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1

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

PubMed

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 ms). Rather, the earliest effects were observed within the timeframe of the N1 component (160-200 ms) 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, Emmajane; Foxe, John J

2012-11-28

2

Neurochemical changes within human early blind occipital cortex.  

PubMed

Early blindness results in occipital cortex neurons responding to a wide range of auditory and tactile stimuli. These changes in tuning properties are accompanied by an extensive reorganization of the occipital cortex that includes alterations in anatomical structure, neurochemical and metabolic pathways. Although it has been established in animal models that neurochemical pathways are heavily affected by early visual deprivation, the effects of blindness on these pathways in humans is still not well characterized. Here, using (1)H magnetic resonance spectroscopy in nine early blind and normally sighted subjects, we find that early blindness is associated with higher levels of creatine, choline and myo-Inositol and indications of lower levels of GABA within the occipital cortex. These results suggest that the cross-modal responses associated with early blindness may, at least in part, be driven by changes within occipital biochemical pathways. PMID:23954804

Weaver, K E; Richards, T L; Saenz, M; Petropoulos, H; Fine, I

2013-08-14

3

Hyperphosphorylated tau in the occipital cortex in aged nondemented subjects.  

PubMed

To determine the extent of neurodegeneration of the visual association cortex, we assessed hyperphosphorylated tau-immunoreactive (HPtau-IR) neurofibrillary tangles in Brodmann Areas 18/19 in nondemented and demented subjects. At least occasional HPtau-IR neurofibrillary tangles were seen in 24% of 59 nondemented subjects with ages at death ranging from 42 to 87 years. The incidence increased to 41% in the 32 nondemented subjects who had HPtau-IR pathology in the hippocampal region. Demented subjects with Braak Stages 0 to III and corticobasal degeneration, frontotemporal lobar degeneration with TAR DNA binding protein 43, vascular cognitive impairment, or dementia with Lewy bodies also had HPtau-IR pathology in Brodmann Areas 18/19. These results support the concept that the occipital association area may have enhanced vulnerability to neurodegeneration. Neuropathologic assessment of these areas is, therefore, recommended, particularly in subjects suspected or known to have had mild cognitive impairment. Occasional HPtau-IR lesions were also seen in the medial temporal gyrus. Thus, the question as to whether scattered HPtau-IR lesions in either temporal or occipital cortex indicate a neurodegenerative disease remains unresolved. Further systematic clinicopathologic studies are needed for an understanding of regional susceptibility to neurodegeneration and the significance of scattered HPtau-IR brain lesions. PMID:19458543

Pikkarainen, Maria; Kauppinen, Tarja; Alafuzoff, Irina

2009-06-01

4

Visually Evoked Responses from Non-Occipital Areas of the Human Cortex.  

National Technical Information Service (NTIS)

Visually evoked neuromagnetic responses from the central area of the cerebral cortex in addition to the usual responses from the occipital areas of primary visual cortex are observed when the velocity of a moving grating pattern was modulated sinusoidally...

O. V. Lounasmaa S. J. Williamson L. Kaufman R. Tanenbaum

1984-01-01

5

Topiramate modulates excitability of the occipital cortex when measured by transcranial magnetic stimulation  

Microsoft Academic Search

The aim of this study was to measure differences in occipital cortex excitability in migraineurs before and after administration of topiramate. We have previously demonstrated occipital cortex hyperexcitability in migraine using an objective technique of magnetic suppression of perceptual accuracy (MSPA). We hypothesized that a neuromodulator such as topiramate would demonstrate differences in MSPA in migraine compared with baseline. Ten

SK Aurora; PM Barrodale; AR Vermaas; CB Rudra

2010-01-01

6

Parieto-occipital cortex and planning of reaching movements: A transcranial magnetic stimulation study  

Microsoft Academic Search

A large amount of evidence supports a role for the parietal and frontal cortex in the planning of reaching movements. Nevertheless, neither the timing of involvement of these areas nor if and how their activity can be influenced by external stimuli has been clarified. The parieto-occipital cortex has been investigated by applying transcranial magnetic stimulation (TMS) at 25% (Time 1),

Pierpaolo Busan; Fabrizio Monti; Mauro Semenic; Gilberto Pizzolato; Piero Paolo Battaglini

2009-01-01

7

TMS of the occipital cortex induces tactile sensations in the fingers of blind Braille readers.  

PubMed

Various non-visual inputs produce cross-modal responses in the visual cortex of early blind subjects. In order to determine the qualitative experience associated with these occipital activations, we systematically stimulated the entire occipital cortex using single pulse transcranial magnetic stimulation (TMS) in early blind subjects and in blindfolded seeing controls. Whereas blindfolded seeing controls reported only phosphenes following occipital cortex stimulation, some of the blind subjects reported tactile sensations in the fingers that were somatotopically organized onto the visual cortex. The number of cortical sites inducing tactile sensations appeared to be related to the number of hours of Braille reading per day, Braille reading speed and dexterity. These data, taken in conjunction with previous anatomical, behavioural and functional imaging results, suggest the presence of a polysynaptic cortical pathway between the somatosensory cortex and the visual cortex in early blind subjects. These results also add new evidence that the activity of the occipital lobe in the blind takes its qualitative expression from the character of its new input source, therefore supporting the cortical deference hypothesis. PMID:17717652

Ptito, M; Fumal, A; de Noordhout, A Martens; Schoenen, J; Gjedde, A; Kupers, R

2007-08-24

8

Shape-specific activation of occipital cortex in an early blind echolocation expert.  

PubMed

We have previously reported that an early-blind echolocating individual (EB) showed robust occipital activation when he identified distant, silent objects based on echoes from his tongue clicks (Thaler, Arnott, & Goodale, 2011). In the present study we investigated the extent to which echolocation activation in EB's occipital cortex reflected general echolocation processing per se versus feature-specific processing. In the first experiment, echolocation audio sessions were captured with in-ear microphones in an anechoic chamber or hallway alcove as EB produced tongue clicks in front of a concave or flat object covered in aluminum foil or a cotton towel. All eight echolocation sessions (2 shapes×2 surface materials×2 environments) were then randomly presented to him during a sparse-temporal scanning fMRI session. While fMRI contrasts of chamber versus alcove-recorded echolocation stimuli underscored the importance of auditory cortex for extracting echo information, main task comparisons demonstrated a prominent role of occipital cortex in shape-specific echo processing in a manner consistent with latent, multisensory cortical specialization. Specifically, relative to surface composition judgments, shape judgments elicited greater BOLD activity in ventrolateral occipital areas and bilateral occipital pole. A second echolocation experiment involving shape judgments of objects located 20° to the left or right of straight ahead activated more rostral areas of EB's calcarine cortex relative to location judgments of those same objects and, as we previously reported, such calcarine activity was largest when the object was located in contralateral hemispace. Interestingly, other echolocating experts (i.e., a congenitally blind individual in Experiment 1, and a late blind individual in Experiment 2) did not show the same pattern of feature-specific echo-processing calcarine activity as EB, suggesting the possible significance of early visual experience and early echolocation training. Together, our findings indicate that the echolocation activation in EB's occipital cortex is feature-specific, and that these object representations appear to be organized in a topographic manner. PMID:23391560

Arnott, Stephen R; Thaler, Lore; Milne, Jennifer L; Kish, Daniel; Goodale, Melvyn A

2013-02-04

9

Changes in occipital cortex activity in early blind humans using a sensory substitution device  

Microsoft Academic Search

The purpose of this study was to investigate the neural networks involved when using an ultrasonic echolocation device, which is a substitution prosthesis for blindness through audition. Using positron emission tomography with fluorodeoxyglucose, regional brain glucose metabolism was measured in the occipital cortex of early blind subjects and blindfolded controls who were trained to use this prosthesis. All subjects were

Anne G De Volder; Mitzi Catalan-Ahumada; Annie Robert; Anne Bol; Daniel Labar; Ann Coppens; Christian Michel; Claude Veraart

1999-01-01

10

Relevance of Spectral Cues for Auditory Spatial Processing in the Occipital Cortex of the Blind  

PubMed Central

We have previously shown that some blind individuals can localize sounds more accurately than their sighted counterparts when one ear is obstructed, and that this ability is strongly associated with occipital cortex activity. Given that spectral cues are important for monaurally localizing sounds when one ear is obstructed, and that blind individuals are more sensitive to small spectral differences, we hypothesized that enhanced use of spectral cues via occipital cortex mechanisms could explain the better performance of blind individuals in monaural localization. Using positron-emission tomography (PET), we scanned blind and sighted persons as they discriminated between sounds originating from a single spatial position, but with different spectral profiles that simulated different spatial positions based on head-related transfer functions. We show here that a sub-group of early blind individuals showing superior monaural sound localization abilities performed significantly better than any other group on this spectral discrimination task. For all groups, performance was best for stimuli simulating peripheral positions, consistent with the notion that spectral cues are more helpful for discriminating peripheral sources. PET results showed that all blind groups showed cerebral blood flow increases in the occipital cortex; but this was also the case in the sighted group. A voxel-wise covariation analysis showed that more occipital recruitment was associated with better performance across all blind subjects but not the sighted. An inter-regional covariation analysis showed that the occipital activity in the blind covaried with that of several frontal and parietal regions known for their role in auditory spatial processing. Overall, these results support the notion that the superior ability of a sub-group of early-blind individuals to localize sounds is mediated by their superior ability to use spectral cues, and that this ability is subserved by cortical processing in the occipital cortex.

Voss, Patrice; Lepore, Franco; Gougoux, Frederic; Zatorre, Robert J.

2011-01-01

11

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

2013-07-05

12

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

13

Stimulation of the occipital or retrosplenial cortex reduces incision pain in rats  

Microsoft Academic Search

The electrical stimulation of the occipital (OC) or retrosplenial (RSC) cortex produces antinociception in the rat tail-flick and formalin tests. This study examined the antinociceptive effects of stimulating the OC or RSC in a rat model of post-incision pain. The involvement of the anterior pretectal nucleus (APtN) as intermediary for the effect of OC or RSC stimulation was also evaluated

Ana Carolina Rossaneis; Gláucia Melo Reis; Wiliam A. Prado

2011-01-01

14

Nonlinear coupling between occipital and motor cortex during motor imagery: a dynamic causal modeling study.  

PubMed

We demonstrate the capacity of dynamic causal modeling to characterize the nonlinear coupling among cortical sources that underlie time-frequency modulations in MEG data. Our experimental task involved the mental rotation of hand drawings that ten subjects used to decide if it was a right or left hand. Reaction times were shorter when the stimuli were presented with a small rotation angle (fast responses) compared to a large rotation angle (slow responses). The grand-averaged data showed that in both cases performance was accompanied by a marked increase in gamma activity in occipital areas and a concomitant decrease in alpha and beta power in occipital and motor regions. Modeling directed (cross) frequency interactions between the two regions revealed that after the stimulus induced a gamma increase and beta decrease in occipital regions, interactions with the motor area served to attenuate these modulations. The difference between fast and slow behavioral responses was manifest as an altered coupling strength in both forward and backward connections, which led to a less pronounced attenuation for more difficult (slow reaction time) trials. This was mediated by a (backwards) beta to gamma coupling from motor till occipital sources, whereas other interactions were mainly within the same frequency. Results are consistent with the theory of predictive coding and suggest that during motor imagery, the influence of motor areas on activity in occipital cortex co-determines performance. Our study illustrates the benefit of modeling experimental responses in terms of a generative model that can disentangle the contributions of intra-areal vis-à-vis inter-areal connections to time-frequency modulations during task performance. PMID:23313570

van Wijk, B C M; Litvak, V; Friston, K J; Daffertshofer, A

2013-01-11

15

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

PubMed

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

2013-08-05

16

Frontal-Occipital Connectivity During Visual Search  

PubMed Central

Abstract Although expectation- and attention-related interactions between ventral and medial prefrontal cortex and stimulus category-selective visual regions have been identified during visual detection and discrimination, it is not known if similar neural mechanisms apply to other tasks such as visual search. The current work tested the hypothesis that high-level frontal regions, previously implicated in expectation and visual imagery of object categories, interact with visual regions associated with object recognition during visual search. Using functional magnetic resonance imaging, subjects searched for a specific object that varied in size and location within a complex natural scene. A model-free, spatial-independent component analysis isolated multiple task-related components, one of which included visual cortex, as well as a cluster within ventromedial prefrontal cortex (vmPFC), consistent with the engagement of both top-down and bottom-up processes. Analyses of psychophysiological interactions showed increased functional connectivity between vmPFC and object-sensitive lateral occipital cortex (LOC), and results from dynamic causal modeling and Bayesian Model Selection suggested bidirectional connections between vmPFC and LOC that were positively modulated by the task. Using image-guided diffusion-tensor imaging, functionally seeded, probabilistic white-matter tracts between vmPFC and LOC, which presumably underlie this effective interconnectivity, were also observed. These connectivity findings extend previous models of visual search processes to include specific frontal–occipital neuronal interactions during a natural and complex search task.

Pantazatos, Spiro P.; Yanagihara, Ted K.; Zhang, Xian; Meitzler, Thomas

2012-01-01

17

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.

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

2012-01-01

18

Recruitment of Occipital Cortex during Sensory Substitution Training Linked to Subjective Experience of Seeing in People with Blindness  

PubMed Central

Over three months of intensive training with a tactile stimulation device, 18 blind and 10 blindfolded seeing subjects improved in their ability to identify geometric figures by touch. Seven blind subjects spontaneously reported ‘visual qualia’, the subjective sensation of seeing flashes of light congruent with tactile stimuli. In the latter subjects tactile stimulation evoked activation of occipital cortex on electroencephalography (EEG). None of the blind subjects who failed to experience visual qualia, despite identical tactile stimulation training, showed EEG recruitment of occipital cortex. None of the blindfolded seeing humans reported visual-like sensations during tactile stimulation. These findings support the notion that the conscious experience of seeing is linked to the activation of occipital brain regions in people with blindness. Moreover, the findings indicate that provision of visual information can be achieved through non-visual sensory modalities which may help to minimize the disability of blind individuals, affording them some degree of object recognition and navigation aid.

Ortiz, Tomas; Poch, Joaquin; Santos, Juan M.; Requena, Carmen; Martinez, Ana M.; Ortiz-Teran, Laura; Turrero, Agustin; Barcia, Juan; Nogales, Ramon; Calvo, Agustin; Martinez, Jose M.; Cordoba, Jose L.; Pascual-Leone, Alvaro

2011-01-01

19

Response properties of auditory activated cells in the occipital cortex of the blind mole rat: an electrophysiological study  

Microsoft Academic Search

Previous studies have demonstrated that despite its blindness, the subterranean blind mole rat ( Spalax ehrenbergi) possesses a noticeable lateral geniculate nucleus and a typical cyto-architectural occipital cortex that are reciprocally connected. These two areas, as revealed by the metabolic tracer 2-deoxyglucose, are activated by auditory stimuli. Using single unit recordings, we show that about 57% of 325 cells located

R. S. Sadka; Z. Wollberg

2004-01-01

20

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

2012-08-07

21

Functional MRI activity in the thalamus and occipital cortex of anesthetized dogs induced by monocular and binocular stimulation.  

PubMed Central

The neuroanatomy of the mammalian visual system has received considerable attention through electrophysiological study of cats and non-human primates, and through neuroimaging of humans. Canine neuroanatomy, however, has received much less attention, limiting our understanding of canine vision and visual pathways. As an early step in applying blood oxygenation level dependant (BOLD) functional magnetic resonance imaging (fMRI) for veterinary use, we compared visual activity in the thalamus and occipital cortex of anesthetized dogs presented with binocular and monocular visual stimuli. Activity in the left and right thalamus and occipital cortex during monocular stimulation was also compared. Six beagles were presented with a vertical grating visual stimulus and scanned at 4 Tesla. Each dog was scanned twice under each of 3 anesthetic protocols (isoflurane, propofol, and fentanyl/midazolam). We found: 1) significant BOLD activation in the lateral geniculate nucleus (LGN) of the thalamus and the occipital cortex; 2) a significantly larger area of activation in the LGN during monocular stimulation than during binocular stimulation; and 3) that activity in the hemisphere contralateral to the stimulus was not significantly greater than that ipsilateral to it. Images Figure 1.

Willis, C K; Quinn, R P; McDonell, W M; Gati, J; Partlow, G; Vilis, T

2001-01-01

22

rTMS of the occipital cortex abolishes Braille reading and repetition priming in blind subjects.  

PubMed

To study the functional involvement of the visual cortex in Braille reading, we applied repetitive transcranial magnetic stimulation (rTMS) over midoccipital (MOC) and primary somatosensory (SI) cortex in blind subjects. After rTMS of MOC, but not SI, subjects made significantly more errors and showed an abolishment of the improvement in reading speed following repetitive presentation of the same word list, suggesting a role of the visual cortex in repetition priming in the blind. PMID:17325278

Kupers, R; Pappens, M; de Noordhout, A Maertens; Schoenen, J; Ptito, M; Fumal, A

2007-02-27

23

Hemispheric differences in frontal and parietal influences on human occipital cortex: Direct confirmation with concurrent TMS-fMRI  

PubMed Central

We used concurrent TMS-fMRI to test directly for hemispheric differences in causal influences of right or left fronto-parietal cortex on activity (BOLD signal) in human occipital cortex. Clinical data and some behavioral TMS studies have been taken to suggest right-hemisphere specialization for top-down modulation of vision in humans, based on deficits such as spatial neglect or extinction in lesioned patients, or findings that TMS to right (versus left) fronto-parietal structures can elicit stronger effects on visual performance. But prior to the recent advent of concurrent TMS and neuroimaging, it was not possible to directly examine the causal impact of one (stimulated) brain region upon others in humans. Here we stimulated frontal or intraparietal cortex in the left or right hemisphere with TMS, inside an MR scanner, while measuring with fMRI any resulting BOLD signal changes in visual areas V1-V4 and V5/MT+. For both frontal and parietal stimulation, we found clear differences between effects of right- versus left-hemisphere TMS on activity in visual cortex, with all differences significant in direct statistical comparisons. Frontal TMS over either hemisphere elicited similar BOLD-decreases for central visual field representations in V1-V4, but only right frontal TMS led to BOLD-increases for peripheral field representations in these regions. Hemispheric differences for effects of parietal TMS were even more marked: Right parietal TMS led to strong BOLD changes in V1-V4 and V5/MT+, but left parietal TMS did not. These data directly confirm that human frontal and parietal cortex shows right-hemisphere specialization for causal influences on visual cortex.

Ruff, Christian C.; Blankenburg, Felix; Bjoertomt, Otto; Bestmann, Sven; Weiskopf, Nikolaus; Driver, Jon

2008-01-01

24

Human Parieto-Occipital Visual Cortex: Lack of Retinotopy and Foveal Magnification.  

National Technical Information Service (NTIS)

The authors recorded whole-scalp neuromagnetic responses to luminance stimuli of varying eccentricities in order to study visual representation in the parietal cortex. The stimuli were semicircles (5.5 deg in radius) presented at horizontal eccentricities...

K. Portin R. Hari

1998-01-01

25

Alfred Walter Campbell and the visual functions of the occipital cortex.  

PubMed

In his pioneering cytoarchitectonic studies of the human brain, Alfred Walter Campbell identified two structurally different areas in the occipital lobes and assigned two different kinds of visual functions to them. The first area, the visuosensory, was essentially on the mesial surface of the calcarine fissure. It was the terminus of nervous impulses generated in the retina and was where simple visual sensations arose. The second area, the visuopsychic, which surrounded or invested the first, was where sensations were interpreted and elaborated into visual perceptions. I argue that Campbell's distinction between the two areas was the starting point for the eventual differentiation of areas V1-V5. After a brief outline of Campbell's early life and education in Australia and of his Scottish medical education and early work as a pathologist at the Lancashire County Lunatic Asylum at Rainhill near Liverpool, I summarise his work on the human brain. In describing the structures he identified in the occipital lobes, I analyse the similarities and differences between them and the related structures identified by Joseph Shaw Bolton. I conclude by proposing some reasons for how that work came to be overshadowed by the later studies of Brodmann and for the more general lack of recognition given Campbell and his work. Those reasons include the effect of the controversies precipitated by Campbell's alliance with Charles Sherrington over the functions of the sensory and motor cortices. PMID:23218905

Macmillan, Malcolm

2012-11-01

26

Tactile-auditory shape learning engages the lateral occipital complex.  

PubMed

Shape is an object property that inherently exists in vision and touch, and is processed in part by the lateral occipital complex (LOC). Recent studies have shown that shape can be artificially coded by sound using sensory substitution algorithms and learned with behavioral training. This finding offers a unique opportunity to test intermodal generalizability of the LOC beyond the sensory modalities in which shape is naturally perceived. Therefore, we investigated the role of the LOC in processing of shape by examining neural activity associated with learning tactile-shape-coded auditory information. Nine blindfolded sighted people learned the tactile-auditory relationship between raised abstract shapes and their corresponding shape-coded sounds over 5 d of training. Using functional magnetic resonance imaging, subjects were scanned before and after training during a task in which they first listened to a shape-coded sound transformation, then touched an embossed shape, and responded whether or not the tactile stimulus matched the auditory stimulus in terms of shape. We found that behavioral scores improved after training and that the LOC was commonly activated during the auditory and tactile conditions both before and after training. However, no significant training-related change was observed in magnitude or size of LOC activity; rather, the auditory cortex and LOC showed strengthened functional connectivity after training. These findings suggest that the LOC is available to different sensory systems for shape processing and that auditory-tactile sensory substitution training leads to neural changes allowing more direct or efficient access to this site by the auditory system. PMID:21613498

Kim, Jung-Kyong; Zatorre, Robert J

2011-05-25

27

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

Microsoft Academic Search

Albinism is a genetic condition associated with abnormalities of the visual system. Defects in melanin production cause underdevelopment of the fovea, reduced retinal cell numbers and abnormal routing of ganglion cell nerve fibres at the optic chiasm. We examined 19 subjects with albinism and 26 control subjects to determine whether retinal abnormalities affect the structure of the visual cortex. Whole-brain,

Elisabeth A. H. Hagen; Gavin C. Houston; Michael B. Hoffmann; Glen Jeffery; Antony B. Morland

2005-01-01

28

Development of neuropeptide Y (NPY) immunoreactive neurons in the rat occipital cortex: A combined immunohistochemical-autoradiographic study  

SciTech Connect

The postnatal development of neuropeptide Y (NPY)-immunoreactive neurons, previously labeled with (3H)thymidine on embryonic days E14-E21, has been studied in the rat occipital cortex. Immunohistochemistry combined with autoradiography showed evidence of a modified inside-out pattern of maturation. NPY-neurons are generated between E14 and E20 and are found in layers II-VI of the cortex and the subcortical white matter. NPY neurons from all these birthdates are overproduced at first, although cells generated at E16 produce the greatest excess, followed by E15 and E17. Some of these transient neurons are found in the wrong layer for their birthdates, and their elimination produces a more correct alignment at maturity. However, most of the NPY neurons that survive are generated at E17, and these cells are found throughout layers II-VI with a preponderance in layer VI. This evidence is strongly suggestive of cell death rather than merely cessation of production of NPY.

Cavanagh, M.E.; Parnavelas, J.G. (University College London (England))

1990-07-22

29

Shape from sound: evidence for a shape operator in the lateral occipital cortex.  

PubMed

A recent view of cortical functional specialization suggests that the primary organizing principle of the cortex is based on task requirements, rather than sensory modality. Consistent with this view, recent evidence suggests that a region of the lateral occipitotemporal cortex (LO) may process object shape information regardless of the modality of sensory input. There is considerable evidence that area LO is involved in processing visual and haptic shape information. However, sound can also carry acoustic cues to an object's shape, for example, when a sound is produced by an object's impact with a surface. Thus, the current study used auditory stimuli that were created from recordings of objects impacting a hard surface to test the hypothesis that area LO is also involved in auditory shape processing. The objects were of two shapes, rods and balls, and of two materials, metal and wood. Subjects were required to categorize the impact sounds in one of three tasks, (1) by the shape of the object while ignoring material, (2) by the material of the object while ignoring shape, or (3) by using all the information available. Area LO was more strongly recruited when subjects discriminated impact sounds based on the shape of the object that made them, compared to when subjects discriminated those same sounds based on material. The current findings suggest that activation in area LO is shape selective regardless of sensory input modality, and are consistent with an emerging theory of perceptual functional specialization of the brain that is task-based rather than sensory modality-based. PMID:21397616

James, Thomas W; Stevenson, Ryan A; Kim, Sunah; Vanderklok, Ross M; James, Karin Harman

2011-03-21

30

Dynamic Modulation of Local Population Activity by Rhythm Phase in Human Occipital Cortex During a Visual Search Task  

PubMed Central

Brain rhythms are more than just passive phenomena in visual cortex. For the first time, we show that the physiology underlying brain rhythms actively suppresses and releases cortical areas on a second-to-second basis during visual processing. Furthermore, their influence is specific at the scale of individual gyri. We quantified the interaction between broadband spectral change and brain rhythms on a second-to-second basis in electrocorticographic (ECoG) measurement of brain surface potentials in five human subjects during a visual search task. Comparison of visual search epochs with a blank screen baseline revealed changes in the raw potential, the amplitude of rhythmic activity, and in the decoupled broadband spectral amplitude. We present new methods to characterize the intensity and preferred phase of coupling between broadband power and band-limited rhythms, and to estimate the magnitude of rhythm-to-broadband modulation on a trial-by-trial basis. These tools revealed numerous coupling motifs between the phase of low-frequency (?, ?, ?, ?, and ? band) rhythms and the amplitude of broadband spectral change. In the ? and ? ranges, the coupling of phase to broadband change is dynamic during visual processing, decreasing in some occipital areas and increasing in others, in a gyrally specific pattern. Finally, we demonstrate that the rhythms interact with one another across frequency ranges, and across cortical sites.

Miller, Kai J.; Hermes, Dora; Honey, Christopher J.; Sharma, Mohit; Rao, Rajesh P. N.; den Nijs, Marcel; Fetz, Eberhard E.; Sejnowski, Terrence J.; Hebb, Adam O.; Ojemann, Jeffrey G.; Makeig, Scott; Leuthardt, Eric C.

2010-01-01

31

Stimulation-Produced Analgesia From the Occipital or Retrosplenial Cortex of Rats Involves Serotonergic and Opioid Mechanisms in the Anterior Pretectal Nucleus  

Microsoft Academic Search

The electrical stimulation of the occipital (OC) or retrosplenial (RSC) cortex produces antinociception in the rat tail-flick test. These cortices send inputs to the anterior pretectal nucleus (APtN) which is implicated in antinociception and nociception. At least muscarinic cholinergic, opioid, and serotonergic mechanisms in the APtN are involved in stimulation-produced antinociception (SPA) from the nucleus. In this study, the injection

Gláucia Melo Reis; Ana Carolina Rossaneis; João Walter S. Silveira; Quintino Moura Dias; Wiliam A. Prado

2011-01-01

32

Occipital Neuralgia  

MedlinePLUS

NINDS Occipital Neuralgia Information Page Table of Contents (click to jump to sections) What is Occipital Neuralgia? Is there any treatment? What is the prognosis? What research is being done? Clinical ...

33

Proton magnetic resonance spectroscopy (1H-MRS) reveals the presence of elevated myo-inositol in the occipital cortex of blind subjects.  

PubMed

This paper is addressed to investigate whether proton magnetic resonance spectroscopy ((1)H-MRS) may provide the means to investigate changes associated to alterations of neural activity and sensory experience in the blind. We examined the relationships between different brain metabolite levels in 10 blind volunteers and 10 sighted subjects matched for age and gender. Adjusted levels of N-acetylaspartate (NAA), creatine (Cr), choline (Cho), glutamate/glutamine (Glx) and myo-inositol (mIno) in the occipital cortex region were quantified in the water-suppressed spectrum using the AMARES estimation algorithms. An unpaired two-tailed t-test was used to determine any significant difference in metabolite ratios. Our results show that none of the blind volunteers presented atrophy or any other MRI detectable degenerative change of the occipital cortex. The main finding was a significant increase of myo-inositol (mIno), a glial marker, in blind subjects compared to sighted controls. This simple sugar-like molecule can be found mainly within astrocytes, and cannot cross the blood-brain barrier. Therefore its increase could reflect glial proliferation or an increase in glial cell size. These results show that (1)H-MRS may help to understand the complex mechanisms involved in brain plasticity and suggest an active role of glial cells in the reorganization of the brain in response to visual deprivation. PMID:19426816

Bernabeu, Angela; Alfaro, Arantxa; García, Milagros; Fernández, Eduardo

2009-05-05

34

G-LOC Syndrome.  

National Technical Information Service (NTIS)

Acceleration (+GZ)-induced loss of consciousness (G LOC) is but one isolated symptom that results when central nervous system (CNS) function is altered by G-stress. Other symptoms and changes also result when reduction of oxygenated blood flow to the CNS ...

J. E. Whinnery

1990-01-01

35

Unedited in vivo detection and quantification of ?-aminobutyric acid in the occipital cortex using short-TE MRS at 3?T.  

PubMed

Short-TE MRS has been proposed recently as a method for the in vivo detection and quantification of ?-aminobutyric acid (GABA) in the human brain at 3?T. In this study, we investigated the accuracy and reproducibility of short-TE MRS measurements of GABA at 3?T using both simulations and experiments. LCModel analysis was performed on a large number of simulated spectra with known metabolite input concentrations. Simulated spectra were generated using a range of spectral linewidths and signal-to-noise ratios to investigate the effect of varying experimental conditions, and analyses were performed using two different baseline models to investigate the effect of an inaccurate baseline model on GABA quantification. The results of these analyses indicated that, under experimental conditions corresponding to those typically observed in the occipital cortex, GABA concentration estimates are reproducible (mean reproducibility error, <20%), even when an incorrect baseline model is used. However, simulations indicate that the accuracy of GABA concentration estimates depends strongly on the experimental conditions (linewidth and signal-to-noise ratio). In addition to simulations, in vivo GABA measurements were performed using both spectral editing and short-TE MRS in the occipital cortex of 14 healthy volunteers. Short-TE MRS measurements of GABA exhibited a significant positive correlation with edited GABA measurements (R?=?0.58, p?occipital cortex. Across all subjects, the average coefficient of variation of these four GABA measurements was 8.7?±?4.9%. This study demonstrates that, under some experimental conditions, short-TE MRS can be employed for the reproducible detection of GABA at 3?T, but that the technique should be used with caution, as the results are dependent on the experimental conditions. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23696182

Near, Jamie; Andersson, Jesper; Maron, Eduard; Mekle, Ralf; Gruetter, Rolf; Cowen, Philip; Jezzard, Peter

2013-05-22

36

Occipital osteodiastasis  

Microsoft Academic Search

Occipital osteodiastasis (OOD) is a prominent traumatic lesion in neonates born by breech, during delivery of after coming\\u000a head. The lesion consists of traumatic separation of the cartilaginous joint between the squamous and lateral portion of the\\u000a occipital bone resulting in a posterior fossa subdural haemorrhage associated with laceration of the cerebellum. We report\\u000a a term female baby with OOD

Sudhir Dixit; Ashish Jain; Suhas Datar; Nagendra Sinha

2010-01-01

37

Activity in the lateral occipital cortex between 200 and 300 ms distinguishes between physically identical seen and unseen stimuli  

PubMed Central

There is converging evidence that electrophysiological responses over posterior cortical regions in the 200–300 ms range distinguish between physically identical stimuli that reach consciousness or remain unseen. Here, we attempt at determining the sources of this awareness-related activity using magneto-encephalographic (MEG). Fourteen subjects were presented with faint colored gratings at threshold for contrast and reported on each trial whether the grating was seen or unseen. Subjects were primed with a color cue that could be congruent or incongruent with the color of the grating, to probe to what extent two co-localized features (color and orientation) would be bound in consciousness. The contrast between neural responses to seen and unseen physically identical gratings revealed a sustained posterior difference between 190 and 350 ms, thereby replicating prior studies. We further show that the main sources of the awareness-related activity were localized bilaterally on the lateral convexity of the occipito-temporal region, in the Lateral Occipital (LO) complex, as well as in the right posterior infero-temporal region. No activity differentiating seen and unseen trials could be observed in frontal or parietal regions in this latency range, even at lower threshold. Color congruency did not improve grating's detection, and the awareness-related activity was independent from color congruency. However, at the neural level, color congruency was processed differently in grating-present and grating-absent trials. The pattern of results suggests the existence of a neural process of color congruency engaging left parietal regions that is affected by the mere presence of another feature, whether this feature reaches consciousness or not. Altogether, our results reveal an occipital source of visual awareness insensitive to color congruency, and a simultaneous parietal source not engaged in visual awareness, but sensitive to the manipulation of co-localized features.

Liu, Ying; Paradis, Anne-Lise; Yahia-Cherif, Lydia; Tallon-Baudry, Catherine

2012-01-01

38

fMRI reveals a lower visual field preference for hand actions in human superior parieto-occipital cortex (SPOC) and precuneus.  

PubMed

Humans are more efficient when performing actions towards objects presented in the lower visual field (VF) than in the upper VF. The present study used slow event-related functional magnetic resonance imaging (fMRI) to examine whether human brain areas implicated in action would show such VF preferences. Participants were asked to fixate one of four different positions allowing objects to be presented in the upper left, upper right, lower left or lower right VF. In some trials they reached to grasp the object with the right hand while in others they passively viewed the object. Crucially, by manipulating the fixation position, rather than the position of the objects, the biomechanics of the movements did not differ across conditions. The superior parieto-occipital cortex (SPOC) and the left precuneus, brain areas implicated in the control of reaching, were significantly more activated when participants grasped objects presented in the lower VF relative to the upper VF. Importantly, no such VF preferences were observed in these regions during passive viewing. This finding fits well with evidence from the macaque neurophysiology that neurons within visuomotor regions over-represent the lower VF relative to the upper VF and indicate that the neural responses within these regions may reflect a functional lower VF advantage during visually-guided actions. PMID:23453790

Rossit, Stéphanie; McAdam, Teresa; McLean, D Adam; Goodale, Melvyn A; Culham, Jody C

2013-01-01

39

Structural and functional changes across the visual cortex of a patient with visual form agnosia.  

PubMed

Loss of shape recognition in visual-form agnosia occurs without equivalent losses in the use of vision to guide actions, providing support for the hypothesis of two visual systems (for "perception" and "action"). The human individual DF received a toxic exposure to carbon monoxide some years ago, which resulted in a persisting visual-form agnosia that has been extensively characterized at the behavioral level. We conducted a detailed high-resolution MRI study of DF's cortex, combining structural and functional measurements. We present the first accurate quantification of the changes in thickness across DF's occipital cortex, finding the most substantial loss in the lateral occipital cortex (LOC). There are reduced white matter connections between LOC and other areas. Functional measures show pockets of activity that survive within structurally damaged areas. The topographic mapping of visual areas showed that ordered retinotopic maps were evident for DF in the ventral portions of visual cortical areas V1, V2, V3, and hV4. Although V1 shows evidence of topographic order in its dorsal portion, such maps could not be found in the dorsal parts of V2 and V3. We conclude that it is not possible to understand fully the deficits in object perception in visual-form agnosia without the exploitation of both structural and functional measurements. Our results also highlight for DF the cortical routes through which visual information is able to pass to support her well-documented abilities to use visual information to guide actions. PMID:23904613

Bridge, Holly; Thomas, Owen M; Minini, Loredana; Cavina-Pratesi, Cristiana; Milner, A David; Parker, Andrew J

2013-07-31

40

Epileptiform transients of the occipital lobe in pediatrics.  

PubMed

Differentiating between benign occipital transients and epileptic discharges from the occipital lobes is imperative. Focal occipital spikes and sharp waves are not always associated with benign disorders. The occurrence of occipital spikes and spike and wave complexes depends on the child's age, the maturation of the occipital cortex, and the cortex's connection with other structures (Beaumanoir et al. 1993). Clinical manifestations also evolve as the patient ages. Seizure semiology is due to the maturation of the visual system and its connections. An infant from birth to twelve months of age could experience autonomic symptoms such as pallor and vomiting with possible minor motor movements. Visual symptoms and/or headaches are usually not noticed until between five and seven years of age. These visual phenomena can continue into adulthood. PMID:24046970

Campbell, Stefan

2013-09-01

41

Deconstructing visual scenes in cortex: gradients of object and spatial layout information.  

PubMed

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

Harel, Assaf; Kravitz, Dwight J; Baker, Chris I

2012-04-03

42

48 CFR 732.406-72 - Establishing an LOC.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Establishing an LOC. 732.406-72 Section 732.406-72...Payments 732.406-72 Establishing an LOC. (a) While the contract will provide for the use of an LOC when it is justified under...

2011-10-01

43

48 CFR 732.406-73 - LOC contract clause.  

Code of Federal Regulations, 2012 CFR

...Advance Payments 732.406-73 LOC contract clause. (a) If payment is to be provided by LOC, the contract shall contain...Contracting offices shall ensure that an appropriate (48 CFR) FAR payment...contract, in the event that the LOC is revoked pursuant to...

2012-10-01

44

48 CFR 732.406-72 - Establishing an LOC.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Establishing an LOC. 732.406-72 Section 732.406-72...Payments 732.406-72 Establishing an LOC. (a) While the contract will provide for the use of an LOC when it is justified under...

2012-10-01

45

48 CFR 732.406-72 - Establishing an LOC.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Establishing an LOC. 732.406-72 Section 732.406-72...Payments 732.406-72 Establishing an LOC. (a) While the contract will provide for the use of an LOC when it is justified under...

2009-10-01

46

48 CFR 732.406-73 - LOC contract clause.  

Code of Federal Regulations, 2011 CFR

...Advance Payments 732.406-73 LOC contract clause. (a) If payment is to be provided by LOC, the contract shall contain...Contracting offices shall ensure that an appropriate (48 CFR) FAR payment...contract, in the event that the LOC is revoked pursuant to...

2011-10-01

47

48 CFR 732.406-72 - Establishing an LOC.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Establishing an LOC. 732.406-72 Section 732.406-72...Payments 732.406-72 Establishing an LOC. (a) While the contract will provide for the use of an LOC when it is justified under...

2010-10-01

48

48 CFR 732.406-73 - LOC contract clause.  

Code of Federal Regulations, 2010 CFR

...Advance Payments 732.406-73 LOC contract clause. (a) If payment is to be provided by LOC, the contract shall contain...Contracting offices shall ensure that an appropriate (48 CFR) FAR payment...contract, in the event that the LOC is revoked pursuant to...

2010-10-01

49

48 CFR 732.406-73 - LOC contract clause.  

Code of Federal Regulations, 2010 CFR

...Advance Payments 732.406-73 LOC contract clause. (a) If payment is to be provided by LOC, the contract shall contain...Contracting offices shall ensure that an appropriate (48 CFR) FAR payment...contract, in the event that the LOC is revoked pursuant to...

2009-10-01

50

Early processing in human LOC is highly responsive to illusory contours but not to salient regions  

PubMed Central

Human electrophysiological studies support a model whereby sensitivity to so-called illusory contour stimuli is first seen within the lateral occipital complex. A challenge to this model posits that the lateral occipital complex is a general site for crude region-based segmentation, based on findings of equivalent hemodynamic activations in the lateral occipital complex to illusory contour and so-called salient region stimuli, a stimulus class that lacks the classic bounding contours of illusory contours. Using high-density electrical mapping of visual evoked potentials, we show that early lateral occipital cortex activity is substantially stronger to illusory contour than to salient region stimuli, while later lateral occipital complex activity is stronger to salient region than to illusory contour stimuli. Our results suggest that equivalent hemodynamic activity to illusory contour and salient region stimuli likely reflects temporally integrated responses, a result of the poor temporal resolution of hemodynamic imaging. The temporal precision of visual evoked potentials is critical for establishing viable models of completion processes and visual scene analysis. We propose that crude spatial segmentation analyses, which are insensitive to illusory contours, occur first within dorsal visual regions, not lateral occipital complex, and that initial illusory contour sensitivity is a function of the lateral occipital complex.

Shpaner, Marina; Murray, Micah M.; Foxe, John J.

2011-01-01

51

Neuropathology of Occipital Horn Syndrome  

Microsoft Academic Search

Occipital horn syndrome, formerly known as Ehlers-Danlos syndrome type IX or X-linked cutis laxa, is an allelic variant of Menkes' syndrome. Although the clinical symptomatology and systemic pathology findings have been well described in occipital horn syndrome, the neuropathology has not previously been reported. A kindred affected by the X-linked occipital horn syndrome is followed at the University of Alabama

Cheryl Ann Palmer; Alan K. Percy

2001-01-01

52

[Epileptic activity of the occipital lobe. Clinico-electroencephalographic contribution].  

PubMed

Our analysis of the course of illness in 14 patients, whose common electroencephalographic characteristic was epileptogenic activity in the occipital area, showed very different clinical symptoms. The first group comprised patients who presented bilateral amaurosis. In four of these cases, the occipital hypersynchronous EEG activity was merely a secondary symptom of either ischaemic hypoxia or of a degenerative process in the occipital visual cortex and was not responsible for the genesis of the actual blindness. In two further cases of monosymptomatic temporary loss of vision, it was difficult to make a differential diagnosis between ictal blindness, respectively status epilepticus amauroticus occurring in a occipital lobe epilepsy and a migraine attack involving the basilar territory. The second group comprised five patients with paroxysmal visual hallucinations respectively illusions. Three of them suffered from hallucinations of the elementary type, respectively flickering fits in the hemianopic field, symptoms which are based on discharges in the visual cortex of the occipital lobe. In a case of one patient with complex visual hallucinations as well as in a further case with visual illusions, it was not possible to find out with certainty their place of origin. A study of these cases shows that the cortical or sub-cortical functional disturbance within the visual system causing the various optical deformations and visual hallucinations, form an inhomogeneous group with different etiology. In the only patient belonging to the third group, whose seizures were i.a. characterized through motor phenomena in the field of the ocular organs and the tonic lateral turning movement of the bulbi of the eyes and of the head, an occipital epileptic crisis with spread of discharges from the occipital pole to the frontomesial surface should be assumed. The occurrence of complex partial seizures, respectively generalized tonic-clonic attacks in two patients of the fourth group who have definite epileptogenic EEG-activity in the occipital area, can be explained by a propagation of paroxysmal activity to the temporal lobe or to the motor cortex. Because of the marked tendency to propagation of the hypersynchronous activity originating in the occipital lobe, many combinations of sensory and/or motor symptoms can occur within the frame-work of occipital epileptic seizures. On the basis of one scalp EEG finding, no final localizing conclusions may be drawn here. PMID:3220420

Schäffler, L; Karbowski, K

1988-09-01

53

Wegener's Disease Presenting with Occipital Condyle Syndrome  

PubMed Central

Tumors or chronic inflammatory lesions of the occipital condyle may cause occipital pain associated with an ipsilateral hypoglossal nerve injury (occipital condyle syndrome). We describe a young woman with recurrent otitis media and occipital condyle syndrome associated with a limited form of Wegener’s disease.

