, especially visual feedback cues, have been shown to alleviate FOG episodes or even prevent episodes from occurring. Here, we examine cortical information flow between occipital, parietal, and motor areas during the pre-movement stage of gait in a PD-with-FOG patient that had a strong positive behavioral response to visual cues, one PD-with-FOG patient without any behavioral response to visual cues, and age-matched healthy controls, before and after training with visual feedback. Results for this case study show differences in cortical information flow between the responding PD-with-FOG patient and the other two subject types, notably, an increased information flow in the beta range. Tentatively suggesting the formation of an alternative cortical sensory-motor pathway during training with visual feedback, these results are proposed as subject for further verification employing larger cohorts of patients. PMID:24409167

Velu, Priya D; Mullen, Tim; Noh, Eunho; Valdivia, Matthew C; Poizner, Howard; Baram, Yoram; de Sa, Virginia R

2014-01-01

234

Vocalization Induced CFos Expression in Marmoset Cortex  

PubMed Central

All non-human primates communicate with conspecifics using vocalizations, a system involving both the production and perception of species-specific vocal signals. Much of the work on the neural basis of primate vocal communication in cortex has focused on the sensory processing of vocalizations, while relatively little data are available for vocal production. Earlier physiological studies in squirrel monkeys had shed doubts on the involvement of primate cortex in vocal behaviors. The aim of the present study was to identify areas of common marmoset (Callithrix jacchus) cortex that are potentially involved in vocal communication. In this study, we quantified cFos expression in three areas of marmoset cortex – frontal, temporal (auditory), and medial temporal – under various vocal conditions. Specifically, we examined cFos expression in these cortical areas during the sensory, motor (vocal production), and sensory–motor components of vocal communication. Our results showed an increase in cFos expression in ventrolateral prefrontal cortex as well as the medial and lateral belt areas of auditory cortex in the vocal perception condition. In contrast, subjects in the vocal production condition resulted in increased cFos expression only in dorsal premotor cortex. During the sensory–motor condition (antiphonal calling), subjects exhibited cFos expression in each of the above areas, as well as increased expression in perirhinal cortex. Overall, these results suggest that various cortical areas outside primary auditory cortex are involved in primate vocal communication. These findings pave the way for further physiological studies of the neural basis of primate vocal communication. PMID:21179582

Miller, Cory T.; DiMauro, Audrey; Pistorio, Ashley; Hendry, Stewart; Wang, Xiaoqin

2010-01-01

235

Medial perirhinal cortex disambiguates confusable objects.  

PubMed

Our brain disambiguates the objects in our cluttered visual world seemingly effortlessly, enabling us to understand their significance and to act appropriately. The role of anteromedial temporal structures in this process, particularly the perirhinal cortex, is highly controversial. In some accounts, the perirhinal cortex is necessary for differentiating between perceptually and semantically confusable objects. Other models claim that the perirhinal cortex neither disambiguates perceptually confusable objects nor plays a unique role in semantic processing. One major hurdle to resolving this central debate is the fact that brain damage in human patients typically encompasses large portions of the anteromedial temporal lobe, such that the identification of individual substructures and precise neuroanatomical locus of the functional impairments has been difficult. We tested these competing accounts in patients with Alzheimer's disease with varying degrees of atrophy in anteromedial structures, including the perirhinal cortex. To assess the functional contribution of each anteromedial temporal region separately, we used a detailed region of interest approach. From each participant, we obtained magnetic resonance imaging scans and behavioural data from a picture naming task that contrasted naming performance with living and non-living things as a way of manipulating perceptual and semantic confusability; living things are more similar to one another than non-living things, which have more distinctive features. We manually traced neuroanatomical regions of interest on native-space cortical surface reconstructions to obtain mean thickness estimates for the lateral and medial perirhinal cortex and entorhinal cortex. Mean cortical thickness in each region of interest, and hippocampal volume, were submitted to regression analyses predicting naming performance. Importantly, atrophy of the medial perirhinal cortex, but not lateral perirhinal cortex, entorhinal cortex or hippocampus, significantly predicted naming performance on living relative to non-living things. These findings indicate that one specific anteromedial temporal lobe region-the medial perirhinal cortex-is necessary for the disambiguation of perceptually and semantically confusable objects. Taken together, these results support a hierarchical account of object processing, whereby the perirhinal cortex at the apex of the ventral object processing system is required to bind properties of not just perceptually, but also semantically confusable objects together, enabling their disambiguation from other similar objects and thus comprehension. Significantly, this model combining a hierarchical object processing architecture with a semantic feature statistic account explains why category-specific semantic impairments for living things are associated with anteromedial temporal lobe damage, and pinpoints the root of this syndrome to perirhinal cortex damage. PMID:23250887

Kivisaari, Sasa L; Tyler, Lorraine K; Monsch, Andreas U; Taylor, Kirsten I

2012-12-01

236

Medial perirhinal cortex disambiguates confusable objects  

PubMed Central

Our brain disambiguates the objects in our cluttered visual world seemingly effortlessly, enabling us to understand their significance and to act appropriately. The role of anteromedial temporal structures in this process, particularly the perirhinal cortex, is highly controversial. In some accounts, the perirhinal cortex is necessary for differentiating between perceptually and semantically confusable objects. Other models claim that the perirhinal cortex neither disambiguates perceptually confusable objects nor plays a unique role in semantic processing. One major hurdle to resolving this central debate is the fact that brain damage in human patients typically encompasses large portions of the anteromedial temporal lobe, such that the identification of individual substructures and precise neuroanatomical locus of the functional impairments has been difficult. We tested these competing accounts in patients with Alzheimer’s disease with varying degrees of atrophy in anteromedial structures, including the perirhinal cortex. To assess the functional contribution of each anteromedial temporal region separately, we used a detailed region of interest approach. From each participant, we obtained magnetic resonance imaging scans and behavioural data from a picture naming task that contrasted naming performance with living and non-living things as a way of manipulating perceptual and semantic confusability; living things are more similar to one another than non-living things, which have more distinctive features. We manually traced neuroanatomical regions of interest on native-space cortical surface reconstructions to obtain mean thickness estimates for the lateral and medial perirhinal cortex and entorhinal cortex. Mean cortical thickness in each region of interest, and hippocampal volume, were submitted to regression analyses predicting naming performance. Importantly, atrophy of the medial perirhinal cortex, but not lateral perirhinal cortex, entorhinal cortex or hippocampus, significantly predicted naming performance on living relative to non-living things. These findings indicate that one specific anteromedial temporal lobe region—the medial perirhinal cortex—is necessary for the disambiguation of perceptually and semantically confusable objects. Taken together, these results support a hierarchical account of object processing, whereby the perirhinal cortex at the apex of the ventral object processing system is required to bind properties of not just perceptually, but also semantically confusable objects together, enabling their disambiguation from other similar objects and thus comprehension. Significantly, this model combining a hierarchical object processing architecture with a semantic feature statistic account explains why category-specific semantic impairments for living things are associated with anteromedial temporal lobe damage, and pinpoints the root of this syndrome to perirhinal cortex damage. PMID:23250887

Tyler, Lorraine K.; Monsch, Andreas U.; Taylor, Kirsten I.

2012-01-01

237

The cerebral cortex of Albert Einstein: a description and preliminary analysis of unpublished photographs  

PubMed Central

Upon his death in 1955, Albert Einstein’s brain was removed, fixed and photographed from multiple angles. It was then sectioned into 240 blocks, and histological slides were prepared. At the time, a roadmap was drawn that illustrates the location within the brain of each block and its associated slides. Here we describe the external gross neuroanatomy of Einstein’s entire cerebral cortex from 14 recently discovered photographs, most of which were taken from unconventional angles. Two of the photographs reveal sulcal patterns of the medial surfaces of the hemispheres, and another shows the neuroanatomy of the right (exposed) insula. Most of Einstein’s sulci are identified, and sulcal patterns in various parts of the brain are compared with those of 85 human brains that have been described in the literature. To the extent currently possible, unusual features of Einstein’s brain are tentatively interpreted in light of what is known about the evolution of higher cognitive processes in humans. As an aid to future investigators, these (and other) features are correlated with blocks on the roadmap (and therefore histological slides). Einstein’s brain has an extraordinary prefrontal cortex, which may have contributed to the neurological substrates for some of his remarkable cognitive abilities. The primary somatosensory and motor cortices near the regions that typically represent face and tongue are greatly expanded in the left hemisphere. Einstein’s parietal lobes are also unusual and may have provided some of the neurological underpinnings for his visuospatial and mathematical skills, as others have hypothesized. Einstein’s brain has typical frontal and occipital shape asymmetries (petalias) and grossly asymmetrical inferior and superior parietal lobules. Contrary to the literature, Einstein’s brain is not spherical, does not lack parietal opercula and has non-confluent Sylvian and inferior postcentral sulci. PMID:23161163

Lepore, Frederick E.; Noe, Adrianne

2013-01-01

238

Anticipating action effects recruits audiovisual movement representations in the ventral premotor cortex.  

PubMed

When table tennis players anticipate the course of the ball while preparing their motor responses, they not only observe their opponents striking the ball but also listen to events such as the sound of racket-ball contact. Because visual stimuli can be detected more easily when accompanied by a sound, we assumed that complementary sensory audiovisual information would influence the anticipation of biological motion, especially when the racket-ball contact is not presented visually, but has to be inferred from continuous movement kinematics and an abrupt sound. Twenty-six observers were examined with fMRI while watching point-light displays (PLDs) of an opposing table tennis player. Their task was to anticipate the resultant ball flight. The sound was presented complementary to the veracious event or at a deviant time point in its kinematics. Results showed that participants performed best in the complementary condition. Using a region-of-interest approach, fMRI data showed that complementary audiovisual stimulation elicited higher activation in the left temporo-occipital middle temporal gyrus (MTGto), the left primary motor cortex, and the right anterior intraparietal sulcus (aIPS). Both hemispheres also revealed higher activation in the ventral premotor cortex (vPMC) and the pars opercularis of the inferior frontal gyrus (BA 44). Ranking the behavioral effect of complementary versus conflicting audiovisual information over participants revealed an association between the complementary information and higher activation in the right vPMC. We conclude that the recruitment of movement representations in the auditory and visual modalities in the vPMC can be influenced by task-relevant cross-modal audiovisual interaction. PMID:25463138

Bischoff, Matthias; Zentgraf, Karen; Pilgramm, Sebastian; Stark, Rudolf; Krüger, Britta; Munzert, Jörn

2014-10-29

239

Training Transfers the Limits on Perception from Parietal to Ventral Cortex  

PubMed Central

Summary Visually guided behavior depends on (1) extracting and (2) discriminating signals from complex retinal inputs, and these perceptual skills improve with practice [1]. For instance, training on aerial reconnaissance facilitated World War II Allied military operations [2]; analysts pored over stereoscopic photographs, becoming expert at (1) segmenting pictures into meaningful items to break camouflage from (noisy) backgrounds, and (2) discriminating fine details to distinguish V-weapons from innocuous pylons. Training is understood to optimize neural circuits that process scene features (e.g., orientation) for particular purposes (e.g., judging position) [3–6]. Yet learning is most beneficial when it generalizes to other settings [7, 8] and is critical in recovery after adversity [9], challenging understanding of the circuitry involved. Here we used repetitive transcranial magnetic stimulation (rTMS) to infer the functional organization supporting learning generalization in the human brain. First, we show dissociable contributions of the posterior parietal cortex (PPC) versus lateral occipital (LO) circuits: extracting targets from noise is disrupted by PPC stimulation, in contrast to judging feature differences, which is affected by LO rTMS. Then, we demonstrate that training causes striking changes in this circuit: after feature training, identifying a target in noise is not disrupted by PPC stimulation but instead by LO stimulation. This indicates that training shifts the limits on perception from parietal to ventral brain regions and identifies a critical neural circuit for visual learning. We suggest that generalization is implemented by supplanting dynamic processing conducted in the PPC with specific feature templates stored in the ventral cortex. PMID:25283780

Chang, Dorita H.F.; Mevorach, Carmel; Kourtzi, Zoe; Welchman, Andrew E.

2014-01-01

240

The Role of Human Parietal Cortex in Attention Networks  

ERIC Educational Resources Information Center

The parietal cortex has been proposed as part of the neural network for guiding spatial attention. However, it is unclear to what degree the parietal cortex contributes to the attentional modulations of activities of the visual cortex and the engagement of the frontal cortex in the attention network. We recorded behavioural performance and…

Han, Shihui; Jiang, Yi; Gu, Hua; Rao, Hengyi; Mao, Lihua; Cui, Yong; Zhai, Renyou

2004-01-01

241

Structure of the cerebral cortex of the humpback whale, Megaptera novaeangliae (Cetacea, Mysticeti, Balaenopteridae).  

PubMed

Cetaceans diverged from terrestrial mammals between 50 and 60 million years ago and acquired, during their adaptation to a fully aquatic milieu, many derived features, including echolocation (in odontocetes), remarkable auditory and communicative abilities, as well as a complex social organization. Whereas brain structure has been documented in detail in some odontocetes, few reports exist on its organization in mysticetes. We studied the cerebral cortex of the humpback whale (Megaptera novaeangliae) in comparison to another balaenopterid, the fin whale, and representative odontocetes. We observed several differences between Megaptera and odontocetes, such as a highly clustered organization of layer II over the occipital and inferotemporal neocortex, whereas such pattern is restricted to the ventral insula in odontocetes. A striking observation in Megaptera was the presence in layer V of the anterior cingulate, anterior insular, and frontopolar cortices of large spindle cells, similar in morphology and distribution to those described in hominids, suggesting a case of parallel evolution. They were also observed in the fin whale and the largest odontocetes, but not in species with smaller brains or body size. The hippocampal formation, unremarkable in odontocetes, is further diminutive in Megaptera, contrasting with terrestrial mammals. As in odontocetes, clear cytoarchitectural patterns exist in the neocortex of Megaptera, making it possible to define many cortical domains. These observations demonstrate that Megaptera differs from Odontoceti in certain aspects of cortical cytoarchitecture and may provide a neuromorphologic basis for functional and behavioral differences between the suborders as well as a reflection of their divergent evolution. PMID:17441195

Hof, Patrick R; Van der Gucht, Estel

2007-01-01

242

Modulation of Ventral Prefrontal Cortex Functional Connections Reflects the Interplay of Cognitive Processes and Stimulus Characteristics  

PubMed Central

Emerging ideas of brain function emphasize the context-dependency of regional contributions to cognitive operations, where the function of a particular region is constrained by its pattern of functional connectivity. We used functional magnetic resonance imaging to examine how modality of input (auditory or visual) affects prefrontal cortex (PFC) functional connectivity for simple working memory tasks. The hypothesis was that PFC would show contextually dependent changes in functional connectivity in relation to the modality of input despite similar cognitive demands. Participants were presented with auditory or visual bandpass-filtered noise stimuli, and performed 2 simple short-term memory tasks. Brain activation patterns independently mapped onto modality and task demands. Analysis of right ventral PFC functional connectivity, however, suggested these activity patterns interact. One functional connectivity pattern showed task differences independent of stimulus modality and involved ventromedial and dorsolateral prefrontal and occipitoparietal cortices. A second pattern showed task differences that varied with modality, engaging superior temporal and occipital association regions. Importantly, these association regions showed nonzero functional connectivity in all conditions, rather than showing a zero connectivity in one modality and nonzero in the other. These results underscore the interactive nature of brain processing, where modality-specific and process-specific networks interact for normal cognitive operations. PMID:18787230

McIntosh, Anthony R.

2009-01-01

243

Location, Location, Location: Alterations in the Functional Topography of Face- but not Object- or Place-Related Cortex in Adolescents with Autism  

PubMed Central

In autism, impairments in face processing are a relatively recent discovery, but have quickly become a widely accepted aspect of the behavioral profile. Only a handful of studies have investigated potential atypicalities in autism in the development of the neural substrates mediating face processing. High-functioning individuals with autism (HFA) and matched typically developing (TD) controls watched dynamic movie vignettes of faces, common objects, buildings, and scenes of navigation while undergoing an fMRI scan. With these data, we mapped the functional topography of category-selective activation for faces bilaterally in the fusiform gyrus, occipital face area, and posterior superior temporal sulcus. Additionally, we mapped category-selective activation for objects in the lateral occipital area and for places in the parahippocampal place area in the two groups. Our findings do not indicate a generalized disruption in the development of the entire ventral visual pathway in autism. Instead, our results suggest that the functional topography of face-related cortex is selectively disrupted in autism and that this alteration is present in early adolescence. Furthermore, for those HFA adolescents who do exhibit face-selective activation, this activation tends to be located in traditionally object-related regions, which supports the hypothesis that perceptual processing of faces in autism may be more akin to the perceptual processing of common objects in TD individuals. PMID:20631857

Scherf, K. Suzanne; Luna, Beatriz; Minshew, Nancy; Behrmann, Marlene

2009-01-01

244

Secure Surgical Method for Catheter Placement via the Occipital Artery to Achieve Retrograde Superselective Intra-Arterial Chemotherapy for Advanced Oral Cancer: Alternative to Approach via the Superficial Temporal Artery.  

PubMed

We describe secure surgical method for catheter placement using ultrasonic scalpel via the occipital artery to achieve retrograde superselective intra-arterial chemotherapy for advanced oral cancer, as alternative to approach via the superficial temporal artery. PMID:24822164

Iwai, Toshinori; Fuwa, Nobukazu; Hirota, Makoto; Mitsudo, Kenji; Tohnai, Iwai

2014-06-01

245

A layered network model of sensory cortex  

SciTech Connect

An integrated computational approach to modeling sensory systems which couples realistic layered neural models of sensory cortex and midbrain nuclei to detailed models of the sense organs (e.g., retina or cochlea) is described. The approach is applied to the auditory system. Through an exercise of the model, it is shown that spatial location of sounds may be a natural consequence of the way cochlear response is mapped onto the cortex. 31 refs., 23 figs., 3 tabs.

Travis, B.J.

1986-01-01

246

Food related processes in the insular cortex  

PubMed Central

The insular cortex is a multimodal brain region with regional cytoarchitectonic differences indicating various functional specializations. As a multisensory neural node, the insular cortex integrates perception, emotion, interoceptive awareness, cognition, and gustation. Regarding the latter, predominantly the anterior part of the insular cortex is regarded as the primary taste cortex. In this review, we will specifically focus on the involvement of the insula in food processing and on multimodal integration of food-related items. Influencing factors of insular activation elicited by various foods range from calorie-content to the internal physiologic state, body mass index or eating behavior. Sensory perception of food-related stimuli including seeing, smelling, and tasting elicits increased activation in the anterior and mid-dorsal part of the insular cortex. Apart from the pure sensory gustatory processing, there is also a strong association with the rewarding/hedonic aspects of food items, which is reflected in higher insular activity and stronger connections to other reward-related areas. Interestingly, the processing of food items has been found to elicit different insular activation in lean compared to obese subjects and in patients suffering from an eating disorder (anorexia nervosa (AN), bulimia nervosa (BN)). The knowledge of functional differences in the insular cortex opens up the opportunity for possible noninvasive treatment approaches for obesity and eating disorders. To target brain functions directly, real-time functional magnetic resonance imaging neurofeedback offers a state-of-the-art tool to learn to control the anterior insular cortex activity voluntarily. First evidence indicates that obese adults have an enhanced ability to regulate the anterior insular cortex. PMID:23986683

Frank, Sabine; Kullmann, Stephanie; Veit, Ralf

2013-01-01

247

Multisensory maps in parietal cortex?  

PubMed Central

Parietal cortex has long been known to be a site of sensorimotor integration. Recent findings in humans have shown that it is divided up into a number of small areas somewhat specialized for eye movements, reaching, and hand movements, but also face-related movements (avoidance, eating), lower body movements, and movements coordinating multiple body parts. The majority of these areas contain rough sensory (receptotopic) maps, including a substantial multisensory representation of the lower body and lower visual field immediately medial to face VIP. There is strong evidence for retinotopic remapping in LIP and face-centered remapping in VIP, and weaker evidence for hand-centered remapping. The larger size of the functionally distinct inferior parietal default mode network in humans compared to monkeys results in a superior and medial displacement of middle parietal areas (e.g., the saccade-related LIP's). Multisensory superior parietal areas located anterior to the angular gyrus such as AIP and VIP are less medially displaced relative to macaque monkeys, so that human LIP paradoxically ends up medial to human VIP. PMID:24492077

Sereno, Martin I; Huang, Ruey-Song

2014-01-01

248

Intracranial spectral amplitude dynamics of perceptual suppression in fronto-insular, occipito-temporal, and primary visual cortex  

PubMed Central

If conscious perception requires global information integration across active distant brain networks, how does the loss of conscious perception affect neural processing in these distant networks? Pioneering studies on perceptual suppression (PS) described specific local neural network responses in primary visual cortex, thalamus and lateral prefrontal cortex of the macaque brain. Yet the neural effects of PS have rarely been studied with intracerebral recordings outside these cortices and simultaneously across distant brain areas. Here, we combined (1) a novel experimental paradigm in which we produced a similar perceptual disappearance and also re-appearance by using visual adaptation with transient contrast changes, with (2) electrophysiological observations from human intracranial electrodes sampling wide brain areas. We focused on broadband high-frequency (50–150 Hz, i.e., gamma) and low-frequency (8–24 Hz) neural activity amplitude modulations related to target visibility and invisibility. We report that low-frequency amplitude modulations reflected stimulus visibility in a larger ensemble of recording sites as compared to broadband gamma responses, across distinct brain regions including occipital, temporal and frontal cortices. Moreover, the dynamics of the broadband gamma response distinguished stimulus visibility from stimulus invisibility earlier in anterior insula and inferior frontal gyrus than in temporal regions, suggesting a possible role of fronto-insular cortices in top–down processing for conscious perception. Finally, we report that in primary visual cortex only low-frequency amplitude modulations correlated directly with perceptual status. Interestingly, in this sensory area broadband gamma was not modulated during PS but became positively modulated after 300 ms when stimuli were rendered visible again, suggesting that local networks could be ignited by top–down influences during conscious perception.

Vidal, Juan R.; Perrone-Bertolotti, Marcela; Kahane, Philippe; Lachaux, Jean-Philippe

2015-01-01

249

Elastic instabilities in a layered cerebral cortex: a revised axonal tension model for cortex folding  

NASA Astrophysics Data System (ADS)

We model the elasticity of the cerebral cortex as a layered material with bending energy along the layers and elastic energy between them in both planar and polar geometries. The cortex is also subjected to axons pulling from the underlying white matter. Above a critical threshold force, a ‘flat’ cortex configuration becomes unstable and periodic undulations emerge, i.e. a buckling instability occurs. These undulations may indeed initiate folds in the cortex. We identify analytically the critical force and the critical wavelength of the undulations. Both quantities are physiologically relevant values. Our model is a revised version of the axonal tension model for cortex folding, with our version taking into account the layered structure of the cortex. Moreover, our model draws a connection with another competing model for cortex folding, namely the differential growth-induced buckling model. For the polar geometry, we study the relationship between brain size and the critical force and wavelength to understand why small mice brains exhibit no folds, while larger human brains do, for example. Finally, an estimate of the bending rigidity constant for the cortex can be made based on the critical wavelength.

Manyuhina, O. V.; Mayett, David; Schwarz, J. M.