Hornik, Alejandro; Rodriguez-Porcel, Federico; Ersahin, Cagatay H.; Kadanoff, Ruth; Biller, Jose

2012-01-01

54

Neuropathology of occipital horn syndrome.  

PubMed

Occipital horn syndrome, formerly known as Ehlers-Danlos syndrome type IX or X-linked cutis laxa, is an allelic variant of Menkes' syndrome. Although the clinical symptomatology and systemic pathology findings have been well described in occipital horn syndrome, the neuropathology has not previously been reported. A kindred affected by the X-linked occipital horn syndrome is followed at the University of Alabama at Birmingham. A severely mentally retarded dysmorphic man, who died at the age of 26 years, never gained the ability to walk or talk. Among other findings at autopsy, the patient had the skeletal anomalies previously described with occipital horn syndrome. Neuropathologic findings included neovascularization and extreme reduplication of the cerebral arteries, in conjunction with cystic medial degeneration; bilateral cerebellar hypoplasia; focal cortical dysplasia, and cerebellar heterotopias. These findings are similar to those seen in the brains of patients with Menkes' syndrome, which is not surprising, given the known phenotypic overlap and the proven allelism of occipital horn syndrome with classic Menkes' syndrome. PMID:11669352

Palmer, C A; Percy, A K

2001-10-01

55

Crystal structure of Homo sapiens protein LOC79017  

SciTech Connect

LOC79017 (MW 21.0 kDa, residues 1-188) was annotated as a hypothetical protein encoded by Homo sapiens chromosome 7 open reading frame 24. It was selected as a target by the Center for Eukaryotic Structural Genomics (CESG) because it did not share more than 30% sequence identity with any protein for which the three-dimensional structure is known. The biological function of the protein has not been established yet. Parts of LOC79017 were identified as members of uncharacterized Pfam families (residues 1-95 as PB006073 and residues 104-180 as PB031696). BLAST searches revealed homologues of LOC79017 in many eukaryotes, but none of them have been functionally characterized. Here, we report the crystal structure of H. sapiens protein LOC79017 (UniGene code Hs.530024, UniProt code O75223, CESG target number go.35223).

Bae, Euiyoung; Bingman, Craig A.; Aceti, David J.; Phillips, Jr., George N. (UW)

2010-02-08

56

Meniscal Repair With the RapidLoc Meniscal Repair Device  

Microsoft Academic Search

Background: The RapidLoc is an all-inside, self-adjusting, flexible meniscal repair device that combines a suture with an anchor component and, by using a reinforced sliding knot, allows for tightening to compress and hold the repaired meniscal segments. The purpose of this study was to evaluate the clinical success of the RapidLoc device. Methods: A prospective consecutive series of meniscal repairs

F. Alan Barber; David A. Coons; Michell Ruiz-Suarez

57

Success on Algorithmic and LOCS vs. Conceptual Chemistry Exam Questions  

Microsoft Academic Search

The performance of freshman science, engineering, and in-service teacher students in three Israeli and American universities on algorithmic, lower-order cognitive skills (LOCS), and conceptual chemistry exam questions was investigated. The driving force for the study was an interest in moving chemistry instruction from an algorithm-oriented factual recall approach dominated by LOCS to a decision-making, problem-solving, and critical thinking approach dominated

Uri Zoller; Aviva Lubezky; Mary B. Nakhleh; Barbara Tessier; Yehudit J. Dori

1995-01-01

58

Manipulating the Arterial Pressure to Prevent G-LOC.  

National Technical Information Service (NTIS)

The procedures that can be used to manipulate the arterial blood pressure at head level are categorized. G-loss of consciousness (G-LOC) is compared with other types of loss of consciousness that may occur in healthy individuals. From a hemodynamic point ...

H. Bjurstedt

1993-01-01

59

A Model for Targeting Strikes in an Loc Network.  

National Technical Information Service (NTIS)

The paper presents a computer model for developing and evaluating a targeting strategy against an opposing force's lines of communication (LOC). The aim is to obtain the greatest reduction in enemy throughput and the greatest time and cost of repair. The ...

R. D. Wollmer M. J. Ondrasek

1969-01-01

60

An ELISA Lab-on-a-Chip (ELISA-LOC).  

PubMed

Laminated object manufacturing (LOM) technology using polymer sheets is an easy and affordable method for rapid prototyping of Lab-on-a-Chip (LOC) systems. It has recently been used to fabricate a miniature 96 sample ELISA lab-on-a-chip (ELISA-LOC) by integrating the washing step directly into an ELISA plate. LOM has been shown to be capable of creating complex 3D microfluidics through the assembly of a stack of polymer sheets with features generated by laser micromachining and by bonding the sheets together with adhesive. A six layer ELISA-LOC was fabricated with an acrylic (poly(methyl methacrylate) (PMMA)) core and five polycarbonate layers micromachined by a CO(2) laser with simple microfluidic features including a miniature 96-well sample plate. Immunological assays can be carried out in several configurations (1 × 96 wells, 2 × 48 wells, or 4 × 24 wells). The system includes three main functional elements: (1) a reagent loading fluidics module, (2) an assay and detection wells plate, and (3) a reagent removal fluidics module. The ELISA-LOC system combines several biosensing elements: (1) carbon nanotube (CNT) technology to enhance primary antibody immobilization, (2) sensitive ECL (electrochemiluminescence) detection, and (3) a charge-coupled device (CCD) detector for measuring the light signal generated by ECL. Using a sandwich ELISA assay, the system detected Staphylococcal enterotoxin B (SEB) at concentrations as low as 0.1 ng/ml, a detection level similar to that reported for conventional ELISA. ELISA-LOC can be operated by a syringe and does not require power for operation. This simple point-of-care (POC) system is useful for carrying out various immunological assays and other complex medical assays without the laboratory required for conventional ELISA, and therefore may be more useful for global healthcare delivery. PMID:23329460

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

2013-01-01

61

Chiari malformation with thick occipital bone.  

PubMed

A case of a Chiari malformation with an extraordinarily thick occipital bone is described. The thick occipital bone might make the posterior fossa narrow with consequent herniation of the cerebellar tonsils to the foramen magnum and formation of a syrinx. At dural plasty, well-developed marginal and occipital sinuses should be deliberately handled with the preservation of normal venous drainage. This case gives us the essence of the occurrence mechanisms of Chiari malformation and foramen magnum decompression. PMID:21339798

Yasuhara, Takao; Miyoshi, Yasuyuki; Date, Isao

2011-02-01

62

Occipital ganglioglioma in an older adult.  

PubMed

Gangliogliomas are rare benign tumors of the central nervous system that typically involve the temporal lobe in younger patients. We present a 63-year-old man with an unusual occipital ganglioma with new seizures resolving after resection. A search of the literature revealed only three reports of occipital ganglioma in adults over 30 years old. Therefore, ganglioglioma of the occipital lobe in older patients is rare, but is a diagnostic consideration. PMID:20727766

Deipolyi, Amy; Auguste, Kurtis I; Yang, Isaac; Tihan, Tarik; Parsa, Andrew T

2010-08-19

63

48 CFR 732.406-71 - Circumstances for use of an LOC.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Circumstances for use of an LOC. 732.406-71 Section 732.406-71 Federal...Advance Payments 732.406-71 Circumstances for use of an LOC. An LOC shall be used under the following circumstances:...

2009-10-01

64

48 CFR 732.406-71 - Circumstances for use of an LOC.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Circumstances for use of an LOC. 732.406-71 Section 732.406-71 Federal...Advance Payments 732.406-71 Circumstances for use of an LOC. An LOC shall be used under the following circumstances:...

2010-10-01

65

48 CFR 732.406-71 - Circumstances for use of an LOC.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Circumstances for use of an LOC. 732.406-71 Section 732.406-71 Federal...Advance Payments 732.406-71 Circumstances for use of an LOC. An LOC shall be used under the following circumstances:...

2012-10-01

66

48 CFR 732.406-71 - Circumstances for use of an LOC.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Circumstances for use of an LOC. 732.406-71 Section 732.406-71 Federal...Advance Payments 732.406-71 Circumstances for use of an LOC. An LOC shall be used under the following circumstances:...

2011-10-01

67

Concurrent occipital hypoplasia, occipital dysplasia, syringohydromyelia, and hydrocephalus in a Yorkshire terrier  

PubMed Central

Magnetic resonance imaging of a 7.5-year-old neutered male Yorkshire terrier with mild generalized ataxia and intermittent neck scratching led to a diagnosis of caudal occipital malformation and syringohydromyelia. Surgical exploration led to a diagnosis of occipital dysplasia with concurrent occipital hypoplasia. Following a dorsal laminectomy of the first cervical vertebra there was no progression or improvement a month later.

Cagle, Laura

2010-01-01

68

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

69

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.

Haist, Frank; Lee, Kang; Stiles, Joan

2010-01-01

70

Differential visually-induced gamma-oscillations in human cerebral cortex  

PubMed Central

SUMMARY Using intracranial electrocorticography, we determined how cortical gamma-oscillations (50–150Hz) were induced by different visual tasks in nine children with focal epilepsy. In all children, full-field stroboscopic flash-stimuli induced gamma-augmentation in the anterior-medial occipital cortex (starting on average at 31-msec after stimulus presentation) and subsequently in the lateral-polar occipital cortex; minimal gamma-augmentation was noted in the inferior occipital-temporal cortex; occipital gamma-augmentation was followed by gamma-attenuation in three children. Central-field picture-stimuli induced sustained gamma-augmentation in the lateral-polar occipital cortex (starting on average at 69-msec) and subsequently in the inferior occipital-temporal cortex in all children and in the posterior frontal cortex in three children; the anterior-medial occipital cortex showed no gamma-augmentation but rather gamma-attenuation. Electrical stimulation of the anterior-medial occipital cortex induced a phosphene in the peripheral-field or eye deviation to the contralateral side, whereas that of the lateral-polar occipital cortex induced a phosphene in the central-field. In summary, full-field, simple and short-lasting visual information might be preferentially processed by the anterior-medial occipital cortex, and subsequently by the lateral-polar occipital cortex. Gamma-attenuation following augmentation in the striate cortex might be associated with a relative refractory-period to flash-stimuli or feed-forward inhibition by other areas. Central-field complex visual information might be processed by a network involving the lateral-polar occipital cortex and the inferior occipital-temporal cortex. A plausible interpretation of posterior-frontal gamma-augmentation during central-field picture stimuli includes activation of the frontal-eye-field for visual searching. Gamma-attenuation in the anterior-medial occipital cortex during central-field picture-stimuli might be associated with relative inattention to the peripheral visual field during central-field object visualization.

Asano, Eishi; Nishida, Masaaki; Fukuda, Miho; Rothermel, Robert; Juhasz, Csaba; Sood, Sandeep

2009-01-01

71

Aeromedical Consultation Service Case Reports: Occipital Migraine.  

National Technical Information Service (NTIS)

Migraine presenting as pain in the occipital region can be a difficult diagnostic problem. Three illustrative cases evaluated at the USAF School of Aerospace Medicine are reviewed. In two, subarachnoid hemorrhage was initially suspected. In the third, sym...

P. L. Richter W. H. King

1970-01-01

72

Extrastriate cortex and medial temporal lobe regions respond differentially to visual feature overlap within preferred stimulus category.  

PubMed

It has been proposed that domain-specific regions in extrastriate cortex, parahippocampal cortex and the medial temporal lobe (MTL, particularly the hippocampus, HC, and perirhinal cortex, PrC) may respond differently to the degree of feature complexity present in sets of visual stimuli, with the latter two regions tuned to represent the differences among stimuli with a high degree of visual overlap or featural ambiguity (Graham, Barense, & Lee, 2010; Cowell, Bussey, & Saksida, 2010a). To test this prediction, healthy participants viewed blocks containing visually similar or visually different exemplars from four stimulus categories (scenes, faces, inanimate objects and animate objects). Independent functional regions of interest were identified in extrastriate and MTL regions that were preferentially responsive to one or more of these visual categories, and the main experimental data interrogated for any evidence of an interaction between visual category and degree of feature overlap. In PrC and posterior HC (PostHC) viewing sets of stimuli with a large number of overlapping features resulted in greater activity than blocks containing items that were more visually distinct. The opposite pattern was found in fusiform face area (FFA), parahippocampal place area (PPA) and lateral occipital complex (LOC). The increased response in the HC and PrC to high visual similarity was seen only for visual categories that effectively activate these regions (PrC-faces and objects; PostHC-scenes). This study confirms that regions throughout the visual ventral stream, parahippocampal cortex and MTL are engaged differentially by visual complexity, consistent with recent lesion experiments in which MTL damage affects discrimination and learning of, as well as recognition memory for, exemplars with a high degree of visual feature overlap. PMID:22820343

Mundy, M E; Downing, P E; Graham, K S

2012-07-20

73

Multiple routes from occipital to temporal cortices during reading  

PubMed Central

Contemporary models of the neural system that supports reading propose that activity in a ventral occipital-temporal area (vOT) drives activity in higher order language areas, for example, those in the posterior and anterior superior temporal sulcus (pSTS and aSTS). We used fMRI with dynamic causal modelling (DCM) to investigate evidence for other routes from visual cortex to the left temporal lobe language areas. First we identified activations in posterior inferior occipital (iO) and vOT areas that were more activated for silent reading than listening to words and sentences; and in pSTS and aSTS areas that were commonly activated for reading relative to false-fonts and listening to words relative to reversed words. Second, in 3 different DCM analyses, we tested whether visual processing of words modulates activity from (1) iO? vOT, iO? pSTS, both or neither; (2) vOT? pSTS, iO?pSTS, both or neither; and (3) pSTS? aSTS, vOT? aSTS, both or neither. We found that reading words increased connectivity (1) from iO to both pSTS and vOT; (2) to pSTS from both iO and vOT; and (3) to aSTS from both vOT and pSTS. These results highlight three potential processing streams in the occipito-temporal cortex: iO?pSTS?aSTS; iO?vOT?aSTS; and iO?vOT?pSTS?aSTS. We discuss these results in terms of cognitive models of reading and propose that efficient reading relies on the integrity of all these pathways.

Richardson, Fiona M.; Seghier, Mohamed L.; Leff, Alex P.; Thomas, Michael S.C.; Price, Cathy J.

2013-01-01

74

Primary occipital myxoma: A rare case report  

PubMed Central

Myxomas are benign tumors arising from mesenchymal tissues throughout the body. These tumors are usually seen in the atrium of heart and the jaw bone. Only a few cases of primary intracranial myxomas have been described in the literature. A rare case of primary myxoma of the occipital region is presented. A 12-year-old boy had mild occipital headache for the past 2 months which was unnoticed. Local hairdresser noticed a bulge in the occipital region while doing haircut and informed the parents and medical opinion was taken. He was seen by a neurosurgeon and after investigations he underwent craniotomy. Near total resection of the tumor was achieved. Histopathology and immunohistochemistry confirmed it to be a myxoma with no underlying cardiac focus. Following surgery the patient had rapid recovery.

Kawatra, Mallika; Bhandari, Virendra; Phatak, Satish; Kulkarni, Deepak

2013-01-01

75

The Share-Loc Project: a WAP-based maritime location system  

Microsoft Academic Search

Automatic Identification Systems (AIS) currently used to detect and warn about possible maritime navigation collisions are a suitable solution for well equipped ships, but are unfortunately quite expensive and difficult to maintain for small ships and pleasure boats. The ShareLoc project purpose is to design and implement an alternative maritime navigation system for small ships and boats. The Share-Loc system

G. Desvignes; G. Lucas De Couville; Evtim Peytchev; Thomas Devogele; S. Fournier; Christophe Claramunt

2002-01-01

76

Hypoplastic occipital condyle and third occipital condyle: Review of their dysembryology.  

PubMed

Disruption or embryologic derailment of the normal bony architecture of the craniovertebral junction (CVJ) may result in symptoms. As studies of the embryology and pathology of hypoplasia of the occipital condyles and third occipital condyles are lacking in the literature, the present review was performed. Standard search engines were accessed and queried for publications regarding hypoplastic occipital condyles and third occipital condyles. The literature supports the notion that occipital condyle hypoplasia and a third occipital condyle are due to malformation or persistence of the proatlas, respectively. The Pax-1 gene is most likely involved in this process. Clinically, condylar hypoplasia may narrow the foramen magnum and lead to lateral medullary compression. Additionally, this maldevelopment can result in transient vertebral artery compression secondary to posterior subluxation of the occiput. Third occipital condyles have been associated with cervical canal stenosis, hypoplasia of the dens, transverse ligament laxity, and atlanto-axial instability causing acute and chronic spinal cord compression. Treatment goals are focused on craniovertebral stability. A better understanding of the embryology and pathology related to CVJ anomalies is useful to the clinician treating patients presenting with these entities. Clin. Anat. 26:928-932, 2013. © 2013 Wiley Periodicals, Inc. PMID:23338989

Tubbs, R Shane; Lingo, Patrick Ryan; Mortazavi, Martin M; Cohen-Gadol, Aaron A

2013-01-21

77

Giant intradiploic pseudomeningocele of occipital bone.  

PubMed

The management of intradiploic CSF collection is controversial. Although it is a benign lesion, even then delay in diagnosis and treatment may lead to significant morbidity. The authors report a very rare case of giant posttraumatic intradiploic pseudomeningocele involving the occipital bone, occipital condyles, and clivus. The pathogenesis and management of intradiploic CSF collection are discussed. This 16-year-old boy presented with a history of enlarging swelling in the suboccipital region associated with headache, lower cranial nerve palsy, and features of high cervical compressive myelopathy. Investigations revealed a giant intradiploic lesion involving the occipital bone, condyles, and clivus associated with secondary basilar invagination, hydrocephalus, and syringomyelia. Intrathecal contrast administration did not reveal communication of intradiploic space with the subarachnoid space. A large occipital craniotomy was performed. A linear fracture and dural defect in the midline was identified, which was closed with fascial graft after removing the inner table of the skull. Cranioplasty was performed using the expanded calvarial bone. Ventriculoperitoneal shunt insertion was performed for hydrocephalus, and the patient improved remarkably. Posttraumatic intradiploic CSF collection, although a benign condition, may present with severe complications if treatment is delayed. Early diagnosis and treatment is essential. The authors suggest that this condition should be treated early, as for growing skull fractures. PMID:22208326

Kumar, Rajinder; Chandra, Sarat P; Sharma, Bhawani Shanker

2012-01-01

78

Third occipital nerve headache: a prevalence study  

Microsoft Academic Search

A consecutive series of 100 patients was studied to determine the prevalence of third occipital nerve headache in patients with chronic neck pain (> three months in duration) after whiplash. Seventy one patients complained of headache associated with their neck pain. Headache was the dominant complaint of 40 patients, but was only a secondary problem for the other 31. Each

S M Lord; L Barnsley; B J Wallis; N Bogduk

1994-01-01

79

PlantLoc: an accurate web server for predicting plant protein subcellular localization by substantiality motif  

PubMed Central

Knowledge of subcellular localizations (SCLs) of plant proteins relates to their functions and aids in understanding the regulation of biological processes at the cellular level. We present PlantLoc, a highly accurate and fast webserver for predicting the multi-label SCLs of plant proteins. The PlantLoc server has two innovative characters: building localization motif libraries by a recursive method without alignment and Gene Ontology information; and establishing simple architecture for rapidly and accurately identifying plant protein SCLs without a machine learning algorithm. PlantLoc provides predicted SCLs results, confidence estimates and which is the substantiality motif and where it is located on the sequence. PlantLoc achieved the highest accuracy (overall accuracy of 80.8%) of identification of plant protein SCLs as benchmarked by using a new test dataset compared other plant SCL prediction webservers. The ability of PlantLoc to predict multiple sites was also significantly higher than for any other webserver. The predicted substantiality motifs of queries also have great potential for analysis of relationships with protein functional regions. The PlantLoc server is available at http://cal.tongji.edu.cn/PlantLoc/.

Tang, Shengnan; Li, Tonghua; Cong, Peisheng; Xiong, Wenwei; Wang, Zhiheng; Sun, Jiangming

2013-01-01

80

Backward masked fearful faces enhance contralateral occipital cortical activity for visual targets within the spotlight of attention.  

PubMed

Spatial attention has been argued to be adaptive by enhancing the processing of visual stimuli within the 'spotlight of attention'. We previously reported that crude threat cues (backward masked fearful faces) facilitate spatial attention through a network of brain regions consisting of the amygdala, anterior cingulate and contralateral visual cortex. However, results from previous functional magnetic resonance imaging (fMRI) dot-probe studies have been inconclusive regarding a fearful face-elicited contralateral modulation of visual targets. Here, we tested the hypothesis that the capture of spatial attention by crude threat cues would facilitate processing of subsequently presented visual stimuli within the masked fearful face-elicited 'spotlight of attention' in the contralateral visual cortex. Participants performed a backward masked fearful face dot-probe task while brain activity was measured with fMRI. Masked fearful face left visual field trials enhanced activity for spatially congruent targets in the right superior occipital gyrus, fusiform gyrus and lateral occipital complex, while masked fearful face right visual field trials enhanced activity in the left middle occipital gyrus. These data indicate that crude threat elicited spatial attention enhances the processing of subsequent visual stimuli in contralateral occipital cortex, which may occur by lowering neural activation thresholds in this retinotopic location. PMID:20702500

Carlson, Joshua M; Reinke, Karen S; LaMontagne, Pamela J; Habib, Reza

2010-08-11

81

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.??

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

1998-01-01

82

Visual evoked potentials in children with occipital epilepsies  

Microsoft Academic Search

The objectives of this study are to see if any visual evoked potential (VEP) differences are present in two forms of occipital epilepsy, childhood epilepsy with occipital paroxysms (CEOP) and symptomatic occipital epilepsy (SOE) with respect to etiology, as CEOP is a benign age- and localization-related idiopathic epilepsy while SOE is a symptomatic form. Nineteen patients with CEOP and 13

Ahmet Gokcay; Ne?e Celeb?soy; Figen Gokcay; Özgül Ekmekc?; Ayfer Ulku

2003-01-01

83

Occipital cortical proton MRS at 4 Tesla in human moderate MDMA polydrug users  

PubMed Central

The recreational drug MDMA (3,4, methylenedioxymethamphetamine; sold under the street name of Ecstasy) is toxic to serotonergic axons in some animal models of MDMA administration. In humans, MDMA use is associated with alterations in markers of brain function that are pronounced in occipital cortex. Among neuroimaging methods, magnetic resonance spectroscopy (MRS) studies of brain metabolites N-acetylaspartate (NAA) and myoinositol (MI) at a field strength of 1.5 Tesla (T) reveal inconsistent results in MDMA users. Because higher field strength proton MRS has theoretical advantages over lower field strengths, we used proton MRS at 4.0 T to study absolute concentrations of occipital cortical NAA and MI in a cohort of moderate MDMA users (n = 9) versus non-MDMA using (n = 7) controls. Mean NAA in non-MDMA users was 10.47 mM (± 2.51), versus 9.83 mM (± 1.94) in MDMA users. Mean MI in non-MDMA users was 7.43 mM (± 1.68), versus 6.57 mM (± 1.59) in MDMA users. There were no statistical differences in absolute metabolite levels for NAA and MI in occipital cortex of MDMA users and controls. These findings are not supportive of MDMA-induced alterations in NAA or MI levels in this small sample of moderate MDMA users. Limitations to this study suggest caution in the interpretation of these results.

Cowan, Ronald L.; Bolo, Nicolas R.; Dietrich, Mary; Haga, Erica; Lukas, Scott E.; Renshaw, Perry F.

2007-01-01

84

Neuroimaging of cognitive functions in human parietal cortex  

Microsoft Academic Search

Functional neuroimaging has proven highly valuable in mapping human sensory regions, particularly visual areas in occipital cortex. Recent evidence suggests that human parietal cortex may also consist of numerous specialized subregions similar to those reported in neurophysiological studies of non-human primates. However, parietal activation generalizes across a wide variety of cognitive tasks and the extension of human brain mapping into

Jody C Culham; Nancy G Kanwisher

2001-01-01

85

Atlanto-occipital subluxation in Down syndrome.  

PubMed

Atlanto-occipital subluxation (AOS) in individuals with Down syndrome is discussed using five new cases and nine patients previously presented in the literature. Although AOS is likely due to ligamentous laxity, it was associated with atlantoaxial instability in only two youngsters. Reducible C1-C2 rotary subluxation was present in a third. Posterior movement of the occiput with respect to C1 occurred on extension and reduced on flexion in all but one individual who demonstrated anterior subluxation. Neurological problems are described in only two individuals: one with severe atlantoaxial subluxation (AAS) and the other with multiple cervical spine anomalies. Since AOS is usually detected on films obtained to screen children with Down syndrome for AAS, the atlanto-occipital joint should be carefully studied on these radiographs. The clinical significance of AOS needs to be determined. PMID:1827521

Stein, S M; Kirchner, S G; Horev, G; Hernanz-Schulman, M

1991-01-01

86

Rock-Magnetic Properties of Drill Core LOC-9 from the Lockne Crater, Sweden  

NASA Astrophysics Data System (ADS)

This study provides a precise analysis of the rock magnetic properties, including characterization of the magnetic phases and identification of them for samples from the LOC-9 core from the Lockne impact crater, Sweden.

Melero Asensio, I.; Martín-Hernández, F.; Ormö, J.

2011-03-01

87

Occipital Proton Magnetic Resonance Spectroscopy (1H-MRS) Reveals Normal Metabolite Concentrations in Retinal Visual Field Defects  

PubMed Central

Background Progressive visual field defects, such as age-related macular degeneration and glaucoma, prevent normal stimulation of visual cortex. We investigated whether in the case of visual field defects, concentrations of metabolites such as N-acetylaspartate (NAA), a marker for degenerative processes, are reduced in the occipital brain region. Methodology/Principal Findings Participants known with glaucoma, age-related macular degeneration (the two leading causes of visual impairment in the developed world), and controls were examined by proton MR spectroscopic (1H-MRS) imaging. Absolute NAA, Creatine and Choline concentrations were derived from a single-voxel in the occipital region of each brain hemisphere. No significant differences in metabolites concentrations were found between the three groups. Conclusions/Significance We conclude that progressive retinal visual field defects do not affect metabolite concentration in visual brain areas suggesting that there is no ongoing occipital degeneration. We discuss the possibility that metabolite change is too slow to be detectable.

Boucard, Christine C.; Hoogduin, Johannes M.; van der Grond, Jeroen; Cornelissen, Frans W.

2007-01-01

88

Multiple routes from occipital to temporal cortices during reading.  

PubMed

Contemporary models of the neural system that supports reading propose that activity in a ventral occipitotemporal area (vOT) drives activity in higher-order language areas, for example, those in the posterior superior temporal sulcus (pSTS) and anterior superior temporal sulcus (aSTS). We used fMRI with dynamic causal modeling (DCM) to investigate evidence for other routes from visual cortex to the left temporal lobe language areas. First we identified activations in posterior inferior occipital (iO) and vOT areas that were more activated for silent reading than listening to words and sentences; and in pSTS and aSTS areas that were commonly activated for reading relative to false-fonts and listening to words relative to reversed words. Second, in three different DCM analyses, we tested whether visual processing of words modulates activity from the following: (1) iO?vOT, iO?pSTS, both, or neither; (2) vOT?pSTS, iO?pSTS, both or neither; and (3) pSTS?aSTS, vOT?aSTS, both, or neither. We found that reading words increased connectivity (1) from iO to both pSTS and vOT; (2) to pSTS from both iO and vOT; and (3) to aSTS from both vOT and pSTS. These results highlight three potential processing streams in the occipitotemporal cortex: iO?pSTS?aSTS; iO?vOT?aSTS; and iO?vOT?pSTS?aSTS. We discuss these results in terms of cognitive models of reading and propose that efficient reading relies on the integrity of all these pathways. PMID:21632945

Richardson, Fiona M; Seghier, Mohamed L; Leff, Alex P; Thomas, Michael S C; Price, Cathy J

2011-06-01

89

Ultrasonic doppler flowmeter-guided occipital nerve block  

PubMed Central

Background Greater occipital nerve block is used in the treatment of headaches and neuralgia in the occipital area. We evaluated the efficacy of ultrasonic doppler flowmeter-guided occipital nerve block in patients experiencing headache in the occipital region in a randomized, prospective, placebo-controlled study. Methods Twenty-six patients, aged 18 to 70, with headache in the occipital region, were included in the study. Patients received a greater occipital nerve block performed either under ultrasonic doppler flowmeter guidance using 1% lidocaine or the traditional method. Sensory examination findings in the occipital region were evaluated. Results The complete block rate of greater occipital nerve blockade in the doppler group was significantly higher than in the control group respectively (76.9% vs. 30.8%, P < 0.05). Only one patient in the control group had a complication (minimal bleeding). Conclusions Ultrasonic doppler flowmeter-guided occipital nerve block may be a useful method for patients suffering headache in the occipital region.

Na, Se Hee; Kim, Tae Wan; Oh, Se-Young; Kweon, Tae Dong; Yoon, Kyung Bong; Yoon, Duck Mi

2010-01-01

90

[Forms of fractures of the occipital condyles].  

PubMed

In contrast to the large fracture system of the base of the skull, little attention has so far been paid to fractures of the occipital condyles. The mechanics of these fractures have mostly been described in the form of case reports. Here an attempt is made to classify fractures of the occipital condyle based on the literature and our own material. Fractures of the condyles in the sense of bursting or the injuries themselves are classified under the following forms of strain: 1. Axial compression (Jefferson type) condylar impression; 2. Axial traction (hangman's type) condylar retraction; 3. Rotation with axial strain condylar retraction; 4. Oblique compression (bursting fracture of the abutment) frontal condylar fracture; contralateral; 5. Oblique traction (horizontal thrust); a tearing at the base of the skull as in a contralateral condylar horizontal fracture; 6. Transverse thrust (longitudinal fracture of the base of the skull) partial condylar avulsion The functional connection between a longitudinal clivus and condylar fracture is illustrated by typical examples. Furthermore, the elliptical deformation model for a burst fracture at the base of the skull in the longitudinal axis is extended by the deeper transverse thrust stabilization of the condyles. PMID:3425007

Saternus, K S

1987-01-01

91

Occipital Proton Magnetic Resonance Spectroscopy (1H-MRS) Reveals Normal Metabolite Concentrations in Retinal Visual Field Defects  

Microsoft Academic Search

BackgroundProgressive visual field defects, such as age-related macular degeneration and glaucoma, prevent normal stimulation of visual cortex. We investigated whether in the case of visual field defects, concentrations of metabolites such as N-acetylaspartate (NAA), a marker for degenerative processes, are reduced in the occipital brain region.Methodology\\/Principal FindingsParticipants known with glaucoma, age-related macular degeneration (the two leading causes of visual impairment

Christine C. Boucard; Johannes M. Hoogduin; Jeroen van der Grond; Frans W. Cornelissen; Laurent Itti

2007-01-01

92

Role of anterior and occipital white matter lesions for smooth eye tracking in myotonic dystrophy  

PubMed Central

Objective: To discover which of these WMLs are relevant in SP impairment? Method: Horizontal sinusoidal SP, the vestibulo-ocular reflex (VOR), and its suppression by fixation (VOR-S) were investigated in 12 patients with MD, and the data obtained were compared with those from a control group. Results: Parallel degradation of SP and VOR-S was found in patients, although the eyes hardly needed to move with VOR-S. VOR in patients was normal. These results indicate a central rather than a peripheral origin for the SP degradation. Magnetic resonance images of the patients' heads were obtained and the WMLs transferred to a standard map. The lesions were mainly located around the occipital and anterior horn of the lateral ventricle. SP performance was then related to lesion site. The largest area of deficit associated lesions appeared to be in the parieto-occipital white matter. The most severe SP impairment, however, was associated with frontal WMLs. Conclusion: The study establishes a link between SP deficits and WMLs in patients with MD, in line with previous observations that, not only parieto-occipital regions, but also the frontal cortex has a crucial role in the gain control of SP.

Kimmig, H; Petrick, M; Orszagh, M; Mergner, T

2002-01-01

93

A household LOC device for online monitoring bacterial pathogens in drinking water with green design concept.  

PubMed

Bacterial waterborne pathogens often threaten the water safety of the drinking water system. In order to protect the health of home users, a household lab-on-a-chip (LOC) device was developed for online monitoring bacterial pathogens in drinking water, which are in accord with green design concept. The chip integrated counter-flow micromixers, a T-junction droplet generator and time-delay channels (TD-Cs), which can mix water sample and reactants into droplets in air flow and incubate the droplets in the LOC for about 18 hours before observation. The detection module was simplified into a transparent observation chamber, from which the home users can evaluate the qualitative result by naked eyes. The liquid waste generated by the LOC system was sterilized and absorbed by quicklime powders. No secondary pollution was found. The preliminary test of the prototype system met its design requirements. PMID:24110035

Zhao, Xinyan; Dong, Tao

2013-07-01

94

Fuel-rod response during the large-break LOCA Test LOC-6. [PWR  

SciTech Connect

The large break Loss of Coolant Accident (LOCA) Test LOC-6 was conducted in the Power Burst Facility (PBF) at the Idaho National Engineering Laboratory by EG and G Idaho, Inc. The objectives of the PBF LOCA tests are to obtain in-pile cladding ballooning data under blowdown and reflood conditions and assess how well out-of-pile ballooning data represent in-pile fuel rod behavior. The primary objective of the LOC-6 test was to determine the effects of internal rod pressures and prior irradiation on the deformation behavior of fuel rods that reached cladding temperatures high in the alpha phase of zircaloy. Test LOC-6 was conducted with four rods of PWR 15 x 15 design with the exception of fuel stack length (89 cm) and enrichment (12.5 W% /sup 235/U). Each rod was surrounded by an individual flow shroud.

Vinjamuri, K.; Cook, B.A.; Hobbins, R.R.

1981-01-01

95

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

96

Loc1p is required for efficient assembly and nuclear export of the 60S ribosomal subunit.  

PubMed

Loc1p is an exclusively nuclear dsRNA-binding protein that affects the asymmetric sorting of ASH1 mRNA to daughter cells in Saccharomyces cerevisiae. In addition to the role in cytoplasmic RNA localization, Loc1p is a constituent of pre-60S ribosomes. Cells devoid of Loc1p display a defect in the synthesis of 60S ribosomal subunits, resulting in "half-mer" polyribosomes. Previously, we reported that Loc1p is located throughout the entire nucleus; however, upon closer inspection we discovered that Loc1p is enriched in the nucleolus consistent with a role in 60S ribosome biogenesis. Given that Loc1p is an RNA-binding protein and presumably functions in the assembly of 60S ribosomal subunits, we investigated if Loc1p has a role in rRNA processing and nuclear export of 60S subunits. Analysis of pre-rRNA processing revealed that loc1Delta cells exhibit gross defects in 25S rRNA synthesis, specifically a delay in processing at sites A0, A1 and A2 in 35S pre-rRNA. Furthermore, loc1Delta cells exhibit nuclear export defects for 60S ribosomal subunits, again, consistent with a role for Loc1p in the assembly of 60S ribosomal subunits. It is attractive to hypothesize that the two phenotypes associated with loc1Delta cells, namely altered ASH1 mRNA localization and ribosome biogenesis, are not mutually exclusive, but that ribosome biogenesis directly impacts mRNA localization. PMID:16871394

Urbinati, Carl R; Gonsalvez, Graydon B; Aris, John P; Long, Roy M

2006-07-27

97

Eye dominance and ct measures of occipital length and width  

Microsoft Academic Search

CT measurements of right and left occipital length and width were correlated with eye dominance for 14 men and 27 women. Female subjects demonstrated little relationship between eye dominance and occipital measurements. For male subjects, however, right eye dominance was significantly correlated with increased lengths and widths for both right and left hemispheres on CT slices W, SM, and SM

Suzanne Craft; Ronald A. Yeo

1990-01-01

98

Differential distribution of NADPH-diaphorase histochemistry in human cerebral cortex.  

PubMed

Beta-nicotinamidedinucleotide phosphate diaphorase (NADPH-d) colocalizes with NOS in the central nervous system. Two types of NADPH-d-positive neurons are present in the primate cerebral cortex: type 1, intensely and Golgi-like labeled neurons, a subset of GABAergic interneurons; type 2, lightly labeled neurons (divided into two subclasses, a first one having a lightly stained cell body bearing only one short process, and a second one showing intense NADPH-d staining with short processes extending radially). We have analyzed the distribution of NADPH-d activity in human frontal, temporal, and occipital cortical areas, finding remarkable laminar and interareal differences in cell size and distribution of the different cell types. There was a clear bias for type 1 neurons in infragranular layers in all areas considered; both in supra- and infragranular layers, their density was highest in frontal, and lowest in temporal cortex. The density of type 2 neurons was lower supragranularly in temporal cortex and infragranularly in occipital cortex. The overall density of type 2 cells was remarkably higher in occipital cortex than in the temporal and frontal ones. Type 1 neurons were significantly larger than type 2, and were smaller in the supragranular than in the infragranular subzone in occipital and temporal cortex. Type 1 cells were significantly larger in frontal cortex than in occipital and temporal cortex, and type 2 cells were significantly smaller in occipital than in temporal and frontal cortex. These area-related differences might reflect differences between heterotypic and homotypic cortex in the regulation of cortical blood flow. PMID:15713254

Garbossa, Diego; Fontanella, Marco; Tomasi, Simone; Ducati, Alessandro; Vercelli, Alessandro

2005-02-01

99

Excited Weak Bosons as Massive Gauge Particles of Transmuted SU(2)(sub L)(Sup Loc) Symmetry.  

National Technical Information Service (NTIS)

In a model with weak bosons based on the SU(2)/sub L//sup loc/ x U(1)/sub Y//sup loc/ symmetry, excited weak gauge bosons, W* and Z*, are introduced as composites generated by four Fermi interactions. From the complementarity viewpoint that requires a new...

M. Yasue

1988-01-01

100

Project CHECO Southeast Asia Report. The Battle for An Loc 5 April - 26 June 1972.  

National Technical Information Service (NTIS)

The battle for An Loc may well prove to be a classic study in the use of tactical airpower in the years to come. It was an interlude in the Vietnam War where COSVN, confident in its own strength, introduced 'a true conventional strategy for the first time...

P. J. Melly P. T. Ringenbach

1973-01-01

101

SensLoc: sensing everyday places and paths using less energy  

Microsoft Academic Search

Continuously understanding a user's location context in colloquial terms and the paths that connect the locations unlocks many opportunities for emerging applications. While extensive research effort has been made on efficiently tracking a user's raw coordinates, few attempts have been made to efficiently provide everyday contextual information about these locations as places and paths. We introduce SensLoc, a practical location

Donnie H. Kim; Younghun Kim; Deborah Estrin; Mani B. Srivastava

2010-01-01

102

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

2011-12-07

103

A case of occipitalization in the human skull.  

PubMed

Occipitalization of the atlas is an osseous anomaly of the craniovertebral junction. The aim of this paper is to present an anatomical variant of the fused atlas with the occipital bone and discuss similar cases described in literature. The skull of an adult male analysed in this study belonged to the cranial collection of the Department of Anatomy of the Jagiellonian University, Medical Collage. A tight bony fusion between the anterior arch of the atlas, the left portion of the posterior arch, the lateral masses of the atlas, and the occipital bone was observed. Hence, the left and right superior articular facets of the atlas were fused with the corresponding occipital condyles. The anteroposterior dimension of both inferior articular facets was the same (20 mm), while the transverse diameter of the right one was considerably smaller (12 mm). The transverse diameter of the left inferior articular facets was 17 mm. The right and the left transverse process of the atlas were normally developed, each of them contained transverse foramen, and they were not fused with the occipital bone. The circumference of the foramen magnum was minimally diminished by the osseous structures of the atlas fused to the occipital bone. The sagittal and transverse diameters of the foramen magnum (38 mm x 34 mm) were within the normal range of variation. However, the asymmetrical anatomy of the inferior articular facets of the atlas give rise to speculation that movement in the atlantoaxial joint was disturbed by assimilation with the occipital bone. PMID:21154282

Skrzat, J; Mróz, I; Jaworek, J K; Walocha, J

2010-08-01

104

Auditory Attention Activates Peripheral Visual Cortex  

Microsoft Academic Search

Background: Recent neuroimaging studies have revealed that putatively unimodal regions of visual cortex can be activated during auditory tasks in sighted as well as in blind subjects. However, the task determinants and functional significance of auditory occipital activations (AOAs) remains unclear. Methodology\\/Principal Findings:We examined AOAs in an intermodalselectiveattention taskto distinguish whether they were stimulus-bound or recruited by higher-level cognitive operations

Anthony D. Cate; Timothy J. Herron; E. William Yund; G. Christopher Stecker; Teemu Rinne; Xiaojian Kang; Christopher I. Petkov; Elizabeth A. Disbrow; David L. Woods

2009-01-01

105

The first 5 minutes after greater occipital nerve block.  

PubMed

We performed greater occipital nerve blocks on 24 migraineurs with unilateral migraine and trigeminal nerve distribution allodynia. Using a visual analog scale for migraine pain, brush allodynia in the trigeminal nerve distribution and photophobia were reduced 64%, 75%, and 67%, respectively, after 5 minutes. Allodynia improved faster than headache. The results of this study suggest that greater occipital nerve blocks initiate an inhibitory process that shuts down several symptom generators. PMID:18549410

Young, William; Cook, Brianna; Malik, Shahram; Shaw, James; Oshinsky, Michael

2008-06-28

106

Early (N170/M170) Face-Sensitivity Despite Right Lateral Occipital Brain Damage in Acquired Prosopagnosia  

PubMed Central

Compared to objects, pictures of faces elicit a larger early electromagnetic response at occipito-temporal sites on the human scalp, with an onset of 130?ms and a peak at about 170?ms. This N170 face effect is larger in the right than the left hemisphere and has been associated with the early categorization of the stimulus as a face. Here we tested whether this effect can be observed in the absence of some of the visual areas showing a preferential response to faces as typically identified in neuroimaging. Event-related potentials were recorded in response to faces, cars, and their phase-scrambled versions in a well-known brain-damaged case of prosopagnosia (PS). Despite the patient’s right inferior occipital gyrus lesion encompassing the most posterior cortical area showing preferential response to faces (“occipital face area”), we identified an early face-sensitive component over the right occipito-temporal hemisphere of the patient that was identified as the N170. A second experiment supported this conclusion, showing the typical N170 increase of latency and amplitude in response to inverted faces. In contrast, there was no N170 in the left hemisphere, where PS has a lesion to the middle fusiform gyrus and shows no evidence of face-preferential response in neuroimaging (no left “fusiform face area”). These results were replicated by a magnetoencephalographic investigation of the patient, disclosing a M170 component only in the right hemisphere. These observations indicate that face-preferential activation in the inferior occipital cortex is not necessary to elicit early visual responses associated with face perception (N170/M170) on the human scalp. These results further suggest that when the right inferior occipital cortex is damaged, the integrity of the middle fusiform gyrus and/or the superior temporal sulcus – two areas showing face-preferential responses in the patient’s right hemisphere – might be necessary to generate the N170 effect.

Prieto, Esther Alonso; Caharel, Stephanie; Henson, Richard; Rossion, Bruno

2011-01-01

107

Ganglioglioma arising from dysplastic cortex.  

PubMed

We report the case of a child who presented at 3 months of age with complex partial seizures, a linear facial nevus, and magnetic resonance imaging (MRI) showing delayed myelination and thickened cortex in the left temporal, parietal, and occipital regions. A repeat 3Tesla MRI scan with and without contrast at 6 months again showed cortical dysplasia of the left hemisphere. No other abnormalities were seen. A third scan at 3 years 6 months showed a 2.5 cm, round, hyperintense lesion on both T(2) and T(1) sequences. The lesion and surrounding dysplastic cortex were resected. Palmini grade IIA dysplasia and a ganglioglioma were diagnosed. These findings suggest that cellular components of cortical dysplasias have oncogenic potential. PMID:21668439

Ortiz-González, Xilma R; Venneti, Sriram; Biegel, Jaclyn A; Rorke-Adams, Lucy B; Porter, Brenda E

2011-06-10

108

Occipital-axis posterior wiring and fusion for atlantoaxial dislocation associated with occipitalization of the atlas. Technical note.  

PubMed

The authors present their technique of occipital-axis posterior wiring and fusion for atlantoaxial dislocation associated with an occipitalized atlas. The technique consists of drilling a 3 x 1-cm horizontal groove in the occipital bone 1 cm posterior to the foramen magnum and building up a bony bridge along the posterior margin of the foramen magnum. This bony bridge is referred to as an "artificial atlas." Conventional wiring and fusion is performed between the artificial atlas and the C-2 lamina, interposing a strut bone graft. Since the compression force on tightening the wire is vertical, a very high degree of stability for the occipital-C-2 complex is achieved, facilitating early mobilization without postoperative redislocation. PMID:8315456

Jain, V K; Takayasu, M; Singh, S; Chharbra, D K; Sugita, K

1993-07-01

109

"What?" and "where?" versus "what is where?": the impact of task on coding of object form and position in the lateral occipital complex.  

PubMed

Fast and accurate recognition of both the identities and positions of objects in visual space is critical to deciphering visual environments. Studies in both humans and nonhuman primates have demonstrated that neural populations in ventral temporal visual areas are jointly tuned to both the form and position of objects, allowing information about the identities of objects to be "tagged" with their positions. Because not all behaviors demand that the identities of objects be associated with position information with equal precision, however, the present study asked whether the spatial tuning of form-encoding populations in the human lateral occipital complex (LOC) is sculpted by task demands. Subjects were scanned using functional magnetic resonance imaging while viewing matches of the game Rock, Paper, Scissors played with exemplar pairs from those categories. Subjects first performed a repetition-detection task that depended on object form but not position; subsequently, subjects viewed the same stimuli while determining the position of each pair's "winner," a task that depended upon the conjunction of object form and position. Compared to data from the initial scan, multivoxel activity patterns evoked in the lateral occipital (LO) subdivision of LOC while subjects judged winners showed enhanced sensitivity to the relative positions of objects in pairs. Although superficially consistent with dynamic position tuning, this effect appears to be attributable to an accompanying task-dependent improvement in the sensitivity of LO populations to object form. The results thus suggest that the spatial tuning of form-encoding populations in LO does not depend upon the precision of spatial information demanded by a task. PMID:23873674

Macevoy, Sean P

2013-07-19

110

Algorithmic, LOCS and HOCS (chemistry) exam questions: performance and attitudes of college students  

Microsoft Academic Search

The performance of freshmen biology and physics-mathematics majors and chemistry majors as well as pre- and in-service chemistry teachers in two Israeli universities on algorithmic (ALG), lower-order cognitive skills (LOCS), and higher-order cognitive skills (HOCS) chemistry exam questions were studied. The driving force for the study was an interest in moving science and chemistry instruction from an algorithmic and factual

Uri Zoller

2002-01-01

111

ELISA-LOC: lab-on-a-chip for enzyme-linked immunodetection.  

PubMed

A miniature 96 sample ELISA-lab-on-a-chip (ELISA-LOC) was designed, fabricated, and tested for immunological detection of Staphylococcal Enterotoxin B (SEB). The chip integrates a simple microfluidics system into a miniature ninety-six sample plate, allowing the user to carry out an immunological assay without a laboratory. Assay reagents are delivered into the assay plate without the need for separate devices commonly used in immunoassays. The ELISA-LOC was constructed using Laminated Object Manufacturing (LOM) technology to assemble six layers with an acrylic (poly(methyl methacrylate) (PMMA)) core and five polycarbonate layers micromachined by a CO(2) laser. The ELISA-LOC has three main functional elements: reagent loading fluidics, assay and detection wells, and reagent removal fluidics, a simple "surface tension" valve used to control the flow. To enhance assay sensitivity and to perform the assay without a lab, ELISA-LOC detection combines several biosensing elements: (1) carbon nanotube (CNT) technology to enhance primary antibody immobilization, (2) sensitive ECL (electrochemiluminescence) detection, and (3) a charge-coupled device (CCD) detector for measuring the light signal generated by ECL. Using a sandwich ELISA assay, the system detected SEB at concentrations as low as 0.1 ng ml(-1), which is similar to the reported sensitivity of conventional ELISA. The fluidics system can be operated by a syringe and does not require power for operation. This simple point-of-care (POC) system is useful for carrying out various immunological assays and other complex medical assays without a laboratory. PMID:20544092

Sun, Steven; Yang, Minghui; Kostov, Yordan; Rasooly, Avraham

2010-06-11

112

Sub-occipital craniectomy in a lion (Panthera leo) with occipital bone malformation and hypovitaminosis A.  

PubMed

Neurologic dysfunction accompanied by malformation of both the skull and the cervical vertebrae has been previously described in lions kept in captivity worldwide, and this dysfunction and malformation were most often related to vitamin A deficiency. Diagnosis of the bone malformation and its effects on the neural tissue was until recently limited to postmortem examination, with characteristic thickening of the bones of the cranial vault, cerebellar herniation, compression of the foramen magnum, and enlargement of the lateral ventricles. For some mildly affected lion cubs with neurologic signs, improvement was reported with excessive vitamin A supplementation. However, definitive diagnosis was only available for those that eventually died or were euthanized. This case documents the antemortem diagnosis of the disease using computed tomographic imaging and liver biopsy. While conservative treatment failed, suboccipital craniectomy removed the thickened occipital bone and was demonstrated to be a successful surgical intervention that can be used to treat more severely affected lions. PMID:18817011

Shamir, Merav H; Shilo, Yael; Fridman, Alon; Chai, Orit; Reifen, Ram; Miara, Limor

2008-09-01

113

LocARNAscan: Incorporating thermodynamic stability in sequence and structure-based RNA homology search  

PubMed Central

Background The search for distant homologs has become an import issue in genome annotation. A particular difficulty is posed by divergent homologs that have lost recognizable sequence similarity. This same problem also arises in the recognition of novel members of large classes of RNAs such as snoRNAs or microRNAs that consist of families unrelated by common descent. Current homology search tools for structured RNAs are either based entirely on sequence similarity (such as blast or hmmer) or combine sequence and secondary structure. The most prominent example of the latter class of tools is Infernal. Alternatives are descriptor-based methods. In most practical applications published to-date, however, the information contained in covariance models or manually prescribed search patterns is dominated by sequence information. Here we ask two related questions: (1) Is secondary structure alone informative for homology search and the detection of novel members of RNA classes? (2) To what extent is the thermodynamic propensity of the target sequence to fold into the correct secondary structure helpful for this task? Results Sequence-structure alignment can be used as an alternative search strategy. In this scenario, the query consists of a base pairing probability matrix, which can be derived either from a single sequence or from a multiple alignment representing a set of known representatives. Sequence information can be optionally added to the query. The target sequence is pre-processed to obtain local base pairing probabilities. As a search engine we devised a semi-global scanning variant of LocARNA’s algorithm for sequence-structure alignment. The LocARNAscan tool is optimized for speed and low memory consumption. In benchmarking experiments on artificial data we observe that the inclusion of thermodynamic stability is helpful, albeit only in a regime of extremely low sequence information in the query. We observe, furthermore, that the sensitivity is bounded in particular by the limited accuracy of the predicted local structures of the target sequence. Conclusions Although we demonstrate that a purely structure-based homology search is feasible in principle, it is unlikely to outperform tools such as Infernal in most application scenarios, where a substantial amount of sequence information is typically available. The LocARNAscan approach will profit, however, from high throughput methods to determine RNA secondary structure. In transcriptome-wide applications, such methods will provide accurate structure annotations on the target side. Availability Source code of the free software LocARNAscan 1.0 and supplementary data are available at http://www.bioinf.uni-leipzig.de/Software/LocARNAscan.

2013-01-01

114

LocARNAscan: Incorporating thermodynamic stability in sequence and structure-based RNA homology search.  

PubMed

BACKGROUND: The search for distant homologs has become an import issue in genome annotation. A particular difficulty is posed by divergent homologs that have lost recognizable sequence similarity. This same problem also arises in the recognition of novel members of large classes of RNAs such as snoRNAsor microRNAs that consist of families unrelated by common descent. Current homology search tools for structured RNAs are either based entirely on sequence similarity (such as blast or hmmer) or combine sequence and secondary structure. The most prominent example of the latter class of tools is Infernal. Alternatives are descriptor-based methods. In most practical applications published to-date, however, the information contained in covariance models or manually prescribed search patterns is dominated by sequence information. Here we ask two related questions: (1) Is secondary structure alone informative for homology search and the detection of novel members of RNA classes? (2) To what extent is the thermodynamic propensity of the target sequence to fold into the correct secondary structure helpful for this task? RESULTS: Sequence-structure alignment can be used as an alternative search strategy. In this scenario, the query consists of a base pairing probability matrix, which can be derived either from a single sequence or from a multiple alignment representing a set of known representatives. Sequence information can be optionally added to the query. The target sequence is pre-processed to obtain local base pairing probabilities. As a search engine we devised a semi-global scanning variant of LocARNA's algorithm for sequence-structure alignment. The LocARNAscan tool is optimized for speed and low memory consumption. In benchmarking experiments on artificial data we observe that the inclusion of thermodynamic stability is helpful, albeit only in a regime of extremely low sequence information in the query. We observe, furthermore, that the sensitivity is bounded in particular by the limited accuracy of the predicted local structures of the target sequence. CONCLUSIONS: Although we demonstrate that a purely structure-based homology search is feasible in principle, it is unlikely to outperform tools such as Infernal in most application scenarios, where a substantial amount of sequence information is typically available. The LocARNAscan approach will profit, however, from high throughput methods to determine RNA secondary structure. In transcriptomewide applications, such methods will provide accurate structure annotations on the target side. AVAILABILITY: Source code of the free software LocARNAscan 1.0 and supplementary data are available at http://www.bioinf.uni-leipzig.de/Software/LocARNAscan. PMID:23601347

Will, Sebastian; Siebauer, Michael F; Heyne, Steffen; Engelhardt, Jan; Stadler, Peter F; Reiche, Kristin; Backofen, Rolf

2013-04-20

115

Het oordeel van leden van cliëntenraden over de kwaliteit van dienstverlening van de Landelijke Organisatie Cliëntenraden (LOC): meetinstrumentontwikkeling  

Microsoft Academic Search

De cliëntenraden van onder meer verzorgingshuizen, verpleeghuizen en thuiszorgorganisaties zijn over het algemeen tevreden over de dienstverlening van de Landelijke Organisatie Cliëntenraden (LOC). Over de bejegening zijn ze onverdeeld positief, de belangenbehartiging kan nog beter. \\u000a \\u000aDikke voldoende\\u000aDe cliëntenraden geven hun landelijke organisatie gemiddeld een 7,3. Cliëntenraden in de verpleeghuizen zijn het meest te spreken over de LOC en geven

M. van Greuningen; J. Rademakers

2008-01-01

116

[Traumatic atlanto-occipital dislocation in a calf].  

PubMed

In a 7-week-old calf neurologic symptoms occurred after an accident in the feeding grid. The calf was alert but in left lateral recumbency. After having been placed on its right side it showed a sideward drift to the left. Following head movement, an asynchronous movement of the eyes could be observed. Lesions of the upper motor neuron system, N. vestibulocochlearis, Nn. oculomotorius, trochlearis and/or abducens as well as N. vagus were suspected. Radiological examination of the occipital region and cervical spine revealed an atlanto-occipital subluxation of the atlas. Based on all these findings, the diagnosis of traumatic atlanto-occipital dislocation was made and the calf was euthanized. The pathological findings confirmed this diagnosis. PMID:22331290

Knubben-Schweizer, G; Friedrich, A; Ebert, U; Hördemann, M; Hagen, R; Nuss, K

2012-01-01

117

Hyperpneumatization of the temporal, occipital and parietal bones.  

PubMed

Hyperpneumatization of the temporal bone with extension into the occipital bone and even the parietal bones is a rare condition. According to a review of the literature, it mostly appears unilaterally in men and on the right side. Often it is discovered when complications like pneumatocele or pneumocephalus appear. The authors review and analyze all reported cases of hyperpneumatization, its symptoms, complications and treatment. We present a patient with extensive pneumatization found in the mastoid process, temporal bone, occipital bone and both parietal bones, who was discovered accidentally. The cause of the extension of pneumatization into the occipital and parietal bone is probably incomplete closure of the occipitomastoid synchondrosis and lambdoid and sagital sutures, which usually close in early adulthood and later, even in the 30s. Asymptomatic patients should be aware of possible complications, and in case of complications, operative therapy is often indicated. PMID:14652772

Rebol, Janez; Munda, Anton; Tos, Mirko

2003-12-03

118

Cervical facet arthropathy and occipital neuralgia: headache culprits.  

PubMed

Cervicogenic headache (CH) is pain referred from the neck. Two common causes are cervical facet arthropathy and occipital neuralgia. Clinical diagnosis is difficult because of the overlying features between primary headaches such as migraine, tension-type headache, and CH. Interventional pain physicians have focused on supporting the clinical diagnosis of CH with confirmatory blocks. The treatment of cervical facet arthropathy as the source of CH is best approached with a multidimensional plan focusing on physical therapy and/or manual therapy. The effective management of occipital neuralgia remains challenging, but both injections and neuromodulation are promising options. PMID:20936382

Hoppenfeld, J D

2010-12-01

119

Traumatic aneurysm of the occipital artery secondary to paintball injury  

Microsoft Academic Search

Paintball is an “extreme sport” that has been steadily growing in popularity since the early 1980s. Although this activity is considered recreational, there are a number of inherent dangers associated. Most notably, the number of head and neck injuries due to paintball participation has been increasing in recent years. In this paper we present the first reported case of occipital

Neely John; James L. Leach; Tyagi Rachana; Francesco T. Mangano

2009-01-01

120

Hyperpneumatization of the temporal, occipital and parietal bones  

Microsoft Academic Search

Hyperpneumatization of the temporal bone with extension into the occipital bone and even the parietal bones is a rare condition. According to a review of the literature, it mostly appears unilaterally in men and on the right side. Often it is discovered when complications like pneumatocele or pneumocephalus appear. The authors review and analyze all reported cases of hyperpneumatization, its

Janez Rebol; Anton Munda; Mirko Tos

2004-01-01

121

Aptamer-NASBA LOC as a prospective tool for systemic therapy of cancer: quantitative detection on signaling molecular profiling.  

PubMed

As the present technology of cancer treatment cannot cure the diseases, a prospective therapy, named 'systemic therapy', brings forth a new trend in cancer treatment. The aptamer-NASBA-based lab-on-a-chip (LOC) for systemic therapy was designed, fabricated and tested as an ultra-sensitive tool to monitor signaling molecular profiling in serum samples. The chip is divided into four parallel functional areas, corresponding to four groups of signaling molecules (i.e. hormones, neurotransmitters, cytokines and tumor biomarkers). The results can help doctors fully understand the body of patients. The chip is modeled on a 384-well microplate, which is completely compatible with common microplate readers in a biological laboratory. It can distinguish 24 signaling molecules in the same blood sample quantitatively and simultaneously. The chip was made of PDMS and silicon with a deposited gold layer, which was coated by aptamers before bonding; then, the LOC was operated by external valves and a vacuum pump. Its performance was demonstrated by detecting the presence of a synthetic peptide, GnRH (gonadotropin-releasing hormone) in artificial samples. The results indicated that the LOC has the potential to quantify traces of biomarkers even at subfemtomolar levels. Compared with our previous immuno-NASBA LOC, the aptamer-NASBA LOC showed an increased sensitivity and better repeatability. PMID:23365958

Zhao, Xinyan; Dong, Tao; Yang, Zhaochu; Karlsen, Haakon

2012-01-01

122

Gyrokinetic Simulations of Diluted Plasmas in the LOC regime in Alcator C-Mod  

NASA Astrophysics Data System (ADS)

Previous investigations of ITG and TEM/ETG turbulence using the reduced gyro-landau fluid code TGLF, and gyrokinetic code GYRO have predicted that in the linear ohmic confinement (LOC) regime in Alcator C-Mod the dilution of the main D ion species by low-Z impurities reduces the ion transport to experimentally observed levels. This analysis assumed an average impurity ion charge Zi= 8. Recent spectroscopic measurements of the impurity ion species in the LOC regime in C-Mod have shown that the average Zi is approximately 9, which at the measured Zeff values (2-4) results in a significant dilution (>10%) of the majority D ion species. By puffing in nitrogen while using a cryopump to keep the density constant, new experiments enabled us to lower Zi to values near 8, thus further increasing dilution. To account for the sensitivity of the turbulent transport on the density (Lne) and temperature (LTe) gradient scale lengths, recently we used TGYRO to improve the agreement between theory and the measurements. The results of such simulations will be presented.

Porkolab, M.; Ennever, P.; Reinke, M. L.; Rice, J.; Rost, C.; Tsujii, N.; Davis, E.; Ernst, D.; Fiore, C.; Greenwald, M.; Hubbard, A.; Hughes, J.; Marmar, E.; Candy, J.; Staebler, G. M.; Waltz, R.

2012-10-01

123

Salient sounds activate human visual cortex automatically.  

PubMed

Sudden changes in the acoustic environment enhance perceptual processing of subsequent visual stimuli that appear in close spatial proximity. Little is known, however, about the neural mechanisms by which salient sounds affect visual processing. In particular, it is unclear whether such sounds automatically activate visual cortex. To shed light on this issue, this study examined event-related brain potentials (ERPs) that were triggered either by peripheral sounds that preceded task-relevant visual targets (Experiment 1) or were presented during purely auditory tasks (Experiments 2-4). In all experiments the sounds elicited a contralateral ERP over the occipital scalp that was localized to neural generators in extrastriate visual cortex of the ventral occipital lobe. The amplitude of this cross-modal ERP was predictive of perceptual judgments about the contrast of colocalized visual targets. These findings demonstrate that sudden, intrusive sounds reflexively activate human visual cortex in a spatially specific manner, even during purely auditory tasks when the sounds are not relevant to the ongoing task. PMID:23699530

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

2013-05-22

124

Clinical and electroencephalographic findings in early and late onset benign childhood epilepsy with occipital paroxysms  

Microsoft Academic Search

Twenty-six patients were studied who had the clinical and electroencephalographic features of benign childhood epilepsy with occipital paroxysms (BCEOP) as defined by the Commission of the International League Against Epilepsy (ILAE). Twelve patients were characterized as having early-onset benign childhood occipital seizures (EBOS) susceptible syndrome, as described by Panayiotopoulos, and 14 patients had late onset childhood idiopathic occipital seizures (LOS).

Min-Lan Tsai; Hsin-Yu Lo; Wun-Tsong Chaou

2001-01-01

125

[A patient with prosopagnosia which developed after an infarction in the left occipital lobe in addition to an old infarction in the right occipital lobe].  

PubMed

A 66-year-old, right-handed male, was admitted to our hospital with difficulty in recognizing faces and colors. He had suffered a stroke in the right occipital region three years earlier that had induced left homonymous hemianopsia, but not prosopagnosia. A neurological examination revealed prosopagnosia, color agnosia, constructional apraxia, and topographical disorientation, but not either hemineglect or dressing apraxia. The patient was unable to distinguish faces of familiar persons such as his family and friends, as well as those of unfamiliar persons such as doctors and nurses. Brain MRI demonstrated an old infarction in the right medial occipital lobe and a new hemorrhagic infarction in the left medial occipital lobe, including the fusiform and lingual gyrus. It is unclear whether a purely right medial occipital lesion can be responsible for prosopagnosia, or whether bilateral medial occipital lesions are necessary for this occurrence. The current case indicated that bilateral medial occipital lesions play an important role in inducing porsopagnosia. PMID:21706834

Iwanaga, Keisuke; Satoh, Akira; Satoh, Hideyo; Seto, Makiko; Ochi, Makoto; Tsujihata, Mitsuhiro

2011-05-01

126

Occipital horn syndrome in a woman: skeletal radiological findings  

Microsoft Academic Search

Ehlers–Danlos type IX syndrome, also called occipital horn syndrome (OHS), is a milder and rare form of Menkes disease where\\u000a the patient reaches adulthood. As an X-linked disease, it typically occurs in male subjects, while female subjects are usually\\u000a healthy carriers. OHS is mainly characterized by connective tissue disorders and slightly subnormal intelligence or signs\\u000a of autonomic dysfunction are the

Alberto Bazzocchi; Rayka Femia; Paola Feraco; Giuseppe Battista; Romeo Canini; Giuseppe Guglielmi

127

Occipital injections for trigemino-autonomic cephalalgias: evidence and uncertainties.  

PubMed

Cluster headache is a debilitating disorder. Oral prophylactic treatments may act with a significant delay, cause side effects, or fail to control the attacks. Injections targeting the occipital nerve have raised interest for the management of CH. Their efficacy is thought to result from the anatomical convergence of trigeminal and cervical afferents in the trigeminal nucleus caudalis. Efficacy and safety of occipital injections are now documented by 2 randomized controlled trials and several case series, though the optimal technique and substance to be injected are still subject to discussion due to varied approaches in the published studies. The evidence supports the use of injected steroids, with or without the addition of an anesthetic. Side effects of local pain are common, but unlikely to be severe. Systemic effects related to steroid absorption are reported but infrequent. Occipital injections provide a rapid benefit on the frequency of attacks and can be used as an adjunct to an oral prophylactic for a quicker improvement. Whether or not this approach can be used without any oral prophylaxis is still to be determined. The technique is easy to master, has a low cost, and should be learned by physicians involved in CH management. PMID:23443504

Leroux, Elizabeth; Ducros, Anne

2013-04-01

128

Magnetic properties of the LOC-9 core, implications for the ejecta emplacement from Lockne crater (Sweden).  

NASA Astrophysics Data System (ADS)

The Lockne crater is a 456 Ma old marine-target impact structure. It has a 7,5km wide inner crater developed in the crystalline basement, which is surrounded by a 3,5km wide brim where the crater excavation removed most of sedimentary cover rocks (mainly limestone and dark shale) before it was covered by the ejecta flap from the basement crater. The crystalline rocks of the basement are mainly granitoids, but several tens of meters thick dolerite sills are included. Here, we provide a precise analysis of the rock magnetic properties from the LOC-9 core. This is a 31,04m long and 42mm in diameter core drilled into the crystalline crater brim and ejecta flap. Thus, it provides an excellent opportunity to study the process of flap formation.

Melero Asensio, I.; Martín-Hernández, F.; Ormö, J.

2012-09-01

129

Constructing scenes from objects in human occipitotemporal cortex  

Microsoft Academic Search

We used functional magnetic resonance imaging (fMRI) to demonstrate the existence of a mechanism in the human lateral occipital (LO) cortex that supports recognition of real-world visual scenes through parallel analysis of within-scene objects. Neural activity was recorded while subjects viewed four categories of scenes and eight categories of 'signature' objects strongly associated with the scenes in three experiments. Multivoxel

Russell A Epstein; Sean P MacEvoy

2011-01-01

130

Activation of the Visual Cortex in Motivated Attention  

Microsoft Academic Search

Functional activation (measured with fMRI) in occipital cortex was more extensive when participants view pictures strongly related to primary motive states (i.e., victims of violent death, viewer-directed threat, and erotica). This functional activity was greater than that observed for less intense emotional (i.e., happy families or angry faces) or neutral images (i.e., household objects, neutral faces). Both the extent and

Margaret M. Bradley; Dean Sabatinelli; Peter J. Lang; Jeffrey R. Fitzsimmons; Wayne King; Paramtap Desai

2003-01-01

131

Cortical and subcortical projections of the middle temporal area (MT) and adjacent cortex in galagos.  

PubMed

Projections of the middle temporal visual area, MT, and of visual cortex adjoining MT were investigated with autoradiographic methods in the prosimian primate, Galago senegalensis. Ipsilateral cortical targets of MT included area 17, area 18, cortex caudal to MT, cortex ventral to MT, and parietal-occipital cortex dorsal to MT. This pattern of projections suggests that extrastriate cortex contains a number of visual subdivisions in addition to MT. Contralateral projections were to MT and parietal-occipital cortex. Projections from MT to areas 17 and 18 connected regions representing similar parts of the visual hemifield while the location of callosal projections in MT matched the location of the injection site in the other hemisphere. Label in area 17 was concentrated in layers I, III, and VI whereas other cortical areas were most densely labeled in the granular and supragranular layers. Subcortical projections of MT included the reticular nucleus of the thalamus, the lateral posterior nucleus, the superior pulvinar, the inferior pulvinar, the superior colliculus, and the pontine nuclei. The projection pattern to the superior and inferior pulvinar nuclei suggests that MT projects in a topographic manner to two subdivisions within each of these structures. Injections in cortex just outside of MT labeled area 18, inferotemporal cortex, parietal-occipital cortex, and, to a lesser extent, MT. The projections to inferotemporal cortex clearly distinguish the bordering cortex from MT. Contralateral cortical terminations were in locations corresponding to the injection site. Subcortical targets were generally similar to those seen after MT injections, although additional projections were observed depending on the location of the injection. Comparison of these results from the prosimian galago with studies in New and Old World monkeys indicates there are substantial similarities in projections. Thus, some of the cortical and thalamic subdivisions described for monkeys appear to exist in prosimians. PMID:7174890

Wall, J T; Symonds, L L; Kaas, J H

1982-10-20

132

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.

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

2011-01-01

133

Temporal stability of visually selective responses in intracranial field potentials recorded from human occipital and temporal lobes.  

PubMed

The cerebral cortex needs to maintain information for long time periods while at the same time being capable of learning and adapting to changes. The degree of stability of physiological signals in the human brain in response to external stimuli over temporal scales spanning hours to days remains unclear. Here, we quantitatively assessed the stability across sessions of visually selective intracranial field potentials (IFPs) elicited by brief flashes of visual stimuli presented to 27 subjects. The interval between sessions ranged from hours to multiple days. We considered electrodes that showed robust visual selectivity to different shapes; these electrodes were typically located in the inferior occipital gyrus, the inferior temporal cortex, and the fusiform gyrus. We found that IFP responses showed a strong degree of stability across sessions. This stability was evident in averaged responses as well as single-trial decoding analyses, at the image exemplar level as well as at the category level, across different parts of visual cortex, and for three different visual recognition tasks. These results establish a quantitative evaluation of the degree of stationarity of visually selective IFP responses within and across sessions and provide a baseline for studies of cortical plasticity and for the development of brain-machine interfaces. PMID:22956795

Bansal, Arjun K; Singer, Jedediah M; Anderson, William S; Golby, Alexandra; Madsen, Joseph R; Kreiman, Gabriel

2012-09-05

134

Adrenal Cortex  

Microsoft Academic Search

\\u000a Histopathological abnormalities of the adrenal cortex include a wide variety of lesions. These range from cortical nodules\\u000a to adrenal cortical adenomas and carcinomas. Many adrenal cortical nodules and tumors are functional and are associated with\\u000a Cushing’s syndrome or hyperaldosteronism. The Weiss criteria are most commonly used to distinguish adenomas from carcinomas.\\u000a \\u000a \\u000a Recent cellular and molecular studies have provided new insights

Hironobu Sasano; Yasuhiro Nakamura; Takuya Moriya; Takashi Suzuki

135

Traumatic aneurysm of the occipital artery secondary to paintball injury.  

PubMed

Paintball is an "extreme sport" that has been steadily growing in popularity since the early 1980s. Although this activity is considered recreational, there are a number of inherent dangers associated. Most notably, the number of head and neck injuries due to paintball participation has been increasing in recent years. In this paper we present the first reported case of occipital artery traumatic pseudoaneurysm resulting from a paintball accident. The presentation, diagnosis and intraoperative findings are detailed. A discussion including a review of the literature is also presented. The authors recommend a re-evaluation of guidelines within the paintball sporting industry, including improvements in protective equipment. PMID:18922630

John, Neely; Leach, James L; Rachana, Tyagi; Mangano, Francesco T

2008-10-14

136

The human cerebral cortex is neither one nor many: neuronal distribution reveals two quantitatively different zones in the gray matter, three in the white matter, and explains local variations in cortical folding  

PubMed Central

The human prefrontal cortex has been considered different in several aspects and relatively enlarged compared to the rest of the cortical areas. Here we determine whether the white and gray matter of the prefrontal portion of the human cerebral cortex have similar or different cellular compositions relative to the rest of the cortical regions by applying the Isotropic Fractionator to analyze the distribution of neurons along the entire anteroposterior axis of the cortex, and its relationship with the degree of gyrification, number of neurons under the cortical surface, and other parameters. The prefrontal region shares with the remainder of the cerebral cortex (except for occipital cortex) the same relationship between cortical volume and number of neurons. In contrast, both occipital and prefrontal areas vary from other cortical areas in their connectivity through the white matter, with a systematic reduction of cortical connectivity through the white matter and an increase of the mean axon caliber along the anteroposterior axis. These two parameters explain local differences in the distribution of neurons underneath the cortical surface. We also show that local variations in cortical folding are neither a function of local numbers of neurons nor of cortical thickness, but correlate with properties of the white matter, and are best explained by the folding of the white matter surface. Our results suggest that the human cerebral cortex is divided in two zones (occipital and non-occipital) that differ in how neurons are distributed across their gray matter volume and in three zones (prefrontal, occipital, and non-occipital) that differ in how neurons are connected through the white matter. Thus, the human prefrontal cortex has the largest fraction of neuronal connectivity through the white matter and the smallest average axonal caliber in the white matter within the cortex, although its neuronal composition fits the pattern found for other, non-occipital areas.

Ribeiro, Pedro F. M.; Ventura-Antunes, Lissa; Gabi, Mariana; Mota, Bruno; Grinberg, Lea T.; Farfel, Jose M.; Ferretti-Rebustini, Renata E. L.; Leite, Renata E. P.; Filho, Wilson J.; Herculano-Houzel, Suzana

2013-01-01

137

The Effect of Cataract Severity and Morphology on the Reliability of the Lens Opacities Classification System II (LOCS II)  

Microsoft Academic Search

Data collected from 3646 eyes in the Italian-American Natural History Study of Age-Related Cataract were used to investigate whether the reliability of the Lens Opacities Classification System II (LOCS II) by the severity of the opacity that is being graded or is influenced by the presence and severity of coexisting opacities. Reliability was assessed by comparing the slit-lamp gradings of

Giovanni Maraini; Paolo Pasquini; Robert D. Sperduto; Mirca Donacini; MariaParrizia Carrieri; Rosamaria Corona; Paolo Graziosi; MariaCarla Tomba; Sally L. Williams

138

Investigating the Influence of the Quasar Spectral Energy Distribution on Emission Lines Using Large-scale LOC Models  

NASA Astrophysics Data System (ADS)

Quasar broad lines exhibit several trends, including the Baldwin effect, an anticorrelation between the emission line equivalent width and continuum luminosity. There is suggestive evidence that the Baldwin effect is driven by the spectral energy distribution (SED). We test this assertion and the efficacy of the locally-optimally-emitting cloud (LOC) model using large-scale Cloudy modeling. We investigate the effect of the SED by constructing a grid of continua in which ?ox and the temperature of the UV cutoff are varied independently. We also vary the LOC radial- and density-distribution indices. We constrain the results using three sets of results: the relationship between ?ox and CIV equivalent width observed by Wu et al. 2009, the relationship between luminosity and ?ox parameterized by Just et al. 2007, and the Baldwin effect results from 19 lines measured in luminosity-sorted quasar composite spectra by Dietrich et al. 2002. We investigate the baseline LOC (column density log(NH)=23.5) as well as high column density log(NH)=24.5, enhanced abundances (Z=5), and alternative SEDs that have a power law in the EUV rather than an exponential cutoff. Our preliminary results show that, for the baseline model, the Baldwin effect is explained by a softening of the SED as well as a decrease of the covering fraction at higher luminosities. The radial and density indices are independent of luminosity and lie near the standard values of -1 and -1. In contrast, the high column model explains the Baldwin effect principally as a softening of the SED with no trend in covering fraction. Both the high metallicity and alternative SED models provide poorer fits. The LOC fails to model some emission lines well, and some evidence for two zones is found. Additional results will be described. This work is funded by NSF AST-0707703.

Leighly, Karen; Hemantha, M. D. P.; Richards, G.

2012-01-01

139

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

PubMed Central

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 RNA matching and alignment of RNA, respectively. The Freiburg RNA tools web server and the software packages of the stand-alone tools are freely accessible at http://rna.informatik.uni-freiburg.de.

Smith, Cameron; Heyne, Steffen; Richter, Andreas S.; Will, Sebastian; Backofen, Rolf

2010-01-01

140

Evaluation of BLID and LOC399959 as candidate genes for high myopia in the Chinese Han population  

PubMed Central

Purpose BH3-like motif containing, cell death inducer (BLID) and LOC399959 are two genes associated with the single nucleotide polymorphism (SNP) rs577948, which is a susceptibility locus for high myopia in Japanese subjects. The purpose of this study was to determine if BLID and LOC399959 are associated with high myopia in Chinese Han subjects. Methods High myopia subjects (n=476) had a spherical refractive error of less than ?6.00 D in at least one eye and/or an axial length greater than 26 mm. Genomic DNA was extracted and genotyped from peripheral blood leukocytes of high myopes and controls (n=275). Using a case-control association study of candidate regions, linkage disequilibrium blocks for 19 tag SNPs (tSNPs), including rs577948, harbored within and surrounding the BLID and LOC399959 genes were analyzed on a MassArray platform using iPlex chemistry. Each of the tSNPs had an r2>0.8 and minor allele frequency >10% in the Chinese Han population. Haplotype association analysis was performed on Haploview 4.1 using Chi-square (?2) tests. Results None of the 19 tSNPs were statistically associated with high myopia. Conclusions While rs577948 may be associated with high myopia in Japanese subjects, it and the other tSNPs near the BLID and LOC399959 genes are not susceptibility loci for high myopia in the Chinese Han population. Thus, associations of SNPs with high myopia as determined by Genome-Wide Association Study (GWAS) may be restricted to certain ethnic or genetically distinct populations. Without systematic replication in other populations, the results of GWAS associations should be interpreted with great caution.

Zhao, Fuxin; Bai, Jian; Chen, Wei; Xue, Anquan; Li, Chaohua; Yan, Zhonghui; Chen, Hui; Lu, Fan; Hu, Yongwu; Qu, Jia; Zeng, Changqing

2010-01-01

141

C2 and CFB Genes in Age-Related Maculopathy and Joint Action with CFH and LOC387715 Genes  

Microsoft Academic Search

BackgroundAge-related maculopathy (ARM) is a common cause of visual impairment in the elderly populations of industrialized countries and significantly affects the quality of life of those suffering from the disease. Variants within two genes, the complement factor H (CFH) and the poorly characterized LOC387715 (ARMS2), are widely recognized as ARM risk factors. CFH is important in regulation of the alternative

Johanna Jakobsdottir; Yvette P. Conley; Robert E. Ferrell; Michael B. Gorin; Michael Nicholas Weedon

2008-01-01

142

Can the traffic locus of control (T-LOC) scale be successfully used to predict Swedish drivers' speeding behaviour?  

PubMed

The first aim of the present study was to examine the factor structure of the traffic locus of control (T-LOC) scale in a Swedish sample of drivers. The second aim was to examine if this scale can be used to predict drivers' speeding behaviour. A sample of Swedish car owners (N=223) completed a questionnaire including questions based on the traffic locus of control (T-LOC) scale as well as questions about their speeding behaviour. The results showed a five factor solution including own skills, own behaviour, other drivers, vehicle/environment and fate. Own behaviour and vehicle/environment could be used to predict drivers' speeding behaviour on roads with a 90 km/h speed limit while none of the variables included in the traffic locus of control (T-LOC) scale could be used to predict drivers' speeding behaviour on roads with a 50 km/h speed limit. On 90 km/h roads own behaviour was positively related to drivers' speeding behaviour while vehicle/environment was negatively related to their speeding behaviour. PMID:20441820

Warner, Henriette Wallén; Ozkan, Türker; Lajunen, Timo

2010-01-21

143

Occipital horn syndrome in a woman: skeletal radiological findings.  

PubMed

Ehlers-Danlos type IX syndrome, also called occipital horn syndrome (OHS), is a milder and rare form of Menkes disease where the patient reaches adulthood. As an X-linked disease, it typically occurs in male subjects, while female subjects are usually healthy carriers. OHS is mainly characterized by connective tissue disorders and slightly subnormal intelligence or signs of autonomic dysfunction are the only apparent neurological abnormalities, in connection with molecular defects in copper metabolism. Our purpose is to report on radiological skeletal findings that may be incidental or investigated when OHS is suspected and to underline the possible involvement and expression in the female. Moreover, the impact of skeletal findings is also highlighted in the prevention of serious complications of the disease. PMID:21553336

Bazzocchi, Alberto; Femia, Rayka; Feraco, Paola; Battista, Giuseppe; Canini, Romeo; Guglielmi, Giuseppe

2011-05-08

144

Cytoarchitectonic mapping of the human dorsal extrastriate cortex.  

PubMed

The dorsal visual stream consists of several functionally specialized areas, but most of their cytoarchitectonic correlates have not yet been identified in the human brain. The cortex adjacent to Brodmann area 18/V2 was therefore analyzed in serial sections of ten human post-mortem brains using morphometrical and multivariate statistical analyses for the definition of areal borders. Two previously unknown cytoarchitectonic areas (hOc3d, hOc4d) were detected. They occupy the medial and, to a smaller extent, lateral surface of the occipital lobe. The larger area, hOc3d, is located dorso-lateral to area V2 in the region of superior and transverse occipital, as well as parieto-occipital sulci. Area hOc4d was identified rostral to hOc3d; it differed from the latter by larger pyramidal cells in lower layer III, thinner layers V and VI, and a sharp cortex-white-matter borderline. The delineated areas were superimposed in the anatomical MNI space, and probabilistic maps were calculated. They show a relatively high intersubject variability in volume and position. Based on their location and neighborhood relationship, areas hOc3d and hOc4d are putative anatomical substrates of functionally defined areas V3d and V3a, a hypothesis that can now be tested by comparing probabilistic cytoarchitectonic maps and activation studies of the living human brain. PMID:22354469

Kujovic, Milenko; Zilles, Karl; Malikovic, Aleksandar; Schleicher, Axel; Mohlberg, Hartmut; Rottschy, Claudia; Eickhoff, Simon B; Amunts, Katrin

2012-02-22

145

Image-Guided Stereotactic Body Radiotherapy for Lung Tumors Using BodyLoc With Tomotherapy: Clinical Implementation and Set-Up Accuracy  

Microsoft Academic Search

We investigated the use of a BodyLoc immobilization and stereotactic localization device combined with TomoTherapy megavoltage CT (MVCT) in lung stereotactic body radiotherapy (SBRT) to reduce set-up uncertainty and treatment time. Eight patients treated with 3–5 fractions of SBRT were retrospectively analyzed. A BodyLoc localizer was used in both CT simulation for localization and the initial patient treatment set-up. Patients

Jining Zhou; Barry Uhl; Kelly Dewitt; Mark Young; Brian Taylor; Ding-Yu Fei; Yeh-Chi Lo

2010-01-01

146

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.

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

2012-01-01

147

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

148

Reduced ?-Aminobutyric Acid in Occipital and Anterior Cingulate Cortices in Primary Insomnia: a Link to Major Depressive Disorder?  

PubMed Central

Insomnia is closely related to major depressive disorder (MDD) both cross-sectionally and longitudinally, and as such, offers potential opportunities to refine our understanding of the neurobiology of both sleep and mood disorders. Clinical and basic science data suggest a role for reduced ?-aminobutyric acid (GABA) in both MDD and primary insomnia (PI). Here, we have utilized single-voxel proton magnetic spectroscopy (1H-MRS) at 4 Tesla to examine GABA relative to total creatine (GABA/Cr) in the occipital cortex (OC), anterior cingulate cortex (ACC), and thalamus in 20 non-medicated adults with PI (12 women) and 20 age- and sex-matched healthy sleeper comparison subjects. PI subjects had significantly lower GABA/Cr in the OC (p=0.0005) and ACC (p=0.03) compared with healthy sleepers. There was no significant difference in thalamic GABA/Cr between groups. After correction for multiple comparisons, GABA/Cr did not correlate significantly with insomnia severity measures among PI subjects. This study is the first to demonstrate regional reductions of GABA in PI in the OC and ACC. Reductions in GABA in similar brain regions in MDD using 1H-MRS suggest a common reduction in cortical GABA among PI and mood disorders.

Plante, David T; Jensen, J Eric; Schoerning, Laura; Winkelman, John W

2012-01-01

149

Differential Sensitivity of Human Visual Cortex to Faces, Letterstrings, and Textures: A Functional Magnetic Resonance Imaging Study  

Microsoft Academic Search

Twelve normal subjects viewed alternating sequences of unfa- miliar faces, unpronounceable nonword letterstrings, and tex- tures while echoplanar functional magnetic resonance images were acquired in seven slices extending from the posterior margin of the splenium to near the occipital pole. These stimuli were chosen to elicit initial category-specific processing in extrastriate cortex while minimizing semantic processing. Over- all, faces evoked

Aina Puce; Truett Allison; Maryam Asgari; John C. Gore; Gregory McCarthy

1996-01-01

150

Electroencephalogram alpha (8–15 Hz) responses to visual stimuli in cat cortex, thalamus, and hippocampus: a distributed alpha network?  