2014-12-01

250

Neuronal Representations of Stimuli in the Mouth: The Primate Insular Taste Cortex, Orbitofrontal Cortex and Amygdala  

Microsoft Academic Search

The responses of 3687 neurons in the macaque primary taste cortex in the insula\\/frontal operculum, orbitofrontal cortex (OFC) and amygdala to oral sensory stimuli reveals principles of representation in these areas. Information about the taste, texture of what is in the mouth (viscosity, fat texture and grittiness, which reflect somatosensory inputs), temperature and capsaicin is represented in all three areas.

Mikiko Kadohisa; Edmund T. Rolls; Justus V. Verhagen

2005-01-01

251

Premotor cortex mediates perceptual performance.  

PubMed

Articulatory goals have long been proposed to mediate perception. Examples include direct realist and constructivist (analysis by synthesis) theories of speech perception. Although the activity in brain regions involved with action production has been shown to be present during action observation (Mirror Neuron System), the relationship of this activity to perceptual performance has not been clearly demonstrated at the event level. To this end we used functional magnetic resonance imaging fMRI and magnetoencephalography MEG to measure brain activity for correct and incorrect trials of an auditory phonetic identification in noise task. FMRI analysis revealed activity in the premotor cortex including the neighboring frontal opercular part of Broca's area (PMC/Broca's) for both perception and production tasks involving the same phonetic stimuli (potential mirror system site) that was significantly greater for correct over incorrect perceptual identification trials. Time-frequency analysis of single trials conducted over MEG current localized to PMC/Broca's using a hierarchical variational Bayesian source analysis technique revealed significantly greater event-related synchronization ERS and desynchronization ERD for correct over incorrect trials in the alpha, beta, and gamma frequency range prior to and after stimulus presentation. Together, these fMRI and MEG results are consistent with the hypothesis that articulatory processes serve to facilitate perceptual performance, while further dispelling concerns that activity found in ventral PMC/Broca's (mirror system) is merely a product of covert production of the perceived action. The finding of performance predictive activity prior to stimulus onset as well as activity related to task difficulty instead of information available in stimulation are consistent with constructivist and contrary to direct realist theories of perception. PMID:20184959

Callan, Daniel; Callan, Akiko; Gamez, Mario; Sato, Masa-aki; Kawato, Mitsuo

2010-06-01

252

Auditory connections and functions of prefrontal cortex  

PubMed Central

The functional auditory system extends from the ears to the frontal lobes with successively more complex functions occurring as one ascends the hierarchy of the nervous system. Several areas of the frontal lobe receive afferents from both early and late auditory processing regions within the temporal lobe. Afferents from the early part of the cortical auditory system, the auditory belt cortex, which are presumed to carry information regarding auditory features of sounds, project to only a few prefrontal regions and are most dense in the ventrolateral prefrontal cortex (VLPFC). In contrast, projections from the parabelt and the rostral superior temporal gyrus (STG) most likely convey more complex information and target a larger, widespread region of the prefrontal cortex. Neuronal responses reflect these anatomical projections as some prefrontal neurons exhibit responses to features in acoustic stimuli, while other neurons display task-related responses. For example, recording studies in non-human primates indicate that VLPFC is responsive to complex sounds including vocalizations and that VLPFC neurons in area 12/47 respond to sounds with similar acoustic morphology. In contrast, neuronal responses during auditory working memory involve a wider region of the prefrontal cortex. In humans, the frontal lobe is involved in auditory detection, discrimination, and working memory. Past research suggests that dorsal and ventral subregions of the prefrontal cortex process different types of information with dorsal cortex processing spatial/visual information and ventral cortex processing non-spatial/auditory information. While this is apparent in the non-human primate and in some neuroimaging studies, most research in humans indicates that specific task conditions, stimuli or previous experience may bias the recruitment of specific prefrontal regions, suggesting a more flexible role for the frontal lobe during auditory cognition. PMID:25100931

Plakke, Bethany; Romanski, Lizabeth M.

2014-01-01

253

Casagrande, V.A. and J.H. Kaas The afferent, intrinsic, and efferent of visual cortex primates. In: Cerebral Cortex, 10, Primary VisualCortex A. Peters  

E-print Network

Casagrande, V.A. and J.H. Kaas The afferent, intrinsic, and efferent of visual cortex primates. In-259. The Afferent, Intrinsic, and Efferent Connections of Primary Visual Cortex in Primates VIVIEN A, CASAGRANDE vi- sual cortex, area 17 or of primates, can be easily identified in most mammals (Kaas, 1987). (also

Casagrande, Vivien

254

Nicotine and Synaptic Plasticity in Prefrontal Cortex  

NSDL National Science Digital Library

Nicotinic receptor activation enhances working memory and attention. The prefrontal cortex is a key brain area involved in working memory, and plasticity of excitatory synaptic transmission within the cortex is likely an important cellular mechanism of memory. A recent study has explored the cellular and synaptic basis of nicotine’s effects on excitability within the prefrontal cortex. The findings suggest that nicotine enhances inhibitory synaptic inputs to layer V pyramidal cells, which suppresses induction of long-term potentiation (LTP). This inhibitory effect can be overcome by stimulating the pyramidal cells in bursts, which suggests a modification in the signal-to-noise ratio for synaptic input. Thus, the impact of strong stimuli on working memory would be enhanced when combined with nicotinic receptor activity. These findings may lead to novel and more effective treatments for memory disorders.

Daniel S. McGehee (University of Chicago; Department of Anesthesia and Critical Care REV)

2007-08-14

255

Spatial updating in human parietal cortex  

NASA Technical Reports Server (NTRS)

Single neurons in monkey parietal cortex update visual information in conjunction with eye movements. This remapping of stimulus representations is thought to contribute to spatial constancy. We hypothesized that a similar process occurs in human parietal cortex and that we could visualize it with functional MRI. We scanned subjects during a task that involved remapping of visual signals across hemifields. We observed an initial response in the hemisphere contralateral to the visual stimulus, followed by a remapped response in the hemisphere ipsilateral to the stimulus. We ruled out the possibility that this remapped response resulted from either eye movements or visual stimuli alone. Our results demonstrate that updating of visual information occurs in human parietal cortex.

Merriam, Elisha P.; Genovese, Christopher R.; Colby, Carol L.

2003-01-01

256

Auditory motion processing after early blindness  

PubMed Central

Studies showing that occipital cortex responds to auditory and tactile stimuli after early blindness are often interpreted as demonstrating that early blind subjects “see” auditory and tactile stimuli. However, it is not clear whether these occipital responses directly mediate the perception of auditory/tactile stimuli, or simply modulate or augment responses within other sensory areas. We used fMRI pattern classification to categorize the perceived direction of motion for both coherent and ambiguous auditory motion stimuli. In sighted individuals, perceived motion direction was accurately categorized based on neural responses within the planum temporale (PT) and right lateral occipital cortex (LOC). Within early blind individuals, auditory motion decisions for both stimuli were successfully categorized from responses within the human middle temporal complex (hMT+), but not the PT or right LOC. These findings suggest that early blind responses within hMT+ are associated with the perception of auditory motion, and that these responses in hMT+ may usurp some of the functions of nondeprived PT. Thus, our results provide further evidence that blind individuals do indeed “see” auditory motion. PMID:25378368

Jiang, Fang; Stecker, G. Christopher; Fine, Ione

2014-01-01

257

Auditory motion processing after early blindness.  

PubMed

Studies showing that occipital cortex responds to auditory and tactile stimuli after early blindness are often interpreted as demonstrating that early blind subjects "see" auditory and tactile stimuli. However, it is not clear whether these occipital responses directly mediate the perception of auditory/tactile stimuli, or simply modulate or augment responses within other sensory areas. We used fMRI pattern classification to categorize the perceived direction of motion for both coherent and ambiguous auditory motion stimuli. In sighted individuals, perceived motion direction was accurately categorized based on neural responses within the planum temporale (PT) and right lateral occipital cortex (LOC). Within early blind individuals, auditory motion decisions for both stimuli were successfully categorized from responses within the human middle temporal complex (hMT+), but not the PT or right LOC. These findings suggest that early blind responses within hMT+ are associated with the perception of auditory motion, and that these responses in hMT+ may usurp some of the functions of nondeprived PT. Thus, our results provide further evidence that blind individuals do indeed "see" auditory motion. PMID:25378368

Jiang, Fang; Stecker, G Christopher; Fine, Ione

2014-01-01

258

Temperature Instability of ReNu with MoistureLoc: A New Theory to Explain the Worldwide Fusarium Keratitis Epidemic of 2004–2006  

PubMed Central

Purpose A 2006 US Food and Drug Administration (FDA) inspection of Bausch & Lomb’s (B&L's) Greenville, South Carolina, manufacturing site indicated that B&L failed to regulate storage and transport temperatures of their products. The present study investigated the effect of storage temperature on the ability of contact lens solutions to inhibit growth of Fusarium species. Methods Six contact lens solutions were studied: ReNu with MoistureLoc (ReNu ML), ReNu MultiPlus, Complete Moistureplus, AQuify, Clear Care, and OPTI-FREE RepleniSH. Two bottles of each solution were separately stored at room temperature and 60°C for 4 weeks, serially diluted, then tested for their ability to inhibit growth of 11 Fusarium isolates (7 of which were associated with the keratitis epidemic). Results ReNu ML demonstrated the greatest decline in efficacy after 60°C storage. Clear Care and ReNu MultiPlus performed the best. Regarding the keratitis epidemic isolates only, the ReNu ML bottle stored at room temperature allowed growth in 27 of 84 combinations vs 67 of 84 combinations with the 60°C stored bottle. Conclusions When exposed to prolonged temperature elevation, ReNu ML loses its in vitro fungistatic activity to a much greater extent than other products. Improper temperature control of ReNu ML may have contributed to the Fusarium keratitis epidemic of 2004–2006. PMID:19277227

Bullock, John D.; Warwar, Ronald E.; Elder, B. Laurel; Northern, William I.

2008-01-01

259

Improved high-temperature operation of InGaAs/AlGaAs LOC SQW diode lasers by incorporation of short-period superlattice quantum-well barriers  

NASA Astrophysics Data System (ADS)

InGaAs/AlGaAs large optical cavity (LOC) single quantum well (SQW) lasers emitting at 980nm were grown incorporating an AlGaAs/GaAs short-period superlattice layer next to the quantum well in order to improve the carrier confinement and thus high-temperature operation. Symmetric and asymmetric structures have been realized. High characteristic temperatures T0 above 300K between 20#C and 50#C operating temperature were measured for the symmetric structures without deterioration of the internal quantum efficiencies (> 90%) and low intrinsic losses (about 1cm-1). The improvement in the characteristic temperature is mainly attributed to the reduced thermionic emission of the carriers out of the quantum well due to the large effective barrier height of the short-period superlattice. Caused by the incorporation of the short-period superlattice the devices showed a higher series resistance, which could be lowered by switching to asymmetric structures. These asymmetric devices had unchanged high internal quantum efficiencies and low intrinsic losses but lower characteristic temperatures of about 250K.

Wiedmann, Nicolas; Jandeleit, Juergen; Mikulla, Michael; Kiefer, Rudolf; Bihlmann, G.; Poprawe, Reinhart; Weimann, Guenter

2001-07-01

260

Flood risk analysis and adaptive strategy in context of uncertainties: a case study of Nhieu Loc Thi Nghe Basin, Ho Chi Minh City  

NASA Astrophysics Data System (ADS)

The Nhieu Loc - Thi Nghe basin is the most important administrative and business area of Ho Chi Minh City. Due to system complexity of the basin such as the increasing trend of rainfall intensity, (tidal) water level and land subsidence, the simulation of hydrological, hydraulic variables for flooding prediction seems rather not adequate in practical projects. The basin is still highly vulnerable despite of multi-million USD investment for urban drainage improvement projects since the last decade. In this paper, an integrated system analysis in both spatial and temporal aspects based on statistical, GIS and modelling approaches has been conducted in order to: (1) Analyse risks before and after projects, (2) Foresee water-related risk under uncertainties of unfavourable driving factors and (3) Develop a sustainable flood risk management strategy for the basin. The results show that given the framework of risk analysis and adaptive strategy, certain urban developing plans in the basin must be carefully revised and/or checked in order to reduce the highly unexpected loss in the future

Ho, Long-Phi; Chau, Nguyen-Xuan-Quang; Nguyen, Hong-Quan

2013-04-01

261

Neural Representations of Contextual Guidance in Visual Search of Real-World Scenes  

PubMed Central

Exploiting scene context and object– object co-occurrence is critical in guiding eye movements and facilitating visual search, yet the mediating neural mechanisms are unknown. We used functional magnetic resonance imaging while observers searched for target objects in scenes and used multivariate pattern analyses (MVPA) to show that the lateral occipital complex (LOC) can predict the coarse spatial location of observers’ expectations about the likely location of 213 different targets absent from the scenes. In addition, we found weaker but significant representations of context location in an area related to the orienting of attention (intraparietal sulcus, IPS) as well as a region related to scene processing (retrosplenial cortex, RSC). Importantly, the degree of agreement among 100 independent raters about the likely location to contain a target object in a scene correlated with LOC’s ability to predict the contextual location while weaker but significant effects were found in IPS, RSC, the human motion area, and early visual areas (V1, V3v). When contextual information was made irrelevant to observers’ behavioral task, the MVPA analysis of LOC and the other areas’ activity ceased to predict the location of context. Thus, our findings suggest that the likely locations of targets in scenes are represented in various visual areas with LOC playing a key role in contextual guidance during visual search of objects in real scenes. PMID:23637176

Preston, Tim J.; Guo, Fei; Das, Koel; Giesbrecht, Barry; Eckstein, Miguel P.

2014-01-01

262

Analogical Reasoning and Prefrontal Cortex: Evidence for Separable Retrieval  

E-print Network

Analogical Reasoning and Prefrontal Cortex: Evidence for Separable Retrieval and Integration of prefrontal cortex (PFC) subregions to two component processes underlying verbal analogical reasoning that verbal analogical reasoning depends on multiple, PFC-mediated computations. Keywords: analogies, anterior

Badre, David

263

Structure and plasticity potential of neural networks in the cerebral cortex  

NASA Astrophysics Data System (ADS)

In this thesis, we first described a theoretical framework for the analysis of spine remodeling plasticity. We provided a quantitative description of two models of spine remodeling in which the presence of a bouton is either required or not for the formation of a new synapse. We derived expressions for the density of potential synapses in the neuropil, the connectivity fraction, which is the ratio of actual to potential synapses, and the number of structurally different circuits attainable with spine remodeling. We calculated these parameters in mouse occipital cortex, rat CA1, monkey V1, and human temporal cortex. We found that on average a dendritic spine can choose among 4-7 potential targets in rodents and 10-20 potential targets in primates. The neuropil's potential for structural circuit remodeling is highest in rat CA1 (7.1-8.6 bits/mum3) and lowest in monkey V1 (1.3-1.5 bits/mum 3 We next studied the role neuron morphology plays in defining synaptic connectivity. As previously stated it is clear that only pairs of neurons with closely positioned axonal and dendritic branches can be synaptically coupled. For excitatory neurons in the cerebral cortex, ). We also evaluated the lower bound of neuron selectivity in the choice of synaptic partners. Post-synaptic excitatory neurons in rodents make synaptic contacts with more than 21-30% of pre-synaptic axons encountered with new spine growth. Primate neurons appear to be more selective, making synaptic connections with more than 7-15% of encountered axons. We next studied the role neuron morphology plays in defining synaptic connectivity. As previously stated it is clear that only pairs of neurons with closely positioned axonal and dendritic branches can be synaptically coupled. For excitatory neurons in the cerebral cortex, such axo-dendritic oppositions, or potential synapses, must be bridged by dendritic spines to form synaptic connections. To explore the rules by which synaptic connections are formed within the constraints imposed by neuron morphology, we compared the distributions of the numbers of actual and potential synapses between pre- and post-synaptic neurons forming different laminar projections in rat barrel cortex. Quantitative comparison explicitly ruled out the hypothesis that individual synapses between neurons are formed independently of each other. Instead, the data are consistent with a cooperative scheme of synapse formation, where multiple-synaptic connections between neurons are stabilized, while neurons that do not establish a critical number of synapses are not likely to remain synaptically coupled. In the above two projects, analysis of potential synapse numbers played an important role in shaping our understanding of connectivity and structural plasticity. In the third part of this thesis, we shift our attention to the study of the distribution of potential synapse numbers. This distribution is dependent on the details of neuron morphology and it defines synaptic connectivity patterns attainable with spine remodeling. To better understand how the distribution of potential synapse numbers is influenced by the overlap and the shapes of axonal and dendritic arbors, we first analyzed uniform disconnected arbors generated in silico. The resulting distributions are well described by binomial functions. We used a dataset of neurons reconstructed in 3D and generated the potential synapse distributions for neurons of different classes. Quantitative analysis showed that the binomial distribution is a good fit to this data as well. All distributions considered clustered into two categories, inhibitory to inhibitory and excitatory to excitatory projections. We showed that the distributions of potential synapse numbers are universally described by a family of single parameter (p) binomial functions, where p = 0.08, and for the inhibitory and p = 0.19 for the excitatory projections. In the last part of this thesis an attempt is made to incorporate some of the biological constraints we considered thus far, into an artificial neural network model. It became

Fares, Tarec Edmond

264

Neural Substrates of Visual Spatial Coding and Visual Feedback Control for Hand Movements in Allocentric and Target-Directed Tasks  

PubMed Central

Neuropsychological evidence suggests that different brain areas may be involved in movements that are directed at visual targets (e.g., pointing or reaching), and movements that are based on allocentric visual information (e.g., drawing or copying). Here we used fMRI to investigate the neural correlates of these two types of movements in healthy volunteers. Subjects (n?=?14) performed right hand movements in either a target-directed task (moving a cursor to a target dot) or an allocentric task (moving a cursor to reproduce the distance and direction between two distal target dots) with or without visual feedback about their hand movement. Movements were monitored with an MR compatible touch panel. A whole brain analysis revealed that movements in allocentric conditions led to an increase in activity in the fundus of the left intra-parietal sulcus (IPS), in posterior IPS, in bilateral dorsal premotor cortex (PMd), and in the lateral occipital complex (LOC). Visual feedback in both target-directed and allocentric conditions led to an increase in activity in area MT+, superior parietal–occipital cortex (SPOC), and posterior IPS (all bilateral). In addition, we found that visual feedback affected brain activity differently in target-directed as compared to allocentric conditions, particularly in the pre-supplementary motor area, PMd, IPS, and parieto-occipital cortex. Our results, in combination with previous findings, suggest that the LOC is essential for allocentric visual coding and that SPOC is involved in visual feedback control. The differences in brain activity between target-directed and allocentric visual feedback conditions may be related to behavioral differences in visual feedback control. Our results advance the understanding of the visual coordinate frame used by the LOC. In addition, because of the nature of the allocentric task, our results have relevance for the understanding of neural substrates of magnitude estimation and vector coding of movements. PMID:21941474

Thaler, Lore; Goodale, Melvyn A.

2011-01-01

265

Cell counts in cerebral cortex of an autistic patient  

Microsoft Academic Search

Numbers of neurons and glia were counted in the cerebral cortex of one well-documented case of autism and two age and sexmatched controls. Areas in which cell counts were made were primary auditory cortex, Broca's speech area, and auditory association cortex. No consistent differences in cell density were found between the brains of the autistic patient and the control patients.

Paul D. Coleman; John Romano; Lowell Lapham; William Simon

1985-01-01

266

The Role of Parietal Cortex in Verbal Working Memory  

Microsoft Academic Search

Neuroimaging studies of normal subjects and studies of pa- tients with focal lesions implicate regions of parietal cortex in verbal working memory (VWM), yet the precise role of parietal cortex in VWM remains unclear. Some evidence (Paulesu et al., 1993; Awh et al., 1996) suggests that the parietal cortex medi- ates the storage of verbal information, but these studies and

John Jonides; Eric H. Schumacher; Edward E. Smith; Robert A. Koeppe; Edward Awh; Patricia A. Reuter-Lorenz; Christy Marshuetz; Christopher R. Willis

1998-01-01

267

The Discovery of Motor Cortex and its Background  

Microsoft Academic Search

In 1870 Gustav Fritsch and Edvard Hitzig showed that electrical stimulation of the cerebral cortex of a dog produced movements. This was a crucial event in the development of modern neuroscience because it was the first good experimental evidence for a) cerebral cortex involvement in motor function, b) the electrical excitability of the cortex, c) topographic representation in the brain,

Charles G. Gross

2007-01-01

268

Development of functional organization of the pallid bat auditory cortex  

Microsoft Academic Search

The primary auditory cortex is characterized by a tonotopic map and a clustered organization of binaural properties. The factors involved in the development of overlain representation of these two properties are unclear. We addressed this issue in the auditory cortex of the pallid bat. The adult pallid bat cortex contains a systematic relationship between best frequency (BF) and binaural properties.

Khaleel A. Razak; Zoltan M. Fuzessery

2007-01-01

269

Cerebral Cortex doi:10.1093/cercor/bhr228  

E-print Network

of Motor Cortex in Squirrels Dylan F. Cooke1 , Jeffrey Padberg2 , Tony Zahner1,3 and Leah Krubitzer1,3 1 species, rats and mice. Here, we examine the topographic organization of motor cortex in the Eastern gray squirrel (Sciurus carolinensis) and cortical connec- tions of motor cortex in the California ground

Krubitzer, Leah A.

270

Neurophotonics applications to motor cortex research  

PubMed Central

Neurophotonics methods offer powerful ways to access neuronal signals and circuits. We highlight recent advances and current themes in this area, emphasizing tools for mapping, monitoring, and manipulating excitatory projection neurons and their synaptic circuits in mouse motor cortex. PMID:25553337

Suter, Benjamin A.; Yamawaki, Naoki; Borges, Katharine; Li, Xiaojian; Kiritani, Taro; Hooks, Bryan M.; Shepherd, Gordon M. G.

2014-01-01

271

Cognitive Neuroscience Phylogeny of the cortex  

E-print Network

other parts of the brain. Also, the relative growth of the white matter beneath the cortex is far greater than elsewhere in the CNS. The neocortex is largest relative to the rest of the brain in humans with evolution in comparison to the rest of the brain. The process by which the neocortex becomes larger

Bressler, Steven L.

272

The insular cortex: a comparative perspective.  