Microsoft Academic Search

To investigate possible functional correlates of alpha (8–15 Hz) oscillations in the electroencephalogram (EEG) intracranial recordings in cats (from thalamus, occipital cortex, and hippocampus) were performed. In response to visual stimuli, event-related alpha oscillations were observed. Such alpha responses were found not only in a specific sensory (visual) pathway but also in the hippocampus, hinting at a possible distributed alpha

Martin Schürmann; Tamer Demiralp; Erol Ba?ar; Canan Ba?ar Eroglu

2000-01-01

151

Central modulation in cluster headache patients treated with occipital nerve stimulation: an FDG-PET study  

PubMed Central

Background Occipital nerve stimulation (ONS) has raised new hope for drug-resistant chronic cluster headache (drCCH), a devastating condition. However its mode of action remains elusive. Since the long delay to meaningful effect suggests that ONS induces slow neuromodulation, we have searched for changes in central pain-control areas using metabolic neuroimaging. Methods Ten drCCH patients underwent an 18FDG-PET scan after ONS, at delays varying between 0 and 30 months. All were scanned with ongoing ONS (ON) and with the stimulator switched OFF. Results After 6-30 months of ONS, 3 patients were pain free and 4 had a ? 90% reduction of attack frequency (responders). In all patients compared to controls, several areas of the pain matrix showed hypermetabolism: ipsilateral hypothalamus, midbrain and ipsilateral lower pons. All normalized after ONS, except for the hypothalamus. Switching the stimulator ON or OFF had little influence on brain glucose metabolism. The perigenual anterior cingulate cortex (PACC) was hyperactive in ONS responders compared to non-responders. Conclusions Metabolic normalization in the pain neuromatrix and lack of short-term changes induced by the stimulation might support the hypothesis that ONS acts in drCCH through slow neuromodulatory processes. Selective activation in responders of PACC, a pivotal structure in the endogenous opioid system, suggests that ONS could restore balance within dysfunctioning pain control centres. That ONS is nothing but a symptomatic treatment might be illustrated by the persistent hypothalamic hypermetabolism, which could explain why autonomic attacks may persist despite pain relief and why cluster attacks recur shortly after stimulator arrest. PET studies on larger samples are warranted to confirm these first results.

2011-01-01

152

Novel Use of Narrow Paddle Electrodes for Occipital Nerve Stimulation-Technical Note.  

PubMed

OBJECTIVES: Occipital nerve stimulation (ONS), an established treatment for medically intractable headache syndromes, has lead migration rates quoted up to 24%. In a series of patients with ideal characteristics for this treatment modality, we describe an operative technique for ONS involving the novel use of narrow paddle electrodes: "S8 Lamitrode" (St. Jude Medical [SJM], St. Paul, MN, USA). MATERIALS AND METHODS: Five patients (occipital neuralgia [ON]?=?4; chronic migraine [CM]?=?1) were treated with ONS between 2010 and 2011. All patients had a successful trial of peripheral neurostimulation (Algotec Ltd, Crawley, UK) therapy. Operative technique involved the use of a park-bench position, allowing simultaneous exposure of the occipital and infraclavicular regions. Through a retromastoid/occipital incision just beneath the external occipital protruberance, exposing the extrafascial plane, the S8 Lamitrode is implanted to intersect both greater occipital nerves for bilateral pain or unilateral greater and lesser occipital nerves for unilateral ON or with significant component of the pain relating to the lesser occipital nerve. RESULTS: Over the median follow-up of 12 months, there were no episodes of lead migration or revision. There also was significant improvement in symptoms in all patients. CONCLUSIONS: This is the first reported use of S8 Lamitrode electrode for ONS. This narrow electrode is suited for this role leading to minimal trauma during surgical placement, facilitates resolution of problems with lead migration, and optimizes effect with stimulation focused more in direction of the occipital nerves without skin involvement. To date, the SJM Genesis neurostimulation system, with percutaneous electrodes only, is CE mark approved in Europe for peripheral nerve stimulation of the occipital nerves for the management of pain and disability for patients diagnosed with intractable CM. Further developments and studies are required for better devices to suit ONS, thereby avoiding frequently encountered problems and which may clarify the role of paddle leads in ONS. PMID:23106950

Abhinav, Kumar; Park, Nicholas D; Prakash, Savithru K; Love-Jones, Sarah; Patel, Nikunj K

2012-10-25

153

Association cortex hypoperfusion in mild dementia with Lewy bodies: a potential indicator of cholinergic dysfunction?  

PubMed Central

Dementia with Lewy bodies (DLB) is often associated with occipital hypometabolism or hypoperfusion, as well as deficits in cholinergic neurotransmission. In this study, 11 mild DLB, 16 mild AD and 16 age-matched controls underwent arterial spin-labeled perfusion MRI (ASL-pMRI) and neuropsychological testing. Patterns of cerebral blood flow (CBF) and cognitive performance were compared. In addition, combined ASL-pMRI and ChEI drug challenge (pharmacologic MRI) was tested as a probe of cholinergic function in 4 of the DLB participants. Frontal and parieto-occipital hypoperfusion was observed in both DLB and AD but was more pronounced in DLB. Following ChEI treatment, perfusion increased in temporal and parieto-occipital cortex, and cognitive performance improved on a verbal fluency task. If confirmed in a larger study, these results provide further evidence for brain cholinergic dysfunction in DLB pathophysiology, and use of pharmacologic MRI as an in vivo measure of cholinergic function.

Inouye, Sharon K.; Dai, Weiying; Press, Daniel Z.; Alsop, David C.

2011-01-01

154

Auditory motion direction encoding in auditory cortex and high-level visual cortex.  

PubMed

The aim of this functional magnetic resonance imaging (fMRI) study was to identify human brain areas that are sensitive to the direction of auditory motion. Such directional sensitivity was assessed in a hypothesis-free manner by analyzing fMRI response patterns across the entire brain volume using a spherical-searchlight approach. In addition, we assessed directional sensitivity in three predefined brain areas that have been associated with auditory motion perception in previous neuroimaging studies. These were the primary auditory cortex, the planum temporale and the visual motion complex (hMT/V5+). Our whole-brain analysis revealed that the direction of sound-source movement could be decoded from fMRI response patterns in the right auditory cortex and in a high-level visual area located in the right lateral occipital cortex. Our region-of-interest-based analysis showed that the decoding of the direction of auditory motion was most reliable with activation patterns of the left and right planum temporale. Auditory motion direction could not be decoded from activation patterns in hMT/V5+. These findings provide further evidence for the planum temporale playing a central role in supporting auditory motion perception. In addition, our findings suggest a cross-modal transfer of directional information to high-level visual cortex in healthy humans. PMID:21692141

Alink, Arjen; Euler, Felix; Kriegeskorte, Nikolaus; Singer, Wolf; Kohler, Axel

2011-06-20

155

The Human Cerebral Cortex Flattens during Adolescence.  

PubMed

The human cerebral cortex appears to shrink during adolescence. To delineate the dynamic morphological changes involved in this process, 52 healthy male and female adolescents (11-17 years old) were neuroimaged twice using magnetic resonance imaging, approximately 2 years apart. Using a novel morphometric analysis procedure combining the FreeSurfer and BrainVisa image software suites, we quantified global and lobar change in cortical thickness, outer surface area, the gyrification index, the average Euclidean distance between opposing sides of the white matter surface (gyral white matter thickness), the convex ("exposed") part of the outer cortical surface (hull surface area), sulcal length, depth, and width. We found that the cortical surface flattens during adolescence. Flattening was strongest in the frontal and occipital cortices, in which significant sulcal widening and decreased sulcal depth co-occurred. Globally, sulcal widening was associated with cortical thinning and, for the frontal cortex, with loss of surface area. For the other cortical lobes, thinning was related to gyral white matter expansion. The overall flattening of the macrostructural three-dimensional architecture of the human cortex during adolescence thus involves changes in gray matter and effects of the maturation of white matter. PMID:24048830

Alemán-Gómez, Yasser; Janssen, Joost; Schnack, Hugo; Balaban, Evan; Pina-Camacho, Laura; Alfaro-Almagro, Fidel; Castro-Fornieles, Josefina; Otero, Soraya; Baeza, Immaculada; Moreno, Dolores; Bargalló, Nuria; Parellada, Mara; Arango, Celso; Desco, Manuel

2013-09-18

156

Differential Contribution of Right and Left Temporo-Occipital and Anterior Temporal Lesions to Face Recognition Disorders  

PubMed Central

In the study of prosopagnosia, several issues (such as the specific or non-specific manifestations of prosopagnosia, the unitary or non-unitary nature of this syndrome and the mechanisms underlying face recognition disorders) are still controversial. Two main sources of variance partially accounting for these controversies could be the qualitative differences between the face recognition disorders observed in patients with prevalent lesions of the right or left hemisphere and in those with lesions encroaching upon the temporo-occipital (TO) or the (right) anterior temporal cortex. Results of our review seem to confirm these suggestions. Indeed, they show that (a) the most specific forms of prosopagnosia are due to lesions of a right posterior network including the occipital face area and the fusiform face area, whereas (b) the face identification defects observed in patients with left TO lesions seem due to a semantic defect impeding access to person-specific semantic information from the visual modality. Furthermore, face recognition defects resulting from right anterior temporal lesions can usually be considered as part of a multimodal people recognition disorder. The implications of our review are, therefore, the following: (1) to consider the components of visual agnosia often observed in prosopagnosic patients with bilateral TO lesions as part of a semantic defect, resulting from left-sided lesions (and not from prosopagnosia proper); (2) to systematically investigate voice recognition disorders in patients with right anterior temporal lesions to determine whether the face recognition defect should be considered a form of “associative prosopagnosia” or a form of the “multimodal people recognition disorder.”

Gainotti, Guido; Marra, Camillo

2011-01-01

157

Sensitivity to syntax in visual cortex  

PubMed Central

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.

Dikker, Suzanne; Rabagliati, Hugh; Pylkkanen, Liina

2009-01-01

158

[Open reduction and dorsal spondylodesis C0-C2 in atlanto-occipital dislocation].  

PubMed

We report the case of a 73-year-old male patient who was suffered trauma after a syncopal fall onto a railway track in the form of an atlanto-occipital dislocation. The diagnostic revealed a bilateral fracture of the occipital condyles coupled with a ventral atlanto-occipital dislocation (Jeanneret type 4) and also an odontoid fracture (Anderson type 2). The patient underwent dorsal spondylodesis of C0-C2 in combination with Magerl's C1-C2 screw fixation. Pre-operatively and postoperatively no neurological abnormalities were found. This rarely occurring and survived traumatological situation is described using the present case as an example. PMID:19557377

John-Puthenveettil, B S; Neff, A; Kröber, M

2009-09-01

159

Diagnosis and treatment of a chronic atlanto-occipital subluxation in a dog.  

PubMed

A 6-year-old Labrador retriever-cross was evaluated for an abnormal gait and head carriage 6 weeks after suffering trauma. The dog was presented with an ambulatory tetraparesis and was reluctant to move his head. Myelography and computed tomography demonstrated a subluxation of the atlanto-occipital joint with compression of the spinomedullary junction and the brain stem by the occipital bone. Removal of the compressive part of the occipital bone resulted in improvement of the clinical signs within 6 weeks, and resolution of clinical signs occurred 8 months after surgery. PMID:17473025

Rylander, Helena; Robles, Juan Carlos

160

Long-Term Effects of Serial Anodal tDCS on Motion Perception in Subjects with Occipital Stroke Measured in the Unaffected Visual Hemifield  

PubMed Central

Transcranial direct current stimulation (tDCS) is a novel neuromodulatory tool that has seen early transition to clinical trials, although the high variability of these findings necessitates further studies in clinically relevant populations. The majority of evidence into effects of repeated tDCS is based on research in the human motor system, but it is unclear whether the long-term effects of serial tDCS are motor-specific or transferable to other brain areas. This study aimed to examine whether serial anodal tDCS over the visual cortex can exogenously induce long-term neuroplastic changes in the visual cortex. However, when the visual cortex is affected by a cortical lesion, up-regulated endogenous neuroplastic adaptation processes may alter the susceptibility to tDCS. To this end, motion perception was investigated in the unaffected hemifield of subjects with unilateral visual cortex lesions. Twelve subjects with occipital ischemic lesions participated in a within-subject, sham-controlled, double-blind study. MRI-registered sham or anodal tDCS (1.5?mA, 20?min) was applied on five consecutive days over the visual cortex. Motion perception was tested before and after stimulation sessions and at 14- and 28-day follow-up. After a 16-day interval an identical study block with the other stimulation condition (anodal or sham tDCS) followed. Serial anodal tDCS over the visual cortex resulted in an improvement in motion perception, a function attributed to MT/V5. This effect was still measurable at 14- and 28-day follow-up measurements. Thus, this may represent evidence for long-term tDCS-induced plasticity and has implications for the design of studies examining the time course of tDCS effects in both the visual and motor systems.

Olma, M. C.; Dargie, R. A.; Behrens, J. R.; Kraft, A.; Irlbacher, K.; Fahle, M.; Brandt, S. A.

2013-01-01

161

ProLoc: prediction of protein subnuclear localization using SVM with automatic selection from physicochemical composition features.  

PubMed

Accurate prediction methods of protein subnuclear localizations rely on the cooperation between informative features and classifier design. Support vector machine (SVM) based learning methods are shown effective for predictions of protein subcellular and subnuclear localizations. This study proposes an evolutionary support vector machine (ESVM) based classifier with automatic selection from a large set of physicochemical composition (PCC) features to design an accurate system for predicting protein subnuclear localization, named ProLoc. ESVM using an inheritable genetic algorithm combined with SVM can automatically determine the best number m of PCC features and identify m out of 526 PCC features simultaneously. To evaluate ESVM, this study uses two datasets SNL6 and SNL9, which have 504 proteins localized in 6 subnuclear compartments and 370 proteins localized in 9 subnuclear compartments. Using a leave-one-out cross-validation, ProLoc utilizing the selected m=33 and 28 PCC features has accuracies of 56.37% for SNL6 and 72.82% for SNL9, which are better than 51.4% for the SVM-based system using k-peptide composition features applied on SNL6, and 64.32% for an optimized evidence-theoretic k-nearest neighbor classifier utilizing pseudo amino acid composition applied on SNL9, respectively. PMID:17291684

Huang, Wen-Lin; Tung, Chun-Wei; Huang, Hui-Ling; Hwang, Shiow-Fen; Ho, Shinn-Ying

2007-01-04

162

A simple planar micromixer with low-pressure drop for disposable lab-on-a-chip (LOC) systems  

NASA Astrophysics Data System (ADS)

In this work the design and fabrication of a novel passive microfluidic mixer capable of achieving mixing in shorter distances and lower Reynolds numbers (Re) is reported. Passive mixers typically rely on the channel geometry to mix fluids, and many previously reported designs work efficiently only at moderate to high Re and are often difficult to fabricate as they incorporate complex 3-D structures within the channel. The mixer design discussed in this work achieves good mixing at low Re, has planar geometry and thus is simpler to fabricate and integrate with existing labon- a-chip (LOC) technologies. The design incorporates triangular notches patterned along the channel walls to laminate the flow, thus enhancing mixing. Numerical and experimental studies to determine the effect of the notch dimensions and placement within the microchannel were carried out to optimize the mixing performance. Results show that the final mixer design is efficient at mixing fluids at low Re. The mixer is fabricated in polydimethylsiloxane (PDMS) bonded to glass slides and tested using fluorescence dyes. Results show that the new design exhibit complete mixing at Re < 0.1 within 7 mm and thus will benefit a wide range of LOC applications where space is limited.

Bhagat, Ali Asgar S.; Peterson, Erik T. K.; Papautsky, Ian

2007-01-01

163

Traumatic Atlanto-Occipital Dislocation Presenting With Dysphagia as the Chief Complaint: A Case Report  

PubMed Central

We report a patient with traumatic atlanto-occipital dislocation who presented with dysphagia as the chief complaint. A 59-year-old man complained of swallowing difficulty for 2 months after trauma to the neck. On physical examination, there was atrophy of the right sternocleidomastoid and upper trapezius muscles, and the tongue was deviated to the right. In a videofluoroscopic swallowing study, penetration and aspiration were not seen, food residue remained in the right vallecula and pyriform sinus, and there was decreased motion of the soft palate, pharynx and larynx. Electromyography confirmed a right spinal accessory nerve lesion. Magnetic resonance imaging confirmed atlanto-occipital dislocation. Dysphagia in atlanto-occipital dislocation is induced by medullary compression and lower cranial nerve injury. Therefore, in survivors who are diagnosed with atlanto-occipital dislocation, any neurological symptoms should be carefully evaluated.

Choi, Eun Hye; Choi, Eun Hi; Shin, Ka Young; Cho, Ah Ra

2013-01-01

164

Occipital TMS has an activity-dependent suppressive effect  

PubMed Central

The effects of transcranial magnetic stimulation (TMS) vary depending on the brain state at the stimulation moment. Four mechanisms have been proposed to underlie these effects: (i) virtual lesion–TMS suppresses neural signals; (ii) preferential activation of less active neurons–TMS drives up activity in the stimulated area, but active neurons are saturating, (iii) noise generation–TMS adds random neuronal activity and its effect interacts with stimulus-intensity; (iv) noise generation–TMS adds random neuronal activity and its effect depends on TMS-intensity. Here we explore these hypotheses by investigating the effects of TMS on early visual cortex on the contrast response function while varying adaptation state of the observers. We tested human participants in an orientation discrimination task, in which performance is contingent upon contrast sensitivity. Before each trial, neuronal activation of visual cortex was altered through contrast adaptation to two flickering gratings. In a factorial design, with or without adaptation, a single TMS pulse was delivered simultaneously with targets of varying contrast. Adaptation decreased contrast sensitivity. The effect of TMS on performance was state-dependent: TMS decreased contrast sensitivity in the absence of adaptation but increased it after adaptation. None of the proposed mechanisms can account for the results in their entirety, in particular, for the facilitatory effect at intermediate to high contrasts after adaptation. We propose an alternative hypothesis: TMS effects are activity-dependent, so that TMS suppresses the most active neurons and thereby changes the balance between excitation and inhibition.

Perini, Francesca; Cattaneo, Luigi; Carrasco, Marisa; Schwarzbach, Jens V.

2012-01-01

165

Recovery of visual-field defects after occipital lobe infarction: a perimetric study  

Microsoft Academic Search

ObjectiveTo assess the temporal course of homonymous visual-field defects due to occipital lobe infarction, by using automated perimetry.Methods32 patients with ischaemic infarction of the occipital lobe were studied prospectively, using a Humphrey Visual Field Analyser II. The visual field of each eye was divided into central, paracentral and peripheral zones. The mean visual sensitivity of each zone was calculated and

Mehmet Çelebisoy; Ne?e Çelebisoy; Ece Bayam; Timur Köse

2010-01-01

166

Magnetic excitations in Tm0.05Y0.95Ni2LOC="pre">11B2C  

NASA Astrophysics Data System (ADS)

We carried out inelastic neutron scattering experiments on Tm0.05Y0.95Ni2LOC="pre">11B2C on IN6, ILL, Grenoble, to determine CF (crystal-electric field)-transitions. We found several low-energetic CF-transitions from which we were able to determine the lower part of the level scheme and the associated matrix-elements. These results are compared to those obtained by Gasser et al. for the full compound TmNi2LOC="pre">11B2C.

Sierks, C.; Loewenhaupt, M.; Freudenberger, J.; Müller, K.-H.; Schober, H.

2000-03-01

167

Characterizing occipital condyle loads under high-speed head rotation.  

PubMed

Because of the need to evaluate anthropomorphic test device (ATD) biofidelity under high-head angular accelerations, the purpose of the present investigation was to develop appropriate instrumentation for intact post mortem human subject (PMHS) testing, validate the instrumentation, and obtain information to characterize the response of the head-neck complex under this loading scenario. A series of rigid-arm pendulum, inertially loaded ATD tests was conducted. Head and neck ATD hydraulic piston chin pull tests were conducted. Subsequently, a series of PMHS tests was conducted to derive the response of the human head-neck under high-rate chin loading. Finally, Hybrid III and THOR-NT ATD head-neck systems were evaluated under the same scenario as the PMHS. A parametric analysis for center of gravity (CG) location and accelerometer orientation determined that even small errors (+/- 3 mm or 2 degrees), produced errors in the force and moment calculations by as much as 17 %. If the moment of inertia (MOI) term was varied by 5 %, resulting moment calculations were affected by as much as 8 %. If the 5 % error in MOI was used to compute occipital condyle moments, and results compared to upper load cell derived moments, peaks differed by as much as 24 %. The head CG and mass MOI should be directly measured for each preparation to obtain accurate results. The injury run on each specimen resulted in predominantly C1-C2 separations or partial separations. The 50(th) percentile probability of AIS=2+ neck injury using tensile force was about 2400 N; for AIS=3+ neck injury the 50(th) percentile risk was about 3180 N. When inserting extension moment as the criteria, the 50(th) percentile probability of an AIS=2+ injury was 51 Nm. The AIS=3+ extension moment at the 50(th) percentile probability was 75 Nm. The new THOR-NT ATD head-neck produced more biofidelic responses with an alternate head-neck junction design compared to the Hybrid III ATD. PMID:17096267

Pintar, Frank A; Yoganandan, Narayan; Baisden, Jamie

2005-11-01

168

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

169

Cortex-sparing fiber dissection: an improved method for the study of white matter anatomy in the human brain  

PubMed Central

Classical fiber dissection of post mortem human brains enables us to isolate a fiber tract by removing the cortex and overlying white matter. In the current work, a modification of the dissection methodology is presented that preserves the cortex and the relationships within the brain during all stages of dissection, i.e. ‘cortex-sparing fiber dissection’. Thirty post mortem human hemispheres (15 right side and 15 left side) were dissected using cortex-sparing fiber dissection. Magnetic resonance imaging study of a healthy brain was analyzed using diffusion tensor imaging (DTI)-based tractography software. DTI fiber tract reconstructions were compared with cortex-sparing fiber dissection results. The fibers of the superior longitudinal fasciculus (SLF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF) were isolated so as to enable identification of their cortical terminations. Two segments of the SLF were identified: first, an indirect and superficial component composed of a horizontal and vertical segment; and second, a direct and deep component or arcuate fasciculus. The IFOF runs within the insula, temporal stem and sagittal stratum, and connects the frontal operculum with the occipital, parietal and temporo-basal cortex. The UF crosses the limen insulae and connects the orbito-frontal gyri with the anterior temporal lobe. Finally, a portion of the ILF was isolated connecting the fusiform gyrus with the occipital gyri. These results indicate that cortex-sparing fiber dissection facilitates study of the 3D anatomy of human brain tracts, enabling the tracing of fibers to their terminations in the cortex. Consequently, it is an important tool for neurosurgical training and neuroanatomical research.

Martino, Juan; De Witt Hamer, Philip C; Vergani, Francesco; Brogna, Christian; de Lucas, Enrique Marco; Vazquez-Barquero, Alfonso; Garcia-Porrero, Juan A; Duffau, Hugues

2011-01-01

170

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

PubMed

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, 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, whereas 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

2013-05-10

171

Dissociation of object and spatial visual processing pathways in human extrastriate cortex  

SciTech Connect

The existence and neuroanatomical locations of separate extrastriate visual pathways for object recognition and spatial localization were investigated in healthy young men. Regional cerebral blood flow was measured by positron emission tomography and bolus injections of H2(15)O, while subjects performed face matching, dot-location matching, or sensorimotor control tasks. Both visual matching tasks activated lateral occipital cortex. Face discrimination alone activated a region of occipitotemporal cortex that was anterior and inferior to the occipital area activated by both tasks. The spatial location task alone activated a region of lateral superior parietal cortex. Perisylvian and anterior temporal cortices were not activated by either task. These results demonstrate the existence of three functionally dissociable regions of human visual extrastriate cortex. The ventral and dorsal locations of the regions specialized for object recognition and spatial localization, respectively, suggest some homology between human and nonhuman primate extrastriate cortex, with displacement in human brain, possibly related to the evolution of phylogenetically newer cortical areas.

Haxby, J.V.; Grady, C.L.; Horwitz, B.; Ungerleider, L.G.; Mishkin, M.; Carson, R.E.; Herscovitch, P.; Schapiro, M.B.; Rapoport, S.I. (National Institutes of Health, Bethesda, MD (USA))

1991-03-01

172

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

173

fMRI reveals greater within- than between-hemifield integration in the human lateral occipital cortex  

Microsoft Academic Search

Early visual areas within each hemisphere (V1, V2, V3 ?VP, V4v) contain distinct representations of the upper and lower quadrants of the contralateral hemifield. As receptive field size increases, the retinotopy in higher-tier visual areas becomes progressively less distinct. Using functional magnetic resonance imaging (fMRI) to map the visual fields, we found that an intermediate level visual area, the lateral

Mary-Ellen Large; Jody Culham; Anil Kuchinad; Adrian Aldcroft; Tutis Vilis

2008-01-01

174

Spatially Selective Representations of Voluntary and Stimulus-Driven Attentional Priority in Human Occipital, Parietal, and Frontal Cortex  

Microsoft Academic Search

When multiple objects are present in a visual scene, they compete for cortical processing in the visual system; selective attention biases this competition so that representations of behaviorally relevant objects enter awareness and irrelevant objects do not. Deployments of selective attention can be voluntary (e.g., shift or attention to a target's expected spatial location) or stimulus driven (e.g., capture of

John T. Serences; Steven Yantis

2006-01-01

175

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.??

Cole, M.

1999-01-01

176

Antecedent occipital alpha band activity predicts the impact of oculomotor events in perceptual switching  

PubMed Central

Oculomotor events such as blinks and saccades transiently interrupt the visual input and, even though this mostly goes undetected, these brief interruptions could still influence the percept. In particular, both blinking and saccades facilitate switching in ambiguous figures such as the Necker cube. To investigate the neural state antecedent to these oculomotor events during the perception of an ambiguous figure, we measured the human scalp electroencephalogram (EEG). When blinking led to perceptual switching, antecedent occipital alpha band activity exhibited a transient increase in amplitude. When a saccade led to switching, a series of transient increases and decreases in amplitude was observed in the antecedent occipital alpha band activity. Our results suggest that the state of occipital alpha band activity predicts the impact of oculomotor events on the percept.

Nakatani, Hironori; van Leeuwen, Cees

2013-01-01

177

Thrombosed traumatic aneurysm of the occipital artery: a case report and review of the literature  

PubMed Central

Introduction Occipital artery aneurysms are very rare vascular lesions. Most cases reported in the literature have been post-traumatic pseudoaneurysms of the occipital artery. Case presentation We report the case of a 14-year-old Caucasian boy presented with a painless non-pulsatile scalp mass that developed rapidly after minor blunt head trauma. The scalp mass was excised six months after the trauma. A pathologic diagnosis of a thrombosed true aneurysm was made. Our patient has had no recurrence of the mass at 15?months follow-up. Conclusions We present a case of a true aneurysm of the occipital artery following minor head trauma. We review the literature for similar cases and discuss the difficulty of establishing a diagnosis prior to surgical intervention.

2012-01-01

178

Visual phenomena and headache in occipital epilepsy: a review, a systematic study and differentiation from migraine.  

PubMed

This is a systematic-prospective study of occipital seizures with elementary visual hallucinations in 18 patients with symptomatic occipital epilepsy. Qualitative and chronological analysis showed that visual seizures usually lasted for seconds to 1-3 minutes. Three patients also had longer visual seizures of 20-150 minutes. Elementary visual hallucinations mainly consisted of coloured and small circular patterns flashing or multiplying in a temporal hemifield. Flashing lights or non-circular patterns were rare. Three patients experienced achromatic flickering lights. None of the patients had the over 4 minute, linear, zigzag, and achromatic or black and white patterns characteristic of migraine visual aura. Blurring of vision could precede visual hallucinations. Visual seizures were usually frequent, often occurring in multiple clusters daily or weekly. They usually occurred alone but they often advanced to other occipital and extra-occipital ictal symptoms. In 7 patients they progressed to temporal lobe seizure manifestations, and in 6 to motor partial seizures or ipsilateral hemiconvulsions. All but 2 had secondary generalised tonic clonic convulsions. Ictal blindness ab initio occurred in 2 and ictal, mainly orbital headache in another 2 patients. One patient had ictal vomiting as an occasional symptom. Postictal headache, often severe and indistinguishable from migraine, occurred in two thirds of the patients, even after brief visual seizures without convulsions. Despite relevant structural lesions in brain imaging, 10 patients had a normal mental and neurological state. In 8 patients, EEG was also normal or nonspecific. Misdiagnosis of visual seizures as visual aura of migraine was common and 3 patients were misdiagnosed as suffering from migraine. The differential diagnosis between migraine and the occipital epilepsies is reviewed. It is concluded that elementary visual hallucinations, blindness or both, alone or followed by headache and vomiting of symptomatic occipital epilepsy are identical to those of idiopathic occipital epilepsy. Progress to temporal lobe structures is different and consistent with symptomatic occipital lobe epilepsy. The clinical diagnosis of visual seizures is easy if individual elements of duration, colour, shape, size, location, movement, speed of development and progress are identified. They are markedly different from visual aura of migraine, although they often trigger migrainous headache, probably by activating trigeminovascular or brain stem mechanisms. PMID:10937155

Panayiotopoulos, C P

1999-12-01

179

Perimetric demonstration of spontaneous visual field recovery following occipital lobe haemorrhage.  

PubMed

A 45-year-old patient on lifelong warfarin therapy after a metal aortic valve replacement developed a homonymous visual field defect following an occipital lobe haemorrhage. The patient received only conservative management and yet described continued improvement in her visual field defect for up to 20 months following the initial cerebral insult. We present the first conclusive illustrative documentation of visual recovery in a patient with an occipital lobe haemorrhage with sequential automated perimetric assessments over an extended period of time. PMID:23988822

Lin, Siying; George, Badie Z; Wilson-Holt, Nicholas J

2013-08-29

180

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.

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

2010-01-01

181

Economic Evaluation of "Pulse Dose" Radiofrequency in the Treatment of Occipital Neuralgia Headache  

PubMed Central

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.

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

2012-01-01

182

Benign occipital unicameral bone cyst causing lower cranial nerve palsies complicated by iophendylate arachnoiditis  

PubMed Central

A 20 year old girl presented with a history of neck and occipital pain for six weeks, which was found to be due to a unicameral bone cyst of the left occipital condylar region. The differential diagnosis of bone cysts in the skull is discussed. Six months after the operation, the patient again presented with backache due to adhesive arachnoiditis. The latter was believed to have arisen as a result of a combination of spinal infective meningitis and intrathecal ethyl iodophenyl undecylate (iophendylate, Myodil, Pantopaque). The nature of meningeal reactions to iophendylate and the part played by intrathecal corticosteroids in relieving the arachnoiditis in the present case are discussed. Images

Bradley, W. G.; Kalbag, R. M.; Ramani, P. S.; Tomlinson, B. E.

1974-01-01

183

A sensitive period for language in the visual cortex: Distinct patterns of plasticity in congenitally versus late blind adults  

PubMed Central

Recent evidence suggests that blindness enables visual circuits to contribute to language processing. We examined whether this dramatic functional plasticity has a sensitive period. BOLD fMRI signal was measured in congenitally blind, late blind (blindness onset 9-years-old or later) and sighted participants while they performed a sentence comprehension task. In a control condition, participants listened to backwards speech and made match/non-match to sample judgments. In both, congenitally and late blind participants BOLD signal increased in bilateral foveal-pericalcarine cortex during response preparation, irrespective of whether the stimulus was a sentence or backwards speech. However, only in congenitally blind people left occipital areas (pericalcarine, extrastriate, fusiform and lateral) responded more to sentences than backwards speech. We conclude that age of blindness onset constrains the non-visual functions of occipital cortex: while plasticity is present in both congenitally and late blind individuals, recruitment of visual circuits for language depends on blindness during childhood.

Bedny, Marina; Pascual-Leone, Alvaro; Dravida, Swethasri; Saxe, Rebecca

2012-01-01

184

Age-related macular degeneration and association of CFH Y402H and LOC387715 A69S polymorphisms in a Turkish population.  

PubMed

Age-related macular degeneration (AMD) is a disease with multifactorial etiology characterized by irreversible loss of central visual acuity. The discovery of susceptive single-nucleotide polymorphisms (SNPs) has progressed our understanding of AMD. Complement factor H (CFH) gene Y402H polymorphism and high-temperature requirement A-1 (HTRA1) LOC387715 gene A69S polymorphisms are the most important SNPs reported in the literature. Determination of genetic risk factors and genotype-phenotype relationship in AMD may result in rapid and cost-effective therapeutic applications for young and old population. In this study, we hypothesized a potential association between CFH gene Y402H and HTRA1 LOC387715 gene A69S polymorphism in Turkish AMD patients. In blood samples from a total of 252 individuals, 147 clinically diagnosed as AMD and the others control, polymorphic sites in CFH, Y402H (Tsp509I T/C), and HTRA1, LOC387715 A69S (FnuHI G/T), were determined by polymerase chain reaction-restriction fragment length polymorphism analysis. There was significant difference between CFH genotypes in the AMD group, TT 21.8%, TC 48.3%, and CC 29.9%, and in the control subjects, TT 45% (p=0.003), TC 41% (p=0.0001), and CC 14% (p=0.0001). Further, the A69S polymorphism of LOC387715 was investigated and found to be significantly associated with AMD. LOC387715 genotypes in the AMD group were GG 30.6%, GT 38.1%, and TT 31.3% and in the control subjects were GG 59% (p=0.027), GT 39% (p=0.0001), and TT 2% (p=0.0001), respectively. We also found that Y402H C and A69S T allele were associated with AMD. This is the first study showing that Y402H and LOC387715 are associated with AMD in Turkish population. PMID:21790300

Soysal, Yasemin; Inan, Umit Übeyt; Küsbeci, Tuncay; Imirzalio?lu, Necat

2011-07-26

185

Linkage disequilibrium analysis in the LOC93081-KDELC1-BIVM region on 13q in bipolar disorder.  

PubMed

Genome-wide scans in bipolar disorder and a meta analysis on published data have provided evidence for linkage to chromosome 13q, although the reported peaks from various studies have not converged in a narrow region. Recently, single nucleotide polymorphisms (SNPs) at the G72/G30 locus have been shown to be associated with bipolar disorder suggesting its potential role in increasing disease risk. The proposed linkage region on 13q extends over a wide span, and could provide a clue to the existence of other susceptibility variants. In the present study, SNPs in the LOC93081-KDELC1-BIVM, a region proximal to G72, were interrogated in two bipolar family series. KDELC1 has a predicted filamin domain and BIVM contains an immunoglobulin-like motif. The small pedigree series yielded a nominally significant global P-value due to under-transmission of a rare haplotype but this finding was not supported by results from the larger series and in the case-control study that compared 278 cases and 277 controls. PMID:15635705

Ferraren, Dilberto O; Liu, Chunyu; Badner, Judith A; Corona, Winston; Rezvani, Azadeh; Monje, Virginia D; Gershon, Elliot S; Bonner, Tom I; Detera-Wadleigh, Sevilla D

2005-02-01

186

Pulsed radiofrequency for the treatment of occipital neuralgia: a prospective study with 6 months of follow-up  

Microsoft Academic Search

BACKGROUND AND OBJECTIVES: Occipital neuralgia is a paroxysmal nonthrobbing, stabbing pain in the area of the greater or lesser occipital nerve caused by irritation of these nerves. Although several therapies have been reported, no criterion standard has emerged. This study reports on the results of a prospective trial with 6 months of follow-up in which pulsed radiofrequency treatment of the

Pascal Vanelderen; T. P. H. Rouwette; Pieter De Vooght; Martine Puylaert; René Heylen; Kris Vissers; Jan Van Zundert

2010-01-01

187

Two periods of processing in the (circum)striate visual cortex as revealed by transcranial magnetic stimulation  

Microsoft Academic Search

To determine the timing of visual processing in the (circum)striate visual cortex, we examined the effect of single pulse transcranial magnetic stimulation over the occipital pole of healthy subjects who were engaged in a forced-choice visual letter identification task.Single letters, subtending a visual angle of 0.35°, were foveally presented for 10 ms and were immediately followed by a mask. We

Erik Corthout; Bob Uttl; Ulf Ziemann; Alan Cowey; Mark Hallett

1998-01-01

188

Elementary visual hallucinations, blindness, and headache in idiopathic occipital epilepsy: differentiation from migraine  

Microsoft Academic Search

This is a qualitative and chronological analysis of ictal and postictal symptoms, frequency of seizures, family history, response to treatment, and prognosis in nine patients with idiopathic occipital epilepsy and visual seizures. Ictal elementary visual hallucinations are stereotyped for each patient, usually lasting for seconds. They consist of mainly multiple, bright coloured, small circular spots, circles, or balls. Mostly, they

C P Panayiotopoulos

1999-01-01

189

Stimulation of the greater occipital nerve induces increased central excitability of dural afferent input  

Microsoft Academic Search

Summary Patients with primary headaches often report pain that involves not only the front of the head, innervated by the first (ophthalmic) division of the trigeminal nerve, but also the back of the head, innervated by the greater occipital nerve (GON) that is a branch of the C2 spinal root. The aim of this work was to study the physiology

Thorsten Bartsch; Peter J. Goadsby

2002-01-01

190

Ponto-Geniculo-Occipital (PGO) Burst Neurons: Correlative Evidence for Neuronal Generators of PGO Waves  

Microsoft Academic Search

A newly discovered class of neurons, ponto-geniculo-occipital (PGO) burst neurons, has PGO wave relationships of phase-leading, stereotyped discharge bursts, and the highest reported discharge specificity and coherence; these neurons thus fulfill correlative criteria for output generator neurons for PGO waves. The PGO burst neurons are recorded in a discrete dorsal brainstem area in apposition to the brachium conjunctivum.

Robert W. McCarley; John P. Nelson; J. Allan Hobson

1978-01-01

191

Autism and visual agnosia in a child with right occipital lobectomy  

Microsoft Academic Search

OBJECTIVESAutistic 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

I Jambaqué; L Mottron; G Ponsot; C Chiron

1998-01-01

192

Autism and visual agnosia in a child with right occipital lobectomy  

Microsoft Academic Search

Objectives—Autistic disorder is a devel- opmental handicap with an unknown neurological basis. Current neuropsycho- logical models for autism suggest an abnormal construction of visual percep- tual representation or a deficit in execu- tive functions. These models predict cerebral lesions in the temporo-occipital or frontal regions of autistic patients. The present study aimed at studying the pres- ence of symptoms of

L Mottron; G Ponsot; C Chiron

2007-01-01

193

The effect of mirthfulness upon amount of discordant right-left occipital EEG alpha  

Microsoft Academic Search

A total of 68 subjects participated in two experiments that tested the effect of exposure to comedy upon amount of discordant right-left occipital EEG alpha. Data from both showed less discordant alpha in the “laughers” and more in the “nonlaughers” at the end of exposure to a filmed comedy, as contrasted by no such group difference before treatment. Experiment 2

Sven Svebak

1982-01-01

194

Perinatal occipital lobe injury in children: analysis of twenty-one cases.  

PubMed

This study used magnetic resonance imaging to analyze causes and clinical courses of pediatric occipital lobe injury. Patients undergoing magnetic resonance imaging for suspected bilateral occipital lobe injury at our Neurodevelopmental Department between July 2007 and June 2011 were included. We evaluated magnetic resonance imaging characteristics, clinical courses, electroencephalogram monitoring, and Denver Development Screen Test scores. Twenty-one infants were examined. Of these, 10 had been born preterm. Thirteen patients demonstrated hypoglycemia. Perinatal period hypoglycemia comprised the most common cause (71.4%) of occipital brain injury. Visual abnormalities were evident in 18 patients. Seventeen (80.9%) patients manifested epilepsy. Infantile spasms were observed in 13 cases (76.5%). According to Denver Development Screen Test assessment, 17 patients demonstrated delayed motor development. Motor function and language improved in 10 patients after effective control of their seizures. Hypoglycemia constitutes the most common cause of occipital injury in infants. Visual impairment, startle episodes, infantile spasms, and motor developmental delay comprise the most common complications, whereas language function is usually spared. PMID:23127266

Wang, San-Mei; Yang, Chang-Shuan; Hou, Yu; Ma, Xiu-Wei; Feng, Zhi-Chun; Liao, Yu-Zhen

2012-12-01

195

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

2012-12-21

196

Spatiotemporal dynamics and functional correlates of evoked neural oscillations with different spectral powers in human visual cortex.  

PubMed

OBJECTIVE: To investigate spatiotemporal characteristics and functional correlates of evoked oscillations (EOs) at different frequency bands in human visual cortex. METHODS: Flash visual evoked potentials (FVEPs) were recorded from 11 epilepsy patients with intracranial electrodes placed over the occipital and adjacent cortices. Spatiotemporal characteristics of spectral powers and correlation with various visual responses elicited by electrical cortical stimulations were analyzed in the same electrodes. RESULTS: High ? (60-150Hz) EOs were first recorded in the cuneus and lingual gyri around the calcarine sulcus. Low ? (30-60Hz) EOs appeared also in the mesial occipital cortex slightly later and lasted longer than high ? EGOs. In contrast, lower frequency (LF) <30Hz EOs were recorded more diffusely from occipital surfaces with delayed onset and longer duration. High ? EOs were predominantly associated with simple form visual responses, whereas low ? and LF EOs were with intermediate form and LF EOs with complex form responses. CONCLUSIONS: FVEP spectral power analysis directly recorded from human visual cortex showed distinct spatiotemporal distributions in high and low ?, or LF bands that have different functional correlates. SIGNIFICANCE: Phase-locked EOs in these frequency bands may have special neuroanatomical and functional organization during early visual processing. PMID:23757378

Kim, Song E; Kim, Won Sup; Kim, Byung Gon; Chung, Dongil; Jeong, Jaeseung; Lee, Jae Sung; Tae, Woo Suk; Hong, Seung Bong; Lee, Hyang Woon

2013-06-01

197

Pharmacogenetic Influence of LOC387715/HTRA1 on the Efficacy of Bevacizumab Treatment for Age-Related Macular Degeneration in a Korean Population  

PubMed Central

Purpose The purpose of this study was to determine the pharmacogenetic effects of complement factor H (CFH) Y402H, LOC387715 and high-temperature requirement factor A1 (HTRA1) genotypes on the treatment of exudative age-related macular degeneration (AMD) by intravitreal bevacizumab injection in a Korean population. Methods Seventy-five patients diagnosed with exudative AMD were treated with intravitreal bevacizumab (2.5 mg) monotherapy. All patients received three initial intravitreal bevacizumab injections every four weeks and were then treated "as needed" based on clinical findings, optical coherence tomography and fluorescein angiography during the 12 month follow-up period after the third injection. Results The difference in visual acuity improvement among the three genotypes of LOC387715 were statistically significant at six months post-treatment (logarithm of the minimum angle of resolution; TT, 0.346; GT, 0.264; GG, 0.188; p = 0.037). Among the LOC387715 genotypes, the number of additional injections was lower in patients who had the risk T allele (GG, 2.143; GT, 2.000; TT, 1.575; p = 0.064). There was no significant difference between visual acuity and central macular thickness change in the CFH Y402H polymorphism group during the 12 month follow-up period. However, the TC group of CFH Y402H required more additional bevacizumab injections than the TT group (TT, 1.517; TC, 3.363; p = 0.020). Conclusions This study demonstrated that different LOC387715/HTRA1 genotypes resulted in different bevacizumab treatment responses on exudative AMD. Patients with the risk allele had an improved treatment response and less need for additional injections. However, patients with the CFH Y402H risk allele needed more additional injections of bevacizumab in order to improve visual acuity. This study illustrates how pharmacogenetic factors may help determine treatment modality and dosing. This could ultimately provide basic data for 'personalized medicine' in AMD.