PubMed

The human insular cortex is involved in a variety of viscerosensory, visceromotor, and interoceptive functions, and plays a role in complex processes such as emotions, music, and language. Across mammals, the insula has considerable morphologic variability. We review the structure and connectivity of the insula in laboratory animals (mouse, domestic cat, macaque monkey), and we present original data on the morphology and cytoarchitecture of insular cortex in less common species including a large carnivore (the Atlantic walrus, Odobenus rosmarus), two artiodactyls (the pigmy hippopotamus, Hexaprotodon liberiensis, and the Western bongo, Tragelaphus eurycerus), two cetaceans (the beluga whale, Delphinapterus leucas, and the minke whale, Balaenoptera acutorostrata), and a sirenian (the Florida manatee, Trichechus manatus latirostris). The insula shows substantial variability in shape, extent, and gyral and sulcal patterns, as well as differences in laminar organization, cellular specialization, and structural association with the claustrum. Our observations reveal that the insular cortex is extremely variable among mammals. These differences could be related to the role exerted by specific and selective pressures on cortical structure during evolution. We conclude that it is not possible to identify a general model of organization for the mammalian insular cortex. PMID:20512368

Butti, Camilla; Hof, Patrick R

2010-06-01

273

The harmonic organization of auditory cortex  

PubMed Central

A fundamental structure of sounds encountered in the natural environment is the harmonicity. Harmonicity is an essential component of music found in all cultures. It is also a unique feature of vocal communication sounds such as human speech and animal vocalizations. Harmonics in sounds are produced by a variety of acoustic generators and reflectors in the natural environment, including vocal apparatuses of humans and animal species as well as music instruments of many types. We live in an acoustic world full of harmonicity. Given the widespread existence of the harmonicity in many aspects of the hearing environment, it is natural to expect that it be reflected in the evolution and development of the auditory systems of both humans and animals, in particular the auditory cortex. Recent neuroimaging and neurophysiology experiments have identified regions of non-primary auditory cortex in humans and non-human primates that have selective responses to harmonic pitches. Accumulating evidence has also shown that neurons in many regions of the auditory cortex exhibit characteristic responses to harmonically related frequencies beyond the range of pitch. Together, these findings suggest that a fundamental organizational principle of auditory cortex is based on the harmonicity. Such an organization likely plays an important role in music processing by the brain. It may also form the basis of the preference for particular classes of music and voice sounds. PMID:24381544

Wang, Xiaoqin

2013-01-01

274

The Piriform Cortex and Human Focal Epilepsy  

PubMed Central

It is surprising that the piriform cortex, when compared to the hippocampus, has been given relatively little significance in human epilepsy. Like the hippocampus, it has a phylogenetically preserved three-layered cortex that is vulnerable to excitotoxic injury, has broad connections to both limbic and cortical areas, and is highly epileptogenic – being critical to the kindling process. The well-known phenomenon of early olfactory auras in temporal lobe epilepsy highlights its clinical relevance in human beings. Perhaps because it is anatomically indistinct and difficult to approach surgically, as it clasps the middle cerebral artery, it has, until now, been understandably neglected. In this review, we emphasize how its unique anatomical and functional properties, as primary olfactory cortex, predispose it to involvement in focal epilepsy. From recent convergent findings in human neuroimaging, clinical epileptology, and experimental animal models, we make the case that the piriform cortex is likely to play a facilitating and amplifying role in human focal epileptogenesis, and may influence progression to epileptic intractability. PMID:25538678

Vaughan, David N.; Jackson, Graeme D.

2014-01-01

275

Motor Cortex Reorganization across the Lifespan  

ERIC Educational Resources Information Center

The brain is a highly dynamic structure with the capacity for profound structural and functional change. Such neural plasticity has been well characterized within motor cortex and is believed to represent one of the neural mechanisms for acquiring and modifying motor behaviors. A number of behavioral and neural signals have been identified that…

Plowman, Emily K.; Kleim, Jeffrey A.

2010-01-01

276

Theory of Orientation Tuning in Visual Cortex  

Microsoft Academic Search

The role of intrinsic cortical connections in processing sensory input and in generating behavioral output is poorly understood. We have examined this issue in the context of the tuning of neuronal responses in cortex to the orientation of a visual stimulus. We analytically study a simple network model that incorporates both orientation-selective input from the lateral geniculate nucleus and orientation-specific

R. Ben-Yishai; R. Lev Bar-Or; H. Sompolinsky

1995-01-01

277

Attentional modulation in human primary olfactory cortex  

Microsoft Academic Search

Central to the concept of attention is the fact that identical stimuli can be processed in different ways. In olfaction, attention may designate the identical flow of air through the nose as either respiration or olfactory exploration. Here we have used functional magnetic resonance imaging (fMRI) to probe this attentional mechanism in primary olfactory cortex (POC). We report a dissociation

Moustafa Bensafi; Jess Porter; Joel Mainland; Brad Johnson; Elizabeth Bremner; Christina Telles; Rehan Khan; Christina Zelano; Noam Sobel

2004-01-01

278

Finger Somatotopy in Human Motor Cortex  

Microsoft Academic Search

Although qualitative reports about somatotopic representation of fingers in the human motor cortex exist, up to now no study could provide clear statistical evidence. The goal of the present study was to reinvestigate finger motor somatotopy by means of a thorough investigation of standardized movements of the index and little finger of the right hand. Using high resolution fMRI at

Roland Beisteiner; Christian Windischberger; Rupert Lanzenberger; Vinod Edward; Ross Cunnington; Marcus Erdler; Andreas Gartus; Bernhard Streibl; Ewald Moser; Lueder Deecke

2001-01-01

279

Cerebellar Cortex: Computation by Extrasynaptic Inhibition?  

E-print Network

receptors for the inhibitory neurotransmitter -amino butyric acid (GABA) has now led to some fundamental cortex, inhibitory inputs to granule cells exhibit prominent tonic and spillover compo- nents resulting. The glomeruli also contain GABAergic synapses that inhibitory Golgi cells make with the granule cells

De Schutter, Erik

280

The post-occipital spinal venous sinus of the Nile crocodile Crocodylus niloticus: its anatomy and use for blood sample collection and intravenous infusions.  

PubMed

The post-occipital sinus of the spinal vein is often used for the collection of blood samples from crocodilians. Although this sampling method has been reported for several crocodilian species, the technique and associated anatomy has not been described in detail in any crocodilian, including the Nile crocodile (Crocodylus niloticus). The anatomy of the cranial neck region was investigated macroscopically, microscopically, radiographically and by means of computed tomography. Latex was injected into the spinal vein and spinal venous sinus of crocodiles to visualise the regional vasculature. The spinal vein ran within the vertebral canal, dorsal to and closely associated with the spinal cord and changed into a venous sinus cranially in the post-occipital region. For blood collection, the spinal venous sinus was accessed through the interarcuate space between the atlas and axis (C1 and C2) by inserting a needle angled just off the perpendicular in the midline through the craniodorsal cervical skin, just cranial to the cranial borders of the first cervical osteoderms. The most convenient method of blood collection was with a syringe and hypodermic needle. In addition, the suitability of the spinal venous sinus for intravenous injections and infusions in live crocodiles was evaluated. The internal diameter of the commercial human epidural catheters used during these investigations was relatively small, resulting in very slow infusion rates. Care should be taken not to puncture the spinal cord or to lacerate the blood vessel wall using this route for blood collection or intravenous infusions. PMID:24831995

Myburgh, Jan G; Kirberger, Robert M; Steyl, Johan C A; Soley, John T; Booyse, Dirk G; Huchzermeyer, Fritz W; Lowers, Russel H; Guillette, Louis J

2014-01-01

281

A new method for automated high-dimensional lesion segmentation evaluated in vascular injury and applied to the human occipital lobe  

PubMed Central

Making robust inferences about the functional neuroanatomy of the brain is critically dependent on experimental techniques that examine the consequences of focal loss of brain function. Unfortunately, the use of the most comprehensive such technique—lesion-function mapping—is complicated by the need for time-consuming and subjective manual delineation of the lesions, greatly limiting the practicability of the approach. Here we exploit a recently-described general measure of statistical anomaly, zeta, to devise a fully-automated, high-dimensional algorithm for identifying the parameters of lesions within a brain image given a reference set of normal brain images. We proceed to evaluate such an algorithm in the context of diffusion-weighted imaging of the commonest type of lesion used in neuroanatomical research: ischaemic damage. Summary performance metrics exceed those previously published for diffusion-weighted imaging and approach the current gold standard—manual segmentation—sufficiently closely for fully-automated lesion-mapping studies to become a possibility. We apply the new method to 435 unselected images of patients with ischaemic stroke to derive a probabilistic map of the pattern of damage in lesions involving the occipital lobe, demonstrating the variation of anatomical resolvability of occipital areas so as to guide future lesion-function studies of the region. PMID:23347558

Mah, Yee-Haur; Jager, Rolf; Kennard, Christopher; Husain, Masud; Nachev, Parashkev

2014-01-01

282

Modulation of Alpha Activity in the Parieto-occipital Area by Distractors during a Visuospatial Working Memory Task: A Magnetoencephalographic Study.  

PubMed

Oscillatory brain activity is known to play an essential role in information processing in working memory. Recent studies have indicated that alpha activity (8-13 Hz) in the parieto-occipital area is strongly modulated in working memory tasks. However, the function of alpha activity in working memory is open to several interpretations, such that alpha activity may be a direct neural correlate of information processing in working memory or may reflect disengagement from information processing in other brain areas. To examine the functional contribution of alpha activity to visuospatial working memory, we introduced visuospatial distractors during a delay period and examined neural activity from the whole brain using magnetoencephalography. The strength of event-related alpha activity was estimated using the temporal spectral evolution (TSE) method. The results were as follows: (1) an increase of alpha activity during the delay period as indicated by elevated TSE curves was observed in parieto-occipital sensors in both the working memory task and a control task that did not require working memory; and (2) an increase of alpha activity during the delay period was not observed when distractors were presented, although TSE curves were constructed only from correct trials. These results indicate that the increase of alpha activity is not directly related to information processing in working memory but rather reflects the disengagement of attention from the visuospatial input. PMID:25244117

Ichihara-Takeda, Satoe; Yazawa, Shogo; Murahara, Takashi; Toyoshima, Takanobu; Shinozaki, Jun; Ishiguro, Masanori; Shiraishi, Hideaki; Ikeda, Nozomu; Matsuyama, Kiyoji; Funahashi, Shintaro; Nagamine, Takashi

2015-03-01

283

Quantitative Analyses of Postmortem Heat Shock Protein mRNA Profiles in the Occipital Lobes of Human Cerebral Cortices: Implications in Cause of Death  

PubMed Central

Quantitative RNA analyses of autopsy materials to diagnose the cause and mechanism of death are challenging tasks in the field of forensic molecular pathology. Alterations in mRNA profiles can be induced by cellular stress responses during supravital reactions as well as by lethal insults at the time of death. Here, we demonstrate that several gene transcripts encoding heat shock proteins (HSPs), a gene family primarily responsible for cellular stress responses, can be differentially expressed in the occipital region of postmortem human cerebral cortices with regard to the cause of death. HSPA2 mRNA levels were higher in subjects who died due to mechanical asphyxiation (ASP), compared with those who died by traumatic injury (TI). By contrast, HSPA7 and A13 gene transcripts were much higher in the TI group than in the ASP and sudden cardiac death (SCD) groups. More importantly, relative abundances between such HSP mRNA species exhibit a stronger correlation to, and thus provide more discriminative information on, the death process than does routine normalization to a housekeeping gene. Therefore, the present study proposes alterations in HSP mRNA composition in the occipital lobe as potential forensic biological markers, which may implicate the cause and process of death. PMID:23135635

Chung, Ukhee; Seo, Joong-Seok; Kim, Yu-Hoon; Son, Gi Hoon; Hwang, Juck-Joon

2012-01-01

284

Psychostimulant treatment and the developing cortex in Attention-Deficit/Hyperactivity Disorder  

PubMed Central

Objective While there has been considerable concern over possible adverse effects of psychostimulants on brain development, no prospective study has examined this issue. We determined whether psychostimulant drug treatment for Attention-deficit/Hyperactivity Disorder (ADHD) was associated with differences in the development of the cerebral cortex during adolescence. Method Change in cortical thickness was estimated from two neuroanatomic magnetic resonance images on 43 subjects with DSM-IV ADHD (mean age at first scan 12.5 years (SD 2.1); second scan 16.4 (SD2.4). Nineteen subjects not treated with psychostimulants between the scans were compared with an age matched group of 24 subjects who received psychostimulants. Further comparison was made against a template derived from 620 scans on 294 typically developing children. Results Treatment defined ADHD groups differed in rate of change of cortical thickness of the right motor strip, the left middle/inferior frontal gyrus; and the right parieto-occipital region (t(41)=2.8, p=0.009) The group difference was due to more rapid cortical thinning in the group ‘off’ psychostimulants (mean cortical thinning of 0.16mm/year, SD 0.17) compared to the ‘on’ group (thinning of 0.03 mm/year, SD 0.11). Comparison against a typically developing cohort showed the cortical thinning in the ‘off’ psychostimulants group was in excess of age appropriate rates. Treatment groups did not differ however in clinical outcome. Conclusions There was no evidence that psychostimulants were associated with ‘slowing’ of overall growth of the cortical mantle. PMID:18794206

Shaw, Philip; Sharp, Wendy; Morrison, Meaghan; Eckstrand, Kristen; Greenstein, Deanna; Clasen, Liv; Evans, Alan; Rapoport, Judith L.

2009-01-01

285

Involvement of the superior temporal cortex in action execution and action observation.  

PubMed

The role of the superior temporal sulcus (STs) in action execution and action observation remains unsettled. In an attempt to shed more light on the matter, we used the quantitative method of (14)C-deoxyglucose to reveal changes in activity, in the cortex of STs and adjacent inferior and superior temporal convexities of monkeys, elicited by reaching-to-grasp in the light or in the dark and by observation of the same action executed by an external agent. We found that observation of reaching-to-grasp activated the components of the superior temporal polysensory area [STP; including temporo-parieto-occipital association area (TPO), PGa, and IPa], the motion complex [including medial superior temporal area (MST), fundus of superior temporal area (FST), and dorsal and ventral parts of the middle temporal area (MTd and MTv, respectively)], and area TS2. A significant part of most of these activations was associated with observation of the goal-directed action, and a smaller part with the perception of arm-motion. Execution of reaching-to-grasp in the light-activated areas TS2, STP partially and marginally, and MT compared with the fixation but not to the arm-motion control. Consequently, MT-activation is associated with the arm-motion and not with the purposeful action. Finally, reaching-to-grasp in complete darkness activated all components of the motion complex. Conclusively, lack of visibility of our own actions involves the motion complex, whereas observation of others' actions engages area STP and the motion complex. Our previous and present findings together suggest that sensory effects are interweaved with motor commands in integrated action codes, and observation of an action or its execution in complete darkness triggers the retrieval of the visual representation of the action. PMID:24990920

Kilintari, Marina; Raos, Vassilis; Savaki, Helen E

2014-07-01

286

FMRI analysis of contrast polarity processing in face-selective cortex in humans and monkeys  

PubMed Central

Recognition is strongly impaired when the normal contrast polarity of faces is reversed. For instance, otherwise-familiar faces become very difficult to recognize when viewed as photographic negatives. Here, we used fMRI to demonstrate related properties in visual cortex: 1) fMRI responses in the human Fusiform Face Area (FFA) decreased strongly (26%) to contrast-reversed faces across a wide range of contrast levels (5.3-100% RMS contrast), in all subjects tested. In a whole brain analysis, this contrast polarity bias was largely confined to the Fusiform Face Area (FFA; p < 0.0001), with possible involvement of a left occipital face-selective region. 2) It is known that reversing facial contrast affects three image properties in parallel (absorbance, shading, and specular reflection). Here, comparison of FFA responses to those in V1 suggests that the contrast polarity bias is produced in FFA only when all three component properties were reversed simultaneously, which suggests a prominent non-linearity in FFA processing. 3) Across a wide range (180°) of illumination source angles, 3D face shapes without texture produced response constancy in FFA, without a contrast polarity bias. 4) Consistent with psychophysics, analogous fMRI biases for normal contrast polarity were not produced by non-face objects, with image statistics similar to the face stimuli. 5) Using fMRI, we also demonstrated a contrast polarity bias in awake behaving macaque monkeys, in the cortical region considered homologous to human FFA. Thus common cortical mechanisms may underlie facial contrast processing across ~ 25 million years of primate evolution. PMID:23518007

Yue, Xiaomin; Nasr, Shahin; Devaney, Kathryn J.; Holt, Daphne J.; Tootell, Roger B.H.

2013-01-01

287

Role of the dorsal premotor cortex in rhythmic auditory-motor entrainment: a perturbational approach by rTMS.  

PubMed

Synchronization of body movements to an external beat is a universal human ability, which has also been recently documented in nonhuman species. The neural substrates of this rhythmic motor entrainment are still under investigation. Correlational neuroimaging data suggest an involvement of the dorsal premotor cortex (dPMC) and the supplementary motor area (SMA). In 14 healthy volunteers, we more specifically investigated the neural network underlying this phenomenon using a causal approach by an established 1-Hz repetitive transcranial magnetic stimulation (rTMS) protocol, which produces a focal suppression of cortical excitability outlasting the stimulation period. Synchronization accuracy between rhythmic cues and right index finger tapping, as measured by the mean time lag (asynchrony) between motor and auditory events, was significantly affected when the right dPMC function was transiently perturbed by "off-line" focal rTMS, whereas the reproduction of the rhythmic sequence per se (inter-tap-interval) was spared. This approach affected metrical rhythms of different complexity, but not non-metrical or isochronous sequences. Conversely, no change in auditory-motor synchronization was observed with rTMS of the SMA, of the left dPMC or over a control site (midline occipital area). Our data strongly support the view that the right dPMC is crucial for rhythmic auditory-motor synchronization in humans. PMID:23236203

Giovannelli, Fabio; Innocenti, Iglis; Rossi, Simone; Borgheresi, Alessandra; Ragazzoni, Aldo; Zaccara, Gaetano; Viggiano, Maria Pia; Cincotta, Massimo

2014-04-01

288

Functional connectivity of the cortex of term and preterm infants and infants with Down's syndrome.  

PubMed

Near-infrared spectroscopy (NIRS) imaging studies have revealed the functional development of the human brain in early infancy. By measuring spontaneous fluctuations in cerebral blood oxygenation with NIRS, we can examine the developmental status of the functional connectivity of networks in the cortex. However, it has not been clarified whether premature delivery and/or chromosomal abnormalities affect the development of the functional connectivity of the cortex. In the current study, we investigated the spontaneous brain activity of sleeping infants who were admitted to a neonatal intensive care unit at term age. We classified them into the 3 following infant groups: (i) term-or-late-preterm, (ii) early-preterm, and (iii) Down's syndrome (DS). We used multichannel NIRS to measure the spontaneous changes in oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) at 10 measurement channels, which covered the frontal, temporal, and occipital regions. In order to reveal the functional connectivity of the cortical networks, we calculated the temporal correlations of the time-course signals among all of the pairs of measurement channels. The functional connectivity was classified into the 4 following types: (i) short-range, (ii) contralateral-transverse, (iii) ipsilateral-longitudinal, and (iv) control. In order to examine whether the local properties of hemodynamics reflected any pathological conditions, we calculated the phase differences between the oxy- and deoxy-Hb time-course signals in the 3 groups. The statistical analyses of the functional connectivity data showed main effects of group and the types of connectivity. For the group effect, the mean functional connectivity of the infants in the term-or-late-preterm group did not differ from that in the early-preterm group, and the mean functional connectivity of the infants in the DS group was lower than that in the other 2 groups. For the effect of types of connectivity, short-range connectivity was highest compared to any of the other types of connectivity, and the second highest connectivity was the contralateral-transverse one. The phase differences between the oxy- and deoxy-Hb changes showed that there were significant differences between the DS group and the other 2 groups. Our findings suggested that the development of the functional connectivity of cortical networks did not differ between term-or-late-preterm infants and early-preterm infants around term-equivalent ages, while DS infants had alterations in their functional connectivity development and local hemodynamics at term age. The highest short-range connectivity and the second highest contralateral-transverse connectivity suggested that the precursors for the basic cortical networks of functional connectivity were present at term age. PMID:23631984

Imai, Makiko; Watanabe, Hama; Yasui, Kojiro; Kimura, Yuki; Shitara, Yoshihiko; Tsuchida, Shinya; Takahashi, Naoto; Taga, Gentaro

2014-01-15

289

Anterior Insular Cortex and Emotional Awareness  

PubMed Central

This paper reviews the foundation for a role of the human anterior insular cortex (AIC) in emotional awareness, defined as the conscious experience of emotions. We first introduce the neuroanatomical features of AIC and existing findings on emotional awareness. Using empathy, the awareness and understanding of other people’s emotional states, as a test case, we then present evidence to demonstrate: 1) AIC and anterior cingulate cortex (ACC) are commonly coactivated as revealed by a meta-analysis, 2) AIC is functionally dissociable from ACC, 3) AIC integrates stimulus-driven and top-down information, and 4) AIC is necessary for emotional awareness. We propose a model in which AIC serves two major functions: integrating bottom-up interoceptive signals with top-down predictions to generate a current awareness state and providing descending predictions to visceral systems that provide a point of reference for autonomic reflexes. We argue that AIC is critical and necessary for emotional awareness. PMID:23749500

Gu, Xiaosi; Hof, Patrick R.; Friston, Karl J.; Fan, Jin

2014-01-01

290

Parietal cortex area 5 and visuomotor behavior.  

PubMed

For years, area 5 of the parietal cortex was thought to be a somatic sensory structure. This view was challenged by recordings during active movements in alert behaving monkeys, which suggested that area 5 also contained populations of neurons that issued nonspecific, context-dependent "commands" about intended motor responses. Recent studies have revealed that area 5 generates a representation of the spatiotemporal form of arm movements and arm postures, although the parameter space of that representation is still controversial. They also showed that many area 5 cells are recipient to centrally generated signals about the motor relevance of external sensory signals. These new results support the hypothesis that area 5 contributes to the sensorimotor guidance of motor behavior, by contributing to the somatomotor and visuomotor transformations presumed to underlie visually guided behavior. However, area 5 appears to be less directly implicated than the premotor cortex in the process of selecting the nature of the response to instructional signals. PMID:8828894

Kalaska, J F

1996-04-01

291

Schrödinger wave holography in brain cortex  

NASA Astrophysics Data System (ADS)

An explanation for electroencephalogram (EEG) activity is proposed. Under suitable assumptions concerning the active transport of Na+-K+ ions through the glial tissue in brain cortex, a Schrödinger-like equation for ion displacement waves is easily obtained. Theoretical wave-propagator diagrams are in perfect agreement with experimental stimulus-response patterns directly recorded on brain cortexes. Conditions for effective Schrödinger wave holography and its greater efficiency in comparison with D'Alembert wave holography, are briefly discussed. The need for ``reference-wave'' recruiting device and for a receptor arrangement, for holographic information recovery in proximity of the signal sources, lead to brain-organization models in good agreement with diagrams reported by neurophysiologists.

Nobili, Renato

1985-12-01

292

Parietal cortex signals come unstuck in time.  

PubMed

Humans and other animals are surprisingly adept at estimating the duration of temporal intervals, even without the use of watches and clocks. This ability is typically studied in the lab by asking observers to indicate their estimate of the time between two external sensory events. The results of such studies confirm that humans can accurately estimate durations on a variety of time scales. Although many brain areas are thought to contribute to the representation of elapsed time, recent neurophysiological studies have linked the parietal cortex in particular to the perception of sub-second time intervals. In this Primer, we describe previous work on parietal cortex and time perception, and we highlight the findings of a study published in this issue of PLOS Biology, in which Schneider and Ghose characterize single-neuron responses during performance of a novel "Temporal Production" task. During temporal production, the observer must track the passage of time without anticipating any external sensory event, and it appears that the parietal cortex may use a unique strategy to support this type of measurement. PMID:23118615

Cook, Erik P; Pack, Christopher C

2012-01-01

293

Parietal Cortex Signals Come Unstuck in Time  

PubMed Central

Humans and other animals are surprisingly adept at estimating the duration of temporal intervals, even without the use of watches and clocks. This ability is typically studied in the lab by asking observers to indicate their estimate of the time between two external sensory events. The results of such studies confirm that humans can accurately estimate durations on a variety of time scales. Although many brain areas are thought to contribute to the representation of elapsed time, recent neurophysiological studies have linked the parietal cortex in particular to the perception of sub-second time intervals. In this Primer, we describe previous work on parietal cortex and time perception, and we highlight the findings of a study published in this issue of PLOS Biology, in which Schneider and Ghose [1] characterize single-neuron responses during performance of a novel “Temporal Production” task. During temporal production, the observer must track the passage of time without anticipating any external sensory event, and it appears that the parietal cortex may use a unique strategy to support this type of measurement. PMID:23118615

Cook, Erik P.; Pack, Christopher C.

2012-01-01

294

Amodal Processing in Human Prefrontal Cortex  

PubMed Central

Information enters the cortex via modality-specific sensory regions, whereas actions are produced by modality-specific motor regions. Intervening central stages of information processing map sensation to behavior. Humans perform this central processing in a flexible, abstract manner such that sensory information in any modality can lead to response via any motor system. Cognitive theories account for such flexible behavior by positing amodal central information processing (e.g., “central executive,” Baddeley and Hitch, 1974; “supervisory attentional system,” Norman and Shallice, 1986; “response selection bottleneck,” Pashler, 1994). However, the extent to which brain regions embodying central mechanisms of information processing are amodal remains unclear. Here we apply multivariate pattern analysis to functional magnetic resonance imaging (fMRI) data to compare response selection, a cognitive process widely believed to recruit an amodal central resource across sensory and motor modalities. We show that most frontal and parietal cortical areas known to activate across a wide variety of tasks code modality, casting doubt on the notion that these regions embody a central processor devoid of modality representation. Importantly, regions of anterior insula and dorsolateral prefrontal cortex consistently failed to code modality across four experiments. However, these areas code at least one other task dimension, process (instantiated as response selection vs response execution), ensuring that failure to find coding of modality is not driven by insensitivity of multivariate pattern analysis in these regions. We conclude that abstract encoding of information modality is primarily a property of subregions of the prefrontal cortex. PMID:23843526

Dux, Paul E.; Tombu, Michael N.; Asplund, Christopher L.; Marois, René

2013-01-01

295

Human sensorimotor cortex represents conflicting visuomotor mappings.  

PubMed

Behavioral studies have shown that humans can adapt to conflicting sensorimotor mappings that cause interference after intensive training. While previous research works indicate the involvement of distinct brain regions for different types of motor learning (e.g., kinematics vs dynamics), the neural mechanisms underlying joint adaptation to conflicting mappings within the same type of perturbation (e.g., different angles of visuomotor rotation) remain unclear. To reveal the neural substrates that represent multiple sensorimotor mappings, we examined whether different mappings could be classified with multivoxel activity patterns of functional magnetic resonance imaging data. Participants simultaneously adapted to opposite rotational perturbations (+90° and - 90°) during visuomotor tracking. To dissociate differences in movement kinematics with rotation types, we used two distinct patterns of target motion and tested generalization of the classifier between different combinations of rotation and motion types. Results showed that the rotation types were classified significantly above chance using activities in the primary sensorimotor cortex and the supplementary motor area, despite no significant difference in averaged signal amplitudes within the region. In contrast, low-level sensorimotor components, including tracking error and movement speed, were best classified using activities of the early visual cortex. Our results reveal that the sensorimotor cortex represents different visuomotor mappings, which permits joint learning and switching between conflicting sensorimotor skills. PMID:23575839

Ogawa, Kenji; Imamizu, Hiroshi

2013-04-10

296

Orbitofrontal cortex mediates inhibition of return.  

PubMed

Recent accounts have proposed that orbitofrontal cerebral cortex mediates the control of behavior based on emotional feedback and its somatic correlates. Here, we describe the performance of a patient with circumscribed damage to orbitofrontal cortex during a task that requires switching between sensory-motor mappings, contingent on the occurrence of positive and negative reward feedbacks. In this test, normal subjects and other patients with prefrontal damage show an increase in latencies for eye movements towards locations at which a negative feedback was presented on the preceding trial. In contrast, our patient does not show this reward-dependent inhibition of return effect on saccades. She was also found to make an increased rate of ocular refixations during visual search and used a disorganized search strategy in a token foraging task. These findings suggest that orbital regions of the prefrontal cortex mediate an inhibitory effect on actions directed towards locations that have been subject to negative reinforcement. Further, this mechanism seems to play a role in controlling natural search and foraging behavior. PMID:12207988

Hodgson, T L; Mort, D; Chamberlain, M M; Hutton, S B; O'Neill, K S; Kennard, C

2002-01-01

297

Chiari I Malformation Associated with Atlanto-Occipital Assimilation Presenting as Orthopnea and Cough Syncope: A Case Report and Review of Literature  

PubMed Central

Although it is not uncommon for patients with Chiari I malformations to present with respiratory complaints, cough syncope is a rare presenting symptom. We report an adult patient who harbored both a Chiari I malformation and atlanto-occipital assimilation who complained of cough syncope, orthopnea, and central sleep apnea. The patient underwent decompressive craniectomy of the posterior fossa and cervical level 2 laminectomy. However, due to a possible initial underappreciation of the profound narrowing of the foramen magnum as a result of these concomitant pathologies, the patient may have had continued impaired cerebrospinal fluid flow, leading to a symptomatic pseudomeningocele and requiring a more extensive decompression that included a cervical level 3 laminectomy as well as a temporary lumbar drain. On 2-year follow-up, he has remained asymptomatic. PMID:25083365

Mangubat, Erwin Zeta; Wilson, Tom; Mitchell, Brian A.; Byrne, Richard W.

2013-01-01

298

Instrumented reduction of a fixed C1–2 subluxation using occipital and C2/C3 fixation: A case report  

PubMed Central

Background Different strategies exist for reduction of the cervical spine. Placement of C1 lateral mass screws is a powerful technique but may be impossible in a degenerative or revision setting. We report the open, posterior-only, and instrumented reduction of a fixed C1–2 subluxation using occipital and C2/C3 fixation. The patient had rheumatoid arthritis and had undergone previous surgery of the cervical spine. Methods We performed a retrospective chart review and focused appraisal of the literature. Results Satisfactory reduction was achieved with this infrequently reported technique. Conclusions/Level of Evidence Spine surgeons may consider the described procedure a viable treatment alternative in problematic subluxations of the cervical spine. Level V.

Meals, Clifton; Harrison, Rachel; Yu, Warren; O'Brien, Joseph

2013-01-01

299

Variations in ncRNA gene LOC284889 and MIF-794CATT repeats are associated with malaria susceptibility in Indian populations  

PubMed Central

Background There are increasing evidences on the role of non-coding RNA (ncRNA) as key regulator of cellular homeostasis. LOC284889 is an uncharacterized ncRNA gene on reverse strand to MIF mapped to 22q11.23. MIF, a lymphokine, regulates innate immune response by up-regulating the expression of TLR4, suppressing the p53 activity and has been shown to be involved in malaria pathogenesis. Methods In this study, the possible effect of MIF variations on malaria susceptibility was investigated by re-sequencing the complete MIF gene along with 1 kb each of 5? and 3? region in 425 individuals from malaria endemic regions of the Orissa and Chhattisgarh states of India. The subjects comprised of 160 cases of severe malaria, 101 of mild malaria and 164 ethnically matched asymptomatic controls. Data were statistically compared between cases and controls for their possible association with Plasmodium falciparum malarial outcome. Results It is the first study, which shows that the allele A (rs34383331T?>?A) in ncRNA is significantly associated with increased risk to P. falciparum malaria [severe: OR?=?2.08, p?=?0.002 and mild: OR?=?2.09, P?=?0.005]. In addition, it has been observed that the higher MIF-794CATT repeats (>5) increases malaria risk (OR?=?1.61, p?=?0.01). Further, diplotype (MIF-794CATT and rs34383331T?>?A) 5 T confers protection to severe malaria (OR?=?0.55, p?=?0.002) while 6A (OR?=?3.07, p?=?0.001) increases malaria risk. Conclusions These findings support the involvement of ncRNA in malarial pathogenesis and further emphasize the complex genetic regulation of malaria outcome. In addition, the study shows that the higher MIF-794CATT repeats (>5) is a risk factor for severe malaria. The study would help in identifying people who are at higher risk to malaria and adapt strategies for prevention and treatment. PMID:24066864

2013-01-01

300

Connectivity Changes Underlying Neurofeedback Training of Visual Cortex Activity  

PubMed Central

Neurofeedback based on real-time functional magnetic resonance imaging (fMRI) is a new approach that allows training of voluntary control over regionally specific brain activity. However, the neural basis of successful neurofeedback learning remains poorly understood. Here, we assessed changes in effective brain connectivity associated with neurofeedback training of visual cortex activity. Using dynamic causal modeling (DCM), we found that training participants to increase visual cortex activity was associated with increased effective connectivity between the visual cortex and the superior parietal lobe. Specifically, participants who learned to control activity in their visual cortex showed increased top-down control of the superior parietal lobe over the visual cortex, and at the same time reduced bottom-up processing. These results are consistent with efficient employment of top-down visual attention and imagery, which were the cognitive strategies used by participants to increase their visual cortex activity. PMID:24609065

Scharnowski, Frank; Rosa, Maria Joao; Golestani, Narly; Hutton, Chloe; Josephs, Oliver

2014-01-01

301

The Hyper-Cortex of Human Collective-Intelligence Systems  

Microsoft Academic Search

Individual-intelligence research, from a neurological perspective, describes the cortex as a medium for performing conceptual abstraction and specification. This idea has been used to explain how motor-cortex regions responsible for different behavioral modalities such as writing and speaking can express the same general concept represented in the cortex. For example, the concept of a dog, abstractly represented in the higher-layers

Marko A. Rodriguez

2005-01-01

302

Fetal Brain Transplants: Reduction of Cognitive Deficits in Rats with Frontal Cortex Lesions  

Microsoft Academic Search

Frontal cortex and cerebellar tissue from fetal rats was implanted into the damaged frontal cortex of adults. Cognitive deficits in spatial alternation learning that follow bilateral destruction of medial frontal cortex were reduced in rats with frontal cortex implants but not in those with implants of cerebellum. Histological evaluation showed that connections were made between the frontal cortex implants and

Randy Labbe; Arthur Firl; Elliott J. Mufson; Donald G. Stein

1983-01-01

303

Individual variation in human motor-sensory (rolandic) cortex.  

PubMed

Eloquent cortex is generally identified using a variety of techniques including direct electrical stimulation to identify motor-sensory, language, and memory cortex and somatosensory evoked potentials to identify motor-sensory cortex. It is important that these areas of cortex be identified so as to prevent damage during the course of neurosurgical procedures. Seventy epilepsy patients undergoing evaluation for epilepsy surgery with chronically implanted subdural grids were retrospectively studied using both somatosensory evoked potentials and direct electrical stimulation. Direct electrical stimulation of motor-sensory cortex elicited responses over a larger area than did somatosensory evoked potentials. A great deal of individual variation was identified using both techniques. The results presented here support previous conclusions that the concept of homunculus somatotopy (point to point representation) of the motor-sensory cortex be abandoned and that of functional mosaicism of the motor-sensory cortex replace the earlier model. The individual variation found in the human motor-sensory cortex will require a continuation of "brain mapping" to identify eloquent cortex so that these vital areas will be spared during neocortical neurosurgical procedures. PMID:17545834

Farrell, Donald F; Burbank, Nicole; Lettich, Ettore; Ojemann, George A

2007-06-01

304

Oral structure representation in human somatosensory cortex.  

PubMed

To clarify the topography of the areas representing whole intraoral structures and elucidate bilateral neuronal projection to those areas in the primary somatosensory (S1) cortex, we recorded somatosensory-evoked magnetic fields (SEFs), which reflect the earliest cortical responses to pure tactile stimulation, using magnetoencephalography and a piezo-driven tactile stimulation device. Subjects consisted of 10 healthy male adults. Following tactile stimulation of 6 sites on the oral mucosa (inferior/superior buccal mucosa, posterior/anterior tongue mucosa, and upper/lower lip mucosa), SEFs with a peak latency of 15 ms (1M) were identified bilaterally. In contrast, SEFs with a peak latency of 30 ms following right index finger tactile stimulation were identified only in the contralateral hemisphere. Equivalent current dipoles (ECDs) generating 15 ms components were found along the posterior wall of the central sulcus, bilaterally. The ECD locations for oral mucosa-representing areas were located inferiorly to those for the index finger, with the following pattern of organization from top to bottom along the central sulcus: index finger, upper or lower lip, anterior or posterior tongue and superior or inferior buccal mucosa, with a wide distribution, covering 30% of the S1 cortex. Source strength for 1M in the ipsilateral hemisphere was weaker than that in the contralateral hemisphere. These results clearly indicate that sensory afferents innervating the intraoral region project to both the contralateral and ipsilateral 3b areas via the trigeminothalamic tract, where contralateral projection is predominant. The results clarify the intraoral structure-representing areas in the S1 cortex, adding those areas to the classical "sensory homunculus". PMID:18672075

Tamura, Yohei; Shibukawa, Yoshiyuki; Shintani, Masuro; Kaneko, Yuzuru; Ichinohe, Tatsuya

2008-10-15

305

Apraxia, pantomime and the parietal cortex  

PubMed Central

Apraxia, a disorder of higher motor cognition, is a frequent and outcome-relevant sequel of left hemispheric stroke. Deficient pantomiming of object use constitutes a key symptom of apraxia and is assessed when testing for apraxia. To date the neural basis of pantomime remains controversial. We here review the literature and perform a meta-analysis of the relevant structural and functional imaging (fMRI/PET) studies. Based on a systematic literature search, 10 structural and 12 functional imaging studies were selected. Structural lesion studies associated pantomiming deficits with left frontal, parietal and temporal lesions. In contrast, functional imaging studies associate pantomimes with left parietal activations, with or without concurrent frontal or temporal activations. Functional imaging studies that selectively activated parietal cortex adopted the most stringent controls. In contrast to previous suggestions, current analyses show that both lesion and functional studies support the notion of a left-hemispheric fronto-(temporal)-parietal network underlying pantomiming object use. Furthermore, our review demonstrates that the left parietal cortex plays a key role in pantomime-related processes. More specifically, stringently controlled fMRI-studies suggest that in addition to storing motor schemas, left parietal cortex is also involved in activating these motor schemas in the context of pantomiming object use. In addition to inherent differences between structural and functional imaging studies and consistent with the dedifferentiation hypothesis, the age difference between young healthy subjects (typically included in functional imaging studies) and elderly neurological patients (typically included in structural lesion studies) may well contribute to the finding of a more distributed representation of pantomiming within the motor-dominant left hemisphere in the elderly. PMID:24967158

Niessen, E.; Fink, G.R.; Weiss, P.H.

2014-01-01

306

Modeling spatial patterns in the visual cortex  

NASA Astrophysics Data System (ADS)

We propose a model for the formation of patterns in the visual cortex. The dynamical units of the model are Kuramoto phase oscillators that interact through a complex network structure embedded in two dimensions. In this way the strength of the interactions takes into account the geographical distance between units. We show that for different parameters, clustered or striped patterns emerge. Using the structure factor as an order parameter we are able to quantitatively characterize these patterns and present a phase diagram. Finally, we show that the model is able to reproduce patterns with cardinal preference, as observed in ferrets.

Daza C., Yudy Carolina; Tauro, Carolina B.; Tamarit, Francisco A.; Gleiser, Pablo M.

2014-10-01

307

Computational Modeling of Orientation Tuning Dynamics in Monkey Primary Visual Cortex  

E-print Network

Computational Modeling of Orientation Tuning Dynamics in Monkey Primary Visual Cortex M. C. Pugh, D, monkey, primary visual cortex, lay- ers. 1 #12;Introduction How visual cells in the primary visual cortex

Pugh, Mary

308

Chemosensory convergence on primary olfactory cortex  

PubMed Central

Food perception and preference formation relies on the ability to combine information from both the taste and olfactory systems. Accordingly, psychophysical investigations in humans and behavioral work in animals has shown that the taste system plays an integral role in odor processing. However, the neural basis for the influence of taste (gustation) on odor (olfaction) remains largely unknown. Here we tested the hypothesis that gustatory influence on olfactory processing occurs at the level of primary olfactory cortex. We recorded activity from single neurons in posterior olfactory (piriform) cortex (pPC) of awake rats while presenting basic taste solutions directly to the tongue. A significant portion of pPC neurons proved to respond selectively to taste stimuli. These taste responses were significantly reduced by blockade of the gustatory epithelium, were unaffected by blockade of the olfactory epithelium and were independent of respiration behavior. In contrast, responses to olfactory stimuli, recorded from the same area, were reduced by nasal epithelial deciliation and phase-locked to the respiration cycle. These results identify pPC as a likely site for gustatory influences on olfactory processing, which play an important role in food perception and preference formation. PMID:23197697

Maier, Joost X.; Wachowiak, Matt; Katz, Donald B.

2012-01-01

309

Mexican hats and pinwheels in visual cortex.  

PubMed

Many models of cortical function assume that local lateral connections are specific with respect to the preferred features of the interacting cells and that they are organized in a Mexican-hat pattern with strong "center" excitation flanked by strong "surround" inhibition. However, anatomical data on primary visual cortex indicate that the local connections are isotropic and that inhibition has a shorter range than excitation. We address this issue in an analytical study of a neuronal network model of the local cortical circuit in primary visual cortex. In the model, the orientation columns specified by the convergent lateral geniculate nucleus inputs are arranged in a pinwheel architecture, whereas cortical connections are isotropic. We obtain a trade-off between the spatial range of inhibition and its time constant. If inhibition is fast, the network can operate in a Mexican-hat pattern with isotropic connections even with a spatially narrow inhibition. If inhibition is not fast, Mexican-hat operation requires a spatially broad inhibition. The Mexican-hat operation can generate a sharp orientation tuning, which is largely independent of the distance of the cell from the pinwheel center. PMID:12601163

Kang, Kukjin; Shelley, Michael; Sompolinsky, Haim

2003-03-01

310

The diglyceride kinase of rat cerebral cortex  

PubMed Central

1. Formation of phosphatidic acid by diglyceride kinase (EC 2.7.1.-) in the presence of ATP and Mg2+ was shown in a homogenate and subcellular fractions of rat cerebral cortex. 2. The kinase was activated by Mg2+. Ca2+ activated to a smaller extent but was inhibitory in the presence of optimum concentration of Mg2+. Activity was greatly increased in the presence of added 1,2-diglyceride. 3. Sodium deoxycholate markedly stimulated the reaction, but other detergents (Cutscum and Triton X-100) did not. 4. Diglyceride kinase was concentrated in the supernatant and microsomal fractions from rat cerebral cortex. The distribution of the kinase in the particulate fractions resembled that of acetylcholinesterase and 5?-nucleotidase. 5. The rate of phosphatidic acid synthesis by the diglyceride kinase route was much greater than reported rates for acylation of 3-glycerophosphate and was also very rapid in comparison with the rates of other steps in the synthesis of phosphoinositides. 6. Acetylcholine had no stimulatory effect on diglyceride kinase of isolated intact nerve-ending particles or of nerve-ending membranes obtained after osmotic shock. PMID:5117567

Lapetina, E. G.; Hawthorne, J. N.

1971-01-01

311

Functional Organization of the Orbitofrontal Cortex  

PubMed Central

Emerging evidence suggests that specific cognitive functions localize to different subregions of orbitofrontal cortex (OFC), but the nature of these functional distinctions remains unclear. One prominent theory, derived from human neuroimaging, proposes that different stimulus valences are processed in separate orbital regions, with medial and lateral OFC processing positive and negative stimuli respectively. Thus far, neurophysiology data have not supported this theory. We attempted to reconcile these accounts by recording neural activity from the full medial-lateral extent of the orbital surface in monkeys receiving rewards and punishments via gain or loss of secondary reinforcement. We found no convincing evidence for valence selectivity in any orbital region. Instead, we report differences between neurons in central OFC and those on the inferior-lateral orbital convexity (IC), in that they encoded different sources of value information provided by the behavioral task. Neurons in IC encoded the value of external stimuli, whereas those in OFC encoded value information derived from the structure of the behavioral task. We interpret these results in light of recent theories of OFC function and propose that these distinctions, not valence selectivity, may shed light on a fundamental organizing principle for value processing in orbital cortex. PMID:24405106

Rich, Erin L.; Wallis, Jonathan D.

2014-01-01

312

Theory of Orientation Tuning in Visual Cortex  

NASA Astrophysics Data System (ADS)

The role of intrinsic cortical connections in processing sensory input and in generating behavioral output is poorly understood. We have examined this issue in the context of the tuning of neuronal responses in cortex to the orientation of a visual stimulus. We analytically study a simple network model that incorporates both orientation-selective input from the lateral geniculate nucleus and orientation-specific cortical interactions. Depending on the model parameters, the network exhibits orientation selectivity that originates from within the cortex, by a symmetry-breaking mechanism. In this case, the width of the orientation tuning can be sharp even if the lateral geniculate nucleus inputs are only weakly anisotropic. By using our model, several experimental consequences of this cortical mechanism of orientation tuning are derived. The tuning width is relatively independent of the contrast and angular anisotropy of the visual stimulus. The transient population response to changing of the stimulus orientation exhibits a slow "virtual rotation." Neuronal cross-correlations exhibit long time tails, the sign of which depends on the preferred orientations of the cells and the stimulus orientation.

Ben-Yishai, R.; Lev Bar-Or, R.; Sompolinsky, H.

1995-04-01

313

Representation of numerosity in posterior parietal cortex  

PubMed Central

Humans and animals appear to share a similar representation of number as an analog magnitude on an internal, subjective scale. Neurological and neurophysiological data suggest that posterior parietal cortex (PPC) is a critical component of the circuits that form the basis of numerical abilities in humans. Patients with parietal lesions are impaired in their ability to access the deep meaning of numbers. Acalculiac patients with inferior parietal damage often have difficulty performing arithmetic (2 + 4?) or number bisection (what is between 3 and 5?) tasks, but are able to recite multiplication tables and read or write numerals. Functional imaging studies of neurologically intact humans performing subtraction, number comparison, and non-verbal magnitude comparison tasks show activity in areas within the intraparietal sulcus (IPS). Taken together, clinical cases and imaging studies support a critical role for parietal cortex in the mental manipulation of numerical quantities. Further, responses of single PPC neurons in non-human primates are sensitive to the numerosity of visual stimuli independent of low-level stimulus qualities. When monkeys are trained to make explicit judgments about the numerical value of such stimuli, PPC neurons encode their cardinal numerical value; without such training PPC neurons appear to encode numerical magnitude in an analog fashion. Here we suggest that the spatial and integrative properties of PPC neurons contribute to their critical role in numerical cognition. PMID:22666194

Roitman, Jamie D.; Brannon, Elizabeth M.; Platt, Michael L.

2012-01-01

314

When Is Early Visual Cortex Activated During Visual Mental Imagery?  

Microsoft Academic Search

Although many neuroimaging studies of visual mental imagery have revealed activation in early visual cortex (Areas 17 or 18), many others have not. The authors review this literature and compare how well 3 models explain the disparate results. Each study was coded 1 or 0, indicating whether activation in early visual cortex was observed, and sets of variables associated with

Stephen M. Kosslyn; William L. Thompson

2003-01-01

315

Chronic Stress Alters Dendritic Morphology in Rat Medial Prefrontal Cortex  

E-print Network

Chronic Stress Alters Dendritic Morphology in Rat Medial Prefrontal Cortex Susan C. Cook,1 Cara L ABSTRACT: Chronic stress produces deficits in cognition accompanied by alterations in neural chemis- try and morphology. Medial prefrontal cortex is a target for glucocorticoids involved in the stress response. We have

Wellman, Cara

316

Olfactocentric Paralimbic Cortex Morphology in Adolescents with Bipolar Disorder  

ERIC Educational Resources Information Center

The olfactocentric paralimbic cortex plays a critical role in the regulation of emotional and neurovegetative functions that are disrupted in core features of bipolar disorder. Adolescence is thought to be a critical period in both the maturation of the olfactocentric paralimbic cortex and in the emergence of bipolar disorder pathology. Together,…

Wang, Fei; Kalmar, Jessica H.; Womer, Fay Y.; Edmiston, Erin E.; Chepenik, Lara G.; Chen, Rachel; Spencer, Linda; Blumberg, Hilary P.