Kang, Haeng Ku; Yoon, Myung Hun; Lee, Dae Hyun

2012-01-01

198

Topiramate raises anterior cingulate cortex glutamine levels in healthy men; a 4.0 T magnetic resonance spectroscopy study  

Microsoft Academic Search

Rationale  Potential mechanisms of action of topiramate include alterations of glutamatergic and GABAergic systems. In particular, topiramate\\u000a has been shown to increase occipital cortex GABA levels, as measured using proton magnetic resonance spectroscopy (MRS).\\u000a \\u000a \\u000a \\u000a Objectives  The purpose of this study was to measure the effect of acute oral topiramate on the GABA precursors glutamate and glutamine\\u000a in the anterior cingulate cortex (ACC)

Constance M. Moore; Megan Wardrop; Blaise de B. Frederick; Perry F. Renshaw

2006-01-01

199

A real-world size organization of object responses in occipito-temporal cortex  

PubMed Central

SUMMARY While there are selective regions of occipito-temporal cortex that respond to faces, letters, and bodies, the large-scale neural organization of most object categories remains unknown. Here we find that object representations can be differentiated along the ventral temporal cortex by their real-world size. In a functional neuroimaging experiment, observers were shown pictures of big and small real-world objects (e.g. table, bathtub; paperclip, cup), presented at the same retinal size. We observed a consistent medial-to-lateral organization of big and small object preferences in the ventral temporal cortex, mirrored along the lateral surface. Regions in the lateral-occipital, infero-temporal, and parahippocampal cortices showed strong peaks of differential real-world size selectivity, and maintained these preferences over changes in retinal size and in mental imagery. These data demonstrate that the real-world size of objects can provide insight into the spatial topography of object representation.

Konkle, Talia; Oliva, Aude

2012-01-01

200

A real-world size organization of object responses in occipitotemporal cortex.  

PubMed

While there are selective regions of occipitotemporal cortex that respond to faces, letters, and bodies, the large-scale neural organization of most object categories remains unknown. Here, we find that object representations can be differentiated along the ventral temporal cortex by their real-world size. In a functional neuroimaging experiment, observers were shown pictures of big and small real-world objects (e.g., table, bathtub; paperclip, cup), presented at the same retinal size. We observed a consistent medial-to-lateral organization of big and small object preferences in the ventral temporal cortex, mirrored along the lateral surface. Regions in the lateral-occipital, inferotemporal, and parahippocampal cortices showed strong peaks of differential real-world size selectivity and maintained these preferences over changes in retinal size and in mental imagery. These data demonstrate that the real-world size of objects can provide insight into the spatial topography of object representation. PMID:22726840

Konkle, Talia; Oliva, Aude

2012-06-21

201

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

202

The Characterization of Childhood Occipital Epilepsy of Gastaut: A Study of Seven Patients.  

PubMed

Characterization of the electroclinical features and evolution of childhood occipital epilepsy of Gastaut (COE-G). Seven children were retrospectively identified as having COE-G and were followed-up clinically using EEGs. Visual manifestations were the most common ictal event. Eye-associated ictal deviation was associated with ipsilateral turning of the head and migraine-like symptoms were frequent. Hemiconvulsions occurred in two children, and only one child had secondary generalized tonic-clonic seizures. In all patients, seizures occurred while awake, while two patients also had seizures while sleeping. EEG showed five patients with occipital spike-wave discharges when their eyes were closed which disappeared once their eyes were opened. Two cases continued having frequent seizures despite antiepileptic drug treatment. These patients also displayed learning difficulties and behavioral impairments after seizure onset. COE-G is a distinctive epileptic syndrome; however, the long-term prognosis for patients with the condition is unclear. PMID:23589070

Shu, Xiao Mei; Zhang, Gui Ping; Yang, Bing Zhu; Li, Juan

2013-04-16

203

Rectangular-patterned Occipital Alopecia Areata: A Report of Three Cases  

PubMed Central

Many reports have described the presence of alopecia areata (AA) associated with other autoimmune diseases, which support the autoimmune nature of AA. Additionally, AA has been reported in association with malignancy as a paraneoplastic symptom. In this report, we describe three patients with diffuse large B-cell lymphoma, alveolar soft part sarcoma, and cavernous sinus arteriovenous fistula with embolization treatment, respectively, who characteristically presented with rectangular-patterned occipital AA.

Shin, Jaeyong; Jang, Hong Sun; Cho, Sung Bin

2012-01-01

204

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

205

Metabolic and Molecular Bases of Menkes Disease and Occipital Horn Syndrome  

Microsoft Academic Search

Menkes disease and occipital horn syndrome (OHS) are related disorders of copper transport that involve abnormal neurodevelopment,\\u000a connective tissue problems, and often premature death. Location of the gene responsible for these conditions on the X chromosome\\u000a was indicated by pedigree analysis from the time of these syndromes' earliest descriptions. Characterization of an affected\\u000a female with an X-autosomal translocation was used

1998-01-01

206

C-loc software  

Microsoft Academic Search

In recent years, geographic information systems (GIS) for consumers (Google Maps and Google Earth, for example) have become very popular, and many people enjoy collecting and editing memories using those media. These systems are well designed to visualize diverse geographical data, but they can not present geographical and chronological information at the same time. Some GIS systems have a chronological

Yasushi Noguchi

2009-01-01

207

Synaptic proteins and choline acetyltransferase loss in visual cortex in dementia with Lewy bodies.  

PubMed

Functional neuroimaging studies have consistently reported abnormalities in the visual cortex in patients with dementia with Lewy bodies (DLB), but their neuropathologic substrates are poorly understood. We analyzed synaptic proteins and choline acetyltransferase (ChAT) in the primary (BA17) and association (BAs18/19) visual cortex in DLB and similar aged control and Alzheimer disease (AD) subjects. We found lower levels of synaptophysin, syntaxin, SNAP-25, and ?-synuclein in DLB subjects versus both aged control (68%-78% and 27%-72% for BA17 and BAs18/19, respectively) and AD cases (54%-67% and 10%-56% for BA17 and BAs18/19, respectively). The loss in ChAT activity in DLB cases was also greater in BA17 (72% and 87% vs AD and control values, respectively) than in BAs18/19 (52% and 65% vs AD and control groups, respectively). The observed synaptic and ChAT changes in the visual cortices were not associated with tau or ?-amyloid pathology in the occipital or the frontal, temporal, and parietal neocortex. However, the neocortical densities of LBs, particular those in BA17 and BAs18/19, correlated with lower synaptic and ChAT levels in these brain areas. These findings draw attention to molecular changes within the primary visual cortex in DLB and correlate with the neuroimaging findings within the occipital lobe in patients with this disorder. PMID:23242284

Mukaetova-Ladinska, Elizabeta B; Andras, Alina; Milne, Joan; Abdel-All, Zeinab; Borr, Iwo; Jaros, Evelyn; Perry, Robert H; Honer, William G; Cleghorn, Andrea; Doherty, Jeanette; McIntosh, Gary; Perry, Elaine K; Kalaria, Raj N; McKeith, Ian G

2013-01-01

208

Pharmacoresistant occipital lobe epilepsy with fixation-off sensitivity in a patient with cerebral calcifications: a video/EEG study.  

PubMed

We describe a unique patient with cerebral calcifications of unknown origin presenting with pharmacoresistant occipital lobe epilepsy and fixation-off sensitivity. Our report further expands the spectrum of seizure disorders associated with fixation-off sensitivity. PMID:21051297

Ferlazzo, Edoardo; Calarese, Tiziana; Genton, Pierre

2010-11-03

209

Hyperfamiliarity for unknown faces after left lateral temporo-occipital venous infarction: a double dissociation with prosopagnosia  

Microsoft Academic Search

Right hemisphere dominance in face processing is well established and unilateral right inferior temporo-occipital damage can result in prosopagnosia. Here, we describe a 21-year-old right-handed woman with acute impairment in face recognition that selectively concerned unfamiliar faces, following a focal left lateral temporo-occipital venous infarct. She was severely impaired in discerning that unknown people seen in everyday life were unfamiliar,

Patrik Vuilleumier; Christine Mohr; Nathalie Valenza; Corinne Wetzel; Theodor Landis

2003-01-01

210

Nuclear shuttling of She2p couples ASH1 mRNA localization to its translational repression by recruiting Loc1p and Puf6p.  

PubMed

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 alpha 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; Chartrand, Pascal

2009-02-25

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

Functional connectivity between motor cortex and globus pallidus in human non-REM sleep  

PubMed Central

Recent evidence suggests that the motor system undergoes very specific modulation in its functional state during the different sleep stages. Here we test the hypothesis that changes in the functional organization of the motor system involve both cortical and subcortical levels and that these distributed changes are interrelated in defined frequency bands. To this end we evaluated functional connectivity between motor and non-motor cortical sites (fronto-central, parieto-occipital) and the globus pallidus (GP) in human non-REM sleep in seven patients undergoing deep brain stimulation (DBS) for dystonia using a variety of spectral measures (power, coherence, partial coherence and directed transfer function (DTF)). We found significant coherence between GP and fronto-central cortex as well as between GP and parieto-occipital cortex in circumscribed frequency bands that correlated with sleep specific oscillations in ‘light sleep’ (N2) and ‘slow-wave sleep’ (N3). These sleep specific oscillations were also reflected in significant coherence between the two cortical sites corroborating previous studies. Importantly, we found two different physiological activities represented within the broad band of significant coherence between 9.5 and 17 Hz. One component occurred in the frequency range of sleep spindles (12.5–17 Hz) and was maximal in the coherence between fronto-central and parieto-occipital cortex as well as between GP and both cortical sites during N2. This component was still present between fronto-central and parieto-occipital cortex in N3. Functional connectivity in this frequency band may be due to a common input to both GP and cortex. The second component consisted of a spectral peak over 9.5–12.5 Hz. Coherence was elevated in this band for all topographical constellations in both N2 and N3, but especially between GP and fronto-central cortex. The DTF suggested that the 9.5–12.5 Hz activity consisted of a preferential drive from GP to the fronto-central cortex in N2, whereas in N3 the DTF between GP and fronto-central cortex was symmetrical. Partial coherence supported distinctive patterns for the 9.5–12.5 and 12.5 and 17 Hz component, so that only coherence in the 9.5–12.5 Hz band was reduced when the effects of GP were removed from the coherence between the two cortical sites. The data suggest that activities in the GP and fronto-central cortex are functionally connected over 9.5–12.5 Hz, possibly as a specific signature of the motor system in human non-REM sleep. This finding is pertinent to the longstanding debate about the nature of alpha–delta sleep as a physiological or pathological feature of non-REM sleep.

Salih, F; Sharott, A; Khatami, R; Trottenberg, T; Schneider, G; Kupsch, A; Brown, P; Grosse, P

2009-01-01

213

The Orbitofrontal Cortex and Reward  

Microsoft Academic Search

The primate 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 odors is represented. The orbitofrontal cortex also receives information about the sight of objects and faces from the temporal

Edmund T. Rolls

2000-01-01

214

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

215

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

2011-06-01

216

Pathology Case Study: Mental Status Changes and a Severe Occipital Headache  

NSDL National Science Digital Library

This is a case study presented by the University of Pittsburgh Department of Pathology in which a 32-year-old man with symptoms of an upper respiratory infection presented himself to the hospital with mental status changes and a severe occipital headache of two days duration. Visitors are given both the microscopic description and radiology results, including images, and are given the opportunity to diagnose the patient. This is an excellent resource for students in the health sciences to familiarize themselves with using patient history and laboratory results to diagnose disease. It is also a helpful site for educators to use to introduce or test student learning in neuropathology.

Lieberman, Andrew P.; Grossman, Robert I.; Lavi, Ehud

2009-10-14

217

Central modulation in cluster headache patients treated with occipital nerve stimulation: an FDG-PET study  

Microsoft Academic Search

Background  Occipital nerve stimulation (ONS) has raised new hope for drug-resistant chronic cluster headache (drCCH), a devastating condition.\\u000a However its mode of action remains elusive. Since the long delay to meaningful effect suggests that ONS induces slow neuromodulation,\\u000a we have searched for changes in central pain-control areas using metabolic neuroimaging.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Ten drCCH patients underwent an 18FDG-PET scan after ONS, at delays

Delphine Magis; Marie-Aurélie Bruno; Arnaud Fumal; Pierre-Yves Gérardy; Roland Hustinx; Steven Laureys; Jean Schoenen

2011-01-01

218

Where are inion and endinion? Variations of the exo- and endocranial morphology of the occipital bone during hominin evolution.  

PubMed

The occipital bone is frequently investigated in paleoanthropological studies because it has several features that help to differentiate various fossil hominin species. Among these features is the separation between inion and endinion, which has been proposed to be an autapomorphic trait in (Asian) Homo erectus. Methodologies are developed here to quantify for the first time the location of these anatomical points, and to interpret their variation due to the complex interactions between exocranial and endocranial size and shape of the occipital and nuchal planes, as well as the occipital lobes and cerebellum. On the basis of our analysis, neither 'the separation between inion and endinion' nor 'endinion below inion' can be considered as an autapomorphic trait in H. erectus, since this feature is a condition shared by extant African great apes and fossil hominins. Moreover, our results show that the exo- and endocranial anatomy of the occipital bone differs between hominins (except Paranthropus boisei specimens and KNM-ER 1805) and great apes. For example, chimpanzees and bonobos are characterized by a very high position of inion and their occipital bone shows an antero-posterior compression. However, these features are partly correlated with their small size when compared with hominins. Asian H. erectus specimens have a thick occipital torus, but do not differ from other robust specimens, neither in this feature nor in the analysed exo- and endocranial proportions of the occipital bone. Finally, the apparent brain size reduction during the Late Pleistocene and variation between the sexes in anatomically modern humans (AMH) reflect that specimens with smaller brains have a relatively larger posterior height of the cerebellum. However, this trend is not the sole explanation for the 'vertical shift' of endinion above inion that appears occasionally and exclusively in AMH. PMID:21855115

Balzeau, Antoine; Grimaud-Hervé, Dominique; Gilissen, Emmanuel

2011-08-19

219

EEG gamma-band phase synchronization between posterior and frontal cortex during mental rotation in humans.  

PubMed

The main purpose of the present paper was: (1) to study the phase synchronization pattern in the gamma-band while performing the classical Shepard-Metzler task of mental rotation; (2) to investigate the role of musical training; and (3) to study hemispheric differences in the degree of synchronization during mental rotation. Multivariate electroencephalograph signals from 20 male subjects (ten musicians and ten non-musicians) were recorded while performing the mental rotation task and also at resting condition. Phase synchronization was measured by a recent index, mean phase coherence. It was found that synchronization between frontal cortex and right parietal cortex was significantly increased during mental rotation with respect to rest, whereby musicians showed significantly higher degrees of synchronization than non-musicians. Left hemispheric dominance in the degree of phase synchronization, stronger in the posterior right parietal and occipital regions, was observed in musicians. Right hemispheric dominance was generally observed in non-musicians. PMID:11585560

Bhattacharya, J; Petsche, H; Feldmann, U; Rescher, B

2001-09-21

220

Category learning increases discriminability of relevant object dimensions in visual cortex.  

PubMed

Learning to categorize objects can transform how they are perceived, causing relevant perceptual dimensions predictive of object category to become enhanced. For example, an expert mycologist might become attuned to species-specific patterns of spacing between mushroom gills but learn to ignore cap textures attributable to varying environmental conditions. These selective changes in perception can persist beyond the act of categorizing objects and influence our ability to discriminate between them. Using functional magnetic resonance imaging adaptation, we demonstrate that such category-specific perceptual enhancements are associated with changes in the neural discriminability of object representations in visual cortex. Regions within the anterior fusiform gyrus became more sensitive to small variations in shape that were relevant during prior category learning. In addition, extrastriate occipital areas showed heightened sensitivity to small variations in shape that spanned the category boundary. Visual representations in cortex, just like our perception, are sensitive to an object's history of categorization. PMID:22490547

Folstein, Jonathan R; Palmeri, Thomas J; Gauthier, Isabel

2012-04-05

221

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

222

The Cerebral Cortex  

Microsoft Academic Search

The cerebral (neocortext) and the limbic system generate all sensory and cognitive perception, as well as voluntary motot activity; the limbic system generates most of our basic emotional and autonomic regulations to the neocortex. We have discovered most of the subcortical\\u000a areas, their connections to the cerebral cortex, and their role in the development; anatomically and functionally. The neocortex\\u000a and

Robert Melillo; Gerry Leisman

223

Reciprocal inhibitory visual-vestibular interaction. Visual motion stimulation deactivates the parieto-insular vestibular cortex.  

PubMed

The vestibular system--a sensor of head accelerations--cannot detect self-motion at constant velocity and thus requires supplementary visual information. The perception of self-motion during constant velocity movement is completely dependent on visually induced vection. This can be linear vection or circular vection (CV). CV is induced by large-field visual motion stimulation during which the stationary subject perceives the moving surroundings as being stable and himself as being moved. To determine the unknown cortical visual-vestibular interaction during CV, we conducted a PET activation study on CV in 10 human volunteers. The PET images of cortical areas activated during visual motion stimulation without CV were compared with those with CV. Hitherto, CV was explained neurophysiologically by visual-vestibular convergence with activation of the vestibular nuclei, thalamic subnuclei and vestibular cortex. If CV were mediated by the vestibular cortex, one would expect that an adequate visual motion stimulus would activate both the visual and vestibular cortex. Contrary to this expectation, it was shown for the first time that visual motion stimulation with CV not only activates a medial parieto-occipital visual area bilaterally, separate from middle temporal/medial superior temporal areas, it also simultaneously deactivates the parieto-insular vestibular cortex. There was a positive correlation between the perceived intensity of CV and relative changes in regional CBF in parietal and occipital areas. These findings support a new functional interpretation: reciprocal inhibitory visual-vestibular interaction as a multisensory mechanism for self-motion perception. Inhibitory visual-vestibular interaction might protect visual perception of self-motion from potential vestibular mismatches caused by involuntary head accelerations during locomotion, and this would allow the dominant sensorial weight during self-motion perception to shift from one sensory modality to the other. PMID:9762962

Brandt, T; Bartenstein, P; Janek, A; Dieterich, M

1998-09-01

224

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.

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

225

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.

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

2011-01-01

226

Occipital condyle screw placement and occipitocervical instrumentation using three-dimensional image-guided navigation.  

PubMed

Occipital condyle (OC) screws are an alternative cephalad fixation point in occipitocervical fusion. Safe placement of occipital, C1 lateral mass, and C2 pars screws have been described previously, but not OC screws. The craniocervical junction is complex, and a thorough understanding of the anatomy is needed. Three-dimensional (3D) image-guided navigation was used in six patients. There were no complications related to image-guided navigation during the placement of 12 OC screws and we found that this navigation can serve as a useful adjunct when placing an OC screw. Technical considerations of placing OC and C1 lateral mass screws are discussed with particular reference to patient positioning and the StealthStation® S7™ image-guided navigational platform (Medtronic, Minneapolis, MN, USA). The reference arc is attached to the head-clamp and faces forward. The optical camera and monitor are positioned at the head of the table for a direct, non-obstructed line-of-sight. To minimize intersegmental movement, the OC should not be drilled until all other screws have been placed. We conclude that 3D image-guided navigation is a useful adjunct that can be safely and effectively used for placement of instrumentation of the upper cervical spine including the OC. PMID:22356730

Le, Tien V; Burkett, Clint; Ramos, Edwin; Uribe, Juan S

2012-02-21

227

Stormy onset with prolonged loss of consciousness in benign childhood epilepsy with occipital paroxysms.  

PubMed Central

In nine of 62 children with benign occipital epilepsy (BOE) the onset was stormy and alarming. The first and often only seizure was characterised by prolonged loss of consciousness lasting up to 12 hours, suggesting an acute cerebral insult. In all but one case there was a tonic aversion either of eyes alone or of both head and eyes which was interpreted as conjugate deviation. The other accompanying ictal motor phenomena were either partial or generalised convulsions. In five patients the seizure was heralded by a headache, and in five cases was accompanied by vomiting. The seizure began with visual symptoms in only one patient. The seizure occurred while awake in seven and during sleep in two. The age at onset was from 3 1/4 to 10 years. Interictal EEGs showed occipital discharges typical of BOE, and the clinical course was benign. In four cases a few partial or complex partial seizures recurred during subsequent anticonvulsant therapy, but in five cases seizures never recurred. Anticonvulsants were discontinued in five patients who remained free from seizures for one to 11 1/2 years after withdrawal of treatment. Sudden coma in a child associated with focal features such as tonic deviation of the head or eyes or both may represent a benign seizure disorder.

Kivity, S; Lerman, P

1992-01-01

228

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

PubMed

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, and 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 [Kaler et al., 1994: Nat Genet 18:195-202]. 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. PMID:8914740

Proud, V K; Mussell, H G; Kaler, S G; Young, D W; Percy, A K

1996-10-01

229

Pulsed radiofrequency therapy versus greater occipital nerve block in the management of refractory cervicogenic headache - a pilot study.  

PubMed

The aim of this pilot study was to compare the efficacy of pulsed radiofrequency to the greater occipital nerve versus a greater occipital nerve block with a mixture of local anaesthetic and steroid in the management of refractory cervicogenic headache. We enrolled 30 patients suffering from refractory cervicogenic headache. Patients were randomly allocated into two groups of fifteen. A greater occipital nerve block with steroid was utilised in group A, while a pulsed radiofrequency treatment was employed in group B. Success of both procedures was evaluated by comparing pre and post intervention Visual Analogue Scale of pain, Medication Quantification Scale - III. and Global Perceived Effect at three and 9 months after the procedures. At three months post therapy a significant decrease in Visual Analogue Scale (p<0.001) was identified (3.2 points in group A, 3.3 points in group B respectively). In group B pain remained reduced even after 9 months (p<0.001) when compared to pre treatment scores. The consumption of analgesic medication was reduced significantly in both groups at three months (p<0.001) and 9 months (p<0.01), respectively. No serious complication was noted. Greater occipital nerve block is a safe, efficient technique in the management of cervicogenic headaches. Despite the lack of high quality scientific evidence (level III or IV) in the literature, we have extensive experience with steroid application and pulsed radiofrequency to the greater occipital nerve and report the beneficial results in our study. PMID:22142523

Gabrhelík, T; Michálek, P; Adamus, M

2011-01-01

230

CX-516 Cortex pharmaceuticals.  

PubMed

CX-516 is one of a series of AMPA modulators under development by Cortex, in collaboration with Shire and Servier, for the potential treatment of Alzheimer's disease (AD), schizophrenia and mild cognitive impairment (MCI) [234221]. By June 2001, CX-516 was in phase II trials for both schizophrenia and attention deficit hyperactivity disorder (ADHD) [412513]. A phase II trial in fragile X syndrome and autism was expected to start in May 2002 [449861]. In October 2001, Cortex was awarded a Phase II SBIR grant of $769,818 from the National Institutes of Mental Health to investigate the therapeutic potential of AMPAkines in schizophrenia. This award was to support a phase IIb study of CX-516 as a combination therapy in schizophrenia patients concomitantly treated with olanzapine. The trial was to enroll 80 patients and employ a randomized, double-blind, placebo-controlled design in which the placebo group was to receive olanzapine plus placebo and the active group was to receive olanzapine plus CX-516 [425982]. In April 2000, Shire and Cortex signed an option agreement in which Shire was to evaluate CX-516for the treatment of ADHD. Under the terms of the agreement, Shire would undertake a double-blind, placebo-controlled evaluation of CX-516 involving ADHD patients. If the study proved effective, Shire would have the right to convert its option into an exclusive worldwide license for the AMPAkines for ADHD under a development and licensing agreement. Should Shire elect to execute this agreement, Shire would bear all future developmental costs [363618]. By February 2002, Cortex and Servier had revealed their intention to begin enrolment for an international study of an AMPAkine compound as a potential treatment for MCI in the near future. Assuming enrollment proceeded as anticipated, results were expected during the second quarter of 2003 [439301]. By May 2002, phase II trials were underway [450134]. In March 2002, Cortex was awarded extended funding under the University of California BioSTAR projectfor the research project: 'Ampakine modulation of brain neurotrophin expression: a novel therapeutic strategy'. This funding was expected to amount to $193,000 over a two-year period [444872]. PMID:12186271

Danysz, Wojciech

2002-07-01

231

Vascular complications (splenic and hepatic artery aneurysms) in the occipital horn syndrome: report of a patient and review of the literature  

Microsoft Academic Search

We report an 18-year-old boy with occipital horn syndrome who developed aneurysms of the splenic and hepatic arteries. Occipital\\u000a horn syndrome, also called X-linked cutis laxa or Ehlers-Danlos syndrome (EDS) type IX, is characterised by a skeletal dysplasia\\u000a which includes occipital horns, broad clavicles, deformed radii, ulnae and humeri, narrow rib cage, undercalcified long bones\\u000a and coxa valga. Distinctive features

Hans-Joachim Mentzel; Jörg Seidel; Susanna Vogt; Lothar Vogt; Werner A. Kaiser

1999-01-01

232

Image-Guided Stereotactic Body Radiotherapy for Lung Tumors Using BodyLoc With Tomotherapy: Clinical Implementation and Set-Up Accuracy  

SciTech Connect

We investigated the use of a BodyLoc immobilization and stereotactic localization device combined with TomoTherapy megavoltage CT (MVCT) in lung stereotactic body radiotherapy (SBRT) to reduce set-up uncertainty and treatment time. Eight patients treated with 3-5 fractions of SBRT were retrospectively analyzed. A BodyLoc localizer was used in both CT simulation for localization and the initial patient treatment set-up. Patients were immobilized with a vacuum cushion on the back and a thermoplastic body cast on the anterior body. Pretreatment MVCT from the TomoTherapy unit was fused with the planning kilovoltage CT (KVCT) before each fraction of treatment to determine interfractional set-up error. The comparison of two MVCTs during a fraction of treatment resulted in the intrafractional uncertainty of the treatment. A total of 224 target isocenter shifts were analyzed to assess these inter- and intrafractional tumor motions. We found that for interfractional shifts, the mean set-up errors and standard deviations were -1.1 {+-} 2.8 mm, -2.5 {+-} 8.7 mm, and 4.1 {+-} 2.6 mm, for lateral, longitudinal, and vertical variation, respectively; the mean setup rotational variation was -0.3 {+-} 0.7 deg.; and the maximum motion was 13.5 mm in the longitudinal direction. For intrafractional shifts, the mean set-up errors and standard deviations were -0.1 {+-} 0.7 mm, -0.3 {+-} 2.0 mm, and 0.5 {+-} 1.1 mm for the lateral, longitudinal, and vertical shifts, respectively; the mean rotational variation was 0.1 {+-} 0.2 deg.; and the maximum motion was 3.8 mm in the longitudinal direction. There was no correlation among patient characteristics, set-up uncertainties, and isocenter shifts, and the interfractional set-up uncertainties were larger than the intrafractional isocenter shift. The results of this study suggested that image-guided stereotactic body radiotherapy using the BodyLoc immobilization system with TomoTherapy can improve treatment accuracy.

Zhou Jining [Center for Cancer Treatment, Sharp Grossmont Hospital, La Mesa, CA (United States); Virginia Commonwealth University, Richmond, VA (United States); Mount Sinai Medical Center, New York, NY (United States)], E-mail: jining.zhou@sharp.com; Uhl, Barry; Dewitt, Kelly; Young, Mark; Taylor, Brian; Fei Dingyu; Lo, Y-C [Center for Cancer Treatment, Sharp Grossmont Hospital, La Mesa, CA (United States); Virginia Commonwealth University, Richmond, VA (United States); Mount Sinai Medical Center, New York, NY (United States)

2010-04-01

233

Placement of occipital condyle screws for occipitocervical fixation in a pediatric patient with occipitocervical instability after decompression for Chiari malformation.  

PubMed

In cadaveric studies and recently in one adult patient the occipital condyle has been studied as an option to allow bone purchase by fixation devices. In the current case the authors describe the use of occipital condyle screws in a child undergoing occipitocervical fixation. To the best of the authors' knowledge this case is the first reported instance of this technique in a pediatric patient. This girl had a history of posterior fossa decompression for Chiari malformation Type I when she was 22 months of age. When she was 6 years old she presented with neck pain on flexion and extension of her head. Magnetic resonance imaging in flexion and extension revealed occipitocervical instability. She underwent an occiput to C-2 posterior arthrodesis with bilateral screw placement in the occipital condyles, C-2 lamina, and C-1 lateral masses. Postoperatively, she was neurologically intact. Computed tomography demonstrated a stable construct, and her cervical pain had resolved on follow-up. PMID:20672939

Bekelis, Kimon; Duhaime, Ann-Christine; Missios, Symeon; Belden, Clifford; Simmons, Nathan

2010-08-01

234

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.

Hatsopoulos, Nicholas G.; Suminski, Aaron J.

2011-01-01

235

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

2012-03-09

236

Lateral mode discrimination and control in high-power single-mode diode lasers of the large-optical-cavity (LOC) type  

SciTech Connect

A comprehensive study of lateral mode discrimination and control in weak-laterally-confining large-optical-cavity (LOC)-type structures is presented. The analysis centers on two types of CDH-LOC laser structures: type A, which supports only the fundamental lateral mode in both the passive and active regimes; and type B, which supports several lateral modes in the passive regime and only the fundamental mode in the active regime. The transverse confinement factor GAMMA is peaked in the center of the structure and varies significantly across the lasing region for both device types. In the passive regime it is found that the effective-index (lateral) profile is a W-shaped waveguide for type A devices and a positive-index waveguide for type B devices. A discussion and analysis of losses in W-guides is also presented. Under carrier injection (i.e., active regime) the evolution of W-guides in CDHLOC structures is presented as a function of increasing current density up to lasing threshold. For both type A and type B devices the effective-index profiles and corresponding lateral far-field patterns are analyzed as a function of threshold mode gain. Carrier-induced bulkindex depressions are found to be in the -0.02 to -0.04 range depending on the value of the threshold mode gain. The corresponding antiguiding parameter, R = k /SUB o/ deltan/deltag, takes values in the -3 to -4 range, which imply values between 6 and 8 for the linewidth enhancement factor ..cap alpha... It is found that by controlling the threshold mode gain (i.e., changing the device length and/or its facet(s) reflectivity) devices of the same cross-sectional geometry can be made to lase either multimode (spatially) or in the fundamental mode.

Butler, J.K.; Botez, D.

1984-08-01

237

Preoperative overtraining protects against form learning deficits after lateral occipital lesions in Galago senegalensis.  

PubMed

Bushbabies (Galago senegalensis) trained on a form discrimination task in a two-choice apparatus prior to partial disruption of the central field representation of vision in striate cortex were found to be protected from postoperative deficit. These same animals were deficient in learning novel form discriminations. Pre- and postoperative tests of these subjects on discrimination of fine stripe patterns and of small food objects gave no evidence of reduced epicritic visual capacities. Results are discussed in terms of an interpretive role in form learning for areas of central field representation in primary visual cortex. PMID:7365001

Marcotte, R R; Ward, J P

1980-04-01

238

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

239

Adrenal cortex ontogenesis.  

PubMed

During the early phases of development, adrenal glands share a common origin with kidneys and gonads. The action of diverse transcription factors, signalling pathways and endocrine signals is required for the individualization of the adrenal primordium and its subsequent differentiation into an adult adrenal gland, with massive remodelling taking place around the time of birth in humans. Here I summarize the most important steps by which the adrenal cortex is shaped and present an overview of the current understanding of the genes and molecular pathways implicated in adrenal development and involved in the pathogenesis of its congenital diseases. Evidence is accumulating that some pivotal factors acting during adrenocortical development also play an important role to regulate the growth of adrenocortical tumors, representing promising therapeutical targets for a biology-oriented therapy. PMID:21115154

Lalli, Enzo

2010-12-01

240

A case with atypical childhood occipital epilepsy "Gastaut type": an ictal migraine manifestation with a good response to intravenous diazepam.  

PubMed

We report the history of a 14-year-old girl with atypical childhood occipital epilepsy "Gastaut type" whose first generalized tonic-clonic seizure was preceded by migraine without aura and followed by a status migrainosus. This status lasted for 3 days despite standard analgesic therapy. An EEG recording revealed an occipital status epilepticus during her migraine complaints. Seven minutes after intravenous administration of 10 mg diazepam under continuous EEG recording, a suppression of the epileptiform discharges over the right occipital was seen, while the headache subsided 3 min later. After precise questioning about the circumstances that possibly could have led to these events, it appeared that she had played for hours with a play station on the new color TV and she had visited an exhibition of Matisse and Bonnard with bright colors and contrast-rich text. Standardized extensive intermittent photic stimulation (IPS), 2 days after the status migrainosus, evoked besides asymmetrical right-sided driving, green spots in her left visual field, while in the EEG sharp waves were recorded over the right parietotemporal region. After further IPS with 20 Hz (eye closure), she started complaining of a light pulsating headache right occipitally and in the EEG right parietotemporal sharp-waves were seen. This lasted for about 10 min. Later, an interictal routine EEG was normal except for some theta over the right temporooccipital area. The most likely diagnosis is an atypical form of occipital epilepsy "Gastaut type." We would therefore advocate recording EEGs with photic stimulation in patients with atypical migraneous features. PMID:17711460

Parisi, Pasquale; Kasteleijn-Nolst Trenité, Dorothée G A; Piccioli, Marta; Pelliccia, Andrea; Luchetti, Anna; Buttinelli, Carla; Villa, Maria Pia

2007-08-17

241

Seeing is believing: neural representations of visual stimuli in human auditory cortex correlate with illusory auditory perceptions.  

PubMed

In interpersonal communication, the listener can often see as well as hear the speaker. Visual stimuli can subtly change a listener's auditory perception, as in the McGurk illusion, in which perception of a phoneme's auditory identity is changed by a concurrent video of a mouth articulating a different phoneme. Studies have yet to link visual influences on the neural representation of language with subjective language perception. Here we show that vision influences the electrophysiological representation of phonemes in human auditory cortex prior to the presentation of the auditory stimulus. We used the McGurk effect to dissociate the subjective perception of phonemes from the auditory stimuli. With this paradigm we demonstrate that neural representations in auditory cortex are more closely correlated with the visual stimuli of mouth articulation, which drive the illusory subjective auditory perception, than the actual auditory stimuli. Additionally, information about visual and auditory stimuli transfer in the caudal-rostral direction along the superior temporal gyrus during phoneme perception as would be expected of visual information flowing from the occipital cortex into the ventral auditory processing stream. These results show that visual stimuli influence the neural representation in auditory cortex early in sensory processing and may override the subjective auditory perceptions normally generated by auditory stimuli. These findings depict a marked influence of vision on the neural processing of audition in tertiary auditory cortex and suggest a mechanistic underpinning for the McGurk effect. PMID:24023823

Smith, Elliot; Duede, Scott; Hanrahan, Sara; Davis, Tyler; House, Paul; Greger, Bradley

2013-09-04

242

Seeing Is Believing: Neural Representations of Visual Stimuli in Human Auditory Cortex Correlate with Illusory Auditory Perceptions  

PubMed Central

In interpersonal communication, the listener can often see as well as hear the speaker. Visual stimuli can subtly change a listener’s auditory perception, as in the McGurk illusion, in which perception of a phoneme’s auditory identity is changed by a concurrent video of a mouth articulating a different phoneme. Studies have yet to link visual influences on the neural representation of language with subjective language perception. Here we show that vision influences the electrophysiological representation of phonemes in human auditory cortex prior to the presentation of the auditory stimulus. We used the McGurk effect to dissociate the subjective perception of phonemes from the auditory stimuli. With this paradigm we demonstrate that neural representations in auditory cortex are more closely correlated with the visual stimuli of mouth articulation, which drive the illusory subjective auditory perception, than the actual auditory stimuli. Additionally, information about visual and auditory stimuli transfer in the caudal–rostral direction along the superior temporal gyrus during phoneme perception as would be expected of visual information flowing from the occipital cortex into the ventral auditory processing stream. These results show that visual stimuli influence the neural representation in auditory cortex early in sensory processing and may override the subjective auditory perceptions normally generated by auditory stimuli. These findings depict a marked influence of vision on the neural processing of audition in tertiary auditory cortex and suggest a mechanistic underpinning for the McGurk effect.

Smith, Elliot; Duede, Scott; Hanrahan, Sara; Davis, Tyler; House, Paul; Greger, Bradley

2013-01-01

243

[The characteristics of the functional topology of Lashley's area in the rat cerebral cortex during different complex visual stimuli under alternative choice conditions].  

PubMed

In the result of our investigation it was determined: a) The ability to discriminate the complicated visual stimuli in rats depends on small part of occipital region of cerebral cortex critically. This is "Lashley zone". b) The location of this part of the cortex is the border between Ocl (17 field) and Oc2.1 (18a field), that and disagrees with the location of K. Lashley's "c" and "b" fields, although it includes largest part of "b" field.; c) The extirpation of this part of cerebral cortex leads to the irreversible loss of visual discrimination skill. But the control experiments demonstrated, that the ability to the keen visual differentiation and motor component of conditioned reflex were maintained. PMID:9583165

Sapetski?, A O

244

Disulfiram stimulates dopamine release from noradrenergic terminals and potentiates cocaine-induced dopamine release in the prefrontal cortex  

Microsoft Academic Search

Rationale  Disulfiram efficacy in treatment of cocaine addiction is attributed to the inhibition of dopamine-?-hydroxylase and reduction\\u000a in brain noradrenaline (NA)\\/dopamine (DA) ratio.\\u000a \\u000a \\u000a \\u000a \\u000a Objectives  Using microdialysis, we investigated if disulfiram causes DA release from noradrenergic terminals and modifies cocaine-induced\\u000a DA release.\\u000a \\u000a \\u000a \\u000a \\u000a Results  Disulfiram reduced extracellular NA in the medial prefrontal (mPF) cortex, occipital cortex, accumbens and caudate nuclei,\\u000a while it markedly increased DA

Paola Devoto; Giovanna Flore; Pierluigi Saba; Roberto Cadeddu; Gian Luigi Gessa

245

Differential activation patterns of occipital and prefrontal cortices during motion processing  

PubMed Central

Visual motion perception is normally mediated by neural processing in the posterior cortex. Focal damage to the Middle Temporal Area (MT), a posterior extrastriate region, induces motion perception impairment. It is unclear, however, how more broadly distributed cortical dysfunction affects this visual behavior and its neural substrates. Schizophrenia manifests itself in a variety of behavioral and perceptual abnormalities that have proved difficult to understand through a dysfunction of any single brain system. One of these perceptual abnormalities involves impaired motion perception. Motion processing provides an opportunity to clarify the roles of multiple cortical networks in both the healthy and schizophrenic brains. Using fMRI, we measured cortical activation while subjects performed two visual motion tasks (direction discrimination and speed discrimination) and one non-motion task (contrast discrimination). Normal controls showed robust cortical activation (BOLD signal changes) in MT during the direction and speed discrimination tasks, documenting primary processing of sensory input in this posterior region. In schizophrenia patients cortical activation was significantly reduced in MT and significantly increased in the inferior convexity of the prefrontal cortex (ICPFC), an area that is normally involved in higher-level cognitive processing. This shift in cortical responses from posterior to prefrontal regions suggests that motion perception in schizophrenia is associated with both deficient sensory processing and compensatory cognitive processing. Further, this result provides evidence that in the context of broadly distributed cortical dysfunction, the usual functional specificity of the cortex becomes modified even across the domains of sensory and cognitive processing.

Chen, Yue; Grossman, Emily D.; Bidwell, L. Cinnamon; Yurgelun-Todd, Deborah; Gruber, Staci A.; Levy, Deborah L.; Nakayama, Ken; Holzman, Philip S.

2008-01-01

246

Experienced Mindfulness Meditators Exhibit Higher Parietal-Occipital EEG Gamma Activity during NREM Sleep.  

PubMed

Over the past several years meditation practice has gained increasing attention as a non-pharmacological intervention to provide health related benefits, from promoting general wellness to alleviating the symptoms of a variety of medical conditions. However, the effects of meditation training on brain activity still need to be fully characterized. Sleep provides a unique approach to explore the meditation-related plastic changes in brain function. In this study we performed sleep high-density electroencephalographic (hdEEG) recordings in long-term meditators (LTM) of Buddhist meditation practices (approximately 8700 mean hours of life practice) and meditation naive individuals. We found that LTM had increased parietal-occipital EEG gamma power during NREM sleep. This increase was specific for the gamma range (25-40 Hz), was not related to the level of spontaneous arousal during NREM and was positively correlated with the length of lifetime daily meditation practice. Altogether, these findings indicate that meditation practice produces measurable changes in spontaneous brain activity, and suggest that EEG gamma activity during sleep represents a sensitive measure of the long-lasting, plastic effects of meditative training on brain function. PMID:24015304

Ferrarelli, Fabio; Smith, Richard; Dentico, Daniela; Riedner, Brady A; Zennig, Corinna; Benca, Ruth M; Lutz, Antoine; Davidson, Richard J; Tononi, Giulio

2013-08-28

247

Category-selective attention modulates unconscious processes in the middle occipital gyrus.  

PubMed

Many studies have revealed the top-down modulation (spatial attention, attentional load, etc.) on unconscious processing. However, there is little research about how category-selective attention could modulate the unconscious processing. In the present study, using functional magnetic resonance imaging (fMRI), the results showed that category-selective attention modulated unconscious face/tool processing in the middle occipital gyrus (MOG). Interestingly, MOG effects were of opposed direction for face and tool processes. During unconscious face processing, activation in MOG decreased under the face-selective attention compared with tool-selective attention. This result was in line with the predictive coding theory. During unconscious tool processing, however, activation in MOG increased under the tool-selective attention compared with face-selective attention. The different effects might be ascribed to an interaction between top-down category-selective processes and bottom-up processes in the partial awareness level as proposed by Kouider, De Gardelle, Sackur, and Dupoux (2010). Specifically, we suppose an "excessive activation" hypothesis. PMID:23518233

Tu, Shen; Qiu, Jiang; Martens, Ulla; Zhang, Qinglin

2013-03-18

248

Experienced Mindfulness Meditators Exhibit Higher Parietal-Occipital EEG Gamma Activity during NREM Sleep  

PubMed Central

Over the past several years meditation practice has gained increasing attention as a non-pharmacological intervention to provide health related benefits, from promoting general wellness to alleviating the symptoms of a variety of medical conditions. However, the effects of meditation training on brain activity still need to be fully characterized. Sleep provides a unique approach to explore the meditation-related plastic changes in brain function. In this study we performed sleep high-density electroencephalographic (hdEEG) recordings in long-term meditators (LTM) of Buddhist meditation practices (approximately 8700 mean hours of life practice) and meditation naive individuals. We found that LTM had increased parietal-occipital EEG gamma power during NREM sleep. This increase was specific for the gamma range (25–40 Hz), was not related to the level of spontaneous arousal during NREM and was positively correlated with the length of lifetime daily meditation practice. Altogether, these findings indicate that meditation practice produces measurable changes in spontaneous brain activity, and suggest that EEG gamma activity during sleep represents a sensitive measure of the long-lasting, plastic effects of meditative training on brain function.