2011-01-01

317

Discourse Production Following Injury to the Dorsolateral Prefrontal Cortex  

ERIC Educational Resources Information Center

Individuals with damage to the prefrontal cortex, and the dorsolateral prefrontal cortex (DLPFC) in particular, often demonstrate difficulties with the formulation of complex language not attributable to aphasia. The present study employed a discourse analysis procedure to characterize the language of individuals with left (L) or right (R) DLPFC…

Coelho, Carl; Le, Karen; Mozeiko, Jennifer; Krueger, Frank; Grafman, Jordan

2012-01-01

318

Decision-making processes following damage to the prefrontal cortex  

Microsoft Academic Search

Summary Recent work has suggested an association between the orbitofrontal cortex in humans and practical decision making. The aim of this study was to investigate the profile of cognitive deficits, with particular emphasis on decision-making processes, following damage to differ- ent sectors of the human prefrontal cortex. Patients with discrete orbitofrontal (OBF) lesions, dorsolateral (DL) lesions, dorsomedial (DM) lesions and

Facundo Manes; Barbara Sahakian; Luke Clark; Robert Rogers; Nagui Antoun; Mike Aitken; Trevor Robbins

2002-01-01

319

Metaphorically Feeling: Comprehending Textural Metaphors Activates Somatosensory Cortex  

ERIC Educational Resources Information Center

Conceptual metaphor theory suggests that knowledge is structured around metaphorical mappings derived from physical experience. Segregated processing of object properties in sensory cortex allows testing of the hypothesis that metaphor processing recruits activity in domain-specific sensory cortex. Using functional magnetic resonance imaging…

Lacey, Simon; Stilla, Randall; Sathian, K.

2012-01-01

320

Integration of emotion and cognition in the lateral prefrontal cortex  

E-print Network

Integration of emotion and cognition in the lateral prefrontal cortex Jeremy R. Gray*, Todd S influence cognition-related neural activity in lateral prefrontal cortex (PFC), as evidence for an integration of emotion and cognition. Participants (n 14) watched short videos intended to induce emotional

321

Selective Attention Gates Visual Processing in the Extrastriate Cortex  

Microsoft Academic Search

Single cells were recorded in the visual cortex of monkeys trained to attend to stimuli at one location in the visual field and ignore stimuli at another. When both locations were within the receptive field of a cell in prestriate area V4 or the inferior temporal cortex, the response to the unattended stimulus was dramatically reduced. Cells in the striate

Jeffrey Moran; Robert Desimone

1985-01-01

322

Distributed coding of sound locations in the auditory cortex  

Microsoft Academic Search

Although the auditory cortex plays an impor- tant role in sound localization, that role is not well understood. In this paper, we examine the nature of spatial representation within the auditory cortex, focusing on three questions. First, are sound-source locations encoded by individual sharply tuned neurons or by activity distributed across larger neuronal populations? Second, do temporal features of neural

G. Christopher Stecker; John C. Middlebrooks

2003-01-01

323

Cholinergic Depletion Prevents Expansion of Topographic Maps in Somatosensory Cortex  

Microsoft Academic Search

Although the role of acetylcholine in processing stimuli in the cerebral cortex is becoming defined, the impact of cholinergic activity on the character of cortical maps remains unclear. In the somatosensory cortex, topographic maps appear capable of lifelong modifications in response to alterations in the periphery. One factor proposed to influence this adaptational ability is the presence of acetylcholine in

Sharon L. Juliano; Wu Ma; Don Eslin

1991-01-01

324

Abnormal Asymmetry in Language Association Cortex in Autism  

E-print Network

Abnormal Asymmetry in Language Association Cortex in Autism Martha R. Herbert, MD, PhD,1 Gordon J Masanori Takeoka, MD,7 Helen Tager-Flusberg, PhD,4 and Verne S. Caviness, Jr., MD1 Autism- related cortex in autistic and control subjects. Subjects included 16 boys with autism (aged 7­11 years

Chabris, Christopher F.

325

The scaling of frontal cortex in primates and carnivores  

E-print Network

The scaling of frontal cortex in primates and carnivores Eliot C. Bush* and John M. Allman Biology primates and 15 carnivores. We find evidence for significant differences in scaling between pri- mates and carnivores. Primate frontal cortex hyperscales relative to the rest of neocortex and the rest of the brain

Allman, John M.

326

Representation of reward feedback in primate auditory cortex.  

PubMed

It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1) the reward expectancy for each trial, (2) the reward-size received, and (3) the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized. PMID:21369350

Brosch, Michael; Selezneva, Elena; Scheich, Henning

2011-01-01

327

Neuronal mechanisms of executive control by the prefrontal cortex  

Microsoft Academic Search

Executive function is considered to be a product of the coordinated operation of various processes to accomplish a particular goal in a flexible manner. The mechanism or system responsible for the coordinated operation of various processes is called executive control. Impairments caused by damage to the prefrontal cortex are often called dysexecutive syndromes. Therefore, the prefrontal cortex is considered to

Shintaro Funahashi

2001-01-01

328

Reduced Anterior Cingulate Cortex Glutamatergic Concentrations in Childhood Major Depression  

ERIC Educational Resources Information Center

Objective: To examine in vivo glutamatergic neurochemical alterations in the anterior cingulate cortex of children with major depressive disorder (MDD). Method: Single-voxel proton magnetic resonance spectroscopic ([.sup.1]H-MRS) examinations of the anterior cingulate cortex were conducted in 13 psychotropic-naive children and adolescents with MDD…

Mirza, Yousha; Tang, Jennifer; Russell, Aileen; Banerjee, S. Preeya; Bhandari, Rashmi; Ivey, Jennifer; Rose, Michelle; Moore, Gregory J.; Rosenberg, David R.

2004-01-01

329

Electrophysiological indices of sleep in the cerebral cortex  

NASA Technical Reports Server (NTRS)

An electrophysiological investigation of the nerve structures in which sleep inhibition develops is discussed. Twenty-four points of the cat's brain were selected for recordings. It was found that the anterior cortex produced delta waves in the initial period of sleep. The waves subsequently spread over the entire cortex. Subsequent investigation reveals similar facts pertinent to other waves in subsequent stages.

Kogan, A. B.; Feldman, G. L.

1973-01-01

330

Location Coding by Opponent Neural Populations in the Auditory Cortex  

Microsoft Academic Search

Although the auditory cortex plays a necessary role in sound localization, physiological investigations in the cortex reveal inhomogeneous sampling of auditory space that is difficult to reconcile with localization behavior under the assumption of local spatial coding. Most neurons respond maximally to sounds located far to the left or right side, with few neurons tuned to the frontal midline. Paradoxically,

G. Christopher Stecker; Ian A. Harrington; John C. Middlebrooks

2005-01-01

331

Insular Cortex Is Involved in Consolidation of Object Recognition Memory  

ERIC Educational Resources Information Center

Extensive evidence indicates that the insular cortex (IC), also termed gustatory cortex, is critically involved in conditioned taste aversion and taste recognition memory. Although most studies of the involvement of the IC in memory have investigated taste, there is some evidence that the IC is involved in memory that is not based on taste. In…

Bermudez-Rattoni, Federico; Okuda, Shoki; Roozendaal, Benno; McGaugh, James L.

2005-01-01

332

Engaging in an auditory task suppresses responses in auditory cortex  

E-print Network

, an effect that was opposite in sign to that elicited by selective attention. In the auditory thalamus task suppressed stimulus-evoked responses in the auditory cortex, in contrast with selective attentionEngaging in an auditory task suppresses responses in auditory cortex Gonzalo H Otazu1, Lung-Hao Tai

Zadorlab, Tony

333

FUNCTIONAL DEGRADATION OF EXTRASTRIATE VISUAL CORTEX IN SENESCENT RHESUS MONKEYS  

E-print Network

FUNCTIONAL DEGRADATION OF EXTRASTRIATE VISUAL CORTEX IN SENESCENT RHESUS MONKEYS S. YU,a Y. WANG--The receptive field properties of striate cortical (V1) cells degrade in senescent macaque monkeys. We have now visual cortex (area V2) in very old rhesus (Macaca mulatta) monkeys. This study provides evidence

Zhou, Yi-Feng

334

Reduction of orbital frontal cortex volume in geriatric depression  

Microsoft Academic Search

Background: Postmortem studies have documented abnormalities in the medial orbital frontal cortex in depressed patients. In this study we evaluated whether atrophy of this region can be identified in older depressed patients using magnetic resonance imaging.Methods: Twenty elderly patients meeting DSM-IV criteria for major depression and 20 matched control subjects were studied. The orbital frontal cortex was measured in both

Te-Jen Lai; Martha E Payne; Christopher E Byrum; David C Steffens; K. Ranga R Krishnan

2000-01-01

335

A six year retrospective review of occipital nerve stimulation practice - controversies and challenges of an emerging technique for treating refractory headache syndromes  

PubMed Central

Background A retrospective review of patients treated with Occipital Nerve Stimulation (ONS) at two large tertiary referral centres has been audited in order to optimise future treatment pathways. Methods Patient’s medical records were retrospectively reviewed, and each patient was contacted by a trained headache expert to confirm clinical diagnosis and system efficacy. Results were compared to reported outcomes in current literature on ONS for primary headaches. Results Twenty-five patients underwent a trial of ONS between January 2007 and December 2012, and 23 patients went on to have permanent implantation of ONS. All 23 patients reached one-year follow/up, and 14 of them (61%) exceeded two years of follow-up. Seventeen of the 23 had refractory chronic migraine (rCM), and 3 refractory occipital neuralgia (ON). 11 of the 19 rCM patients had been referred with an incorrect headache diagnosis. Nine of the rCM patients (53%) reported 50% or more reduction in headache pain intensity and or frequency at long term follow-up (11–77 months). All 3 ON patients reported more than 50% reduction in pain intensity and/or frequency at 28–31 months. Ten (43%) subjects underwent surgical revision after an average of 11 ± 7 months from permanent implantation - in 90% of cases due to lead problems. Seven patients attended a specifically designed, multi-disciplinary, two-week pre-implant programme and showed improved scores across all measured psychological and functional parameters independent of response to subsequent ONS. Conclusions Our retrospective review: 1) confirms the long-term ONS success rate in refractory chronic headaches, consistent with previously published studies; 2) suggests that some headaches types may respond better to ONS than others (ON vs CM); 3) calls into question the role of trial stimulation in ONS; 4) confirms the high rate of complications related to the equipment not originally designed for ONS; 5) emphasises the need for specialist multidisciplinary care in these patients. PMID:23919570

2013-01-01

336

Orthogonal acoustic dimensions define auditory field maps in human cortex.  

PubMed

The functional organization of human auditory cortex has not yet been characterized beyond a rudimentary level of detail. Here, we use functional MRI to measure the microstructure of orthogonal tonotopic and periodotopic gradients forming complete auditory field maps (AFMs) in human core and belt auditory cortex. These AFMs show clear homologies to subfields of auditory cortex identified in nonhuman primates and in human cytoarchitectural studies. In addition, we present measurements of the macrostructural organization of these AFMs into "clover leaf" clusters, consistent with the macrostructural organization seen across human visual cortex. As auditory cortex is at the interface between peripheral hearing and central processes, improved understanding of the organization of this system could open the door to a better understanding of the transformation from auditory spectrotemporal signals to higher-order information such as speech categories. PMID:23188798

Barton, Brian; Venezia, Jonathan H; Saberi, Kourosh; Hickok, Gregory; Brewer, Alyssa A

2012-12-11

337

Motor cortex feedback influences sensory processing by modulating network state  

PubMed Central

Summary Long range cortico-cortical communication may have important roles in context-dependent sensory processing, yet we know very little about how these pathways influence their target regions. We studied the influence of primary motor cortex activity on primary somatosensory cortex in the mouse whisker system. We show that primary motor and somatosensory cortices undergo coherent, context-dependent changes in network state. Moreover, we show that motor cortex activity can drive changes in somatosensory cortex network state. A series of experiments demonstrate the involvement of the direct cortico-cortical feedback pathway, providing temporally precise and spatially targeted modulation of network dynamics. Cortically-mediated changes in network state significantly impact sensory coding, with activated states increasing the reliability of responses to complex stimuli. By influencing network state, cortico-cortical communication from motor cortex may ensure that during active exploration the relevant sensory region is primed for enhanced sensory discrimination. PMID:23850595

Zagha, Edward; Casale, Amanda E.; Sachdev, Robert N. S.; McGinley, Matthew J.; McCormick, David A.

2013-01-01

338

Old and new hypotheses about the homology of the compound bones from the cheek and otico-occipital regions of the anuran skull.  

PubMed

We studied the larval development of compound bones from the otico-occipital and cheek regions in species of the neobatrachian genera Batrachyla, Hylorina, Leptodactylus, Odontophrynus and Pleurodema. Comparisons were made using a set of Ambystoma spp. (Caudata) and Ceratophrys ornata (Anura; Ceratophryidae) larvae. As suggested by previous studies, we verified the compound nature of the exoccipital (two centers, anurans only), frontoparietal (one center, most anurans and Ambystoma; three centers, some anurans), and squamosal (two centers, all anurans and Ambystoma) bones. We discuss old and new homology hypotheses for each of the compound bone centers in the context of the most widely accepted scenario of lissamphibian origins and relationships, i.e., monophyletic Lissamphibia that includes the clade Batrachia (Caudata+Anura) and the most divergent Gymnophiona. Our findings have a direct impact on our understanding of the composition of the skull in Lissamphibia. We recognized the presence of the following bones: (i) opisthotic (fused to the exoccipital) and tabular (fused to the squamosal) in Batrachia (Anura+Caudata) and (ii) supratemporal (fused to the parietal portion of the frontoparietal) in Anura. Separate centers of the parietal were found only in Pleurodema. PMID:23835144

Alcalde, Leandro; Basso, Néstor G

2013-08-01

339

Cerebral blood flow modeling in primate cortex  

PubMed Central

We report new results on blood flow modeling over large volumes of cortical gray matter of primate brain. We propose a network method for computing the blood flow, which handles realistic boundary conditions, complex vessel shapes, and complex nonlinear blood rheology. From a detailed comparison of the available models for the blood flow rheology and the phase separation effect, we are able to derive important new results on the impact of network structure on blood pressure, hematocrit, and flow distributions. Our findings show that the network geometry (vessel shapes and diameters), the boundary conditions associated with the arterial inputs and venous outputs, and the effective viscosity of the blood are essential components in the flow distribution. In contrast, we show that the phase separation effect has a minor function in the global microvascular hemodynamic behavior. The behavior of the pressure, hematocrit, and blood flow distributions within the network are described through the depth of the primate cerebral cortex and are discussed. PMID:20648040

Guibert, Romain; Fonta, Caroline; Plouraboué, Franck

2010-01-01

340

Diffeomorphic Sulcal Shape Analysis on the Cortex  

PubMed Central

We present a diffeomorphic approach for constructing intrinsic shape atlases of sulci on the human cortex. Sulci are represented as square-root velocity functions of continuous open curves in ?3, and their shapes are studied as functional representations of an infinite-dimensional sphere. This spherical manifold has some advantageous properties – it is equipped with a Riemannian metric on the tangent space and facilitates computational analyses and correspondences between sulcal shapes. Sulcal shape mapping is achieved by computing geodesics in the quotient space of shapes modulo scales, translations, rigid rotations and reparameterizations. The resulting sulcal shape atlas preserves important local geometry inherently present in the sample population. The sulcal shape atlas is integrated in a cortical registration framework and exhibits better geometric matching compared to the conventional euclidean method. We demonstrate experimental results for sulcal shape mapping, cortical surface registration, and sulcal classification for two different surface extraction protocols for separate subject populations. PMID:22328177

Joshi, Shantanu H.; Cabeen, Ryan P.; Joshi, Anand A.; Sun, Bo; Dinov, Ivo; Narr, Katherine L.; Toga, Arthur W.; Woods, Roger P.

2014-01-01

341

The primary visual cortex fills in color  

PubMed Central

One of the most important goals of visual processing is to reconstruct adequate representations of surfaces in a scene. It is thought that surface representation is produced mainly in the midlevel vision and that area V1 (the primary visual cortex) activity is solely due to feedback from the midlevel stage. Here, we measured functional MRI signals corresponding to “neon color spreading”: an illusory transparent surface with long-range color filling-in, one of the important mediums in reconstructing a surface. The experiment was conducted with careful controls of attention, which can send feedback signals from higher visual areas. Activity for filling-in was observed only in V1, whereas activity for illusory contours was observed in multiple visual areas. These results indicate that surface representation is produced by multiple rather than single processing. PMID:15596726

Sasaki, Yuka; Watanabe, Takeo

2004-01-01

342

Population codes in the visual cortex  

PubMed Central

Every sensory event elicits activity in a broad population of cells that is distributed within and across cortical areas. How these neurons function together to represent the sensory environment is a major question in systems neuroscience. A number of proposals have been made, and recent advances in multi-neuronal recording have begun to allow researchers to test the predictions of these population-coding theories. In this review, I provide an introduction to some of the key concepts in population coding and describe several studies in the recent literature. The focus of this review is on sensory representation in the visual cortex and related perceptual decisions. The frameworks used to study population coding include population vectors, linear decoders, and Bayesian inference. Simple examples are provided to illustrate these concepts. Testing theories of population coding is an emerging subject in systems neuroscience, but advances in multi-neuronal recording and analysis suggest that an understanding is within reach. PMID:23542219

Tanabe, Seiji

2013-01-01

343

Preparatory Attention Relies on Dynamic Interactions between Prelimbic Cortex and Anterior Cingulate Cortex  

PubMed Central

An emerging view of prefrontal cortex (PFC) function is that multiple PFC areas process information in parallel, rather than as distinct modules. Two key functions assigned to the PFC are the regulation of top-down attention and stimulus-guided action. Electrophysiology and lesion studies indicate the involvement of both the anterior cingulate cortex (ACC) and prelimbic cortex (PL) in these functions. Little is known, however, about how these cortical regions interact. We recorded single unit spiking and local field potentials (LFPs) simultaneously in rodents during a sustained attention task and assessed interactions between the ACC and PL by measuring spike–LFP phase synchrony and LFP–LFP phase synchrony between these areas. We demonstrate that the magnitude of synchrony between the ACC and PL, before stimulus onset, predicts the subjects' behavioral choice after the stimulus. Furthermore, neurons switched from a state of beta synchrony during attention to a state of delta synchrony before the instrumental action. Our results indicate that multiple PFC areas interact during attention and that the same neurons may participate in segregated assemblies that support both attention and action. PMID:22419680

Totah, Nelson K. B.; Jackson, Mark E.

2013-01-01

344

Evidence for inhibitory deficits in the prefrontal cortex in schizophrenia.  

PubMed

Abnormal gamma-aminobutyric acid inhibitory neurotransmission is a key pathophysiological mechanism underlying schizophrenia. Transcranial magnetic stimulation can be combined with electroencephalography to index long-interval cortical inhibition, a measure of GABAergic receptor-mediated inhibitory neurotransmission from the frontal and motor cortex. In previous studies we have reported that schizophrenia is associated with inhibitory deficits in the dorsolateral prefrontal cortex compared to healthy subjects and patients with bipolar disorder. The main objective of the current study was to replicate and extend these initial findings by evaluating long-interval cortical inhibition from the dorsolateral prefrontal cortex in patients with schizophrenia compared to patients with obsessive-compulsive disorder. A total of 111 participants were assessed: 38 patients with schizophrenia (average age: 35.71 years, 25 males, 13 females), 27 patients with obsessive-compulsive disorder (average age: 36.15 years, 11 males, 16 females) and 46 healthy subjects (average age: 33.63 years, 23 females, 23 males). Long-interval cortical inhibition was measured from the dorsolateral prefrontal cortex and motor cortex through combined transcranial magnetic stimulation and electroencephalography. In the dorsolateral prefrontal cortex, long-interval cortical inhibition was significantly reduced in patients with schizophrenia compared to healthy subjects (P = 0.004) and not significantly different between patients with obsessive-compulsive disorder and healthy subjects (P = 0.5445). Long-interval cortical inhibition deficits in the dorsolateral prefrontal cortex were also significantly greater in patients with schizophrenia compared to patients with obsessive-compulsive disorder (P = 0.0465). There were no significant differences in long-interval cortical inhibition across all three groups in the motor cortex. These results demonstrate that long-interval cortical inhibition deficits in the dorsolateral prefrontal cortex are specific to patients with schizophrenia and are not a generalized deficit that is shared by disorders of severe psychopathology. PMID:25524710

Radhu, Natasha; Garcia Dominguez, Luis; Farzan, Faranak; Richter, Margaret A; Semeralul, Mawahib O; Chen, Robert; Fitzgerald, Paul B; Daskalakis, Zafiris J

2015-02-01

345

Lipid Pathway Alterations in Parkinson's Disease Primary Visual Cortex  

PubMed Central

Background We present a lipidomics analysis of human Parkinson's disease tissues. We have focused on the primary visual cortex, a region that is devoid of pathological changes and Lewy bodies; and two additional regions, the amygdala and anterior cingulate cortex which contain Lewy bodies at different disease stages but do not have as severe degeneration as the substantia nigra. Methodology/Principal Findings Using liquid chromatography mass spectrometry lipidomics techniques for an initial screen of 200 lipid species, significant changes in 79 sphingolipid, glycerophospholipid and cholesterol species were detected in the visual cortex of Parkinson's disease patients (n?=?10) compared to controls (n?=?10) as assessed by two-sided unpaired t-test (p-value <0.05). False discovery rate analysis confirmed that 73 of these 79 lipid species were significantly changed in the visual cortex (q-value <0.05). By contrast, changes in 17 and 12 lipid species were identified in the Parkinson's disease amygdala and anterior cingulate cortex, respectively, compared to controls; none of which remained significant after false discovery rate analysis. Using gas chromatography mass spectrometry techniques, 6 out of 7 oxysterols analysed from both non-enzymatic and enzymatic pathways were also selectively increased in the Parkinson's disease visual cortex. Many of these changes in visual cortex lipids were correlated with relevant changes in the expression of genes involved in lipid metabolism and an oxidative stress response as determined by quantitative polymerase chain reaction techniques. Conclusions/Significance The data indicate that changes in lipid metabolism occur in the Parkinson's disease visual cortex in the absence of obvious pathology. This suggests that normalization of lipid metabolism and/or oxidative stress status in the visual cortex may represent a novel route for treatment of non-motor symptoms, such as visual hallucinations, that are experienced by a majority of Parkinson's disease patients. PMID:21387008

Cheng, Danni; Jenner, Andrew M.; Shui, Guanghou; Cheong, Wei Fun; Mitchell, Todd W.; Nealon, Jessica R.; Kim, Woojin S.; McCann, Heather; Wenk, Markus R.; Halliday, Glenda M.; Garner, Brett

2011-01-01

346

Carotid endarterectomy for treatment of tandem carotid stenosis in the presence of the anomalous origin of the occipital artery arising from the cervical internal carotid artery: a case report  

PubMed Central

Introduction Branches from the cervical portion of the internal carotid artery are rare. In most cases, atherosclerotic stenosis is found at the bifurcation of the internal and external carotid arteries. However, when associated with atherosclerotic carotid artery disease, the origin of the rare branches arising from the internal carotid artery can be another site of stenosis. This report describes a rare case of such tandem carotid stenosis treated by carotid endarterectomy and the importance of the possibility of stenosis at the origin of the anomalous branch from the internal carotid artery. Case presentation A 73-year-old Japanese woman presented with transient left hemiparesis and vertigo. Magnetic resonance angiography seemed to indicate two stenotic lesions distal to the right internal carotid artery in addition to the origin of the right internal carotid artery, and angiography indicated tandem stenotic lesions of the internal carotid artery. The patient was successfully treated with right carotid endarterectomy, including the distal stenotic lesion of internal carotid artery, and postoperative angiography indicated that the occipital artery arose from the internal carotid artery. Conclusion It is important to recognize rare cases of the anomalous origin of the occipital artery from the internal carotid artery and the possibility that the origin of such an anomalous occipital artery may be the cause of stenosis. PMID:24199618

2013-01-01

347

Top-down and bottom-up influences on the left ventral occipito-temporal cortex during visual word recognition: an analysis of effective connectivity.  

PubMed

The functional role of the left ventral occipito-temporal cortex (vOT) in visual word processing has been studied extensively. A prominent observation is higher activation for unfamiliar but pronounceable letter strings compared to regular words in this region. Some functional accounts have interpreted this finding as driven by top-down influences (e.g., Dehaene and Cohen [2011]: Trends Cogn Sci 15:254-262; Price and Devlin [2011]: Trends Cogn Sci 15:246-253), while others have suggested a difference in bottom-up processing (e.g., Glezer et al. [2009]: Neuron 62:199-204; Kronbichler et al. [2007]: J Cogn Neurosci 19:1584-1594). We used dynamic causal modeling for fMRI data to test bottom-up and top-down influences on the left vOT during visual processing of regular words and unfamiliar letter strings. Regular words (e.g., taxi) and unfamiliar letter strings of pseudohomophones (e.g., taksi) were presented in the context of a phonological lexical decision task (i.e., "Does the item sound like a word?"). We found no differences in top-down signaling, but a strong increase in bottom-up signaling from the occipital cortex to the left vOT for pseudohomophones compared to words. This finding can be linked to functional accounts which assume that the left vOT contains neurons tuned to complex orthographic features such as morphemes or words [e.g., Dehaene and Cohen [2011]: Trends Cogn Sci 15:254-262; Kronbichler et al. [2007]: J Cogn Neurosci 19:1584-1594]: For words, bottom-up signals converge onto a matching orthographic representation in the left vOT. For pseudohomophones, the propagated signals do not converge, but (partially) activate multiple orthographic word representations, reflected in increased effective connectivity. PMID:23670980

Schurz, Matthias; Kronbichler, Martin; Crone, Julia; Richlan, Fabio; Klackl, Johannes; Wimmer, Heinz

2014-04-01

348

Transcranial direct current stimulation over right posterior parietal cortex changes prestimulus alpha oscillation in visual short-term memory task.  

PubMed

Alpha band activity changes accompanied with the level attentional state, and recent studies suggest that such oscillation is associated with activities in the posterior parietal cortex. Here we show that artificially elevating parietal activity via positively-charged electric current through the skull can rapidly and effortlessly change people's prestimulus alpha power and improve subsequent performance on a visual short-term memory (VSTM) task. This modulation of alpha power and behavioral performance, however, is dependent on people's natural VSTM capability such that only the low performers benefitted from the stimulation, whereas high performers did not. This behavioral dichotomy is accounted by prestimulus alpha powers around the parieto-occipital regions: low performers showed decreased prestimulus alpha power, suggesting improvement in attention deployment in the current paradigm, whereas the high performers did not benefit from tDCS as they showed equally-low prestimulus alpha power before and after the stimulation. Together, these results suggest that prestimulus alpha power, especially in low performers, can be modulated by anodal stimulation and alter subsequent VSTM performance/capacity. Thus, measuring alpha before stimulus onset may be as important as measuring other VSTM-related electrophysiological components such as attentional allocation and memory capacity related components (i.e. N2 posterior-contralateral, N2pc, or contralateral delay activity, CDA). In addition, low VSTM performers perhaps do not suffer not only from poor VSTM capacity, but also from broad attentional mechanisms, and prestimulus alpha may be an useful tool in understanding the nature of individual differences in VSTM. PMID:24807400

Hsu, Tzu-Yu; Tseng, Philip; Liang, Wei-Kuang; Cheng, Shih-Kuen; Juan, Chi-Hung

2014-09-01

349

The spatiotopic 'visual' cortex of the blind  

NASA Astrophysics Data System (ADS)

Visual cortex activity in the blind has been shown in sensory tasks. Can it be activated in memory tasks? If so, are inherent features of its organization meaningfully employed? Our recent results in short-term blindfolded subjects imply that human primary visual cortex (V1) may operate as a modality-independent 'sketchpad' for working memory (Likova, 2010a). Interestingly, the spread of the V1 activation approximately corresponded to the spatial extent of the images in terms of their angle of projection to the subject. We now raise the questions of whether under long-term visual deprivation V1 is also employed in non-visual memory task, in particular in congenitally blind individuals, who have never had visual stimulation to guide the development of the visual area organization, and whether such spatial organization is still valid for the same paradigm that was used in blindfolded individuals. The outcome has implications for an emerging reconceptualization of the principles of brain architecture and its reorganization under sensory deprivation. Methods: We used a novel fMRI drawing paradigm in congenitally and late-onset blind, compared with sighted and blindfolded subjects in three conditions of 20s duration, separated by 20s rest-intervals, (i) Tactile Exploration: raised-line images explored and memorized; (ii) Tactile Memory Drawing: drawing the explored image from memory; (iii) Scribble: mindless drawing movements with no memory component. Results and Conclusions: V1 was strongly activated for Tactile Memory Drawing and Tactile Exploration in these totally blind subjects. Remarkably, after training, even in the memory task, the mapping of V1 activation largely corresponded to the angular projection of the tactile stimuli relative to the ego-center (i.e., the effective visual angle at the head); beyond this projective boundary, peripheral V1 signals were dramatically reduced or even suppressed. The matching extent of the activation in the congenitally blind rules out vision-based explanatory mechanisms, and supports the more radical idea of V1 as a modality-independent 'projection screen' or a 'sketchpad', whose mapping scales to the projective dimensions of objects explored in the peri-personal space.

Likova, Lora

2012-03-01

350

A functional microcircuit for cat visual cortex.  

PubMed Central

1. We have studied in vivo the intracellular responses of neurones in cat visual cortex to electrical pulse stimulation of the cortical afferents and have developed a microcircuit that simulates much of the experimental data. 2. Inhibition and excitation are not separable events, because individual neurones are embedded in microcircuits that contribute strong population effects. Synchronous electrical activation of the cortex inevitably set in motion a sequence of excitation and inhibition in every neurone we recorded. The temporal form of this response depends on the cortical layer in which the neurone is located. Superficial layer (layers 2+3) pyramidal neurones show a more marked polysynaptic excitatory phase than the pyramids of the deep layers (layers 5+6). 3. Excitatory effects on pyramidal neurones, particularly the superficial layer pyramids, are in general not due to monosynaptic input from thalamus, but polysynaptic input from cortical pyramids. Since the thalamic input is transient it does not provide the major, sustained excitation arriving at any cortical neurone. Instead the intracortical excitatory connections provide the major component of the excitation. 4. The polysynaptic excitatory response would be sustained well after the stimulus, were it not for the suppressive effect of intracortical inhibition induced by the pulse stimulation. 5. Intracellular recording combined with ionophoresis of gamma-aminobutyric acid (GABA) agonists and antagonists showed that intracortical inhibition is mediated by GABAA and GABAB receptors. The GABAA component occurs in the early phase of the impulse response. It is reflected in the strong hyperpolarization that follows the excitatory response and lasts about 50 ms. The GABAB component occurs in the late phase of the response, and is reflected in a sustained hyperpolarization that lasts some 200-300 ms. Both components are seen in all cortical pyramidal neurones. However, the GABAA component appears more powerful in deep layer pyramids than superficial layer pyramids. 6. The microcircuit simulates with good fidelity the above data from experiments in vivo and provides a novel explantation for the apparent lack of significant inhibition during visual stimulation. The basic circuit may be common to all cortical areas studied and thus the microcircuit may be a 'canonical' microcircuit for neocortex. PMID:1666655

Douglas, R J; Martin, K A

1991-01-01

351

Cortex Matures Faster in Youths With Highest IQ  

MedlinePLUS

... Past Issues Research News From NIH Cortex Matures Faster in Youths With Highest IQ Past Issues / Summer ... for high-level thinking circuitry. It also thins faster during the late teens, likely due to the ...

352

Visual Field Map Clusters in Macaque Extrastriate Visual Cortex  

E-print Network

The macaque visual cortex contains >30 different functional visual areas, yet surprisingly little is known about the underlying organizational principles that structure its components into a complete "visual" unit. A recent ...

Kolster, Hauke

353

Superimposed Hemifields in Primary Visual Cortex of Achiasmic Individuals  

E-print Network

In the rare condition of achiasma, the visual cortex in each hemisphere receives information from both halves of the visual field. How is this “doubling” of information accommodated in V1? In this issue of Neuron, Hoffmann ...

Sinha, Pawan

354

CHRYSOTILE ASBESTOS IN KIDNEY CORTEX OF CHRONICALLY GAVAGED RATS  

EPA Science Inventory

Using the transmission electron microscope, asbestos fibers have been assessed in kidney cortex of four groups of rats previously exposed to intermediate range feeding grade chrysotile asbestos. Newborn rats, from mothers gavaged with asbestos during pregnancy, were gavaged twice...

355

The laryngeal motor cortex: its organization and connectivity.  

PubMed

Our ability to learn and control the motor aspects of complex laryngeal behaviors, such as speech and song, is modulated by the laryngeal motor cortex (LMC), which is situated in the area 4 of the primary motor cortex and establishes both direct and indirect connections with laryngeal motoneurons. In contrast, the LMC in monkeys is located in the area 6 of the premotor cortex, projects only indirectly to laryngeal motoneurons and its destruction has essentially no effect on production of species-specific calls. These differences in cytoarchitectonic location and connectivity may be a result of hominid evolution that led to the LMC shift from the phylogenetically 'old' to 'new' motor cortex in order to fulfill its paramount function, that is, voluntary motor control of human speech and song production. PMID:24929930

Simonyan, Kristina

2014-10-01

356

Age effects on atrophy rates of entorhinal cortex and hippocampus  

E-print Network

WMH, or hypertension in a highly selected elderly populationhypertension on entorhinal cortex (ERC) and hippocampal atrophy rates were explored in a longitudinal MRI study with 42 cognitively normal (CN) elderly

2006-01-01

357

Antidepressant Effect of Optogenetic Stimulation of the Medial Prefrontal Cortex  

E-print Network

Brain stimulation and imaging studies in humans have highlighted a key role for the prefrontal cortex in clinical depression; however, it remains unknown whether excitation or inhibition of prefrontal cortical neuronal ...

Covington III, Herbert E.

358

The orbitofrontal cortex in methamphetamine addiction: involvement in fear  

E-print Network

The orbitofrontal cortex in methamphetamine addiction: involvement in fear Rita Z. Goldstein addiction. NeuroReport 13:2253^2257 c 2002 Lippincott Williams & Wilkins. Key words: Constraint superfactor; Drug addiction; Fear; Glucose metabolism; Harm avoidance scale; Inhibitory control; Methamphetamine

Goldstein, Rita

359

Differential activation of the lateral premotor cortex during action observation  

PubMed Central

Background Action observation leads to neural activation of the human premotor cortex. This study examined how the level of motor expertise (expert vs. novice) in ballroom dancing and the visual viewpoint (internal vs. external viewpoint) influence this activation within different parts of this area of the brain. Results Sixteen dance experts and 16 novices observed ballroom dance videos from internal or external viewpoints while lying in a functional magnetic resonance imaging scanner. A conjunction analysis of all observation conditions showed that action observation activated distinct networks of premotor, parietal, and cerebellar structures. Experts revealed increased activation in the ventral premotor cortex compared to novices. An internal viewpoint led to higher activation of the dorsal premotor cortex. Conclusions The present results suggest that the ventral and dorsal premotor cortex adopt differential roles during action observation depending on the level of motor expertise and the viewpoint. PMID:20673366

2010-01-01

360

Localization of steroidogenic enzymes in adrenal cortex and its disorders.  

PubMed

Immunolocalization and in situ hybridization analysis of steroidogenic enzymes demonstrated the localization of steroidogenesis in the adrenal cortex and its disorders. The findings obtained provided new insights into adrenocortical hormonal metabolism, especially through establishing endocrine-pathological correlation. PMID:7889106

Sasano, H

1994-10-01

361

The Anterior Cingulate Cortex The Evolution of an Interface between  

E-print Network

for the experiencing of emotion as the result of impulses coming from the hypothalamic region, in the same way noted that tumors pressing on the cingu- late cortex produced "loss of spontaneity in emotion, thought

Allman, John M.

362

Lateral prefrontal cortex and self-control in intertemporal choice.  

PubMed

Disruption of function of left, but not right, lateral prefrontal cortex (LPFC) with low-frequency repetitive transcranial magnetic stimulation (rTMS) increased choices of immediate rewards over larger delayed rewards. rTMS did not change choices involving only delayed rewards or valuation judgments of immediate and delayed rewards, providing causal evidence for a neural lateral-prefrontal cortex-based self-control mechanism in intertemporal choice. PMID:20348919

Figner, Bernd; Knoch, Daria; Johnson, Eric J; Krosch, Amy R; Lisanby, Sarah H; Fehr, Ernst; Weber, Elke U

2010-05-01

363

Functional involvement of cerebral cortex in adult sleepwalking  

Microsoft Academic Search

\\u000a Abstract\\u000a   The pathophysiology of adult sleepwalking is still poorly understood. However, it is widely accepted that sleepwalking is\\u000a a disorder of arousal. Arousal circuits widely project to the cortex, including motor cortex. We hypothesized that functional\\u000a abnormality of these circuits could lead to changes in cortical excitability in sleepwalkers, even during wakefulness. We\\u000a used transcranial magnetic stimulation (TMS) to examine

A. Oliviero; G. Della Marca; P. A. Tonali; F. Pilato; E. Saturno; M. Dileone; M. Rubino; V. Di Lazzaro

2007-01-01

364

The Evolution of Auditory Cortex: The Core Areas  

Microsoft Academic Search

\\u000a An alternative title might be “What, if Anything, is AI?” AI, of course, is primary auditory cortex, an area of cortex that\\u000a likely all mammals have. Thus, this seems a naive or a puzzling question. Yet, an important issue is hidden in this question.\\u000a And this type of question was formulated long ago: “What, if anything, is a rabbit?” (Wood

Jon H. Kaas

365

Beta Oscillation Dynamics in Extrastriate Cortex after Removal of Primary Visual Cortex  

PubMed Central

The local field potential (LFP) in visual cortex is typically characterized by the following spectral pattern: before the onset of a visual stimulus, low-frequency oscillations (beta, 12–20 Hz) dominate, whereas during the presentation of a stimulus these oscillations diminish and are replaced by fluctuations at higher frequencies (gamma, >30 Hz). The origin of beta oscillations in vivo remains unclear, as is the basis of their suppression during visual stimulation. Here we investigate the contribution of ascending input from primary visual cortex (V1) to beta oscillation dynamics in extrastriate visual area V4 of behaving monkeys. We recorded LFP activity in V4 before and after resecting a portion of V1. After the surgery, the visually induced gamma LFP activity in the lesion projection zone of V4 was markedly reduced, consistent with previously reported spiking responses (Schmid et al., 2013). In the beta LFP range, the lesion had minimal effect on the normal pattern of spontaneous oscillations. However, the lesion led to a surprising and permanent reversal of the normal beta suppression during visual stimulation, with visual stimuli eliciting beta magnitude increases up to 50%, particularly in response to moving stimuli. This reversed beta activity pattern was specific to stimulus locations affected by the V1 lesion. Our results shed light on the mechanisms of beta activity in extrastriate visual cortex: The preserved spontaneous oscillations point to a generation mechanism independent of the geniculostriate pathway, whereas the positive beta responses support the contribution of visual information to V4 via direct thalamo-extrastriate projections. PMID:25164679

Schmiedt, Joscha T.; Maier, Alexander; Fries, Pascal; Saunders, Richard C.; Leopold, David A.

2014-01-01

366

Auditory cortex is required for fear potentiation of gap detection.  

PubMed

Auditory cortex is necessary for the perceptual detection of brief gaps in noise, but is not necessary for many other auditory tasks such as frequency discrimination, prepulse inhibition of startle responses, or fear conditioning with pure tones. It remains unclear why auditory cortex should be necessary for some auditory tasks but not others. One possibility is that auditory cortex is causally involved in gap detection and other forms of temporal processing in order to associate meaning with temporally structured sounds. This predicts that auditory cortex should be necessary for associating meaning with gaps. To test this prediction, we developed a fear conditioning paradigm for mice based on gap detection. We found that pairing a 10 or 100 ms gap with an aversive stimulus caused a robust enhancement of gap detection measured 6 h later, which we refer to as fear potentiation of gap detection. Optogenetic suppression of auditory cortex during pairing abolished this fear potentiation, indicating that auditory cortex is critically involved in associating temporally structured sounds with emotionally salient events. PMID:25392510

Weible, Aldis P; Liu, Christine; Niell, Cristopher M; Wehr, Michael

2014-11-12

367

Cortex Integrity Relevance in Muscle Synergies in Severe Chronic Stroke  

PubMed Central

Background: Recent experimental evidence has indicated that the motor system coordinates muscle activations through a linear combination of muscle synergies that are specified at the spinal or brainstem networks level. After stroke upper limb impairment is characterized by abnormal patterns of muscle activations or synergies. Objective: This study aimed at characterizing the muscle synergies in severely affected chronic stroke patients. Furthermore, the influence of integrity of the sensorimotor cortex on synergy modularity and its relation with motor impairment was evaluated. Methods: Surface electromyography from 33 severely impaired chronic stroke patients was recorded during 6 bilateral movements. Muscle synergies were extracted and synergy patterns were correlated with motor impairment scales. Results: Muscle synergies extracted revealed different physiological patterns dependent on the preservation of the sensorimotor cortex. Patients without intact sensorimotor cortex showed a high preservation of muscle synergies. On the contrary, patients with intact sensorimotor cortex showed poorer muscle synergies preservation and an increase in new generated synergies. Furthermore, the preservation of muscle synergies correlated positively with hand functionality in patients with intact sensorimotor cortex and subcortical lesions only. Conclusion: Our results indicate that severely paralyzed chronic stroke patient with intact sensorimotor cortex might sculpt new synergy patterns as a response to maladaptive compensatory strategies. PMID:25294998

García-Cossio, Eliana; Broetz, Doris; Birbaumer, Niels; Ramos-Murguialday, Ander

2014-01-01

368

Behavior Modulates Effective Connectivity between Cortex and Striatum  

PubMed Central

It has been notoriously difficult to understand interactions in the basal ganglia because of multiple recurrent loops. Another complication is that activity there is strongly dependent on behavior, suggesting that directional interactions, or effective connections, can dynamically change. A simplifying approach would be to examine just the direct, monosynaptic projections from cortex to striatum and contrast this with the polysynaptic feedback connections from striatum to cortex. Previous work by others on effective connectivity in this pathway indicated that activity in cortex could be used to predict activity in striatum, but that striatal activity could not predict cortical activity. However, this work was conducted in anesthetized or seizing animals, making it impossible to know how free behavior might influence effective connectivity. To address this issue, we applied Granger causality to local field potential signals from cortex and striatum in freely behaving rats. Consistent with previous results, we found that effective connectivity was largely unidirectional, from cortex to striatum, during anesthetized and resting states. Interestingly, we found that effective connectivity became bidirectional during free behaviors. These results are the first to our knowledge to show that striatal influence on cortex can be as strong as cortical influence on striatum. In addition, these findings highlight how behavioral states can affect basal ganglia interactions. Finally, we suggest that this approach may be useful for studies of Parkinson's or Huntington's diseases, in which effective connectivity may change during movement. PMID:24618981

Nakhnikian, Alexander; Rebec, George V.; Grasse, Leslie M.; Dwiel, Lucas L.; Shimono, Masanori; Beggs, John M.

2014-01-01

369

Organization of the somatosensory cortex in elephant shrews (E. edwardii).  

PubMed

The superorder Afrotheria consists of a diverse group of mammals, including elephants, hyraxes, dugongs, sea cows, aardvarks, tenrecs, golden moles, and elephant shrews. Recent studies suggest this clade diverged from other placental mammals 100 million years ago and thus may represent the sister group to the remaining placental mammals. Despite this important taxonomic position, relatively few studies have investigated cortical organization in these species. Here we present results of an investigation of the somatosensory cortex in the Cape elephant shrew (Elephantulus edwardii). Using multiunit electrophysiological recording techniques, we identified a topographic map of the elephant shrew's body in a location and orientation consistent with the primary somatosensory cortex (S1). The elephant shrew's elongated snout, extensive facial vibrissae, and long tongue accounted for a large portion of the somatosensory representation, located in a relatively rostral area of cortex. Evidence for an additional somatosensory area, presumed to be secondary somatosensory cortex (S2), was found just lateral to S1. Visual and auditory responsive areas were also identified and the extent of visual cortex appeared to be quite large in these highly visual mammals. Despite the elephant shrew's exceptionally well-developed eyes, ears, and vibrissae, there were no anatomical correlates to sensory areas, or body part representations (e.g., barrels), that could be identified in the flatted cortex. PMID:16847884

Dengler-Crish, Christine M; Crish, Samuel D; O'Riain, M Justin; Catania, Kenneth C

2006-08-01

370

Ongoing physiological processes in the cerebral cortex  

PubMed Central

Functional magnetic resonance imaging (fMRI) has revealed that the human brain undergoes prominent, regional hemodynamic fluctuations when a subject is at rest. These ongoing fluctuations exhibit distinct patterns of spatiotemporal synchronization that have been dubbed “resting state functional connectivity”, and which currently serve as a principal tool to investigate neural networks in the normal and pathological human brain. Despite the wide application of this approach in human neuroscience, the neural mechanisms that give rise to spontaneous fMRI correlations are largely unknown. Here we review results of recent electrophysiological studies in the cerebral cortex of humans and nonhuman primates that link neural activity to ongoing fMRI fluctuations. We begin by describing results obtained with simultaneous fMRI and electrophysiological measurements that allow for the identification of direct neural correlates of resting state functional connectivity. We next highlight experiments that investigate the correlational structure of spontaneous neural signals, including the spatial variation of signal coherence over the cortical surface, across cortical laminae, and between the two hemispheres. In the final section we speculate on the origins and potential consequences of ongoing signals for normal brain function, and point out inherent limitations of the fMRI correlation approach. PMID:22040739

Leopold, David A.; Maier, Alexander

2011-01-01

371

Navigating actions through the rodent parietal cortex  

PubMed Central

The posterior parietal cortex (PPC) participates in a manifold of cognitive functions, including visual attention, working memory, spatial processing, and movement planning. Given the vast interconnectivity of PPC with sensory and motor areas, it is not surprising that neuronal recordings show that PPC often encodes mixtures of spatial information as well as the movements required to reach a goal. Recent work sought to discern the relative strength of spatial vs. motor signaling in PPC by recording single unit activity in PPC of freely behaving rats during selective changes in either the spatial layout of the local environment or in the pattern of locomotor behaviors executed during navigational tasks. The results revealed unequivocally a predominant sensitivity of PPC neurons to locomotor action structure, with subsets of cells even encoding upcoming movements more than 1 s in advance. In light of these and other recent findings in the field, I propose that one of the key contributions of PPC to navigation is the synthesis of goal-directed behavioral sequences, and that the rodent PPC may serve as an apt system to investigate cellular mechanisms for spatial motor planning as traditionally studied in humans and monkeys. PMID:24860475

Whitlock, Jonathan R.