Ferrarelli, Fabio; Smith, Richard; Dentico, Daniela; Riedner, Brady A.; Zennig, Corinna; Benca, Ruth M.; Lutz, Antoine; Davidson, Richard J.; Tononi, Giulio

2013-01-01

249

Oscillatory Activity in Human Parietal and Occipital Cortex Shows Hemispheric Lateralization and Memory Effects in a Delayed Double-Step Saccade Task  

Microsoft Academic Search

We applied magnetoencephalography (MEG) to record oscillatory brain activity from human subjects engaged in planning a double- step saccade. In the experiments, subjects (n 5 8) remembered the locations of 2 sequentially flashed targets (each followed by a 2-s delay), presented in either the left or right visual hemifield, and then made saccades to the 2 locations in sequence. We

W. Pieter Medendorp; Geerten F. I. Kramer; Ole Jensen; Robert Oostenveld; Jan-Mathijs Schoffelen; P. Fries

2006-01-01

250

Resting-state functional MRI: Functional connectivity analysis of the visual cortex in primary open-angle glaucoma patients.  

PubMed

Purpose: To analyze functional connectivity (FC) of the visual cortex using resting-state functional MRI in human primary open-angle glaucoma (POAG) patients. Materials and Methods: Twenty-two patients with known POAG and 22 age-matched controls were included in this IRB-approved study. Subjects were evaluated by 3 T MR using resting-state blood oxygenation level dependent and three-dimensional brain volume imaging (3D-BRAVO) MRI. Data processing was performed with standard software. FC maps were generated from Brodmann areas (BA) 17/18/19/7 in a voxel-wise fashion. Region of interest analysis was used to specifically examine FC among each pair of BA17/18/19/7. Results: Voxel-wise analyses demonstrated decreased FC in the POAG group between the primary visual cortex (BA17) and the right inferior temporal, left fusiform, left middle occipital, right superior occipital, left postcentral, right precentral gyri, and anterior lobe of the left cerebellum. Increased FC was found between BA17 and the left cerebellum, right middle cerebellar peduncle, right middle frontal gyrus, and extra-nuclear gyrus (P < 0.05). In terms of the higher visual cortices (BA18/19), positive FC was disappeared with the cerebellar vermis, right middle temporal, and right superior temporal gyri (P < 0.05). Negative FC was disappeared between BA18/19 and the right insular gyrus (P < 0.05). Region of interest analysis demonstrated no statistically significant differences in FC between the POAG patients relative to the controls (P > 0.05). Conclusion: Changes in FC of the visual cortex are found in patients with POAG. These include alterations in connectivity between the visual cortex and associative visual areas along with disrupted connectivity between the primary and higher visual areas. Hum Brain Mapp 34:2455-2463, 2013. © 2012 Wiley Periodicals, Inc. PMID:22461380

Dai, Hui; Morelli, John N; Ai, Fei; Yin, Dazhi; Hu, Chunhong; Xu, Dongrong; Li, Yonggang

2012-03-28

251

Chemosensory Learning in the Cortex  

PubMed Central

Taste is a primary reinforcer. Olfactory–taste and visual–taste association learning takes place in the primate including human orbitofrontal cortex to build representations of flavor. Rapid reversal of this learning can occur using a rule-based learning system that can be reset when an expected taste or flavor reward is not obtained, that is by negative reward prediction error, to which a population of neurons in the orbitofrontal cortex responds. The representation in the orbitofrontal cortex but not the primary taste or olfactory cortex is of the reward value of the visual/olfactory/taste input as shown by devaluation experiments in which food is fed to satiety, and by correlations of the activations with subjective pleasantness ratings in humans. Sensory-specific satiety for taste, olfactory, visual, and oral somatosensory inputs produced by feeding a particular food to satiety is implemented it is proposed by medium-term synaptic adaptation in the orbitofrontal cortex. Cognitive factors, including word-level descriptions, modulate the representation of the reward value of food in the orbitofrontal cortex, and this effect is learned it is proposed by associative modification of top-down synapses onto neurons activated by bottom-up taste and olfactory inputs when both are active in the orbitofrontal cortex. A similar associative synaptic learning process is proposed to be part of the mechanism for the top-down attentional control to the reward value vs. the sensory properties such as intensity of taste and olfactory inputs in the orbitofrontal cortex, as part of a biased activation theory of selective attention.

Rolls, Edmund T.

2011-01-01

252

Cortex registration: a geometric approach  

NASA Astrophysics Data System (ADS)

We have devised and implemented a novel method for calculating the high dimensional field relating the brain surfaces (cortex) of an arbitrary pair of subjects. This non-rigid registration method uses crest lines as anatomical landmarks and various geometrical techniques such as geodesic voronoi diagram, barycentric flattening and barycentric coordinates to partition the cortex into meaningful regions and achieve a spatially accurate matching. Finally, the multilevel B-splines method is used to compute a C2 continuous warping field.

Stylianou, Georgios

2005-04-01

253

Binary Coding in Auditory Cortex  

Microsoft Academic Search

Neurons are often assumed to operate in a highly unreliable manner: a neuron can signal the same stimulus with a variable number of action potentials. However, much of the experimental evidence supporting this view was obtained in the visual cortex. We have, therefore, assessed trial-to-trial variability in the auditory cortex of the rat. To ensure single-unit isolation, we used cell-attached

Michael Deweese; Anthony M. Zador

2002-01-01

254

Reading without the left ventral occipito-temporal cortex.  

PubMed

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

2012-09-25

255

Structure of a second crystal form of Bence-Jones protein Loc: Strikingly different domain associations in two crystal forms of a single protein  

SciTech Connect

The authors have determined the structure of the immunoglobulin light-chain dimer Loc in a second crystal form that was grown from distilled water. The crystal structure was determined to 2.8-{angstrom} resolution; the R factor is 0.22. The two variable domains are related by local 2-fold axes and form an antigen binding pocket. The variable domain-variable domain interaction observed in this crystal form differs from the one exhibited by the protein when crystallized from ammonium sulfate in which the two variable domains formed a protrusion. The structure attained in the distilled water crystals is similar to, but not identical with, the one observed for the Mcg light-chain dimer in crystals grown from ammonium sulfate. Thus, two strikingly different structures were attained by this multisubunit protein in crystals grown under two different, commonly used, crystallization techniques. The quaternary interactions exhibited by the protein in the two crystal forms are sufficiently different to suggest fundamentally different interpretations of the structural basis for the function of this protein. This observation may have general implications regarding the use of single crystallographic determinations for detailed identification of structural and functional relationships. On the other hand, proteins whose structures can be altered by manipulation of crystallization conditions may provide useful systems for study of fundamental structural chemistry.

Schiffer, M.; Ainsworth, C.; Xu, Z.B.; Carperos, W.; Olsen, K.; Solomon, A.; Stevens, F.J.; Chang, C.H. (Argonne National Laboratory, IL (USA))

1989-05-02

256

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

257

Learning optimizes decision templates in the human visual cortex.  

PubMed

Translating sensory information into perceptual decisions is a core challenge faced by the brain. This ability is understood to rely on weighting sensory evidence in order to form mental templates of the critical differences between objects. Learning is shown to optimize these templates for efficient task performance [1-4], but the neural mechanisms underlying this improvement remain unknown. Here, we identify the mechanisms that the brain uses to implement templates for perceptual decisions through experience. We trained observers to discriminate visual forms that were randomly perturbed by noise. To characterize the internal stimulus template that observers learn when performing this task, we adopted a classification image approach (e.g., [5-7]) for the analysis of both behavioral and fMRI data. By reverse correlating behavioral and multivoxel pattern responses with noisy stimulus trials, we identified the critical image parts that determine the observers' choice. Observers learned to integrate information across locations and weight the discriminative image parts. Training enhanced shape processing in the lateral occipital area, which was shown to reflect size-invariant representations of informative image parts. Our findings demonstrate that learning optimizes mental templates for perceptual decisions by tuning the representation of informative image parts in higher ventral cortex. PMID:24012311

Kuai, Shu-Guang; Levi, Dennis; Kourtzi, Zoe

2013-09-05

258

Bilateral effects of unilateral visual cortex lesions in human.  

PubMed

We studied the vision of 12 patients with unilateral lesions of the visual cortex. All had a VI-type scotoma located in the contralateral visual fields, as expected, and visual acuity of 20/30 or better. Our aim was to test the hypothesis that they also had a visual deficit in their ipsilesional or 'good' visual fields. The first experiment tested the subjects' ability to respond to transient signals presented at unpredictable temporal intervals and spatial locations amongst many spatially random and identical distracter elements. The results showed that, compared with controls, the lesion group had a significantly reduced sensitivity to signal and increased response times affecting both hemifields. In a second experiment, we tested the useful field of view (UFOV) in two of the patients under conditions of differing attention demand. Both showed bilateral constriction, compatible with the results of the first experiment. One possible explanation for the bilateral effects of unilateral occipital lobe lesions is damage to interhemispheric connections along their presplenial course, affecting the synthesis of visual information from both hemifields (i.e. the interhemispheric diaschisis effects put forth by von Monakow). The trouble is task dependent and can be construed as a global reduction in visual attention capacity. It is subtle in comparison with the contralesional V1-type scotoma that Holmes measured, yet may account for unexplained complaints of reduced performance in some patients, particularly in tasks with high visual information processing demands, such as reading and automobile driving. PMID:8673504

Rizzo, M; Robin, D A

1996-06-01

259

Resolution of life-threatening dysphagia caused by caudal occipital malformation syndrome following foramen magnum decompressive surgery.  

PubMed

A Cavalier King Charles Spaniel was presented with acute onset, life-threatening dysphagia suspected to be secondary to medulla oblongata compression caused by caudal occipital malformation syndrome. The patient required urgent tracheostomy tube placement to remain stable and was subsequently cured of the presenting neurological deficits by foramen magnum decompressive surgery. Neurogenic dysphagia is a relatively common presenting sign in human Chiari malformation syndromes, but has not been described as a major clinical sign in veterinary patients. Caudal occipital malformation syndrome should be included in the differential diagnosis list for susceptible breeds presenting with dysphagia. Early recognition favours expeditious surgical intervention and a positive outcome in human patients, and this may also be the case in veterinary patients. PMID:22827623

Graham, K J; Black, A P; Brain, P H

2012-08-01

260

Osteoradionecrosis of the cervical vertebrae and occipital bone: A case report and brief review of the literature  

Microsoft Academic Search

Osteoradionecrosis (ORN) is a common complication of radiation therapy. We present the first case reported in the literature of ORN involving the first and second cervical vertebrae and occipital bone in a patient who was treated with surgery and radiation therapy 9 years prior for a TxN3M0 squamous cell carcinoma of the left neck arising from an unknown primary origin.

Alan A. Tan Lim; Daniel W. Karakla; Dale V. Watkins

1999-01-01

261

Duraplasty with freeze-dried cadaveric dura versus occipital pericranium for Chiari type I malformation: Comparative study  

Microsoft Academic Search

Summary  During the period from October 1, 1989 to October 1, 1995 a total of 26 cases of Chiari type I malformation not associated\\u000a with syringomyelia were attended in our Hospital. All patients underwent cranio-cervical decompression, with occipital craniectomy\\u000a and removal of the posterior arch of C1. In 3\\/26 (11.5%) cases an additional C2 laminectomy had to be performed and in

V. Vanaclocha; N. Saiz-Sapena

1997-01-01

262

Hepatocellular Carcinoma in an African American Man with a Noncirrhotic Liver Presented Initially as an Occipital Mass  

Microsoft Academic Search

An 88-year-old African American man with no signifi cant medical history was referred to our hospital for evaluation of a rapidly growing, painless right occipital mass associ- ated with severe, progressively worsening headaches that were unresponsive to over-the-counter drugs, ataxic gait, and an unexplained 20-lb weight loss over a period of 2 months. Th e patient had no history of

Maged Khalil; Zili He; Ashraf Aziz; William Steier; Shetra Sivamurthy; Ming Liu

263

Geometry of the articular facets of the lateral atlanto-axial joints in the case of occipitalization.  

PubMed

This study investigates if atlanto-occipital fusion affects the size and geometrical configuration of the articular facets of the atlanto-axial joint. Morphometric analysis was performed on the male adult skull, the occipital bone of which is assimilated with the first cervical vertebrae (the atlas). The perimeter, Feret's diameter, surface area, and circularity of the inferior articular fa-cets were measured. However, we did not observe significant bilateral differences in size of the inferior articular facets of the assimilated atlas compared to normal first cervical vertebrae. Geometrical conformation of the articular facets of the atlas and axis was assessed using a coordinate measuring machine (PMM - 12106, Leitz). The results obtained from this machine indicated that the inferior articular facets of the assimilated atlas presented asymmetrical orientation compared to the normal anatomy of the atlas. Hence, in the case of occipitalization, the gap between the articulating facets of the atlas and the axis was measured to be greater than in the normal atlanto-axial joint. Computer assisted tomography was applied to visualise the anatomical relationship between the inferior articular facets of the assimilated atlas and the corresponding facets located on the axis. In this case, radiographic examination revealed that the bilaterally articulating facets (inferior and superior) showed disproportion in their adjustment within the lateral atlanto-axial joints. Thus, we concluded that the fusion of the atlas with the occipital bone altered the geometry of the inferior articular facets of the atlas and influenced the orientation of the superior articular facets of the axis. PMID:21154284

Ryniewicz, A M; Skrzat, J; Ryniewicz, A; Ryniewicz, W; Walocha, J

2010-08-01

264

Pain Relief after Cervical Ganglionectomy (C2 and C3) for the Treatment of Medically Intractable Occipital Neuralgia  

Microsoft Academic Search

Occipital neuralgia (ON) presents a diagnostic challenge because of the wide variety of symptoms, surgical findings, and postsurgical outcomes. Surgical removal of the second (C2) or third (C3) cervical sensory dorsal root ganglion is an option to treat ON. The goal of this study was to evaluate the short-term and the long-term efficacy of these procedures for management of cervical

Feridun Acar; Jonathan Miller; Kiarash J. Golshani; Zvi H. Israel; Shirley McCartney; Kim J. Burchiel

2008-01-01

265

C1-C2 instability with severe occipital headache in the setting of vertebral artery facet complex erosion.  

PubMed

PURPOSE: An exact understanding of patient vertebral artery anatomy is essential to safely place screws at the atlanto-axial level in posterior arthrodesis. We aim to report a case of erosion of the left vertebral artery into the C1-C2 facet complex with resultant rotatory and lateral listhesis presenting with severe occipital headache. This represents a novel etiology for this diagnosis and our report illustrates technical considerations when instrumenting the C1-C2 segment. METHODS: We report a case of severe occipital headache due to C1-C2 instability with resultant left C2 nerve compression in the setting of erosion of the vertebral artery into the C1-C2 facet complex. RESULTS: A 68-year-old woman presented with a 12-month history of progressively debilitating headache and neck pain with atlanto-axial instability. Computed tomography (CT) angiography demonstrated erosion of the left vertebral artery into the left C1-C2 facet complex. In addition, the tortuous vertebral arteries had eroded into the C2 pedicles, eliminating the possibility for posterior pedicle screw placement. The patient underwent posterior arthrodesis of C1-C2 utilizing bilateral lateral mass fixation into C1 and bilateral trans-laminar fixation into C2 with resolution of all preoperative complaints. CONCLUSIONS: This study constitutes the first report of a tortuous vertebral artery causing the partial destruction of a C1-C2 facet complex, as well as instability, with the clinical presentation of severe occipital headache. It hereby presents a novel etiology for both the development of C1-C2 segment instability as well as the development of occipital headache. Careful evaluation of such lesions utilizing CT angiography is important when formulating a surgical plan. PMID:23616203

Taher, Fadi; Bokums, Kristaps; Aichmair, Alexander; Hughes, Alexander P

2013-04-25

266

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

267

Altered intrinsic neuronal interactions in the visual cortex of the blind.  

PubMed

In congenital blindness, the brain develops under severe sensory deprivation and undergoes remarkable plastic changes in both structure and function. Visually deprived occipital cortical regions are histologically and morphologically altered and exhibit a strikingly remodeled functional state: absolute levels of neural activity are heightened and are modulated by nonvisual sensory stimulation as well as higher cognitive processes. However, the neuronal mechanisms that underlie this altered functional state remain largely unknown. Here, we show that the visual cortex of the congenitally blind exhibits a characteristic gain in frequency-specific intrinsic neuronal interactions. We studied oscillatory activity in 11 congenitally blind humans and matched sighted control subjects with magnetoencephalography at rest. We found increased spontaneous correlations of delta band (1-3 Hz) and gamma band (76-128 Hz) oscillations across the visual cortex of the blind that were functionally coupled. Local delta phase modulated gamma amplitude. Furthermore, classical resting rhythms (8-20 Hz) were reduced in amplitude but showed no altered correlation pattern. Our results suggest that both decreased inhibition and circuit mechanisms that support active processing are intrinsic features underlying the altered functional state of the visual cortex in congenitally blind individuals. PMID:24155311

Hawellek, David J; Schepers, Inga M; Roeder, Brigitte; Engel, Andreas K; Siegel, Markus; Hipp, Joerg F

2013-10-23

268

Anodal Transcranial Direct Current Stimulation Reduces Psychophysically Measured Surround Suppression in the Human Visual Cortex  

PubMed Central

Transcranial direct current stimulation (tDCS) is a safe, non-invasive technique for transiently modulating the balance of excitation and inhibition within the human brain. It has been reported that anodal tDCS can reduce both GABA mediated inhibition and GABA concentration within the human motor cortex. As GABA mediated inhibition is thought to be a key modulator of plasticity within the adult brain, these findings have broad implications for the future use of tDCS. It is important, therefore, to establish whether tDCS can exert similar effects within non-motor brain areas. The aim of this study was to assess whether anodal tDCS could reduce inhibitory interactions within the human visual cortex. Psychophysical measures of surround suppression were used as an index of inhibition within V1. Overlay suppression, which is thought to originate within the lateral geniculate nucleus (LGN), was also measured as a control. Anodal stimulation of the occipital poles significantly reduced psychophysical surround suppression, but had no effect on overlay suppression. This effect was specific to anodal stimulation as cathodal stimulation had no effect on either measure. These psychophysical results provide the first evidence for tDCS-induced reductions of intracortical inhibition within the human visual cortex.

Spiegel, Daniel P.; Hansen, Bruce C.; Byblow, Winston D.; Thompson, Benjamin

2012-01-01

269

The response of face-selective cortex with single face parts and part combinations  

PubMed Central

A critical issue in object recognition research is how the parts of an object are analyzed by the visual system and combined into a perceptual whole. However, most of the previous research has examined how changes to object parts influence recognition of the whole, rather than recognition of the parts themselves. This is particularly true of the research on face recognition, and especially with questions related to the neural substrates. Here, we investigated patterns of BOLD fMRI brain activation with internal face parts (features) presented singly and in different combinations. A preference for single features over combinations was found in the occipital face area (OFA) as well as a preference for the two-eyes combination stimulus over other combination stimulus types. The fusiform face area (FFA) and lateral occipital cortex (LO) showed no preferences among the single feature and combination stimulus types. The results are consistent with a growing view that the OFA represents processes involved in early, feature-based analysis.

Dachille, Lindsay R.; Gold, Jason M.; James, Thomas W.

2012-01-01

270

Altered dynamic coupling of lateral occipital complex during visual perception in schizophrenia  

PubMed Central

Introduction There is mounting evidence that visual perception abnormalities in schizophrenia are partly explained by a dysfunction of the lateral occipital complex (LO). We previously demonstrated that schizophrenia patients had broader topography and reduced magnitude of activity of LO. However, the functional connectivity of LO with other brain regions during visual perception has not been directly investigated in schizophrenia. Material and Methods Eighteen patients with schizophrenia and eighteen matched controls performed a backward masking task during functional magnetic resonance imaging (fMRI). Stimulus onset asynchronies were manipulated to change the level of target visibility. To examine connectivity with LO function we conducted psychophysiological interactions (PPI) analyses using: 1) a region of interest (ROI) approach and 2) a whole brain analysis. ROIs were defined based on a contrast of trials on which a target was presented versus null trials in which no stimuli were presented. Results Eleven ROIs were identified. Both groups showed similar strength of coupling between LO and the 11 ROIs when visibility was not taken into account. Healthy controls showed clear changes in coupling between LO and prefrontal and parietal regions as a function of target visibility (higher coupling with more visible targets). In comparison, patients showed reduced dynamic coupling with LO in the right superior frontal gyrus (significant after correcting for multiple comparisons) and a trend for reduced coupling in the left precuneus and left inferior frontal regions. Whole brain analysis identified additional regions that showed dynamic coupling with LO in healthy controls, but not in patients. Discussion The increased coupling between LO and higher-level parietal and prefrontal regions during visual awareness in healthy controls likely reflects visual reentrant processing. The lack of modulation of coupling between LO and key prefrontal and parietal regions found in schizophrenia may partly reflect abnormalities in LO tuning. The altered LO coupling may contribute to visual perception abnormalities in schizophrenia.

Harvey, Philippe-Olivier; Lee, Junghee; Cohen, Mark S.; Engel, Stephen A.; Glahn, David C.; Nuechterlein, Keith H.; Wynn, Jonathan K.; Green, Michael F.

2011-01-01

271

[Merosin-positive congenital muscular dystrophy, white matter abnormalities, and bilateral posterior occipital cortical dysplasia].  

PubMed

Congenital muscular dystrophy (CMD) is one of the most frequent dystrophies of childhood, which is commonly characterized by neonatal muscle impairment with or without clinical evidence of central nervous system involvement. CMDs were classified into five clinically distinct forms: the two classical CMDs with and without deficit of the a2 laminin chain (merosin) caused by mutations on chromosome 6q2, the Fukuyama CMD (severe form, initially described in Japanese patients and recently linked to the chromosome 9q31-33), Walker-Warburg syndrome and the muscle-eye-brain disease described in Finnish patients. The majority of these forms have severe clinical and imagiological involvement of SNC. This aspect is rarely observed on classical CMD, particularly in the merosin-positive form. We describe a case of a 28 year-old woman, with clinical and histopathological signs of classical CMD merosin-positive (no deficient), without mental retardation, but with epilepsy. MRI T2 weighted images, revealed diffuse and symetrical high signal white matter of both cerebral hemispheres, affecting corpos calosum, posterior arms of internal capsules and the piramidal tract to mesencephalon. It also disclosed diffuse and symetrical high signal of basal ganglia, specially, the head of caudate nuclei. These were associated with bilateral occipital posterior cortical dysplasia. The observed imagiological pattern could represent a new subtype of CMD, hybrid between classical CMD and the severe forms, however it is not clear where it fits in the spectrum. This case denotes the possible envolvement of SNC in patients merosin-positives. Based on this findings we suggest doing MRI scans to all patients with CMD no deficient in merosin. PMID:12868400

Ribeiro, Valentina T; Moreira, Nuno Canto; Teixeira, João; Guimarães, António; Cruz, Romeu; Lima, Lopes

272

Linkage to chromosome 2q36.1 in autosomal dominant Dandy-Walker malformation with occipital cephalocele and evidence for genetic heterogeneity  

Microsoft Academic Search

We previously reported a Vietnamese-American family with isolated autosomal dominant occipital cephalocele. Upon further neuroimaging\\u000a studies, we have recharacterized this condition as autosomal dominant Dandy-Walker with occipital cephalocele (ADDWOC). A\\u000a similar ADDWOC family from Brazil was also recently described. To determine the genetic etiology of ADDWOC, we performed genome-wide\\u000a linkage analysis on members of the Vietnamese-American and Brazilian pedigrees. Linkage

Ali Jalali; Kimberly A. Aldinger; Ajit Chary; David G. Mclone; Robin M. Bowman; Luan Cong Le; Phillip Jardine; Ruth Newbury-Ecob; Andrew Mallick; Nadereh Jafari; Eric J. Russell; John Curran; Pam Nguyen; Karim Ouahchi; Charles Lee; William B. Dobyns; Kathleen J. Millen; Joao M. Pina-Neto; John A. Kessler; Alexander G. Bassuk

2008-01-01

273

Differential effects of low-frequency rTMS at the occipital pole on visual-induced alpha desynchronization and visual-evoked potentials  

Microsoft Academic Search

Visual-induced alpha desynchronization (VID) and visual-evoked potentials (VEPs) characterize occipital activation in response to visual stimulation but their exact relationship is unclear. Here, we tested the hypothesis that VID and VEPs reflect different aspects of cortical activation. For this purpose, we determined whether VID and VEPs are differentially modulated by low-frequency repetitive transcranial magnetic stimulation (rTMS) over the occipital pole.

G. Thut; H. Theoret; A. Pfennig; J. Ives; F. Kampmann; G. Northoff; A Pascual-Leone

2003-01-01

274

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

2013-04-11

275

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

276

Adaptive Information Processing in Auditory Cortex.  

National Technical Information Service (NTIS)

The fact that learning induces frequency-specific modification of receptive fields in auditory cortex implies that the functional organization of auditory (and perhaps other sensory) cortex comprises an adaptively-constituted information base. This projec...

N. M. Weinberger

1988-01-01

277

Isomer separation of LOC=  

Microsoft Academic Search

Radioactive copper isotopes were ionized with the resonance ionization laser ion source (RILIS) at the on-line isotope separator ISOLDE (CERN). Using the different hyperfine structure in the 3d104s 2S1\\/2 - 3d104p 2P01\\/2 transition the low- and high-spin isomers of 70Cu were selectively enhanced by tuning the laser wavelength. The light was provided by a narrow-bandwidth dye laser pumped by copper

U. Köster; V. N. Fedoseyev; V. I. Mishin; L. Weissman; M. Huyse; K. Kruglov; W. F. Mueller; P. Van Duppen; J. Van Roosbroeck; P. Thirolf; H. G. Thomas; D. Weisshaar; W. Schulze; R. Borcea; M. La Commara; H. Schatz; K. Schmidt; S. Röttger; G. Huber; V. Sebastian; K. L. Kratz; R. Catherall; U. Georg; J. Lettry; M. Oinonen; H. L. Ravn; H. Simon

2000-01-01

278

Excitations of liquid LOC=  

Microsoft Academic Search

We report on neutron inelastic scattering measurements of the elementary excitations in liquid 4He in porous aerogel and Vycor glass. The measured dynamical structure factor is very similar to bulk 4He, with a similar temperature dependence. The small changes in the energy and width of the phonon-roton excitations and their temperature dependences reported earlier in aerogel are critically examined and

B. Fåk; O. Plantevin; H. R. Glyde

2000-01-01

279

The adrenal cortex and life  

Microsoft Academic Search

The template for our understanding of the physiological role of the adrenal cortex was set by Hans Selye, who demonstrated its key involvement in the response to stress, of whatever origin, and who also introduced the terms glucocorticoid and mineralocorticoid. Despite this, from the late 1940s on there was certainly general awareness of the multiple actions of glucocorticoids, including effects

Gavin P. Vinson

2009-01-01

280

Acquired Chiari malformation secondary to atlantoaxial vertical subluxation in a patient with rheumatoid arthritis combined with atlanto-occipital assimilation.  

PubMed

A 65-year-old woman with a history of rheumatoid arthritis presented with a rare case of acquired Chiari malformation secondary to atlantoaxial vertical subluxation, associated with congenital atlanto-occipital assimilation. Syringomyelia and tetraparesis improved immediately after posterior fossa decompression and simultaneous occipito-cervical junction fusion. The progression of acquired Chiari malformation is not well known. We concluded that coexisting assimilation accelerated crowded foramen magnum following atlantoaxial vertical subluxation and induced acquired Chiari malformation over the course of a few years. PMID:23006887

Kimura, Yuiko; Seichi, Atsushi; Gomi, Akira; Kojima, Masahiro; Inoue, Hirokazu; Kimura, Atsushi

2012-01-01

281

Retrospective review of MEG visual evoked hemifield responses prior to resection of temporo-parieto-occipital lesions.  

PubMed

Visual evoked cortical magnetic field (VEF) waveforms were recorded from both hemifields in 21 patients with temporo-parieto-occipital mass lesions to identify preserved visual pathways. Fifteen patients had visual symptoms pre-operatively. Magnetoencephalographic (MEG) VEF responses were detected, using single equivalent current dipole (ECD), in 17/21 patients studied. Displaced or abnormal responses were seen in 15 patients with disruption of pathway in one patient. Three of 21 patients had alterations in the surgical approach or the planned resection based on the MEG findings. The surgical outcome for these three patients suggests that the MEG study may have played a useful role in pre-surgical planning. PMID:16292486

Grover, K M; Bowyer, S M; Rock, J; Rosenblum, M L; Mason, K M; Moran, J E; Smith, B J; Barkley, G L

2006-04-01

282

Herpes simplex encephalitis with occipital localization in an infant: a different route of entry in the brain system?  

PubMed

Herpes simplex encephalitis classically involves the periventricular white matter in infants and the mesial temporal lobes, inferior frontal lobes, and insula in older children and adults. However, the increasing use of polymerase chain reaction to detect viral DNA in the cerebrospinal fluid has allowed the expansion of the spectrum of radiologic findings possibly associated with herpes simplex encephalitis. This study presents a rare case of a previously healthy infant with herpes simplex encephalitis with occipital involvement and permanent visual impairment. Possible pathogenic mechanisms are discussed. PMID:23668872

Venturini, Elisabetta; Chiappini, Elena; Fonda, Claudio; Galli, Luisa; de Martino, Maurizio

2013-06-01

283

Spatial working memory in human extrastriate cortex  

Microsoft Academic Search

The performance of spatial working memory tasks is known to evoke activity in a set of higher-order association areas, including the prefrontal cortex, posterior parietal cortex and the frontal and supplementary eye fields. Recent physiological studies in monkey have shown that memory-related activity also is found in extrastriate cortex [J. Neurophysiol. 84 (2000) 677]. We conducted functional magnetic resonance imaging

Rebecca A. Berman; Carol L. Colby

2002-01-01

284

Proton T1 relaxation times of metabolites in human occipital white and gray matter at 7 T.  

PubMed

Proton T1 relaxation times of metabolites in the human brain have not previously been published at 7 T. In this study, T1 values of CH3 and CH2 group of N-acetylaspartate and total creatine as well as nine other brain metabolites were measured in occipital white matter and gray matter at 7 T using an inversion-recovery technique combined with a newly implemented semi-adiabatic spin-echo full-intensity acquired localized spectroscopy sequence (echo time = 12 ms). The mean T1 values of metabolites in occipital white matter and gray matter ranged from 0.9 to 2.2 s. Among them, the T1 of glutathione, scyllo-inositol, taurine, phosphorylethanolamine, and N-acetylaspartylglutamate were determined for the first time in the human brain. Significant differences in T1 between white matter and gray matter were found for water (-28%), total choline (-14%), N-acetylaspartylglutamate (-29%), N-acetylaspartate (+4%), and glutamate (+8%). An increasing trend in T1 was observed when compared with previously reported values of N-acetylaspartate (CH3 ), total creatine (CH3 ), and total choline at 3 T. However, for N-acetylaspartate (CH3 ), total creatine, and total choline, no substantial differences compared to previously reported values at 9.4 T were discernible. The T1 values reported here will be useful for the quantification of metabolites and signal-to-noise optimization in human brain at 7 T. PMID:22648904

Xin, Lijing; Schaller, Benoît; Mlynarik, Vladimir; Lu, Huanxiang; Gruetter, Rolf

2012-05-30

285

Modified wound dissection preserving the greater occipital nerve in foramen magnum decompression: a technique to reduce postoperative pain.  

PubMed

Patients undergoing foramen magnum decompression for Chiari malformation may experience severe postoperative pain in the area innervated by the greater occipital nerve (GON). We developed a modified dissection to lessen this pain. A midline skin incision was extended 2?cm in a cephalad direction to the inion and the skin was minimally retracted. After exposing the occipital bone, the semispinalis capitis and the trapezius muscles were detached subperiosteally in a caudal-to-cephalad direction. Consequently, the muscles and skin containing the GON were retracted in a single layer. We retrospectively compared the intensity of postoperative pain recorded on the visual analogue scale (VAS) by patients who underwent decompression using our (group A, n?=?5) and the conventional layer-by-layer dissection technique (group B, n?=?5). The VAS scores were not different on the day of surgery, but subsequently they fell faster in group A. Group A patients received a mild analgesic for a short period. Group B patients required a stronger analgesic for prolonged periods. Postoperative GON numbness/tenderness was observed only in group B. With respect to most evaluation criteria, the difference between the two groups was significant. Our anatomically rational dissection that protects the GON results in less postoperative pain. PMID:23904996

Shimizu, Satoru; Yamazaki, Tomoya; Kondo, Koji; Utsuki, Satoshi; Oka, Hidehiro; Nakayama, Kenji; Yamamoto, Isao; Fujii, Kiyotaka

2012-08-01

286

Modified Wound Dissection Preserving the Greater Occipital Nerve in Foramen Magnum Decompression: A Technique to Reduce Postoperative Pain  

PubMed Central

Patients undergoing foramen magnum decompression for Chiari malformation may experience severe postoperative pain in the area innervated by the greater occipital nerve (GON). We developed a modified dissection to lessen this pain. A midline skin incision was extended 2?cm in a cephalad direction to the inion and the skin was minimally retracted. After exposing the occipital bone, the semispinalis capitis and the trapezius muscles were detached subperiosteally in a caudal-to-cephalad direction. Consequently, the muscles and skin containing the GON were retracted in a single layer. We retrospectively compared the intensity of postoperative pain recorded on the visual analogue scale (VAS) by patients who underwent decompression using our (group A, n?=?5) and the conventional layer-by-layer dissection technique (group B, n?=?5). The VAS scores were not different on the day of surgery, but subsequently they fell faster in group A. Group A patients received a mild analgesic for a short period. Group B patients required a stronger analgesic for prolonged periods. Postoperative GON numbness/tenderness was observed only in group B. With respect to most evaluation criteria, the difference between the two groups was significant. Our anatomically rational dissection that protects the GON results in less postoperative pain.

Shimizu, Satoru; Yamazaki, Tomoya; Kondo, Koji; Utsuki, Satoshi; Oka, Hidehiro; Nakayama, Kenji; Yamamoto, Isao; Fujii, Kiyotaka

2012-01-01

287

LAMA2 stop-codon mutation: merosin-deficient congenital muscular dystrophy with occipital polymicrogyria, epilepsy and psychomotor regression.  

PubMed

Merosin-deficient congenital muscular dystrophy (MD) type 1A (MDC1A) is one of the most frequent forms of CMD in Western countries. The classical form, characterized by a total lack of laminin alpha2 chain expression, usually shows severe clinical features; cases with complete laminin alpha2 deficiency and mild phenotype have also been reported, although the mechanisms underlying the lack of genotype-phenotype correlation have not been elucidated. Epilepsy and focal cortical dysplasia-in addition to the classical diffuse white matter abnormalities-have been described in some of these patients associated with cognitive deterioration. We report on a patient with total laminin alpha2 deficiency due to a homozygous stop-codon mutation in the LAMA2 gene, with mild evolution. When 6.9 years old, she developed focal occipital seizures and absence-like status when awake, with probable relation to an extensive bilateral occipital micropolygyria. Soon afterwards she lost ambulation and developed cognitive deterioration. Our case confirms that the clinical spectrum of MDC1A is more heterogeneous than previously thought. PMID:18406646

Vigliano, Piernanda; Dassi, Patrizia; Di Blasi, Claudia; Mora, Marina; Jarre, Laura

2008-04-11

288

Normal variation in fronto-occipital circuitry and cerebellar structure with an autism-associated polymorphism of CNTNAP2  

PubMed Central

Recent genetic studies have implicated a number of candidate genes in the pathogenesis of Autism Spectrum Disorder (ASD). Polymorphisms of CNTNAP2 (contactin-associated like protein-2), a member of the neurexin family, have already been implicated as a susceptibility gene for autism by at least 3 separate studies. We investigated variation in white and grey matter morphology using structural MRI and diffusion tensor imaging. We compared volumetric differences in white and grey matter and fractional anisotropy values in control subjects characterised by genotype at rs7794745, a single nucleotide polymorphism in CNTNAP2. Homozygotes for the risk allele showed significant reductions in grey and white matter volume and fractional anisotropy in several regions that have already been implicated in ASD, including the cerebellum, fusiform gyrus, occipital and frontal cortices. Male homozygotes for the risk alleles showed greater reductions in grey matter in the right frontal pole and in FA in the right rostral fronto-occipital fasciculus compared to their female counterparts who showed greater reductions in FA of the anterior thalamic radiation. Thus a risk allele for autism results in significant cerebral morphological variation, despite the absence of overt symptoms or behavioural abnormalities. The results are consistent with accumulating evidence of CNTNAP2's function in neuronal development. The finding suggests the possibility that the heterogeneous manifestations of ASD can be aetiologically characterised into distinct subtypes through genetic-morphological analysis.

Tan, Geoffrey C.Y.; Doke, Thomas F.; Ashburner, John; Wood, Nicholas W.; Frackowiak, Richard S.J.

2010-01-01

289

Effect of Prenatal Protein Malnutrition on Long-Term Potentiation and BDNF Protein Expression in the Rat Entorhinal Cortex after Neocortical and Hippocampal Tetanization  

PubMed Central

Reduction of the protein content from 25 to 8% casein in the diet of pregnant rats results in impaired neocortical long-term potentiation (LTP) of the offspring together with lower visuospatial memory performance. The present study was aimed to investigate whether this type of maternal malnutrition could result in modification of plastic capabilities of the entorhinal cortex (EC) in the adult progeny. Unlike normal eutrophic controls, 55–60-day-old prenatally malnourished rats were unable to develop LTP in the medial EC to tetanizing stimulation delivered to either the ipsilateral occipital cortex or the CA1 hippocampal region. Tetanizing stimulation of CA1 also failed to increase the concentration of brain-derived neurotrophic factor (BDNF) in the EC of malnourished rats. Impaired capacity of the EC of prenatally malnourished rats to develop LTP and to increase BDNF levels during adulthood may be an important factor contributing to deficits in learning performance having adult prenatally malnourished animals.

Hernandez, Alejandro; Burgos, Hector; Mondaca, Mauricio; Barra, Rafael; Nunez, Hector; Perez, Hernan; Soto-Moyano, Ruben; Sierralta, Walter; Fernandez, Victor; Olivares, Ricardo; Valladares, Luis

2008-01-01

290

Insular cortex epilepsy: an overview.  

PubMed

In this review the authors discuss insular cortex epilepsy, an under-recognized localization-related syndrome that may explain some temporal (but also frontal and parietal lobe) epilepsy surgery failures. The insula may generate a variety of symptoms (including visceral, motor and somatosensory) that mimic temporal, frontal or parietal lobe onset seizures. Intracerebral electrodes directly implanted in the insula are currently the only way to confirm insular seizures. Consideration should be given to exploration of the insular cortex in MRI negative patients with seizure semiology consistent with insular onset seizures. Electroencephalographers should have a low threshold to sample this region, especially in the absence of a structural lesion. Microneurosurgical technical advances allow resective surgery of the insula with relatively low morbidity. PMID:19760905

Nguyen, Dang Khoa; Nguyen, Dong Bach; Malak, Ramez; Bouthillier, Alain

2009-08-01

291

The prefrontal cortex in sleep  

Microsoft Academic Search

Experimental data indicate a role for the prefrontal cortex in mediating normal sleep physiology, dreaming and sleep-deprivation phenomena. During nonrandom-eye-movement (NREM) sleep, frontal cortical activity is characterized by the highest voltage and the slowest brain waves compared to other cortical regions. The differences between the self-awareness experienced in waking and its diminution in dreaming can be explained by deactivation of

Amir Muzur; Edward F. Pace-Schott; J. Allan Hobson

2002-01-01

292

Effect of transcranial magnetic stimulation on single-unit activity in the cat primary visual cortex  

PubMed Central

Transcranial magnetic stimulation (TMS) has become a well established procedure for testing and modulating the neuronal excitability of human brain areas, but relatively little is known about the cellular processes induced by this rather coarse stimulus. In a first attempt, we performed extracellular single-unit recordings in the primary visual cortex (area 17) of the anaesthetised and paralysed cat, with the stimulating magnetic field centred at the recording site (2 × 70 mm figure-of-eight coil). The effect of single biphasic TMS pulses, which induce a lateral-to-medial electric current within the occipital pole of the right hemisphere, was tested for spontaneous as well as visually evoked activity. For cat visual cortex we found that a single TMS pulse elicited distinct episodes of enhanced and suppressed activity: in general, a facilitation of activity was found during the first 500 ms, followed thereafter by a suppression of activity lasting up to a few seconds. Strong stimuli exceeding 50 % of maximal stimulator output could also lead to an early suppression of activity during the first 100–200 ms, followed by stronger (rebound) facilitation. Early suppression and facilitation of activity may be related to a more or less direct stimulation of inhibitory and excitatory interneurons, probably with different thresholds. The late, long-lasting suppression is more likely to be related to metabotropic or metabolic processes, or even vascular responses. The time course of facilitation/inhibition may provide clues regarding the action of repetitive TMS application.

Moliadze, Vera; Zhao, Yongqiang; Eysel, Ulf; Funke, Klaus

2003-01-01

293

Surround suppression in the human visual cortex: an analysis using magnetoencephalography.  

PubMed

The responses of neurons in the primate and cat primary visual cortices (V1s) to the stimuli within their classical receptive fields (CRFs) are markedly suppressed by the surrounding stimuli outside CRFs. In the present study, we show that a similar suppressive effect occurs for visually evoked magnetic responses in the human visual cortex. The initial peak amplitude of the magnetic response (at a latency of around 90 ms) to a test grating accompanied by high-contrast surround gratings was smaller than that for the test without the surround. Current source localization with a single dipole model indicated that the initial response originated from cortical activity near the occipital pole in the contralateral hemisphere to the visual stimulation. The peak amplitude for the test decreased with increasing surround contrast, and increased with increasing test contrast. The contrast dependence and the early development of the surround suppression were in agreement with the results of the V1 single-cell studies of monkeys and cats. We suggest that the surround suppression of the initial peak amplitude of the magnetic response may be ascribed to the inhibition of the neural activity at the early processing stage(s), presumably at V1, in the human visual cortex. PMID:12128013

Ohtani, Yoshio; Okamura, Shoichi; Yoshida, Yoshikazu; Toyama, Keisuke; Ejima, Yoshimichi

2002-07-01

294

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

2012-04-17

295

The contributions of sensory dominance and attentional bias to cross-modal enhancement of visual cortex excitability.  

PubMed

Approaching or looming sounds (L-sounds) have been shown to selectively increase visual cortex excitability [Romei, V., Murray, M. M., Cappe, C., & Thut, G. Preperceptual and stimulus-selective enhancement of low-level human visual cortex excitability by sounds. Current Biology, 19, 1799-1805, 2009]. These cross-modal effects start at an early, preperceptual stage of sound processing and persist with increasing sound duration. Here, we identified individual factors contributing to cross-modal effects on visual cortex excitability and studied the persistence of effects after sound offset. To this end, we probed the impact of different L-sound velocities on phosphene perception postsound as a function of individual auditory versus visual preference/dominance using single-pulse TMS over the occipital pole. We found that the boosting of phosphene perception by L-sounds continued for several tens of milliseconds after the end of the L-sound and was temporally sensitive to different L-sound profiles (velocities). In addition, we found that this depended on an individual's preferred sensory modality (auditory vs. visual) as determined through a divided attention task (attentional preference), but not on their simple threshold detection level per sensory modality. Whereas individuals with "visual preference" showed enhanced phosphene perception irrespective of L-sound velocity, those with "auditory preference" showed differential peaks in phosphene perception whose delays after sound-offset followed the different L-sound velocity profiles. These novel findings suggest that looming signals modulate visual cortex excitability beyond sound duration possibly to support prompt identification and reaction to potentially dangerous approaching objects. The observed interindividual differences favor the idea that unlike early effects this late L-sound impact on visual cortex excitability is influenced by cross-modal attentional mechanisms rather than low-level sensory processes. PMID:23384192

Romei, Vincenzo; Murray, Micah M; Cappe, Céline; Thut, Gregor

2013-02-05

296

Reduced Activity of Protein Kinase C in the Frontal Cortex of Subjects with Regressive Autism: Relationship with Developmental Abnormalities  

PubMed Central

Autism is a neurodevelopmental disorder with unknown etiology. In some cases, typically developing children regress into clinical symptoms of autism, a condition known as regressive autism. Protein kinases are essential for G-protein-coupled receptor-mediated signal transduction, and are involved in neuronal functions, gene expression, memory, and cell differentiation. Recently, we reported decreased activity of protein kinase A (PKA) in the frontal cortex of subjects with regressive autism. In the present study, we analyzed the activity of protein kinase C (PKC) in the cerebellum and different regions of cerebral cortex from subjects with regressive autism, autistic subjects without clinical history of regression, and age-matched control subjects. In the frontal cortex of subjects with regressive autism, PKC activity was significantly decreased by 57.1% as compared to age-matched control subjects (p = 0.0085), and by 65.8% as compared to non-regressed autistic subjects (p = 0.0048). PKC activity was unaffected in the temporal, parietal and occipital cortices, and in the cerebellum in both autism groups, i.e., regressive and non-regressed autism as compared to control subjects. These results suggest brain region-specific alteration of PKC activity in the frontal cortex of subjects with regressive autism. Further studies showed a negative correlation between PKC activity and restrictive, repetitive and stereotyped pattern of behavior (r= -0.084, p = 0.0363) in autistic individuals, suggesting involvement of PKC in behavioral abnormalities in autism. These findings suggest that regression in autism may be attributed, in part, to alterations in G-protein-coupled receptor-mediated signal transduction involving PKA and PKC in the frontal cortex.

Ji, Lina; Chauhan, Abha; Chauhan, Ved

2012-01-01

297

Cortical connectivity suggests a role in limb coordination for macaque area PE of the superior parietal cortex.  

PubMed

In macaques, superior parietal lobule area 5 has been described as occupying an extensive region, which includes the caudal half of the postcentral convexity as well as the medial bank of the intraparietal sulcus. Modern neuroanatomical methods have allowed the identification of various areas within this region. In the present study, we investigated the corticocortical afferent projections of one of these subdivisions, area PE. Our results demonstrate that PE, defined as a single architectonic area that contains a topographic map of the body, forms specific connections with somatic and motor fields. Thus, PE receives major afferents from parietal areas, mainly area 2, PEc, several areas in the medial bank of the intraparietal sulcus, opercular areas PGop/PFop, and the retroinsular area, frontal afferents from the primary motor cortex, the supplementary motor area, and the caudal subdivision of dorsal premotor cortex, as well as afferents from cingulate areas PEci, 23, and 24. The presence and relative strength of these connections depend on the location of injection sites, so that lateral PE receives preferential input from anterior sectors of the medial bank of intraparietal sulcus and from the ventral premotor cortex, whereas medial PE forms denser connections with area PEc and motor fields. In contrast with other posterior parietal areas, there are no projections to PE from occipital or prefrontal cortices. Overall, the sensory and motor afferents to PE are consistent with functions in goal-directed movement but also hint at a wider variety of motor coordination roles. PMID:23575861

Bakola, Sophia; Passarelli, Lauretta; Gamberini, Michela; Fattori, Patrizia; Galletti, Claudio

2013-04-10

298

Evidence of Ferrichromite of Extraterrestrial Origin by Means of Rock Magnetic Studies from the LOC-9 Drill Core (lockne Crater, Sweden)  

NASA Astrophysics Data System (ADS)

The Lockne (456 Ma) marine-target impact structure is a concentric with a 7.5 km wide inner crater in the crystalline basement, and an up to 3.5 km wide brim where the sedimentary target succession is partially or completely removed. Much of the crater is covered by sediments deposited during the resurge of seawater, as well as by secular sediments. The LOC-9 core is 31.04m long and was drilled into the crystalline crater brim and the proximal ejecta flap of the inner crater. The ejecta flap at this location is mainly brecciated basalt with some blending of dark shale just at the contact with the more intact granitic basement. Published studies of the resurge deposits by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) show the presence of ferrichromite particles interpreted to be meteoritic material. Here we combine complete rock magnetic characterization of the magnetic signal along the core with the characterization of the ferrichromite phase. Rock magnetic analysis includes low-field magnetic susceptibility, hysteresis loops, isothermal remanent magnetization (IRM) acquisition curves, coercivity spectra derived from IRM acquisition curves, back field IRM demagnetization curves and thermomagnetic curves. Additionally, a compositional analysis of a magnetic extract with SEM-EDX was done in order to identify the dominant magnetic fraction. Magnetite and titanomagnetite with different Ti content are identified as the main carriers of the magnetic signal along the core, based on the thermomagnetic curves, the saturation magnetization measured in the hysteresis loops, and the IRM acquisition curves. Pyrite is indicated by the thermomagnetic curve at one location in the core. A high coercivity phase is also observed in some samples. The coercivity spectral analysis shows one single population of magnetic minerals that dominates the magnetic signal at a level where the magnetic susceptibility is particularly high. The median destructive field is consistent with values reported at positions in the core with lower susceptibility and the dispersion parameter is well constrained with average values suggesting no significant diagenesis. The level immediately above the brecciated basement is composed of a relatively high amount of target material. At this depth, thermomagnetic curves reveal the presence of a magnetic phase with low Curie unblocking temperature (˜ 100 °C). No evidence of transformation of goethite into hematite is noted, which suggests the ferrichromite to be of extraterrestrial origin. This exotic phase is characterized by rock magnetic parameters derived from thermomagnetic curves, IRM acquisition curves, and hysteresis loops. The estimated Curie temperature is also consistent with a 50% content Cr, as reported by previous SEM studies of material from the Lockne crater. We conclude that rock magnetic studies complement other methods in the detection of potential extraterrestrial component in impactites.

Melero Asensio, I.; Martin Hernandez, F.; Örmo, J.; Guerrero-Suarez, S.

2011-12-01

299

Portraits or people? Distinct representations of face identity in the human visual cortex.  

PubMed

Humans can identify individual faces under different viewpoints, even after a single encounter. We determined brain regions responsible for processing face identity across view changes after variable delays with several intervening stimuli, using event-related functional magnetic resonance imaging during a long-term repetition priming paradigm. Unfamiliar faces were presented sequentially either in a frontal or three-quarter view. Each face identity was repeated once after an unpredictable lag, with either the same or another viewpoint. Behavioral data showed significant priming in response time, irrespective of view changes. Brain imaging results revealed a reduced response in the lateral occipital and fusiform cortex with face repetition. Bilateral face-selective fusiform areas showed view-sensitive repetition effects, generalizing only from three-quarter to front-views. More medial regions in the left (but not in the right) fusiform showed repetition effects across all types of viewpoint changes. These results reveal that distinct regions within the fusiform cortex hold view-sensitive or view-invariant traces of novel faces, and that face identity is represented in a view-sensitive manner in the functionally defined face-selective areas of both hemispheres. In addition, our finding of a better generalization after exposure to a 3/4-view than to a front-view demonstrates for the first time a neural substrate in the fusiform cortex for the common recognition advantage of three-quarter faces. This pattern provides new insights into the nature of face representation in the human visual system. PMID:16102236

Pourtois, Gilles; Schwartz, Sophie; Seghier, Mohamed L; Lazeyras, François; Vuilleumier, Patrik

2005-07-01

300

Abnormal Anatomical Connectivity between the Amygdala and Orbitofrontal Cortex in Conduct Disorder  

PubMed Central

Objective Previous research suggested that structural and functional abnormalities within the amygdala and orbitofrontal cortex contribute to the pathophysiology of Conduct Disorder (CD). Here, we investigated whether the integrity of the white-matter pathways connecting these regions is abnormal and thus may represent a putative neurobiological marker for CD. Methods Diffusion Tensor Imaging (DTI) was used to investigate white-matter microstructural integrity in male adolescents with childhood-onset CD, compared with healthy controls matched in age, sex, intelligence, and socioeconomic status. Two approaches were employed to analyze DTI data: voxel-based morphometry of fractional anisotropy (FA), an index of white-matter integrity, and virtual dissection of white-matter pathways using tractography. Results Adolescents with CD displayed higher FA within the right external capsule relative to controls (T?=?6.08, P<0.05, Family-Wise Error, whole-brain correction). Tractography analyses showed that FA values within the uncinate fascicle (connecting the amygdala and orbitofrontal cortex) were abnormally increased in individuals with CD relative to controls. This was in contrast with the inferior frontal-occipital fascicle, which showed no significant group differences in FA. The finding of increased FA in the uncinate fascicle remained significant when factoring out the contribution of attention-deficit/hyperactivity disorder symptoms. There were no group differences in the number of streamlines in either of these anatomical tracts. Conclusions These results provide evidence that CD is associated with white-matter microstructural abnormalities in the anatomical tract that connects the amygdala and orbitofrontal cortex, the uncinate fascicle. These results implicate abnormal maturation of white-matter pathways which are fundamental in the regulation of emotional behavior in CD.

Passamonti, Luca; Fairchild, Graeme; Fornito, Alex; Goodyer, Ian M.; Nimmo-Smith, Ian; Hagan, Cindy C.; Calder, Andrew J.

2012-01-01

301

13C MRS of occipital and frontal lobes at 3 T using a volume coil for stochastic proton decoupling  

PubMed Central

Previously, we devised a novel strategy for in vivo 13C MRS using [2-13C]glucose infusion and low-power proton decoupling, and proposed that this strategy could be used to acquire 13C MR spectra from the frontal lobe of the human brain. Here, we demonstrate, for the first time, in vivo 13C MRS of human frontal lobe acquired at 3 T. Because the primary metabolites of [2-13C]glucose can be decoupled using very-low-radiofrequency power, we used a volume coil for proton decoupling in this study. The homogeneous B1 field of the volume coil was found to significantly enhance the decoupling efficiency of the stochastic decoupling sequence. Detailed specific absorption rates inside the human head were analyzed using the finite difference time domain method to ensure experimental safety. In vivo 13C spectra from the occipital and frontal lobes of the human brain were obtained. At a decoupling power of 30 W (time-averaged power, 2.45 W), the spectra from the occipital lobe showed well-resolved spectral resolution and excellent signal-to-noise ratio. Although frontal lobe 13C spectra were affected by local B0 field inhomogeneity, we demonstrated that the spectral quality could be improved using post-acquisition data processing. In particular, we showed that the frontal lobe glutamine C5 at 178.5 ppm and aspartate C4 at 178.3 ppm could be spectrally resolved with effective proton decoupling and B0 field correction. Because of its large spatial coverage, volume coil decoupling provides the potential to acquire 13C MRS from more than one brain region simultaneously.

Li, Shizhe; Zhang, Yan; Wang, Shumin; Araneta, Maria Ferraris; Johnson, Christopher S.; Xiang, Yun; Innis, Robert B.; Shen, Jun

2011-01-01

302

Multi-voxel pattern analysis of selective representation of visual working memory in ventral temporal and occipital regions.  

PubMed

While previous results from univariate analysis showed that the activity level of the parahippocampal gyrus (PHG) but not the fusiform gyrus (FG) reflects selective maintenance of the cued picture category, present results from multi-voxel pattern analysis (MVPA) showed that the spatial response patterns of both regions can be used to differentiate the selected picture category in working memory. The ventral temporal and occipital areas including the PHG and FG have been shown to be specialized in perceiving and processing different kinds of visual information, though their role in the representation of visual working memory remains unclear. To test whether the PHG and FG show spatial response patterns that reflect selective maintenance of task-relevant visual working memory in comparison with other posterior association regions, we reanalyzed data from a previous fMRI study of visual working memory with a cue inserted during the delay period of a delayed recognition task. Classification of FG and PHG activation patterns for the selected category (face or scene) during the cue phase was well above chance using classifiers trained with fMRI data from the cue or probe phase. Classification of activity in other temporal and occipital regions for the cued picture category during the cue phase was relatively less consistent even though classification of their activity during the probe recognition was comparable with the FG and PHG. In sum, these findings suggest that the FG and PHG carry information relevant to the cued visual category, and their spatial activation patterns during selective maintenance seem to match those during visual recognition. PMID:23380167

Han, Xufeng; Berg, Alexander C; Oh, Hwamee; Samaras, Dimitris; Leung, Hoi-Chung

2013-02-04

303

Propagating Waves in Visual Cortex: A Large-Scale Model of Turtle Visual Cortex  

Microsoft Academic Search

This article describes a large-scale model of turtle visual cortex that simulates the propagating waves of activity seen in real turtle cortex. The cortex model contains 744 multicompartment models of pyramidal cells, stellate cells, and horizontal cells. Input is provided by an array of 201 geniculate neurons modeled as single compartments with spike-generating mechanisms and axons modeled as delay lines.

Zoran Nenadic; Bijoy K. Ghosh; Philip Ulinski

2003-01-01

304

Prefrontal cortex glutamate and extraversion  

PubMed Central

Extraversion is considered one of the core traits of personality. Low extraversion has been associated with increased vulnerability to affective and anxiety disorders. Brain imaging studies have linked extraversion, approach behaviour and the production of positive emotional states to the dorsolateral prefrontal cortex (DLPFC) and glutamatergic neurotransmission. However, the relationship between extraversion and glutamate in the DLPFC has not been investigated so far. In order to address this issue, absolute glutamate concentrations in the DLPFC and the visual cortex as a control region were measured by 3-Tesla proton magnetic resonance spectroscopy (1H-MRS) in 29 subjects with high and low extraversion. We found increased glutamate levels in the DLPFC of introverts as compared with extraverts. The increased glutamate concentration was specific for the DLPFC and negatively associated with state anxiety. Although preliminary, results indicate altered top-down control of DLPFC due to reduced glutamate concentration as a function of extraversion. Glutamate measurement with 1H-MRS may facilitate the understanding of biological underpinnings of personality traits and psychiatric diseases associated with dysfunctions in approach behaviour and the production of positive emotional states.

Schubert, Florian; Jaedke, Maren; Gallinat, Jurgen; Bajbouj, Malek

2012-01-01

305

Merosin-negative congenital muscular dystrophy, occipital epilepsy with periodic spasms and focal cortical dysplasia. Report of three Italian cases in two families  

Microsoft Academic Search

We report clinical, EEG and neuroimaging findings of three patients in two Italian families with merosin-negative congenital muscular dystrophy (CMD), drug-resistant occipital epilepsy, diffuse persistent cerebral white matter changes and focal cortical dysplasia. Clinical and epilepsy histories, EEG and neuroimaging findings were very similar in all patients. Seizures started in childhood and mainly consisted of periodic spasms, a particular type

Antonella Pini; Luciano Merlini; Fernando M. S. Tome´; Martine Chevallay; Giuseppe Gobbi

1996-01-01

306

Childhood Epilepsy With Occipital Paroxysms: Difficulties in Distinct Segregation Into Either the Early-Onset or Late-Onset Epilepsy Subtypes  

Microsoft Academic Search

The Commission on Classification and Terminology of the International League Against Epilepsy Childhood rigidly segregated epilepsy with occipital paroxysms into 2 separate syndromes with different predominant seizure types: early-onset seizure susceptibility type consisting of prolonged infrequent, nocturnal autonomic seizures and accompanied by eye deviation and ictal vomiting and late onset with short diurnal frequent seizures and visual ictal manifestations along

Jacob Genizi; Nathanel Zelnik; Sarit Ravid; Eli Shahar

2007-01-01

307

Development of columnar structures in visual cortex  

Microsoft Academic Search

Many features of visual scenes are represented in the visual cortex in the form of maps. The best studied of these are the maps of features such as ocular dominance and orientation in primary visual cortex (V1). The beautifully regular structure of these maps and their dependence on patterns of neural activity have inspired several dieren t computational models. In

Miguel A. Carreira-Perpi; Georey J. Goodhill

2001-01-01

308

Bistability in the actin cortex  

PubMed Central

Multi-color fluorescence imaging experiments of wave forming Dictyostelium cells have revealed that actin waves separate two domains of the cell cortex that differ in their actin structure and phosphoinositide composition. We propose a bistable model of actin dynamics to account for these experimental observation. The model is based on the simplifying assumption that the actin cytoskeleton is composed of two distinct network types, a dendritic and a bundled network. The two structurally different states that were observed in experiments correspond to the stable fixed points in the bistable regime of this model. Each fixed point is dominated by one of the two network types. The experimentally observed actin waves can be considered as trigger waves that propagate transitions between the two stable fixed points. PACS Codes: 87.16.Ln, 87.17.Aa, 89.75.Fb

2010-01-01

309

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

310

Novel method of knotless vesicourethral anastomosis during robot-assisted radical prostatectomy: feasibility study and early outcomes in 30 patients using the interlocked barbed unidirectional V-LOC180 suture  

PubMed Central

Purpose: Our purpose was to describe the safety and feasibility of a running posterior reconstruction (PR) integrated with continuous vesicourethral anastomosis (VUA) using a novel self-cinching unidirectional barbed suture in robot-assisted radical prostatectomy (RARP). Methods: Between March and October 2010, 30 consecutive patients with organ-confined prostate cancer underwent RARP by an experienced single surgeon (KCZ). Upon completion of radical prostatectomy, urinary reconstruction was carried out using 2 knotless, interlocked 6-inches 3-0 V-Loc-180 suture. The left tail of the suture was initially used for PR (starting at 5-o’clock and ran to re-approximate the retrotrigonal layer to the rectourethralis) followed by left-sided VUA (from 6- to 12-o’clock), while the right-sided suture completed the right-sided VUA. Assurance of watertight closure with an intraoperative 300 cc saline visual cystogram was performed in all cases prior to case completion. Perioperative outcomes and 30-day complications were recorded. Results: All anastamoses were performed without assistance and without knot tying. Median time for nurse setup and urinary reconstruction was 40 seconds (interquartile range [IQR] 25–60) and 14.6 min (IQR 10–18), respectively. The need to readjust suture tension or place Lapra-Ty clips (Ethicon Endo-Surgery, Cincinnati, OH) to establish watertight closure was observed in 2 cases (7%). No patient had clinical urinary leak and there was no urinary retention after catheter removal on mean postoperative day 5 (IQR 4–6). Conclusions: Our clinical experience with a novel technique using the interlocked V-Loc suture during RARP for both PR and anastomosis appears to be safe and efficient. Using the barbed suture prevents slippage and eliminates the need for bedside assistance to maintain suture tension or knot tying, thus assuring watertight tissue closure.

Zorn, Kevin C.; Widmer, Hugues; Lattouf, Jean-Baptiste; Liberman, Dan; Bhojani, Naeem; Trinh, Quoc-Dien; Sun, Maxine; Karakiewicz, Pierre I.; Denis, Ronald; El-Hakim, Assaad

2011-01-01

311

Enhanced occipital and anterior cingulate activation in men but not in women during exposure to angry and fearful male faces  

Microsoft Academic Search

Blood-oxygenation-level-dependent signal was measured with functional magnetic resonance imaging in 24 healthy young subjects\\u000a (12 men and 12 women) during viewing of angry, fearful, and neutral male and female face pictures. Exposure to angry male\\u000a as opposed to angry female faces activated the visual cortex and the anterior cingulate gyrus significantly more in men than\\u000a in women. A similar sex-differential

Håkan Fischer; Peter Fransson; Christopher I. Wright; Lars Bäckman

2004-01-01

312

Carotid and vertebral artery injury in survivors of atlanto-occipital dislocation: case reports and literature review.  

PubMed

Atlanto-occipital dislocation (AOD) usually results in immediate death from transection of the upper cervical spinal cord near the spinomedullary junction. However, over the last several decades increasing numbers of AOD survivors have been identified. Although many of these patients initially demonstrate profound neurologic deficits, a number who survive have regained most or all neurologic functions, indicating that they did not suffer mechanical disruption of the spinal cord at the time of AOD. In the survivors, a growing body of evidence indicates that many of the initial neurologic deficits are related to vascular injury to the carotid or vertebral arteries and their branches. We recently encountered three AOD survivors with no evidence of mechanical injury to the spinal cord in which angiography demonstrated vascular injury to the internal carotid artery in the form of vasospasm in one case and to the vertebral arteries in the forms of focal stenosis at the site of dural penetration, focal stenosis and distal vasospasm, and focal stenosis with distal intimal flap and dissection in one case each. Autopsy after one of the three died after cardiac arrest demonstrated diffuse infarction of the cerebrum, cerebellum, midbrain, brainstem, and upper cervical spinal cord without evidence of mechanical laceration or transection of the spinal cord. Recovery of neurologic function in two cases following prompt immobilization and angiography suggests that neurologic deficits secondary to vascular injury are potentially reversible. PMID:2002530

Lee, C; Woodring, J H; Walsh, J W

1991-03-01

313

Occipital nerve stimulation in medically intractable, chronic cluster headache. The ICON study: Rationale and protocol of a randomised trial.  

PubMed

BACKGROUND: About 10% of cluster headache patients have the chronic form. At least 10% of this chronic group is intractable to or cannot tolerate medical treatment. Open pilot studies suggest that occipital nerve stimulation (ONS) might offer effective prevention in these patients. Controlled neuromodulation studies in treatments inducing paraesthesias have a general problem in blinding. We have introduced a new design in pain neuromodulation by which we think we can overcome this problem. METHODS/DESIGN: We propose a prospective, randomised, double-blind, parallel-group international clinical study in medically intractable, chronic cluster headache patients of high- versus low-amplitude ONS. Primary outcome measure is the mean number of attacks over the last four weeks. After a study period of six months there is an open extension phase of six months. Alongside the randomised trial an economic evaluation study is performed. DISCUSSION: The ICON study will show if ONS is an effective preventive therapy for patients suffering medically intractable chronic cluster headache and if there is a difference between high- and low-amplitude stimulation. The innovative design of the study will, for the first time, assess efficacy of ONS in a blinded way. PMID:23720502

Wilbrink, Leopoldine A; Teernstra, Onno Pm; Haan, Joost; van Zwet, Erik W; Evers, Silvia Maa; Spincemaille, Geert H; Veltink, Peter H; Mulleners, Wim; Brand, Ronald; Huygen, Frank Jpm; Jensen, Rigmor H; Paemeleire, Koen; Goadsby, Peter J; Visser-Vandewalle, Veerle; Ferrari, Michel D

2013-05-29

314

[Clinical features of unruptured vertebral artery dissection presenting as isolated occipital headache and/or neck pain].  

PubMed

Vertebral artery dissection(VAD)presenting as isolated occipital headache and/or neck pain is being increasingly diagnosed because of the development of magnetic resonance imaging(MRI). While a majority of the patients diagnosed with this condition shows a favorable prognosis, the pain may be a predictor of fatal stroke in some patients. We aimed to find out the features of headache with VAD, identify the clinical manifestations indicative of VAD, and determine the ideal diagnostic approach to this condition to avoid fatal stroke. We reviewed medical records of 41 consecutive patients who showed VAD with isolated headache and were diagnosed between 1995 and 2008. All patients experienced pain in the occipitocervical area ipsilateral to the affected VA. Pain showed a sudden onset in 21(51%)patients, was persistent over several days in 31(76%)patients, and was severe enough to disable daily life activities in 34(83%)patients. Progression of stenosis or aneurysmal dilatation of the vessel was identified on follow-up imaging(angiography, magnetic resonance angiography)in 7 patients(17%), and was found within 14 days after pain onset in 6 of these patients(86%). Patients with persistent, severe, and unilateral pain in the occipitocervical area should undergo MRI examination, including surface anatomy scanning(SAS)imaging, and the possibility of VAD should be considered in their diagnosis. Once VAD is diagnosed, the patient should undergo meticulous blood pressure control, bed rest, and repeated MRI examination for at least 2 weeks after onset. PMID:23542792

Echigo, Tadashi; Matsui, Hiroki; Oka, Hideki; Hashimoto, Yoichi; Hino, Akihiko; Shiomi, Naoto; Kasuya, Hidetoshi

2013-04-01

315

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.

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

2012-01-01

316

Glutamic Acid Decarboxylase in Kitten Striate Cortex.  

National Technical Information Service (NTIS)

Degeneration of the thalamic fibers in the visual cortex of turtles leads to an increase in the numerical density of cortical synapses with flattened vesicles and symmetrical membrane differentiations (Smith and Ebner, 1980). This change correlates with a...

F. F. Ebner M. F. Bear D. E. Schmechel

1985-01-01

317

Extrastriate cortex: A signature of perception grows.  

PubMed

Neuronal activity in area MT of the extrastriate visual cortex is correlated with the choices monkeys make on perceptual tasks. New evidence suggests that this correlation is stronger on some tasks than others. PMID:11566118

Britten, K H

2001-09-18

318

Somatosensory responses in a human motor cortex.  

PubMed

Somatic sensory signals provide a major source of feedback to motor cortex. Changes in somatosensory systems after stroke or injury could profoundly influence brain computer interfaces (BCI) being developed to create new output signals from motor cortex activity patterns. We had the unique opportunity to study the responses of hand/arm area neurons in primary motor cortex to passive joint manipulation in a person with a long-standing brain stem stroke but intact sensory pathways. Neurons responded to passive manipulation of the contralateral shoulder, elbow, or wrist as predicted from prior studies of intact primates. Thus fundamental properties and organization were preserved despite arm/hand paralysis and damage to cortical outputs. The same neurons were engaged by attempted arm actions. These results indicate that intact sensory pathways retain the potential to influence primary motor cortex firing rates years after cortical outputs are interrupted and may contribute to online decoding of motor intentions for BCI applications. PMID:23343902

Shaikhouni, Ammar; Donoghue, John P; Hochberg, Leigh R

2013-01-23

319

Information Processing in Mammalian Visual Cortex.  

National Technical Information Service (NTIS)

This report used a combination of physiological and anatomical approaches to elucidate the functional organization of visual cortex in the macaque monkey. One project was a single cell analysis of texture vision, using texture patterns of the type develop...

D. C. Van Essen

1986-01-01

320

Evaluative vs. trait representation in intergroup social judgments: distinct roles of anterior temporal lobe and prefrontal cortex.  

PubMed

When interacting with someone from another social group, one's responses may be influenced by both stereotypes and evaluations. Given behavioral results suggesting that stereotypes and evaluative associations operate independently, we used fMRI to test whether these biases are mediated by distinct brain systems. White participants viewed pairs of Black or White faces and judged them based on an evaluation (who would you befriend?) or a stereotype-relevant trait (who is more likely to enjoy athletic activities?). Multi-voxel pattern analysis revealed that a predominantly occipital network represented race in a context-invariant manner. However, lateral orbitofrontal cortex preferentially represented race during friendship judgments, whereas anterior medial prefrontal cortex preferentially represented race during trait judgments. Furthermore, representation of race in left temporal pole correlated with a behavioral measure of evaluative bias during friendship judgments and, independently, a measure of stereotyping during trait judgments. Whereas early sensory regions represent race in an apparently invariant manner, representations in higher-level regions are multi-componential and context-dependent. PMID:22975194

Gilbert, Sam J; Swencionis, Jillian K; Amodio, David M

2012-09-10

321

Practice makes perfect: the neural substrates of tactile discrimination by Mah-Jong experts include the primary visual cortex  

PubMed Central

Background It has yet to be determined whether visual-tactile cross-modal plasticity due to visual deprivation, particularly in the primary visual cortex (V1), is solely due to visual deprivation or if it is a result of long-term tactile training. Here we conducted an fMRI study with normally-sighted participants who had undergone long-term training on the tactile shape discrimination of the two dimensional (2D) shapes on Mah-Jong tiles (Mah-Jong experts). Eight Mah-Jong experts and twelve healthy volunteers who were naïve to Mah-Jong performed a tactile shape matching task using Mah-Jong tiles with no visual input. Furthermore, seven out of eight experts performed a tactile shape matching task with unfamiliar 2D Braille characters. Results When participants performed tactile discrimination of Mah-Jong tiles, the left lateral occipital cortex (LO) and V1 were activated in the well-trained subjects. In the naïve subjects, the LO was activated but V1 was not activated. Both the LO and V1 of the well-trained subjects were activated during Braille tactile discrimination tasks. Conclusion The activation of V1 in subjects trained in tactile discrimination may represent altered cross-modal responses as a result of long-term training.

Saito, Daisuke N; Okada, Tomohisa; Honda, Manabu; Yonekura, Yoshiharu; Sadato, Norihiro

2006-01-01

322

Somatosensory cortex stimulation for deafferentation pain  

Microsoft Academic Search

Functional neuroimaging has demonstrated that a relationship exists between the intensity of deafferentation pain and the\\u000a degree of deafferentation- related reorganization of the primary somatosensory cortex. It has also revealed that this cortical\\u000a reorganization can be reversed after the attenuation of pain. Deafferentation pain is also associated with hyperactivity of\\u000a the somatosensory thalamus and cortex. Therefore, in order to suppress

Dirk Ridder; G. De Mulder; E. Verstraeten; S. Sunaert; A. Moller

323

Schrödinger wave holography in brain cortex  

Microsoft Academic Search

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

Renato Nobili

1985-01-01

324

Bilateral parietal cortex function during motor imagery  

Microsoft Academic Search

The aim of this study was to investigate the involvement of the parietal cortex during motor imagery (MI). In experiment one,\\u000a participants imagined a sequence of upper limb movements during FMRI scanning. Statistical parametric mapping revealed a network\\u000a of activation consistent with previous MI research, including activation in right and left inferior and superior parietal\\u000a cortex. In experiment two, participants

Melanie K. Fleming; Cathy M. Stinear; Winston D. Byblow

2010-01-01

325

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

326

Food related processes in the insular cortex.  

PubMed

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

2013-08-23

327

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

PubMed

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

Falk, Dean; Lepore, Frederick E; Noe, Adrianne

2012-11-16

328

Retinotopic mapping of the peripheral visual field to human visual cortex by functional magnetic resonance imaging.  

PubMed

Retinotopic mapping is a key property of organization in the human occipital cortex. The retinotopic organization of the central visual field of visual areas V1, V2, and V3 has been well established. We used fMRI to measure the retinotopic map of the peripheral visual field (eccentricity up to 60°). We estimated the sizes of the visual areas between 0° and 60° and obtained results consistent with anatomical studies. We also estimated the cortical distances and magnification factors for reconstruction of the retinotopic map using the peripheral wedge dipole model. By comparing the retinotopic map with the flattened surface, we analyzed the datasets used to reconstruct the map. We found that: (1) the percentage of the striate cortex devoted to peripheral vision in humans is significantly larger than that in the macaque, (2) the estimate of the scaling factor in linear magnification is larger than that found in previous studies focusing on central vision, and (3) the estimate of the peripheral factor in the dipolar model is too large to make the curve direction of the dipolar map in the periphery equivalent to that in the center. On the basis of our results, we revised the dipolar map to fit our conditions. The revised map in humans has a similar elliptical shape to that of macaques, and the central parts of the two species are the same. The different parts of the map are the peripheral regions, for which the peripheral wedge dipole model in humans is reversed compared to that of macaques. PMID:22438122

Wu, Jinglong; Yan, Tianyi; Zhang, Zhen; Jin, Fengzhe; Guo, Qiyong

2012-03-22

329

Encoding touch and the orbitofrontal cortex.  

PubMed

Lesion studies on nonhuman primates utilizing recognition memory tests have shown that the orbitofrontal cortex is critical for the encoding of novel information, and anatomical studies have shown that the orbitofrontal cortex forms part of a mnemonic circuit that connects limbic medial temporal areas with higher-order lateral frontal cortical regions. Furthermore, functional neuroimaging studies have demonstrated increased activity in the orbitofrontal cortex of the human brain during the encoding of novel visual and auditory information. The present positron emission tomography study examined brain activity related to the encoding of tactile information. Cerebral blood flow (CBF) in normal human subjects during the tactile exploration of novel stimuli from a related set of textures and patterns, as well as from a set of aversive tactile stimuli, was compared with CBF during a control condition involving familiar tactile stimuli. The results demonstrate that the right rostral orbitofrontal cortex is involved in the active encoding of novel tactile information, while a more caudal region of the orbitofrontal cortex, which is more closely connected with limbic and autonomic regions of the brain, was activated when subjects explored novel aversive tactile stimuli. These results suggest that the orbitofrontal cortex, through its connections with the limbic areas of the medial temporal lobe, influences the processing of incoming information and thus contributes to its encoding. PMID:18172850

Frey, Stephen; Zlatkina, Veronika; Petrides, Michael

2009-02-01

330

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

331

The role of inhibition in oscillatory wave dynamics in the cortex.  

PubMed

Cortical oscillations arise during behavioral and mental tasks, and all temporal oscillations have particular spatial patterns. Studying the mechanisms that generate and modulate the spatiotemporal characteristics of oscillations is important for understanding neural information processing and the signs and symptoms of dynamical diseases of the brain. Nevertheless, it remains unclear how GABAergic inhibition modulates these oscillation dynamics. Using voltage-sensitive dye imaging, pharmacological methods, and tangentially cut occipital neocortical brain slices (including layers 3-5) of Sprague-Dawley rat, we found that GABAa disinhibition with bicuculline can progressively simplify oscillation dynamics in the presence of carbachol in a concentration-dependent manner. Additionally, GABAb disinhibition can further simplify oscillation dynamics after GABAa receptors are blocked. Both GABAa and GABAb disinhibition increase the synchronization of the neural network. Theta frequency (5-15-Hz) oscillations are reliably generated by using a combination of GABAa and GABAb antagonists alone. These theta oscillations have basic spatiotemporal patterns similar to those generated by carbachol/bicuculline. These results are illustrative of how GABAergic inhibition increases the complexity of patterns of activity and contributes to the regulation of the cortex. PMID:22805065

Xiao, Ying; Huang, Xiao-Ying; Van Wert, Stephen; Barreto, Ernest; Wu, Jian-Young; Gluckman, Bruce J; Schiff, Steven J

2012-07-01

332

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.

McIntosh, Anthony R.

2009-01-01

333

Voxel-based morphometry reveals reduced grey matter volume in the temporal cortex of developmental prosopagnosics.  

PubMed

Individuals with developmental prosopagnosia exhibit severe and lasting difficulties in recognizing faces despite the absence of apparent brain abnormalities. We used voxel-based morphometry to investigate whether developmental prosopagnosics show subtle neuroanatomical differences from controls. An analysis based on segmentation of T1-weighted images from 17 developmental prosopagnosics and 18 matched controls revealed that they had reduced grey matter volume in the right anterior inferior temporal lobe and in the superior temporal sulcus/middle temporal gyrus bilaterally. In addition, a voxel-based morphometry analysis based on the segmentation of magnetization transfer parameter maps showed that developmental prosopagnosics also had reduced grey matter volume in the right middle fusiform gyrus and the inferior temporal gyrus. Multiple regression analyses relating three distinct behavioural component scores, derived from a principal component analysis, to grey matter volume revealed an association between a component related to facial identity and grey matter volume in the left superior temporal sulcus/middle temporal gyrus plus the right middle fusiform gyrus/inferior temporal gyrus. Grey matter volume in the lateral occipital cortex was associated with component scores related to object recognition tasks. Our results demonstrate that developmental prosopagnosics have reduced grey matter volume in several regions known to respond selectively to faces and provide new evidence that integrity of these areas relates to face recognition ability. PMID:19887506

Garrido, Lúcia; Furl, Nicholas; Draganski, Bogdan; Weiskopf, Nikolaus; Stevens, John; Tan, Geoffrey Chern-Yee; Driver, Jon; Dolan, Ray J; Duchaine, Bradley

2009-12-01

334

Integration of "what" and "where" in frontal cortex during visual imagery of scenes.  

PubMed

Imagination is a key function for many human activities, such as reminiscing, learning, or planning. Unravelling its neuro-biological basis is paramount to grasp the essence of our thoughts. Previous neuroimaging studies have identified brain regions subserving the visualisation of "what?" (e.g. faces or objects) and "where?" (e.g. spatial layout) content of mental images. However, the functional role of a common set of involved regions - the frontal regions - and their interplay with the "what" and "where" regions, has remained largely unspecified. This study combines functional MRI and electroencephalography to examine the full-brain network that underlies the visual imagery of complex scenes and to investigate the spectro-temporal properties of its nodes, especially of the frontal cortex. Our results indicate that frontal regions integrate the "what" and "where" content of our thoughts into one visually imagined scene. We link early synchronisation of anterior theta and beta oscillations to regional activation of right and central frontal cortices, reflecting retrieval and integration of information. These frontal regions orchestrate remote occipital-temporal regions (including calcarine sulcus and parahippocampal gyrus) that encode the detailed representations of the objects, and parietal "where" regions that encode the spatial layout into forming one coherent mental picture. Specifically the mesial superior frontal gyrus appears to have a principal integrative role, as its activity during the visualisation of the scene predicts subsequent performance on the imagery task. PMID:22186678

de Borst, Aline W; Sack, Alexander T; Jansma, Bernadette M; Esposito, Fabrizio; de Martino, Federico; Valente, Giancarlo; Roebroeck, Alard; di Salle, Francesco; Goebel, Rainer; Formisano, Elia

2011-12-13

335

Scratching beneath the surface: new insights into the functional properties of the lateral occipital area and parahippocampal place area.  

PubMed

We used fMRI on neurologically intact humans to investigate whether or not there are different neural substrates for the different kinds of information that a visual surface signals (shape from texture vs material properties from texture). Participants attended to differences in the shape (flat/convex), texture and color (wood/rock), or material properties (soft/hard) of a set of circular surfaces. Attending to shape activated the contour-sensitive lateral occipital (LO) area, and attending to texture activated a region of the collateral sulcus (CoS) that overlaps with the parahippocampal place area (PPA). Interestingly, attending to material properties activated the same texture-sensitive region in the CoS. These results demonstrate the existence of different neural substrates for the different types of information that a visual surface signals. With regard to object shape, the organization of the LO area may be complex, with neurons tuned not only to the outline shape of objects, but also to their surface curvature independent of contour. Moreover, to our knowledge, this is the first study to demonstrate that processing surface texture, which occurs within the scene-sensitive PPA, is a route to accessing knowledge about an object's material properties. With this in mind, we propose that models of visual cortical organization should focus not only on the particular stimulus category to which a region maximally responds (e.g., objects, scenes), but also on the stimulus attributes that best support the processing of that category (e.g., shape, texture, material properties). PMID:21632946

Cant, Jonathan S; Goodale, Melvyn A

2011-06-01

336

Reduction in post-synaptic scaffolding PSD-95 and SAP-102 protein levels in the Alzheimer inferior temporal cortex is correlated with disease pathology.  

PubMed

N-methyl-D-aspartate (NMDA) receptor-evoked excitotoxicity contributes to region-specific loss of glutamatergic synapses responsible for cognitive decline in Alzheimer's disease (AD). Here, the post-synaptic scaffold proteins PSD-95 and SAP-102, which regulate NMDA receptor synaptic activity and expression, were investigated in human AD autopsy brain tissue. Using absolute quantification real-time PCR, we detected reduced expression of synaptophysin in both the pathologically susceptible inferior temporal cortex and hippocampus, consistent with previous reports. PSD-95 and SAP-102 mRNA was reduced, albeit not significantly. Proteins were precisely quantified against recombinant truncated protein standards. No differences were observed for proteins in AD spared occipital cortex between AD cases and controls. PSD-95 and SAP-102 protein expression was markedly reduced in the AD inferior temporal cortex. Both mRNA and protein levels were reduced according to disease severity. SAP102 protein levels were significantly reduced in AD subjects carrying a copy of the APOE?4 allele. This is the first study to investigate SAP-102 in the aging human brain and suggest a possible mechanism for NMDA receptor expression aberrations in AD. PMID:20634587

Proctor, Dustin T; Coulson, Elizabeth J; Dodd, Peter R

2010-01-01

337

Decreased activation of lateral orbitofrontal cortex during risky choices under uncertainty is associated with disadvantageous decision-making and suicidal behavior.  