2014-01-01

372

Mnemonic neuronal activity in somatosensory cortex.  

PubMed Central

Single-unit activity was recorded from the hand areas of the somatosensory cortex of monkeys trained to perform a haptic delayed matching to sample task with objects of identical dimensions but different surface features. During the memory retention period of the task (delay), many units showed sustained firing frequency change, either excitation or inhibition. In some cases, firing during that period was significantly higher after one sample object than after another. These observations indicate the participation of somatosensory neurons not only in the perception but in the short-term memory of tactile stimuli. Neurons most directly implicated in tactile memory are (i) those with object-selective delay activity, (ii) those with nondifferential delay activity but without activity related to preparation for movement, and (iii) those with delay activity in the haptic-haptic delayed matching task but no such activity in a control visuo-haptic delayed matching task. The results indicate that cells in early stages of cortical somatosensory processing participate in haptic short-term memory. PMID:8927629

Zhou, Y D; Fuster, J M

1996-01-01

373

Optogenetic dissection of medial prefrontal cortex circuitry  

PubMed Central

The medial prefrontal cortex (mPFC) is critically involved in numerous cognitive functions, including attention, inhibitory control, habit formation, working memory and long-term memory. Moreover, through its dense interconnectivity with subcortical regions (e.g., thalamus, striatum, amygdala and hippocampus), the mPFC is thought to exert top-down executive control over the processing of aversive and appetitive stimuli. Because the mPFC has been implicated in the processing of a wide range of cognitive and emotional stimuli, it is thought to function as a central hub in the brain circuitry mediating symptoms of psychiatric disorders. New optogenetics technology enables anatomical and functional dissection of mPFC circuitry with unprecedented spatial and temporal resolution. This provides important novel insights in the contribution of specific neuronal subpopulations and their connectivity to mPFC function in health and disease states. In this review, we present the current knowledge obtained with optogenetic methods concerning mPFC function and dysfunction and integrate this with findings from traditional intervention approaches used to investigate the mPFC circuitry in animal models of cognitive processing and psychiatric disorders. PMID:25538574

Riga, Danai; Matos, Mariana R.; Glas, Annet; Smit, August B.; Spijker, Sabine; Van den Oever, Michel C.

2014-01-01

374

Encoding frequency contrast in primate auditory cortex.  

PubMed

Changes in amplitude and frequency jointly determine much of the communicative significance of complex acoustic signals, including human speech. We have previously described responses of neurons in the core auditory cortex of awake rhesus macaques to sinusoidal amplitude modulation (SAM) signals. Here we report a complementary study of sinusoidal frequency modulation (SFM) in the same neurons. Responses to SFM were analogous to SAM responses in that changes in multiple parameters defining SFM stimuli (e.g., modulation frequency, modulation depth, carrier frequency) were robustly encoded in the temporal dynamics of the spike trains. For example, changes in the carrier frequency produced highly reproducible changes in shapes of the modulation period histogram, consistent with the notion that the instantaneous probability of discharge mirrors the moment-by-moment spectrum at low modulation rates. The upper limit for phase locking was similar across SAM and SFM within neurons, suggesting shared biophysical constraints on temporal processing. Using spike train classification methods, we found that neural thresholds for modulation depth discrimination are typically far lower than would be predicted from frequency tuning to static tones. This "dynamic hyperacuity" suggests a substantial central enhancement of the neural representation of frequency changes relative to the auditory periphery. Spike timing information was superior to average rate information when discriminating among SFM signals, and even when discriminating among static tones varying in frequency. This finding held even when differences in total spike count across stimuli were normalized, indicating both the primacy and generality of temporal response dynamics in cortical auditory processing. PMID:24598525

Malone, Brian J; Scott, Brian H; Semple, Malcolm N

2014-06-01

375

Sentence processing in the cerebral cortex.  

PubMed

Human language is a unique faculty of the mind. It has been the ultimate mystery throughout the history of neuroscience. Despite many aphasia and functional imaging studies, the exact correlation between cortical language areas and subcomponents of the linguistic system has not been established. One notable drawback is that most functional imaging studies have tested language tasks at the word level, such as lexical decision and word generation tasks, thereby neglecting the syntactic aspects of the language faculty. As proposed by Chomsky, the critical knowledge of language involves universal grammar (UG), which governs the syntactic structure of sentences. In this article, we will review recent advances made by functional neuroimaging studies of language, focusing especially on sentence processing in the cerebral cortex. We also present the recent results of our functional magnetic resonance imaging (fMRI) study intended to identify cortical areas specifically involved in syntactic processing. A study of sentence processing that employs a newly developed technique, optical topography (OT), is also presented. Based on these findings, we propose a modular specialization of Broca's area, Wernicke's area, and the angular gyrus/supramarginal gyrus. The current direction of research in neuroscience is beginning to establish the existence of distinct modules responsible for our knowledge of language. PMID:11164248

Sakai, K L; Hashimoto, R; Homae, F

2001-01-01

376

Gene Expression Changes in the Prefrontal Cortex, Anterior Cingulate Cortex and Nucleus Accumbens of Mood Disorders Subjects That Committed Suicide  

E-print Network

in the postmortem brains of teenage suicide victims. Am Jfrontal cortex of suicide victims. Brain Res 633: 297–304.victims in the NACC. Discussion A gene expression survey by microarrays in three brain

2012-01-01

377

Orbitofrontal Cortex Biases Attention to Emotional Events  

PubMed Central

We examined the role of orbitofrontal (OF) cortex in regulating emotion-attention interaction and the balance between involuntary and voluntary attention allocation. We studied patients with OF lesion applying reaction time (RT) and event-related potential (ERP) measures in a lateralized visual discrimination task with novel task-irrelevant affective pictures (unpleasant, pleasant or neutral) preceding a neutral target. This allowed for comparing the effects of automatic attention allocation to emotional vs neutral stimuli on subsequent voluntary attention allocation to target stimuli. N2-P3a and N2-P3b ERP components served as measures of involuntary and voluntary attention allocation correspondingly. Enhanced N2-P3a amplitudes to emotional distractors and reduced N2-P3b amplitudes to targets preceded by emotional distractors were observed in healthy subjects, suggesting automatic emotional orienting interfered with subsequent voluntary orienting. OF patients showed an opposite pattern with tendency towards reduced N2-P3a responses to emotional distractors, suggesting impaired automatic orienting to emotional stimuli due to orbitofrontal damage. Enhanced N2-P3b responses to targets preceded by any affective distractor was observed in OF patients, suggesting bias towards voluntary target-related attention allocation due to orbitofrontal lesion. Behavioral evidence indicated that LVF attention performance was modulated by emotional stimuli. Specifically, OF patients responded faster to LVF targets subsequent to pleasant emotional distractors. We suggest damage to the orbitofrontal circuitry leads to dysbalance between voluntary and involuntary attention allocation in the context of affective distracters with predisposition to posterior target related processing over frontal novelty and affect related processing. Furthermore, we suggest orbitofrontal influence on emotion- attention interaction is valence and hemisphere dependent. PMID:22413757

Hartikainen, K.M.; Ogawa, K.H.; Knight, R.T.

2012-01-01

378

Spatial integration in mouse primary visual cortex  

PubMed Central

Responses of many neurons in primary visual cortex (V1) are suppressed by stimuli exceeding the classical receptive field (RF), an important property that might underlie the computation of visual saliency. Traditionally, it has proven difficult to disentangle the underlying neural circuits, including feedforward, horizontal intracortical, and feedback connectivity. Since circuit-level analysis is particularly feasible in the mouse, we asked whether neural signatures of spatial integration in mouse V1 are similar to those of higher-order mammals and investigated the role of parvalbumin-expressing (PV+) inhibitory interneurons. Analogous to what is known from primates and carnivores, we demonstrate that, in awake mice, surround suppression is present in the majority of V1 neurons and is strongest in superficial cortical layers. Anesthesia with isoflurane-urethane, however, profoundly affects spatial integration: it reduces the laminar dependency, decreases overall suppression strength, and alters the temporal dynamics of responses. We show that these effects of brain state can be parsimoniously explained by assuming that anesthesia affects contrast normalization. Hence, the full impact of suppressive influences in mouse V1 cannot be studied under anesthesia with isoflurane-urethane. To assess the neural circuits of spatial integration, we targeted PV+ interneurons using optogenetics. Optogenetic depolarization of PV+ interneurons was associated with increased RF size and decreased suppression in the recorded population, similar to effects of lowering stimulus contrast, suggesting that PV+ interneurons contribute to spatial integration by affecting overall stimulus drive. We conclude that the mouse is a promising model for circuit-level mechanisms of spatial integration, which relies on the combined activity of different types of inhibitory interneurons. PMID:23719206

Vaiceliunaite, Agne; Erisken, Sinem; Franzen, Florian; Katzner, Steffen

2013-01-01

379

Auditory trace fear conditioning requires perirhinal cortex  

PubMed Central

The hippocampus is well-known to be critical for trace fear conditioning, but nothing is known about the importance of perirhinal cortex (PR), which has reciprocal connections with hippocampus. PR damage severely impairs delay fear conditioning to ultrasonic vocalizations (USVs) and discontinuous tones (pips), but has no effect on delay conditioning to continuous tones (Kholodar-Smith, Allen, and Brown, in press). Here we demonstrate that trace auditory fear conditioning also critically depends on PR function. The trace interval between the CS offset and the US onset was 16 s. Pre-training neurotoxic lesions were produced through multiple injections of N-methyl-D-aspartate along the full length of PR, which was directly visualized during the injections. Control animals received injections with phosphate-buffered saline. Three-dimensional reconstructions of the lesion volumes demonstrated that the neurotoxic damage was well-localized to PR and included most of its anterior-posterior extent. Automated video analysis quantified freezing behavior, which served as the conditional response. PR-damaged rats were profoundly impaired in trace conditioning to either of three different CSs (a USV, tone pips, and a continuous tone) as well as conditioning to the training context. Within both the lesion and control groups, the type of cue had no effect on the mean CR. The overall PR lesion effect size was 2.7 for cue conditioning and 3.9 for context conditioning. We suggest that the role of PR in trace fear conditioning may be distinct from some of its more perceptual functions. The results further define the essential circuitry underlying trace fear conditioning to auditory cues. PMID:18678265

Kholodar-Smith, D.B.; Boguszewski, P.; Brown, T.H.

2008-01-01

380

Decoding Sound and Imagery Content in Early Visual Cortex  

PubMed Central

Summary Human early visual cortex was traditionally thought to process simple visual features such as orientation, contrast, and spatial frequency via feedforward input from the lateral geniculate nucleus (e.g., [1]). However, the role of nonretinal influence on early visual cortex is so far insufficiently investigated despite much evidence that feedback connections greatly outnumber feedforward connections [2–5]. Here, we explored in five fMRI experiments how information originating from audition and imagery affects the brain activity patterns in early visual cortex in the absence of any feedforward visual stimulation. We show that category-specific information from both complex natural sounds and imagery can be read out from early visual cortex activity in blindfolded participants. The coding of nonretinal information in the activity patterns of early visual cortex is common across actual auditory perception and imagery and may be mediated by higher-level multisensory areas. Furthermore, this coding is robust to mild manipulations of attention and working memory but affected by orthogonal, cognitively demanding visuospatial processing. Crucially, the information fed down to early visual cortex is category specific and generalizes to sound exemplars of the same category, providing evidence for abstract information feedback rather than precise pictorial feedback. Our results suggest that early visual cortex receives nonretinal input from other brain areas when it is generated by auditory perception and/or imagery, and this input carries common abstract information. Our findings are compatible with feedback of predictive information to the earliest visual input level (e.g., [6]), in line with predictive coding models [7–10]. PMID:24856208

Vetter, Petra; Smith, Fraser W.; Muckli, Lars

2014-01-01

381

Decoding sound and imagery content in early visual cortex.  

PubMed

Human early visual cortex was traditionally thought to process simple visual features such as orientation, contrast, and spatial frequency via feedforward input from the lateral geniculate nucleus (e.g., [1]). However, the role of nonretinal influence on early visual cortex is so far insufficiently investigated despite much evidence that feedback connections greatly outnumber feedforward connections [2-5]. Here, we explored in five fMRI experiments how information originating from audition and imagery affects the brain activity patterns in early visual cortex in the absence of any feedforward visual stimulation. We show that category-specific information from both complex natural sounds and imagery can be read out from early visual cortex activity in blindfolded participants. The coding of nonretinal information in the activity patterns of early visual cortex is common across actual auditory perception and imagery and may be mediated by higher-level multisensory areas. Furthermore, this coding is robust to mild manipulations of attention and working memory but affected by orthogonal, cognitively demanding visuospatial processing. Crucially, the information fed down to early visual cortex is category specific and generalizes to sound exemplars of the same category, providing evidence for abstract information feedback rather than precise pictorial feedback. Our results suggest that early visual cortex receives nonretinal input from other brain areas when it is generated by auditory perception and/or imagery, and this input carries common abstract information. Our findings are compatible with feedback of predictive information to the earliest visual input level (e.g., [6]), in line with predictive coding models [7-10]. PMID:24856208

Vetter, Petra; Smith, Fraser W; Muckli, Lars

2014-06-01

382

Thermochemoradiation Therapy Using Superselective Intra-arterial Infusion via Superficial Temporal and Occipital Arteries for Oral Cancer With N3 Cervical Lymph Node Metastases  

SciTech Connect

Purpose: To evaluate the therapeutic results and histopathological effects of treatment with thermochemoradiation therapy using superselective intra-arterial infusion via the superficial temporal and occipital arteries for N3 cervical lymph node metastases of advanced oral cancer. Methods and Materials: Between April 2005 and September 2010, 9 patients with N3 cervical lymph node metastases of oral squamous cell carcinoma underwent thermochemoradiation therapy using superselective intra-arterial infusion with docetaxel (DOC) and cisplatin (CDDP). Treatment consisted of hyperthermia (2-8 sessions), superselective intra-arterial infusions (DOC, total 40-60 mg/m{sup 2}; CDDP, total 100-150 mg/m{sup 2}) and daily concurrent radiation therapy (total, 40-60 Gy) for 4-6 weeks. Results: Six of 9 patients underwent neck dissection 5-8 weeks after treatment. In four of these 6 patients, all metastatic lymph nodes, including those at N3, were grade 3 (non-viable tumor cells present) or grade 4 (no tumor cells present) tumors, as classified by the system by Shimosato et al (Shimosato et al Jpn J Clin Oncol 1971;1:19-35). In 2 of these 6 patients, the metastatic lymph nodes were grade 2b (destruction of tumor structures with a small amount of residual viable tumor cells). The other 3 patients did not undergo neck dissection due to distant metastasis after completion of thermochemoradiation therapy (n=2) and refusal (n=1). The patient who refused neck dissection underwent biopsy of the N3 lymph node and primary sites and showed grade 3 cancer. During follow-up, 5 patients were alive without disease, and 4 patients died due to pulmonary metastasis (n=3) and noncancer-related causes (n=1). Five-year survival and locoregional control rates were 51% and 88%, respectively. Conclusions: Thermochemoradiation therapy using intra-arterial infusion provided good histopathologic effects and locoregional control rates in patients with N3 metastatic lymph nodes. However, patients with N3 metastatic lymph nodes experienced a high rate of distant metastases.

Mitsudo, Kenji, E-mail: mitsudo@yokohama-cu.ac.jp [Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama (Japan)] [Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama (Japan); Koizumi, Toshiyuki; Iida, Masaki; Iwai, Toshinori; Oguri, Senri [Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama (Japan)] [Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama (Japan); Yamamoto, Noriyuki [Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya (Japan)] [Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya (Japan); Itoh, Yoshiyuki [Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya (Japan)] [Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya (Japan); Kioi, Mitomu; Hirota, Makoto; Tohnai, Iwai [Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama (Japan)] [Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama (Japan)

2012-08-01

383

Resting-state fMRI reveals functional connectivity between face-selective perirhinal cortex and the fusiform face area related to face inversion.  

PubMed

Studies examining the neural correlates of face perception and recognition in humans have revealed multiple brain regions that appear to play a specialized role in face processing. These include an anterior portion of perirhinal cortex (PrC) that appears to be homologous to the face-selective 'anterior face patch' recently reported in non-human primates. Electrical stimulation studies in the macaque indicate that the anterior face patch is strongly connected with other face-selective patches of cortex, even in the absence of face stimuli. The intrinsic functional connectivity of face-selective PrC and other regions of the face-processing network in humans are currently less well understood. Here, we examined resting-state fMRI connectivity across five face-selective regions in the right hemisphere that were identified with separate functional localizer scans: the PrC, amygdala (Amg), superior temporal sulcus, fusiform face area (FFA), and occipital face area. A partial correlation technique, controlling for fluctuations in occipitotemporal cortex that were not face specific, revealed connectivity between the PrC and the FFA, as well as the Amg. When examining the 'unique' connectivity of PrC within this face processing network, we found that the connectivity between the PrC and the FFA as well as that between the PrC and the Amg persisted even after controlling for potential mediating effects of other face-selective regions. Lastly, we examined the behavioral relevance of PrC connectivity by examining inter-individual differences in resting-state fluctuations in relation to differences in behavioral performance for a forced-choice recognition memory task that involved judgments on upright and inverted faces. This analysis revealed a significant correlation between the increased accuracy for upright faces (i.e., the face inversion effect) and the strength of connectivity between the PrC and the FFA. Together, these findings point to a high degree of functional integration of face-selective aspects of PrC in the face processing network with notable behavioral relevance. PMID:24531049

O'Neil, Edward B; Hutchison, R Matthew; McLean, D Adam; Köhler, Stefan

2014-05-15

384

Distributed auditory sensory input within the mouse olfactory cortex.  

PubMed

The mammalian olfactory cortex is commonly considered critical for odor information processing and perception. It is becoming increasingly apparent, however, that the olfactory cortex receives input from multiple sensory channels. Previous work from our group demonstrated the presence of auditory sensory convergence within one olfactory cortical structure, the olfactory tubercle (OT). Interestingly, anatomical evidence for auditory input into the neighboring olfactory piriform cortex (PCX) posits the possibility that auditory sensory input is a distributed property of the olfactory cortex. To address this question, we performed in vivo extracellular recordings from the OT and PCX of anesthetized mice and measured modulations in unit firing in the presence of tones. In support for auditory sensory input being a distributed feature of the olfactory cortex, we found that 29% of units sampled within the PCX display tone-evoked responses. This population compares with that found within the OT using the same stimuli (37%). While overall tone-evoked response magnitudes were comparable between the two structures, tone signal : noise was significantly greater within the OT than in the PCX. No effect of tone frequency (1-55 kHz) was found within either structure, with most units being narrowly tuned to a single frequency. These results suggest that a major portion of odor-evoked output from the olfactory bulb (i.e. that entering the OT and PCX) is subject to auditory sensory input in a manner that may modulate odor information processing, odor-guided behaviors and perception. PMID:23189957

Varga, Adrienn G; Wesson, Daniel W

2013-02-01

385

Timing-dependent plasticity in human primary somatosensory cortex  

PubMed Central

Animal experiments suggest that cortical sensory representations may be remodelled as a consequence of changing synaptic efficacy by timing-dependent associative neuronal activity. Here we describe a timing-based associative form of plasticity in human somatosensory cortex. Paired associative stimulation (PAS) was performed by combining repetitive median nerve stimulation with transcranial magnetic stimulation (TMS) over the contralateral postcentral region. PAS increased exclusively the amplitude of the P25 component of the median nerve-evoked somatosensory-evoked potential (MN-SSEP), which is probably generated in the superficial cortical layers of area 3b. SSEP components reflecting neuronal activity in deeper cortical layers (N20 component) or subcortical regions (P14 component) remained constant. PAS-induced enhancement of P25 amplitude displayed topographical specificity both for the recording (MN-SSEP versus tibial nerve-SSEP) and the stimulation (magnetic stimulation targeting somatosensory versus motor cortex) arrangements. Modulation of P25 amplitude was confined to a narrow range of interstimulus intervals (ISIs) between the MN pulse and the TMS pulse, and the sign of the modulation changed with ISIs differing by only 15 ms. The function describing the ISI dependence of PAS effects on somatosensory cortex resembled one previously observed in motor cortex, shifted by ?7 ms. The findings suggest a simple model of modulation of excitability in human primary somatosensory cortex, possibly by mechanisms related to the spike-timing-dependent plasticity of neuronal synapses located in upper cortical layers. PMID:15845584

Wolters, Alexander; Schmidt, Arne; Schramm, Axel; Zeller, Daniel; Naumann, Markus; Kunesch, Erwin; Benecke, Reiner; Reiners, Karlheinz; Classen, Joseph

2005-01-01

386

Neurovascular Coupling and Decoupling in the Cortex during Voluntary Locomotion  

PubMed Central

Hemodynamic signals are widely used to infer neural activity in the brain. We tested the hypothesis that hemodynamic signals faithfully report neural activity during voluntary behaviors by measuring cerebral blood volume (CBV) and neural activity in the somatosensory cortex and frontal cortex of head-fixed mice during locomotion. Locomotion induced a large and robust increase in firing rate and gamma-band (40–100 Hz) power in the local field potential in the limb representations in somatosensory cortex, and was accompanied by increases in CBV, demonstrating that hemodynamic signals are coupled with neural activity in this region. However, in the frontal cortex, CBV did not change during locomotion, but firing rate and gamma-band power both increased, indicating a decoupling of neural activity from the hemodynamic signal. These results show that hemodynamic signals are not faithful indicators of the mean neural activity in the frontal cortex during locomotion; thus, the results from fMRI and other hemodynamic imaging methodologies for studying neural processes must be interpreted with caution. PMID:25122897

Huo, Bing-Xing; Smith, Jared B.

2014-01-01

387

Stimulating the Lip Motor Cortex with Transcranial Magnetic Stimulation  

PubMed Central

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception. Researchers have used single-pulse and repetitive TMS to stimulate the lip representation in the motor cortex. The excitability of the lip motor representation can be investigated by applying single TMS pulses over this cortical area and recording TMS-induced motor evoked potentials (MEPs) via electrodes attached to the lip muscles (electromyography; EMG). Larger MEPs reflect increased cortical excitability. Studies have shown that excitability increases during listening to speech as well as during viewing speech-related movements. TMS can be used also to disrupt the lip motor representation. A 15-min train of low-frequency sub-threshold repetitive stimulation has been shown to suppress motor excitability for a further 15-20 min. This TMS-induced disruption of the motor lip representation impairs subsequent performance in demanding speech perception tasks and modulates auditory-cortex responses to speech sounds. These findings are consistent with the suggestion that the motor cortex contributes to speech perception. This article describes how to localize the lip representation in the motor cortex and how to define the appropriate stimulation intensity for carrying out both single-pulse and repetitive TMS experiments. PMID:24962266

Möttönen, Riikka; Rogers, Jack; Watkins, Kate E.

2014-01-01

388

The Interplay between Estrogen and Fetal Adrenal Cortex  

PubMed Central

Estrogen is a steroid hormone that regulates embryogenesis, cell proliferation and differentiation, organogenesis, the timing of parturition, and fetal imprinting by carrying chemical messages from glands to cells within tissues or organs in the body. During development, placenta is the primary source of estrogen production but estrogen can only be produced if the fetus or the mother supplies dehydroepiandrosterone (DHEA), the estrogen prohormone. Studies show that the fetal zone of the fetal adrenal cortex supplies 60% of DHEA for placental estrogen production, and that placental estrogen in turn modulates the morphological and functional development of the fetal adrenal cortex. As such, in developed countries where humans are exposed daily to environmental estrogens, there is concern that the development of fetal adrenal cortex, and in turn, placental estrogen production may be disrupted. This paper discusses fetal adrenal gland development, how endogenous estrogen regulates the structure and function of the fetal adrenal cortex, and highlights the potential role that early life exposure to environmental estrogens may have on the development and endocrinology of the fetal adrenal cortex. PMID:22536492

Kaludjerovic, Jovana; Ward, Wendy E.

2012-01-01

389

Basilar artery pseudoaneurysm presenting at 5-month follow-up after traumatic atlanto-occipital dislocation in a 7-year-old girl treated with intracranial stent placement and coiling  

PubMed Central

Atlanto-occipital dislocation (AOD) is a grave injury that is rarely survivable. Patients who do survive often have long-term sequelae resulting from the intracranial damage sustained during the traumatic event. The high impact needed to cause AOD is translated to the intracranial vessels, which can lead to vascular injury. Pseudoaneurysm is one of the possible outcomes of damage to the vessel wall. We present a case of basilar artery pseudoaneurysm diagnosed 5?months after a traumatic AOD who was treated with intracranial stent placement and coiling. PMID:23389747

Griauzde, Julius; Gemmete, Joseph J; Chaudhary, Neeraj; Pandey, Aditya S; Garton, Hugh J

2013-01-01

390

Magnetic source imaging in posterior cortex epilepsies.  

PubMed

Posterior cortex epilepsies (PCE) are characterized by less satisfying postoperative results than temporal lobe epilepsies and are thus challenging for non-invasive presurgical investigations. The objective of this study was to evaluate the performance of magnetic source imaging (MSI) in PCE, validating the results by the SEEG (stereoelectroencephalography) definition of irritative and epileptogenic zones (IZ and EZ). Fourteen PCE surgery candidates were investigated using MSI and SEEG. LCMV (Linearly Constrained Minimum Variance) and MUSIC algorithms were used. IZ was quantified using a semi-automatic detection of interictal spikes. EZ was quantified using the epileptogenicity index (EI) method that accounts for both the propensity of a brain area to generate rapid discharges and the time for this area to get involved in the seizure. EI values range from 0 (no epileptogenicity) to 1 (maximal epileptogenicity). Levels of concordance between MSI and IZ, MSI and EZ were determined as follows: A = localized on MSI and SEEG for the site of value 1 (IZ and EZ quantification), B = localized on MSI and SEEG for a part of the IZ or a structure involved in the EZ (without the maximal value 1), C = localized on MSI and not SEEG, D = localized on SEEG and not MSI, E = localized on MSI and SEEG, discordant for site. Five PCE cases were characterized by focal IZ, nine by distributed IZ between several distant brain areas. MSI allowed to determinate IZ in 4/5 focal IZ cases. In case of distributed IZ, levels of concordance were A (2 cases), B (4 cases) and D (3 cases). In most distributed cases, MSI allowed to localize only a part of the IZ. Medial temporal involvement in the IZ was frequent (9/12 cases) and not evidenced by MSI. The brain area that demonstrated the maximal value of EI was shown by MSI in four out of five (80 %) focal IZ cases, in two out of nine (22 %) distributed cases. MSI results depend on IZ characteristics. A distributed IZ organization presents difficulties for MSI and highlights the need for further methodological approaches. PMID:25352165

Badier, Jean-Michel; Bartolomei, Fabrice; Chauvel, Patrick; Bénar, Christian-George; Gavaret, Martine

2015-01-01

391

The dynamics of visual responses in the primary visual cortex.  

PubMed

There is a transformation in behavior in the visual system of cats and primates, from neurons in the Lateral Geniculate Nucleus (LGN) that are not tuned for orientation to orientation-tuned cells in primary visual cortex (V1). The visual stimuli that excite V1 can be well controlled, and the thalamic inputs to V1 from the LGN have been measured precisely. Much has been learned about basic principles of cortical neurophysiology on account of the intense investigation of the transformation between LGN and V1. Here we present a discussion of different models for visual cortex and orientation selectivity, and then discuss our own experimental findings about the dynamics of orientation selectivity. We consider what these theoretical analyses and experimental results imply about cerebral cortical function. The conclusion is that there is a very important role for intracortical interactions, especially cortico-cortical inhibition, in producing neurons in the visual cortex highly selective for orientation. PMID:17925238

Shapley, Robert; Hawken, Michael; Xing, Dajun

2007-01-01

392

Double dissociation of 'what' and 'where' processing in auditory cortex.  

PubMed

Studies of cortical connections or neuronal function in different cerebral areas support the hypothesis that parallel cortical processing streams, similar to those identified in visual cortex, may exist in the auditory system. However, this model has not yet been behaviorally tested. We used reversible cooling deactivation to investigate whether the individual regions in cat nonprimary auditory cortex that are responsible for processing the pattern of an acoustic stimulus or localizing a sound in space could be doubly dissociated in the same animal. We found that bilateral deactivation of the posterior auditory field resulted in deficits in a sound-localization task, whereas bilateral deactivation of the anterior auditory field resulted in deficits in a pattern-discrimination task, but not vice versa. These findings support a model of cortical organization that proposes that identifying an acoustic stimulus ('what') and its spatial location ('where') are processed in separate streams in auditory cortex. PMID:18408717

Lomber, Stephen G; Malhotra, Shveta

2008-05-01

393

Associative Hebbian Synaptic Plasticity in Primate Visual Cortex  

PubMed Central

In primates, the functional connectivity of adult primary visual cortex is susceptible to be modified by sensory training during perceptual learning. It is widely held that this type of neural plasticity might involve mechanisms like long-term potentiation (LTP) and long-term depression (LTD). NMDAR-dependent forms of LTP and LTD are particularly attractive because in rodents they can be induced in a Hebbian manner by near coincidental presynaptic and postsynaptic firing, in a paradigm termed spike timing-dependent plasticity (STDP). These fundamental properties of LTP and LTD, Hebbian induction and NMDAR dependence, have not been examined in primate cortex. Here we demonstrate these properties in the primary visual cortex of the rhesus macaque (Macaca mulatta), and also show that, like in rodents, STDP is gated by neuromodulators. These findings indicate that the cellular principles governing cortical plasticity are conserved across mammalian species, further validating the use of rodents as a model system. PMID:24872561

Huang, Shiyong; Rozas, Carlos; Treviño, Mario; Contreras, Jessica; Yang, Sunggu; Song, Lihua; Yoshioka, Takashi; Lee, Hey-Kyoung

2014-01-01

394

Regional increase of cerebral cortex thickness in juvenile myoclonic epilepsy.  

PubMed

The goal of this study was to characterize cerebral cortex thickness patterns in juvenile myoclonic epilepsy (JME). Surface-based morphometry (SBM) was applied to process brain magnetic resonance images acquired from 24 patients with JME and 40 healthy controls and quantify cerebral cortex thickness. Differences in cortical thickness between patients and controls were determined using generalized linear model (covariates: age and gender). In patients with JME, thickness increase was detected bilaterally within localized regions in the orbitofrontal and mesial frontal cortices. Such thickness patterns coexisted with significant bilateral reduction in thalamic volume. These findings confirm that the underlying mechanisms in JME are related to aberrant corticothalamic structure and indicate that frontal cortex abnormalities are possibly linked to regional increase in cerebral cortical thickness. PMID:23944956

Alhusaini, Saud; Ronan, Lisa; Scanlon, Cathy; Whelan, Christopher D; Doherty, Colin P; Delanty, Norman; Fitzsimons, Mary

2013-09-01

395

Topological analysis of population activity in visual cortex  

PubMed Central

Information in the cortex is thought to be represented by the joint activity of neurons. Here we describe how fundamental questions about neural representation can be cast in terms of the topological structure of population activity. A new method, based on the concept of persistent homology, is introduced and applied to the study of population activity in primary visual cortex (V1). We found that the topological structure of activity patterns when the cortex is spontaneously active is similar to those evoked by natural image stimulation and consistent with the topology of a two sphere. We discuss how this structure could emerge from the functional organization of orientation and spatial frequency maps and their mutual relationship. Our findings extend prior results on the relationship between spontaneous and evoked activity in V1 and illustrates how computational topology can help tackle elementary questions about the representation of information in the nervous system. PMID:18831634

Singh, Gurjeet; Memoli, Facundo; Ishkhanov, Tigran; Sapiro, Guillermo; Carlsson, Gunnar; Ringach, Dario L.

2009-01-01

396

Spatiotemporal dynamics underlying object completion in human ventral visual cortex.  

PubMed

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. PMID:25043420

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

2014-08-01

397

Task context impacts visual object processing differentially across the cortex.  

PubMed

Perception reflects an integration of "bottom-up" (sensory-driven) and "top-down" (internally generated) signals. Although models of visual processing often emphasize the central role of feed-forward hierarchical processing, less is known about the impact of top-down signals on complex visual representations. Here, we investigated whether and how the observer's goals modulate object processing across the cortex. We examined responses elicited by a diverse set of objects under six distinct tasks, focusing on either physical (e.g., color) or conceptual properties (e.g., man-made). Critically, the same stimuli were presented in all tasks, allowing us to investigate how task impacts the neural representations of identical visual input. We found that task has an extensive and differential impact on object processing across the cortex. First, we found task-dependent representations in the ventral temporal and prefrontal cortex. In particular, although object identity could be decoded from the multivoxel response within task, there was a significant reduction in decoding across tasks. In contrast, the early visual cortex evidenced equivalent decoding within and across tasks, indicating task-independent representations. Second, task information was pervasive and present from the earliest stages of object processing. However, although the responses of the ventral temporal, prefrontal, and parietal cortex enabled decoding of both the type of task (physical/conceptual) and the specific task (e.g., color), the early visual cortex was not sensitive to type of task and could only be used to decode individual physical tasks. Thus, object processing is highly influenced by the behavioral goal of the observer, highlighting how top-down signals constrain and inform the formation of visual representations. PMID:24567402

Harel, Assaf; Kravitz, Dwight J; Baker, Chris I

2014-03-11

398

The Organization of Dorsal Frontal Cortex in Humans and Macaques  

PubMed Central

The human dorsal frontal cortex has been associated with the most sophisticated aspects of cognition, including those that are thought to be especially refined in humans. Here we used diffusion-weighted magnetic resonance imaging (DW-MRI) and functional MRI (fMRI) in humans and macaques to infer and compare the organization of dorsal frontal cortex in the two species. Using DW-MRI tractography-based parcellation, we identified 10 dorsal frontal regions lying between the human inferior frontal sulcus and cingulate cortex. Patterns of functional coupling between each area and the rest of the brain were then estimated with fMRI and compared with functional coupling patterns in macaques. Areas in human medial frontal cortex, including areas associated with high-level social cognitive processes such as theory of mind, showed a surprising degree of similarity in their functional coupling patterns with the frontal pole, medial prefrontal, and dorsal prefrontal convexity in the macaque. We failed to find evidence for “new” regions in human medial frontal cortex. On the lateral surface, comparison of functional coupling patterns suggested correspondences in anatomical organization distinct from those that are widely assumed. A human region sometimes referred to as lateral frontal pole more closely resembled area 46, rather than the frontal pole, of the macaque. Overall the pattern of results suggest important similarities in frontal cortex organization in humans and other primates, even in the case of regions thought to carry out uniquely human functions. The patterns of interspecies correspondences are not, however, always those that are widely assumed. PMID:23884933

Mars, Rogier B.; Noonan, MaryAnn P.; Neubert, Franz-Xaver; Jbabdi, Saad; O'Reilly, Jill X.; Filippini, Nicola; Thomas, Adam G.; Rushworth, Matthew F.

2013-01-01

399

Similarities between GCS and human motor cortex: complex movement coordination  

NASA Astrophysics Data System (ADS)

The "Gran Telescopio de Canarias" (GTC1) is an optical-infrared 10-meter segmented mirror telescope at the ORM observatory in Canary Islands (Spain). The GTC control system (GCS), the brain of the telescope, is is a distributed object & component oriented system based on RT-CORBA and it is responsible for the management and operation of the telescope, including its instrumentation. On the other hand, the Human motor cortex (HMC) is a region of the cerebrum responsible for the coordination of planning, control, and executing voluntary movements. If we analyze both systems, as far as the movement control of their mechanisms and body parts is concerned, we can find extraordinary similarities in their architectures. Both are structured in layers, and their functionalities are comparable from the movement conception until the movement action itself: In the GCS we can enumerate the Sequencer high level components, the Coordination libraries, the Control Kit library and the Device Driver library as the subsystems involved in the telescope movement control. If we look at the motor cortex, we can also enumerate the primary motor cortex, the secondary motor cortices, which include the posterior parietal cortex, the premotor cortex, and the supplementary motor area (SMA), the motor units, the sensory organs and the basal ganglia. From all these components/areas we will analyze in depth the several subcortical regions, of the the motor cortex, that are involved in organizing motor programs for complex movements and the GCS coordination framework, which is composed by a set of classes that allow to the high level components to transparently control a group of mechanisms simultaneously.

Rodríguez, Jose A.; Macias, Rosa; Molgo, Jordi; Guerra, Dailos

2014-07-01

400

Task context impacts visual object processing differentially across the cortex  

PubMed Central

Perception reflects an integration of “bottom-up” (sensory-driven) and “top-down” (internally generated) signals. Although models of visual processing often emphasize the central role of feed-forward hierarchical processing, less is known about the impact of top-down signals on complex visual representations. Here, we investigated whether and how the observer’s goals modulate object processing across the cortex. We examined responses elicited by a diverse set of objects under six distinct tasks, focusing on either physical (e.g., color) or conceptual properties (e.g., man-made). Critically, the same stimuli were presented in all tasks, allowing us to investigate how task impacts the neural representations of identical visual input. We found that task has an extensive and differential impact on object processing across the cortex. First, we found task-dependent representations in the ventral temporal and prefrontal cortex. In particular, although object identity could be decoded from the multivoxel response within task, there was a significant reduction in decoding across tasks. In contrast, the early visual cortex evidenced equivalent decoding within and across tasks, indicating task-independent representations. Second, task information was pervasive and present from the earliest stages of object processing. However, although the responses of the ventral temporal, prefrontal, and parietal cortex enabled decoding of both the type of task (physical/conceptual) and the specific task (e.g., color), the early visual cortex was not sensitive to type of task and could only be used to decode individual physical tasks. Thus, object processing is highly influenced by the behavioral goal of the observer, highlighting how top-down signals constrain and inform the formation of visual representations. PMID:24567402

Harel, Assaf; Kravitz, Dwight J.; Baker, Chris I.

2014-01-01

401

Primary somatosensory cortex hand representation dynamically modulated by motor output.  

PubMed

The brain's primary motor and primary somatosensory cortices are generally viewed as functionally distinct entities. Here we show by means of magnetoencephalography with a phantom-limb patient, that movement of the phantom hand leads to a change in the response of the primary somatosensory cortex to tactile stimulation. This change correlates with the described conscious perception and suggests a greater degree of functional unification between the primary motor and somatosensory cortices than is currently realized. We suggest that this may reflect the evolution of this part of the human brain, which is thought to have occurred from an undifferentiated sensorimotor cortex. PMID:24433220

McGeoch, Paul D; Brang, David; Huang, Mingxiong; Ramachandran, V S

2015-02-01

402

Plasticity in the prefrontal cortex of adult rats  

PubMed Central

We review the plastic changes of the prefrontal cortex of the rat in response to a wide range of experiences including sensory and motor experience, gonadal hormones, psychoactive drugs, learning tasks, stress, social experience, metaplastic experiences, and brain injury. Our focus is on synaptic changes (dendritic morphology and spine density) in pyramidal neurons and the relationship to behavioral changes. The most general conclusion we can reach is that the prefrontal cortex is extremely plastic and that the medial and orbital prefrontal regions frequently respond very differently to the same experience in the same brain and the rules that govern prefrontal plasticity appear to differ for those of other cortical regions. PMID:25691857

Kolb, Bryan; Gibb, Robbin

2015-01-01

403

Using speech and electrocorticography to map human auditory cortex.  

PubMed

Much less is known about the organization of the human auditory cortex compared to non-human primate auditory cortices. In an effort to further investigate the response properties of human auditory cortex, we present preliminary findings from human subjects implanted with depth electrodes in Heschl's gyrus (HG) as part of their neurosurgical treatment of epilepsy. Each subject had electrocorticography (ECoG) responses taken from medial and lateral HG in response to both speech and non-speech stimuli, including during speech production. Responses were somewhat variable across subjects, but posteromedial HG demonstrated frequency following responses to the stimuli in all subjects to some degree. Results and implications are discussed. PMID:25571557

Greenlee, Jeremy D W; Behroozmand, Roozbeh; Nourski, Kirill V; Oya, Hiroyuki; Kawasaki, Hiroto; Howard, Matthew A

2014-08-01

404

Speech hastening during electrical stimulation of left premotor cortex.  

PubMed

Cortical and axonal electrical stimulation of left premotor cortex and SMA during awake brain surgery yielded unique behavioral responses. In two patients, there was involuntary acceleration of speech (i.e., speech hastening) during a counting or picture naming task. In one patient, stimulation led to a deceleration of the rate with which three different tasks were performed (arm movements, finger tapping and counting). Possible explanatory mechanisms are discussed, and the literature on so-called "negative motor areas" is shortly reviewed. It is argued that the function of loops between cortex and basal ganglia were modulated via stimulation of frontostriatal and/or fronto-opercular pathways. PMID:25544638

Rutten, Geert-Jan

2015-02-01

405

SPEECH-CODING AND TRAINING-INDUCED PLASTICITY IN AUDITORY CORTEX OF NORMAL AND DYSLEXIA  

E-print Network

SPEECH-CODING AND TRAINING-INDUCED PLASTICITY IN AUDITORY CORTEX OF NORMAL AND DYSLEXIA MODEL RATS anymore... #12;SPEECH-CODING AND TRAINING-INDUCED PLASTICITY IN AUDITORY CORTEX OF NORMAL AND DYSLEXIA

Kilgard, Michael P.

406

White matter hyperintensities and amyloid are independently associated with entorhinal cortex volume among individuals with mild  

E-print Network

White matter hyperintensities and amyloid are independently associated with entorhinal cortex of Alzheimer's disease (AD) pathogenesis emphasize the role of b-amyloid (Ab), tau deposition-weighted magnetic resonance imaging scans. We examined the association between entorhinal cortex volume

407

Computational Modeling of Orientation Tuning Dynamics in Monkey Primary Visual Cortex  

E-print Network

Computational Modeling of Orientation Tuning Dynamics in Monkey Primary Visual Cortex M. C. Pugh, D, monkey, primary visual cortex, lay­ ers. 1 #12; Introduction How visual cells in the primary visual

Pugh, Mary

408

The right parietal cortex and time perception: back to Critchley and the Zeitraffer phenomenon  

Microsoft Academic Search

We investigated the involvement of the posterior parietal cortex in time perception by temporarily disrupting normal functioning in this region, in subjects making prospective judgements of time or pitch. Disruption of the right posterior parietal cortex significantly slowed reaction times when making time, but not pitch, judgements. Similar interference with the left parietal cortex and control stimulation over the vertex

Iona Alexander; Alan Cowey; Vincent Walsh

2005-01-01

409

RAPID COMMUNICATION Attention-Regulated Activity in Human Primary Visual Cortex  

E-print Network

RAPID COMMUNICATION Attention-Regulated Activity in Human Primary Visual Cortex TAKEO WATANABE,1 known history of neurological dis-visual cortex. J. Neurophysiol. 79: 2218­2221, 1998. Effects of ease visual cortex (area V1) were examined. Local cerebral oxygenation changes (an index of neuronal activity

Watanabe, Takeo

410

The retrosplenial cortex and emotion: new insights from functional neuroimaging of the human brain  

Microsoft Academic Search

Little is known about the function of the retrosplenial cortex and until recently, there was no evidence that it had any involvement in emotional processes. Surprisingly, recent functional neuroimaging studies show that the retrosplenial cortex is consistently activated by emotionally salient words. A review of the functional neuroimaging literature reveals a previously overlooked pattern of observations: the retrosplenial cortex is

Richard J. Maddock

1999-01-01

411

Impaired Error-Likelihood Prediction in Medial Prefrontal Cortex in Schizophrenia  

E-print Network

Ã?Ã? Ã? Ã?Ã?Ã? Ã? Ã?Ã? Impaired Error-Likelihood Prediction in Medial Prefrontal Cortex in Schizophrenia Prefrontal Cortex in Schizophrenia, NeuroImage (2010), doi: 10.1016/j.neuroimage.2010.09.027 This is a PDF-Likelihood Prediction in Medial Prefrontal Cortex in Schizophrenia Adam Krawitza* , Todd S. Braverb , Deanna M. Barchb

412

The Functional Organization and Cortical Connections of Motor Cortex in Squirrels Dylan F. Cooke1  

E-print Network

the topographic organization of motor cortex in the Eastern gray squirrel (Sciurus carolinensis) and corticalThe Functional Organization and Cortical Connections of Motor Cortex in Squirrels Dylan F. Cooke1 connec- tions of motor cortex in the California ground squirrel (Spermophi- lus beecheyi). We distinguish

Krubitzer, Leah A.

413

Cerebral Cortex doi:10.1093/cercor/bhs068  

E-print Network

Cerebral Cortex doi:10.1093/cercor/bhs068 Boosting Human Learning by Hypnosis Dezso Nemeth1 in striatum-related procedural learning. In our study, hypnosis was used as a tool to reduce the competition between these 2 systems. We compared learning in hypnosis and in the alert state and found that hypnosis

Nemeth, Dezso

414

Model of Familiarity Discrimination in the Perirhinal Cortex  

Microsoft Academic Search

Much evidence indicates that recognition memory involves two separable processes, recollection and familiarity discrimination, with familiarity discrimination being dependent on the perirhinal cortex of the temporal lobe. Here, we describe a new neural network model designed to mimic the response patterns of perirhinal neurons that signal information concerning the novelty or familiarity of stimuli. The model achieves very fast and

Rafal Bogacz; Malcolm W. Brown; Christophe G. Giraud-carrier

2001-01-01

415

Role of Frontal Cortex in Attentional Capture by Singleton Distractors  

ERIC Educational Resources Information Center

The role of frontal cortex in selective attention to visual distractors was examined in an attentional capture task in which participants searched for a unique shape in the presence or absence of an additional colour singleton distractor. The presence of the additional singleton was associated with slower behavioural responses to the shape target,…

de Fockert, Jan W.; Theeuwes, Jan