PubMed

Decision-making impairment has been linked to orbitofrontal cortex lesions and to different disorders including substance abuse, aggression and suicidal behavior. Understanding the neurocognitive mechanisms of these impairments could facilitate the development of effective treatments. In the current study, we aimed to explore the neural and cognitive basis of poor decision-making ability associated with the vulnerability to suicidal behavior, a public health issue in most western countries. Twenty-five not currently depressed male patients, 13 of whom had a history of suicidal acts (suicide attempters) and 12 of whom had none (affective controls), performed an adapted version of the Iowa Gambling Task during functional Magnetic Resonance Imaging. Task-related functional Regions-of-Interest were independently defined in 15 male healthy controls performing the same task (Lawrence et al., 2009). In comparison to affective controls, suicide attempters showed 1) poorer performance on the gambling task 2) decreased activation during risky relative to safe choices in left lateral orbitofrontal and occipital cortices 3) no difference for the contrast between wins and losses. Altered processing of risk under conditions of uncertainty, associated with left lateral orbitofrontal cortex dysfunction, could explain the decision-making deficits observed in suicide attempters. These impaired cognitive and neural processes may represent future predictive markers and therapeutic targets in a field where identification of those at risk is poor and specific treatments are lacking. These results also add to our growing understanding of the role of the orbitofrontal cortex in decision-making and psychopathology. PMID:20302946

Jollant, Fabrice; Lawrence, Natalia S; Olie, Emilie; O'Daly, Owen; Malafosse, Alain; Courtet, Philippe; Phillips, Mary L

2010-03-17

338

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

PubMed Central

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 microarrays and quantitative PCR, the mRNA expression profiles of these two neuroanatomical regions were compared in postmortem brain tissue from RTT patients and normal controls. A subset of genes was differentially expressed in the frontal cortex of RTT brains, some of which are known to be associated with neurological disorders (clusterin and cytochrome c oxidase subunit 1) or are involved in synaptic vesicle cycling (dynamin 1). RNAi-mediated knockdown of MeCP2 in vitro, followed by further expression analysis demonstrated that the same direction of abnormal expression was recapitulated with MeCP2 knockdown, which for cytochrome c oxidase subunit 1 was associated with a functional respiratory chain defect. Chromatin immunoprecipitation (ChIP) analysis showed that MeCP2 associated with the promoter regions of some of these genes suggesting that loss of MeCP2 function may be responsible for their overexpression. Conclusions This study has shed more light on the subset of aberrantly expressed genes that result from MECP2 mutations. The mitochondrion has long been implicated in the pathogenesis of RTT, however it has not been at the forefront of RTT research interest since the discovery of MECP2 mutations. The functional consequence of the underexpression of cytochrome c oxidase subunit 1 indicates that this is an area that should be revisited.

2010-01-01

339

The adrenal cortex and life.  

PubMed

The template for our understanding of the physiological role of the adrenal cortex was set by Hans Selye, who demonstrated its key involvement in the response to stress, of whatever origin, and who also introduced the terms glucocorticoid and mineralocorticoid. Despite this, from the late 1940s on there was certainly general awareness of the multiple actions of glucocorticoids, including effects on the thymus and immune system, cardiovascular system, water balance, and the CNS. For these reasons, and perhaps because in the early studies of the actions of individual steroids there was less clear-cut difference between them, there was some initial resistance to the use of these terms. Today they are universal and unchallenged. It can be argued that, with respect to the glucocorticoids, this term colours our perception of their physiological importance, and may be misleading. By taking evidence from disease states, emphasis is placed on extreme conditions that do not necessarily reveal normal physiology. In particular, evidence for the role of glucocorticoid regulation of gluconeogenesis and blood glucose in the normal subject or animal is inconclusive. Similarly, while highly plausible theories explaining glucocorticoid actions on inflammation or the immune system as part of normal physiology have been presented, direct evidence to support them is hard to find. Under extreme conditions of chronic stress, the cumulative actions of glucocorticoids on insulin resistance or immunocompromise may indeed seem to be actually damaging. Two well-documented and long recognized situations create huge variation in glucocorticoid secretion. These are the circadian rhythm, and the acute response to mild stress, such as handling, in the rat. Neither of these can be adequately explained by the need for glucocorticoid action, as we currently understand it, particularly on carbohydrate metabolism or on the immune system. Perhaps we should re-examine other targets at the physiological level. At the present time, some of these seem to be out of fashion. PMID:18840500

Vinson, Gavin P

2008-09-17

340

Grid alignment in entorhinal cortex.  

PubMed

The spatial responses of many of the cells recorded in all layers of rodent medial entorhinal cortex (mEC) show mutually aligned grid patterns. Recent experimental findings have shown that grids can often be better described as elliptical rather than purely circular and that, beyond the mutual alignment of their grid axes, ellipses tend to also orient their long axis along preferred directions. Are grid alignment and ellipse orientation aspects of the same phenomenon? Does the grid alignment result from single-unit mechanisms or does it require network interactions? We address these issues by refining a single-unit adaptation model of grid formation, to describe specifically the spontaneous emergence of conjunctive grid-by-head-direction cells in layers III, V, and VI of mEC. We find that tight alignment can be produced by recurrent collateral interactions, but this requires head-direction (HD) modulation. Through a competitive learning process driven by spatial inputs, grid fields then form already aligned, and with randomly distributed spatial phases. In addition, we find that the self-organization process is influenced by any anisotropy in the behavior of the simulated rat. The common grid alignment often orients along preferred running directions (RDs), as induced in a square environment. When speed anisotropy is present in exploration behavior, the shape of individual grids is distorted toward an ellipsoid arrangement. Speed anisotropy orients the long ellipse axis along the fast direction. Speed anisotropy on its own also tends to align grids, even without collaterals, but the alignment is seen to be loose. Finally, the alignment of spatial grid fields in multiple environments shows that the network expresses the same set of grid fields across environments, modulo a coherent rotation and translation. Thus, an efficient metric encoding of space may emerge through spontaneous pattern formation at the single-unit level, but it is coherent, hence context-invariant, if aided by collateral interactions. PMID:22892761

Si, Bailu; Kropff, Emilio; Treves, Alessandro

2012-08-15

341

Brain Region-Specific Decrease in the Activity and Expression of Protein Kinase A in the Frontal Cortex of Regressive Autism  

PubMed Central

Autism is a severe neurodevelopmental disorder that is characterized by impaired language, communication, and social skills. In regressive autism, affected children first show signs of normal social and language development but eventually lose these skills and develop autistic behavior. Protein kinases are essential in G-protein-coupled, receptor-mediated signal transduction and are involved in neuronal functions, gene expression, memory, and cell differentiation. We studied the activity and expression of protein kinase A (PKA), a cyclic AMP–dependent protein kinase, in postmortem brain tissue samples from the frontal, temporal, parietal, and occipital cortices, and the cerebellum of individuals with regressive autism; autistic subjects without a clinical history of regression; and age-matched developmentally normal control subjects. The activity of PKA and the expression of PKA (C-?), a catalytic subunit of PKA, were significantly decreased in the frontal cortex of individuals with regressive autism compared to control subjects and individuals with non-regressive autism. Such changes were not observed in the cerebellum, or the cortices from the temporal, parietal, and occipital regions of the brain in subjects with regressive autism. In addition, there was no significant difference in PKA activity or expression of PKA (C-?) between non-regressive autism and control groups. These results suggest that regression in autism may be associated, in part, with decreased PKA-mediated phosphorylation of proteins and abnormalities in cellular signaling.

Ji, Lina; Chauhan, Ved; Flory, Michael J.; Chauhan, Abha

2011-01-01

342

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.

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

2009-01-01

343

Perirhinal cortex and temporal lobe epilepsy  

PubMed Central

The perirhinal cortex—which is interconnected with several limbic structures and is intimately involved in learning and memory—plays major roles in pathological processes such as the kindling phenomenon of epileptogenesis and the spread of limbic seizures. Both features may be relevant to the pathophysiology of mesial temporal lobe epilepsy that represents the most refractory adult form of epilepsy with up to 30% of patients not achieving adequate seizure control. Compared to other limbic structures such as the hippocampus or the entorhinal cortex, the perirhinal area remains understudied and, in particular, detailed information on its dysfunctional characteristics remains scarce; this lack of information may be due to the fact that the perirhinal cortex is not grossly damaged in mesial temporal lobe epilepsy and in models mimicking this epileptic disorder. However, we have recently identified in pilocarpine-treated epileptic rats the presence of selective losses of interneuron subtypes along with increased synaptic excitability. In this review we: (i) highlight the fundamental electrophysiological properties of perirhinal cortex neurons; (ii) briefly stress the mechanisms underlying epileptiform synchronization in perirhinal cortex networks following epileptogenic pharmacological manipulations; and (iii) focus on the changes in neuronal excitability and cytoarchitecture of the perirhinal cortex occurring in the pilocarpine model of mesial temporal lobe epilepsy. Overall, these data indicate that perirhinal cortex networks are hyperexcitable in an animal model of temporal lobe epilepsy, and that this condition is associated with a selective cellular damage that is characterized by an age-dependent sensitivity of interneurons to precipitating injuries, such as status epilepticus.

Biagini, Giuseppe; D'Antuono, Margherita; Benini, Ruba; de Guzman, Philip; Longo, Daniela; Avoli, Massimo

2013-01-01

344

Real-time successive face learning by association cortex - entorhinal cortex - hippocampal formation model  

Microsoft Academic Search

In the brain, it is thought that the shape recognition system and the spatial recognition systems operate in parallel. An association cortex entorhinal cortex - hippocampal formation model (AEH model) was constructed based on the existing neurophysiological knowledge. Using the AEH model, we developed a real-time individual discrimination system, which operated similarly to human perception. The whole face was detected

Jyun-ichi NITTA; Hironobu TAKANO; K. Nakamura

2003-01-01

345

Activation-dependent enhancements of synaptic strength in pyriform cortex efferents to the entorhinal cortex  

Microsoft Academic Search

The entorhinal cortex is reciprocally connected with both neocortical sensory areas and the hippocampal formation, and is thought to play a pivotal role in learning and memory. Changes in synaptic strength are thought to provide the major neurophysiological basis for memory formation, but little is known about synaptic plasticity in the entorhinal cortex. The objectives of this research were to

Clifton Andrew Chapman

1996-01-01

346

Activation-dependent enhancements of synaptic strength in pyriform cortex efferents to the entorhinal cortex  

Microsoft Academic Search

The entorhinal cortex is reciprocally connected with both neocortical sensory areas and the hippocampal formation, and is thought to play a pivotal role in learning and memory. Changes in synaptic strength are thought to provide the major neurophysiological basis for memory formation, but little is known about synaptic plasticity in the entorhinal cortex. The objectives of this research were to

Clifton Andrew Chapman

1995-01-01

347

Encoding and retrieval of artificial visuoauditory memory traces in the auditory cortex requires the entorhinal cortex.  

PubMed

Damage to the medial temporal lobe impairs the encoding of new memories and the retrieval of memories acquired immediately before the damage in human. In this study, we demonstrated that artificial visuoauditory memory traces can be established in the rat auditory cortex and that their encoding and retrieval depend on the entorhinal cortex of the medial temporal lobe in the rat. We trained rats to associate a visual stimulus with electrical stimulation of the auditory cortex using a classical conditioning protocol. After conditioning, we examined the associative memory traces electrophysiologically (i.e., visual stimulus-evoked responses of auditory cortical neurons) and behaviorally (i.e., visual stimulus-induced freezing and visual stimulus-guided reward retrieval). The establishment of a visuoauditory memory trace in the auditory cortex, which was detectable by electrophysiological recordings, was achieved over 20-30 conditioning trials and was blocked by unilateral, temporary inactivation of the entorhinal cortex. Retrieval of a previously established visuoauditory memory was also affected by unilateral entorhinal cortex inactivation. These findings suggest that the entorhinal cortex is necessary for the encoding and involved in the retrieval of artificial visuoauditory memory in the auditory cortex, at least during the early stages of memory consolidation. PMID:23761892

Chen, Xi; Guo, Yiping; Feng, Jingyu; Liao, Zhengli; Li, Xinjian; Wang, Haitao; Li, Xiao; He, Jufang

2013-06-12

348

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

349

Damage to left anterior temporal cortex predicts impairment of complex syntactic processing: A lesion-symptom mapping study.  

PubMed

Sentence processing problems form a common consequence of left-hemisphere brain injury, in some patients to such an extent that their pattern of language performance is characterized as "agrammatic". However, the location of left-hemisphere damage that causes such problems remains controversial. It has been suggested that the critical site for syntactic processing is Broca's area of the frontal cortex or, alternatively, that a more widely distributed network is responsible for syntactic processing. The aim of this study was to identify brain regions that are required for successful sentence processing. Voxel-based lesion-symptom mapping (VLSM) was used to identify brain regions where injury predicted impaired sentence processing in 50 native speakers of Icelandic with left-hemisphere stroke. Sentence processing was assessed by having individuals identify which picture corresponded to a verbally presented sentence. The VLSM analysis revealed that impaired sentence processing was best predicted by damage to a large left-hemisphere temporo-parieto-occipital area. This is likely due to the multimodal nature of the sentence processing task, which involves auditory and visual analysis, as well as lexical and syntactic processing. Specifically impaired processing of noncanonical sentence types, when compared with canonical sentence processing, was associated with damage to the left-hemisphere anterior superior and middle temporal gyri and the temporal pole. Anterior temporal cortex, therefore, appears to play a crucial role in syntactic processing, and patients with brain damage to this area are more likely to present with receptive agrammatism than patients in which anterior temporal cortex is spared. Hum Brain Mapp 34:2715-2723, 2013. © 2012 Wiley Periodicals, Inc. PMID:22522937

Magnusdottir, S; Fillmore, P; den Ouden, D B; Hjaltason, H; Rorden, C; Kjartansson, O; Bonilha, L; Fridriksson, J

2012-04-21

350

A Computational Model of Cerebral Cortex Folding  

PubMed Central

The geometric complexity and variability of the human cerebral cortex has long intrigued the scientific community. As a result, quantitative description of cortical folding patterns and the understanding of underlying folding mechanisms have emerged as important research goals. This paper presents a computational 3-dimensional geometric model of cerebral cortex folding initialized by MRI data of a human fetal brain and deformed under the governance of a partial differential equation modeling cortical growth. By applying different simulation parameters, our model is able to generate folding convolutions and shape dynamics of the cerebral cortex. The simulations of this 3D geometric model provide computational experimental support to the following hypotheses: 1) Mechanical constraints of the skull regulate the cortical folding process. 2) The cortical folding pattern is dependent on the global cell growth rate of the whole cortex. 3) The cortical folding pattern is dependent on relative rates of cell growth in different cortical areas. 4) The cortical folding pattern is dependent on the initial geometry of the cortex.

Nie, Jingxin; Guo, Lei; Li, Gang; Faraco, Carlos; Miller, L Stephen; Liu, Tianming

2010-01-01

351

Millisecond encoding precision of auditory cortex neurons  

PubMed Central

Neurons in auditory cortex are central to our perception of sounds. However, the underlying neural codes, and the relevance of millisecond-precise spike timing in particular, remain debated. Here, we addressed this issue in the auditory cortex of alert nonhuman primates by quantifying the amount of information carried by precise spike timing about complex sounds presented for extended periods of time (random tone sequences and natural sounds). We investigated the dependence of stimulus information on the temporal precision at which spike times were registered and found that registering spikes at a precision coarser than a few milliseconds significantly reduced the encoded information. This dependence demonstrates that auditory cortex neurons can carry stimulus information at high temporal precision. In addition, we found that the main determinant of finely timed information was rapid modulation of the firing rate, whereas higher-order correlations between spike times contributed negligibly. Although the neural coding precision was high for random tone sequences and natural sounds, the information lost at a precision coarser than a few milliseconds was higher for the stimulus sequence that varied on a faster time scale (random tones), suggesting that the precision of cortical firing depends on the stimulus dynamics. Together, these results provide a neural substrate for recently reported behavioral relevance of precisely timed activity patterns with auditory cortex. In addition, they highlight the importance of millisecond-precise neural coding as general functional principle of auditory processing—from the periphery to cortex.

Kayser, Christoph; Logothetis, Nikos K.; Panzeri, Stefano

2010-01-01

352

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.

Thaler, Lore; Goodale, Melvyn A.

2011-01-01

353

Sexual differentiation of mammalian frontal cortex  

SciTech Connect

The pattern of distribution of the progesterone binding sites was examined in selected nuclei of the brain of male and female rat. In female rats the frontal cortex resulted to be the region with the highest concentration of /sup 3/H R5020 biding sites. However, in male rats the same region showed very little progestin binding activity. When female rats were androgenized via neonatal exposure to testosterone, the progestin binding activity of the frontal cortex became similar to that observed in male rats. The present investigation indicates that sexual differentiation of the rat brain may include also brain regions not clearly involved in sex related functions like the frontal cortex. 30 references, 2 figures, 1 table.

Maggi, A.; Zucchi, I.

1987-03-23

354

The prefrontal cortex: categories, concepts and cognition.  

PubMed Central

The ability to generalize behaviour-guiding principles and concepts from experience is key to intelligent, goal-directed behaviour. It allows us to deal efficiently with a complex world and to adapt readily to novel situations. We review evidence that the prefrontal cortex-the cortical area that reaches its greatest elaboration in primates-plays a central part in acquiring and representing this information. The prefrontal cortex receives highly processed information from all major forebrain systems, and neurophysiological studies suggest that it synthesizes this into representations of learned task contingencies, concepts and task rules. In short, the prefrontal cortex seems to underlie our internal representations of the 'rules of the game'. This may provide the necessary foundation for the complex behaviour of primates, in whom this structure is most elaborate.

Miller, Earl K; Freedman, David J; Wallis, Jonathan D

2002-01-01

355

Attentional modulation of human auditory cortex.  

PubMed

Attention powerfully influences auditory perception, but little is understood about the mechanisms whereby attention sharpens responses to unattended sounds. We used high-resolution surface mapping techniques (using functional magnetic resonance imaging, fMRI) to examine activity in human auditory cortex during an intermodal selective attention task. Stimulus-dependent activations (SDAs), evoked by unattended sounds during demanding visual tasks, were maximal over mesial auditory cortex. They were tuned to sound frequency and location, and showed rapid adaptation to repeated sounds. Attention-related modulations (ARMs) were isolated as response enhancements that occurred when subjects performed pitch-discrimination tasks. In contrast to SDAs, ARMs were localized to lateral auditory cortex, showed broad frequency and location tuning, and increased in amplitude with sound repetition. The results suggest a functional dichotomy of auditory cortical fields: stimulus-determined mesial fields that faithfully transmit acoustic information, and attentionally labile lateral fields that analyze acoustic features of behaviorally relevant sounds. PMID:15156150

Petkov, Christopher I; Kang, Xiaojian; Alho, Kimmo; Bertrand, Olivier; Yund, E William; Woods, David L

2004-05-23

356

Auditory spatial processing in the human cortex.  

PubMed

The auditory system codes spatial locations in a way that deviates from the spatial representations found in other modalities. This difference is especially striking in the cortex, where neurons form topographical maps of visual and tactile space but where auditory space is represented through a population rate code. In this hemifield code, sound source location is represented in the activity of two widely tuned opponent populations, one tuned to the right and the other to the left side of auditory space. Scientists are only beginning to uncover how this coding strategy adapts to various spatial processing demands. This review presents the current understanding of auditory spatial processing in the cortex. To this end, the authors consider how various implementations of the hemifield code may exist within the auditory cortex and how these may be modulated by the stimulation and task context. As a result, a coherent set of neural strategies for auditory spatial processing emerges. PMID:22492193

Salminen, Nelli H; Tiitinen, Hannu; May, Patrick J C

2012-04-09

357

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

358

Mapping receptive fields in primary visual cortex  

PubMed Central

Nearly 40 years ago, in the pages of this journal, Hubel and Wiesel provided the first description of receptive fields in the primary visual cortex of higher mammals. They defined two classes of cortical cells, ‘simple’ and ‘complex’, based on neural responses to simple visual stimuli. The notion of a hierarchy of receptive fields, where increasingly intricate receptive fields are constructed from more elementary ones, was introduced. Since those early days we have witnessed the birth of quantitative methods to map receptive fields and mathematical descriptions of simple and complex cell function. Insights gained from these models, along with new theoretical concepts, are refining our understanding of receptive field structure and the underlying cortical circuitry. Here, I provide a brief historical account of the evolution of receptive field mapping in visual cortex along with the associated conceptual advancements, and speculate on the shape novel theories of the cortex may take as a result these measurements.

Ringach, Dario L

2004-01-01

359

Prefrontal Cortex and Somatosensory Cortex in Tactile Crossmodal Association: An Independent Component Analysis of ERP Recordings  

PubMed Central

Our previous studies on scalp-recorded event-related potentials (ERPs) showed that somatosensory N140 evoked by a tactile vibration in working memory tasks was enhanced when human subjects expected a coming visual stimulus that had been paired with the tactile stimulus. The results suggested that such enhancement represented the cortical activities involved in tactile-visual crossmodal association. In the present study, we further hypothesized that the enhancement represented the neural activities in somatosensory and frontal cortices in the crossmodal association. By applying independent component analysis (ICA) to the ERP data, we found independent components (ICs) located in the medial prefrontal cortex (around the anterior cingulate cortex, ACC) and the primary somatosensory cortex (SI). The activity represented by the IC in SI cortex showed enhancement in expectation of the visual stimulus. Such differential activity thus suggested the participation of SI cortex in the task-related crossmodal association. Further, the coherence analysis and the Granger causality spectral analysis of the ICs showed that SI cortex appeared to cooperate with ACC in attention and perception of the tactile stimulus in crossmodal association. The results of our study support with new evidence an important idea in cortical neurophysiology: higher cognitive operations develop from the modality-specific sensory cortices (in the present study, SI cortex) that are involved in sensation and perception of various stimuli.

Wang, Liping; Lenz, Fred A.; Hsiao, Steven S.; Bodner, Mark; Hong, Bo; Zhou, Yong-Di

2007-01-01

360

A neuronal model of the language cortex  

Microsoft Academic Search

Abstract We modelled,language-learning processes in a brain-inspired model,of the language,cortex. The network,consisted of neuron-like elements,(graded-response units) and,mimicked,the neuroanatomical,areas in the perisylvian language,cortex and,the intrinsic and mutual,connections,within and,between,them. Speaking words,creates correlated activity in motor,and auditory,cortical systems. This correlated activity might play an important role in setting up word representations at the neuronal level [D.B. Fry, The development of the phonological system

Max Garagnani; Thomas Wennekers; Friedemann Pulvermüller

2007-01-01

361

Olfactory consciousness and gamma oscillation couplings across the olfactory bulb, olfactory cortex, and orbitofrontal cortex  

PubMed Central

The orbitofrontal cortex receives multi-modality sensory inputs, including olfactory input, and is thought to be involved in conscious perception of the olfactory image of objects. Generation of olfactory consciousness may require neuronal circuit mechanisms for the “binding” of distributed neuronal activities, with each constituent neuron representing a specific component of an olfactory percept. The shortest neuronal pathway for odor signals to reach the orbitofrontal cortex is olfactory sensory neuron—olfactory bulb—olfactory cortex—orbitofrontal cortex, but other pathways exist, including transthalamic pathways. Here, we review studies on the structural organization and functional properties of the shortest pathway, and propose a model of neuronal circuit mechanisms underlying the temporal bindings of distributed neuronal activities in the olfactory cortex. We describe a hypothesis that suggests functional roles of gamma oscillations in the bindings. This hypothesis proposes that two types of projection neurons in the olfactory bulb, tufted cells and mitral cells, play distinct functional roles in bindings at neuronal circuits in the olfactory cortex: tufted cells provide specificity-projecting circuits which send odor information with early-onset fast gamma synchronization, while mitral cells give rise to dispersedly-projecting feed-forward binding circuits which transmit the response synchronization timing with later-onset slow gamma synchronization. This hypothesis also suggests a sequence of bindings in the olfactory cortex: a small-scale binding by the early-phase fast gamma synchrony of tufted cell inputs followed by a larger-scale binding due to the later-onset slow gamma synchrony of mitral cell inputs. We discuss that behavioral state, including wakefulness and sleep, regulates gamma oscillation couplings across the olfactory bulb, olfactory cortex, and orbitofrontal cortex.

Mori, Kensaku; Manabe, Hiroyuki; Narikiyo, Kimiya; Onisawa, Naomi

2013-01-01

362

Olfactory consciousness and gamma oscillation couplings across the olfactory bulb, olfactory cortex, and orbitofrontal cortex.  

PubMed

The orbitofrontal cortex receives multi-modality sensory inputs, including olfactory input, and is thought to be involved in conscious perception of the olfactory image of objects. Generation of olfactory consciousness may require neuronal circuit mechanisms for the "binding" of distributed neuronal activities, with each constituent neuron representing a specific component of an olfactory percept. The shortest neuronal pathway for odor signals to reach the orbitofrontal cortex is olfactory sensory neuron-olfactory bulb-olfactory cortex-orbitofrontal cortex, but other pathways exist, including transthalamic pathways. Here, we review studies on the structural organization and functional properties of the shortest pathway, and propose a model of neuronal circuit mechanisms underlying the temporal bindings of distributed neuronal activities in the olfactory cortex. We describe a hypothesis that suggests functional roles of gamma oscillations in the bindings. This hypothesis proposes that two types of projection neurons in the olfactory bulb, tufted cells and mitral cells, play distinct functional roles in bindings at neuronal circuits in the olfactory cortex: tufted cells provide specificity-projecting circuits which send odor information with early-onset fast gamma synchronization, while mitral cells give rise to dispersedly-projecting feed-forward binding circuits which transmit the response synchronization timing with later-onset slow gamma synchronization. This hypothesis also suggests a sequence of bindings in the olfactory cortex: a small-scale binding by the early-phase fast gamma synchrony of tufted cell inputs followed by a larger-scale binding due to the later-onset slow gamma synchrony of mitral cell inputs. We discuss that behavioral state, including wakefulness and sleep, regulates gamma oscillation couplings across the olfactory bulb, olfactory cortex, and orbitofrontal cortex. PMID:24137148

Mori, Kensaku; Manabe, Hiroyuki; Narikiyo, Kimiya; Onisawa, Naomi

2013-10-16

363

The roles of "face" and "non-face" areas during individual face perception: evidence by fMRI adaptation in a brain-damaged prosopagnosic patient.  

PubMed

Two regions in the human occipito-temporal cortex respond preferentially to faces: 'the fusiform face area' ('FFA') and the 'occipital face area' ('OFA'). Whether these areas have a dominant or exclusive role in face perception, or if sub-maximal responses in other visual areas such as the lateral occipital complex (LOC) are also involved, is currently debated. To shed light on this issue, we tested normal participants and PS, a well-known brain-damaged patient presenting a face-selective perception deficit (prosopagnosia) [Rossion, B., Caldara, R., Seghier, M., Schuller, A. M., Lazeyras, F., Mayer, E. (2003). A network of occipito-temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing. Brain 126 2381-2395.], with functional magnetic resonance imaging (fMRI). Of particular interest, the right hemisphere lesion of the patient PS encompasses the 'OFA' but preserves the 'FFA' and LOC [Sorger, B., Goebel, R., Schiltz, C., Rossion, B. (2007). Understanding the functional neuroanatomy of acquired prosopagnosia. NeuroImage 35, 836-852.]. Using fMRI-adaptation, we found a dissociation between the coding of individual exemplars in the structurally intact 'FFA', which was impaired for faces but preserved for objects in the patient PS's brain. Most importantly, a larger response to different faces than repeated faces was found in the ventral part of the LOC both for normals and the patient, next to the right hemisphere lesion. Thus, following prosopagnosia, areas that do not respond preferentially to faces such as the ventral part of the LOC (vLOC) may still be recruited for compensatory or residual individual face perception. Overall, these observations indicate that several high-level visual areas in the human brain contribute to individual face perception. However, a subset of these areas in the right hemisphere, those responding preferentially to faces ('FFA' and 'OFA'), appear to be critical for this function. PMID:18164628

Dricot, Laurence; Sorger, Bettina; Schiltz, Christine; Goebel, Rainer; Rossion, Bruno

2007-11-22

364

Binocularly Driven Neurons Invisual Cortex of Split-Chiasm Cats.  

National Technical Information Service (NTIS)

In cats with midsagittal section of the optic chiasm, some visual cortex neurons can be driven not only by the ipsilateral eye, through the direct geniculocortical pathways, but also by the contralateral eye, through the opposite visual cortex and corpus ...

G. Berlucchi G. Rizzolatti

1967-01-01

365

Microglia in the Cerebral Cortex in Autism  

ERIC Educational Resources Information Center

|We immunocytochemically identified microglia in fronto-insular (FI) and visual cortex (VC) in autopsy brains of well-phenotyped subjects with autism and matched controls, and stereologically quantified the microglial densities. Densities were determined blind to phenotype using an optical fractionator probe. In FI, individuals with autism had…

Tetreault, Nicole A.; Hakeem, Atiya Y.; Jiang, Sue; Williams, Brian A.; Allman, Elizabeth; Wold, Barbara J.; Allman, John M.

2012-01-01

366

Artistic rendering of the visual cortex  

Microsoft Academic Search

In this paper we explain the processing in the first layers of the visual cortex by simple, complex and end- stopped cells, plus grouping cells for line, edge, keypoint and saliency detection. Three visualisations are presented: (a) an integrated scheme that shows activities of simple, complex and end-stopped cells, (b) artistic combinations of selected activity maps that give an impression

Roberto Lam; João Rodrigues

367

Concurrent tonotopic processing streams in auditory cortex.  

PubMed

The basis for multiple representations of equivalent frequency ranges in auditory cortex was studied with physiological and anatomical methods. Our goal was to trace the convergence of thalamic, commissural, and corticocortical information upon two tonotopic fields in the cat, the primary auditory cortex (AI) and the anterior auditory field (AAF). Both fields are among the first cortical levels of processing. After neurophysiological mapping of characteristic frequency, we injected different retrograde tracers at separate, frequency-matched loci in AI and AAF. We found differences in their projections that support the notion of largely segregated parallel processing streams in the auditory thalamus and cerebral cortex. In each field, ipsilateral cortical input amounts to approximately 70% of the number of cells projecting to an isofrequency domain, while commissural and thalamic sources are each approximately 15%. Labeled thalamic and cortical neurons were concentrated in tonotopically predicted regions and in smaller loci far from their spectrally predicted positions. The few double-labeled thalamic neurons (<2%) are consistent with the hypothesis that information to AI and AAF travels along independent processing streams despite widespread regional overlap of thalamic input sources. Double labeling is also sparse in both the corticocortical and commissural systems ( approximately 1%), confirming their independence. The segregation of frequency-specific channels within thalamic and cortical systems is consistent with a model of parallel processing in auditory cortex. The global convergence of cells outside the targeted frequency domain in AI and AAF could contribute to context-dependent processing and to intracortical plasticity and reorganization. PMID:15028648

Lee, Charles C; Imaizumi, Kazuo; Schreiner, Christoph E; Winer, Jeffery A

2004-04-01

368

The neuropsychological impact of insular cortex lesions  

Microsoft Academic Search

Influential models based on an increasing body of neuroimaging evidence propose that insular cortex integrates cognitive, affective, sensory and autonomic information to create a consciously perceived, ‘feeling state.’ To appraise these models and evaluate interpretations of neuroimaging findings, the authors review evidence pertaining to the psychological and behavioural consequences of insula lesions. The authors focus on the emotional, perceptual, sensorimotor

Catherine L Jones; Jamie Ward; Hugo D Critchley

2010-01-01

369

Feature uncertainty activates anterior cingulate cortex.  

PubMed

In visual discrimination tasks, the relevant feature to discriminate is defined before stimulus presentation. In feature uncertainty tasks, a cue about the relevant feature is provided after stimulus offset. We used (15)O-butanol positron emission tomography (PET) in order to investigate brain activation during a feature uncertainty task. There was greater activity during the feature uncertainty task, compared with stimulus detection and discrimination of orientation and spatial frequency, in the lateral and medial prefrontal cortex, the cuneus, superior temporal and inferior parietal cortex, cortical motor areas, and the cerebellum. The most robust and consistent activation was observed in the dorsal anterior cingulate cortex (Brodmann area 32; x = 0 y = 16, z = 40). The insula, located near the claustrum (x = -38, y = 8, z = 4), was activated during the discrimination tasks compared with the feature uncertainty condition. These results suggest that the dorsal anterior cingulate cortex is important in feature uncertainty conditions, which include divided attention, expectancy under uncertainty, and cognitive monitoring. PMID:14689507

Kéri, Szabolcs; Decety, Jean; Roland, Per E; Gulyás, Balázs

2004-01-01

370

Auditory processing in primate cerebral cortex  

Microsoft Academic Search

Auditory information is relayed from the ventral nucleus of the medial geniculate complex to a core of three primary or primary-like areas of auditory cortex that are cochleotopically organized and highly responsive to pure tones. Auditory information is then distributed from the core areas to a surrounding belt of about seven areas that are less precisely cochleotopic and generally more

Jon H Kaas; Troy A Hackett; Mark Jude Tramo

1999-01-01

371

Parietal cortex: from sight to action  

Microsoft Academic Search

Recent findings have altered radically our thinking about the functional role of the parietal cortex. According to this view, the parietal lobe consists of a multiplicity of areas with specific connections to the frontal lobe. These areas, together with the frontal areas to which they are connected, mediate distinct sensorimotor transformations related to the control of hand, arm, eye or

Giacomo Rizzolatti; Leonardo Fogassi; Vittorio Gallese

1997-01-01

372

INTENTIONAL MAPS IN POSTERIOR PARIETAL CORTEX  

Microsoft Academic Search

? Abstract The posterior parietal cortex (PPC), historically believed to be a sensory structure, is now viewed as an area important for sensory-motor integration. Among its functions is the forming of intentions, that is, high-level cognitive plans for movement. There is a map of intentions within the PPC, with different subregions dedicated to the planning of eye movements, reaching movements,

Richard A. Andersen; Christopher A. Buneo

2002-01-01

373

The left parietal cortex and motor attention  

Microsoft Academic Search

The posterior parietal cortex, particularly in the right hemisphere, is crucially important for covert orienting; lesions impair the ability to disengage the focus of covert orienting attention from one potential saccade target to another (Posner, M. I. et al., Journal of Neuroscience, 1984, 4, 1863–1874). We have developed a task where precues allow subjects to covertly prepare subsequent cued hand

Matthew F. S. Rushworth; Philip D. Nixon; Shelley Renowden; Derick T. Wade; Richard E. Passingham

1997-01-01

374

Space Coding in Primate Posterior Parietal Cortex  

Microsoft Academic Search

Neuropsychological studies of patients with lesions of right frontal (premotor) or posterior parietal cortex often show severe impairments of attentive sensorimotor behavior. Such patients frequently manifest symptoms like hemispatial neglect or extinction. Interestingly, these behavioral deficits occur across different sensory modalities and are often organized in head- or body-centered coordinates. These neuropsychological data provide evidence for the existence of a

Frank Bremmer; Anja Schlack; Jean-René Duhamel; Werner Graf; Gereon R. Fink

2001-01-01

375

Whole cortex, 64 channel SQUID biomagnetometer system  

Microsoft Academic Search

The authors report on the development and testing of a novel, whole cortex, 64-channel superconducting quantum interference device (SQUID) biomagnetometer system operating in an unshielded environment. The essential features of this instrument, including the cryogenics system, the room-temperature digital electronics, and signal processing capabilities, are described. A noise cancellation scheme is incorporated which allows extraction of biomagnetic signals over the

J. Vrba; K. Betts; M. Burbank; T. Cheung; A. A. Fife; G. Haid; P. R. Kubik; S. Lee; J. McCubbin; J. McKay; D. McKenzie; P. Spear; B. Taylor; M. Tillotson; D. Cheyne; H. Weinberg

1993-01-01

376

Phonological Feature Representations in Auditory Cortex  

Microsoft Academic Search

Although phonemes are the smallest linguistic units that speakers are usually aware of, a good deal of linguistic evidence indicates that sub-phonemic features are the smallest building blocks of language. We present evidence from biomagnetic studies that indicate that representations of discrete phonological feature categories are available to left-hemisphere auditory cortex. Sequences of voiced (\\/bæ, dæ, gæ\\/) and voiceless (\\/pæ,

Colin Phillips; Thomas Pellathy

2000-01-01

377

Ventromedial Prefrontal Cortex Lesions and Motivational Internalism  

Microsoft Academic Search

This article discusses the argument by Roskies to the effect that ventromedial prefrontal cortex (VMPFC) patients are a living counterexample to motivational internalism. Motivational internalism is a philosophical position according to which moral judgments are accompanied by a particular motivational force that induces agents to act accordingly. Roskies takes into account a very strong version of motivational internalism and claims

Tommaso Bruni

2012-01-01

378

Graded persistent activity in entorhinal cortex neurons  

Microsoft Academic Search

Working memory represents the ability of the brain to hold externally or internally driven information for relatively short periods of time. Persistent neuronal activity is the elementary process underlying working memory but its cellular basis remains unknown. The most widely accepted hypothesis is that persistent activity is based on synaptic reverberations in recurrent circuits. The entorhinal cortex in the parahippocampal

Alexei V. Egorov; Bassam N. Hamam; Erik Fransén; Michael E. Hasselmo; Angel A. Alonso

2002-01-01

379

What does the retrosplenial cortex do?  

Microsoft Academic Search

The past decade has seen a transformation in research on the retrosplenial cortex (RSC). This cortical area has emerged as a key member of a core network of brain regions that underpins a range of cognitive functions, including episodic memory, navigation, imagination and planning for the future. It is now also evident that the RSC is consistently compromised in the

John P. Aggleton; Eleanor A. Maguire; Seralynne D. Vann

2009-01-01

380

Motor cortex inhibition induced by acoustic stimulation  

Microsoft Academic Search

The influence of the brainstem motor system on cerebral motor areas may play an important role in motor control in health and disease. A new approach to investigate this interaction in man is combining acoustic stimulation activating the startle system with transcranial magnetic stimulation (TMS) over the motor cortex. However, it is unclear whether the inhibition of TMS responses following

Andrea A. Kühn; Andrew Sharott; Thomas Trottenberg; Andreas Kupsch; Peter Brown

2004-01-01

381

Homeostatic Metaplasticity in the Human Somatosensory Cortex  

Microsoft Academic Search

Long-term potentiation (LTP) and long-term depression (LTD) are regulated by homeostatic control mechanisms to maintain synaptic strength in a physiological range. Although homeostatic metaplasticity has been demonstrated in the human motor cortex, little is known to which extent it operates in other cortical areas and how it links to behavior. Here we tested homeostatic interactions between two stimulation protocolspaired associative

Barbara Bliem; J. Florian M. Müller-dahlhaus; Hubert R. Dinse; Ulf Ziemann

2008-01-01

382

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

383

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

384

Eye Dominance in the Visual Cortex  

Microsoft Academic Search

The projection from the contralateral eye dominates the cat's visual cortex. Binocular neurones in any small region have their receptive fields more widely scattered over the ipsilateral retina than over the contralateral. Stereoscopic vision may depend on this difference in the two projections.

Colin Blakemore; John D. Pettigrew

1970-01-01

385

[Visceral field of the rat insular cortex].  

PubMed

Structural-functional organisation of the cortical insular area relating to processes of the visceral functions control, was analysed. Representation of gastrointestinal, respiratory, and cardiovascular systems in the area, is given. Sites of respective neuronal groups and specifics of their spatial organisation within the area, were found. The data obtained suggest a scheme of the rat insular cortex's visceral field. PMID:11195217

Bagaev, V A; Aleksandrov, V G

2000-11-01

386

Excitatory neuronal connectivity in the barrel cortex  

PubMed Central

Neocortical areas are believed to be organized into vertical modules, the cortical columns, and the horizontal layers 1–6. In the somatosensory barrel cortex these columns are defined by the readily discernible barrel structure in layer 4. Information processing in the neocortex occurs along vertical and horizontal axes, thereby linking individual barrel-related columns via axons running through the different cortical layers of the barrel cortex. Long-range signaling occurs within the neocortical layers but also through axons projecting through the white matter to other neocortical areas and subcortical brain regions. Because of the ease of identification of barrel-related columns, the rodent barrel cortex has become a prototypical system to study the interactions between different neuronal connections within a sensory cortical area and between this area and other cortical as well subcortical regions. Such interactions will be discussed specifically for the feed-forward and feedback loops between the somatosensory and the somatomotor cortices as well as the different thalamic nuclei. In addition, recent advances concerning the morphological characteristics of excitatory neurons and their impact on the synaptic connectivity patterns and signaling properties of neuronal microcircuits in the whisker-related somatosensory cortex will be reviewed. In this context, their relationship between the structural properties of barrel-related columns and their function as a module in vertical synaptic signaling in the whisker-related cortical areas will be discussed.

Feldmeyer, Dirk

2012-01-01

387

Efferent connections of the medial prefrontal cortex in the rabbit  

Microsoft Academic Search

The different cytoarchitectonic regions of the medial prefrontal cortex (mPFC) have recently been shown to play divergent\\u000a roles in associative learning in rabbits. To determine if these subareas of the mPFC, including areas 24 (anterior cingulate\\u000a cortex), 25 (infralimbic cortex), and 32 (prelimbic cortex) have differential efferent connections with other cortical and\\u000a subcortical areas in the rabbit, anterograde and retrograde

Shirley L. Buchanan; Richard H. Thompson; Brian L. Maxwell; D. A. Powell

1994-01-01

388

Cell Counts in Cerebral Cortex of an Autistic Patient.  

ERIC Educational Resources Information Center

|Numbers of neurons and glia were counted in the cerebral cortex of one case of autism and two age- and sex-matched controls. Cell counts were made in primary auditory cortex, Broca's speech area, and auditory association cortex. No consistent differences in cell density were found between brains of autistic and control patients. (Author/CL)|

Coleman, Paul D.; And Others

1985-01-01

389

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

390

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

391

Maps of space in human frontoparietal cortex.  

PubMed

Prefrontal cortex (PFC) and posterior parietal cortex (PPC) are neural substrates for spatial cognition. We here review studies in which we tested the hypothesis that human frontoparietal cortex may function as a priority map. According to priority map theory, objects or locations in the visual world are represented by neural activity that is proportional to their attentional priority. Using functional magnetic resonance imaging (fMRI), we first identified topographic maps in PFC and PPC as candidate priority maps of space. We then measured fMRI activity in candidate priority maps during the delay periods of a covert attention task, a spatial working memory task, and a motor planning task to test whether the activity depended on the particular spatial cognition. Our hypothesis was that some, but not all, candidate priority maps in PFC and PPC would be agnostic with regard to what was being prioritized, in that their activity would reflect the location in space across tasks rather than a particular kind of spatial cognition (e.g., covert attention). To test whether patterns of delay period activity were interchangeable during the spatial cognitive tasks, we used multivariate classifiers. We found that decoders trained to predict the locations on one task (e.g., working memory) cross-predicted the locations on the other tasks (e.g., covert attention and motor planning) in superior precentral sulcus (sPCS) and in a region of intraparietal sulcus (IPS2), suggesting that these patterns of maintenance activity may be interchangeable across the tasks. Such properties make sPCS in frontal cortex and IPS2 in parietal cortex viable priority map candidates, and suggest that these areas may be the human homologs of the monkey frontal eye field (FEF) and lateral intraparietal area (LIP). PMID:23603831

Jerde, Trenton A; Curtis, Clayton E

2013-04-18

392

Association Analysis of Variation in/Near FTO, CDKAL1, SLC30A8, HHEX, EXT2, IGF2BP2, LOC387761, and CDKN2B With Type 2 Diabetes and Related Quantitative Traits in Pima Indians  

PubMed Central

OBJECTIVE—In recent genome-wide association studies, variants in CDKAL1, SLC30A8, HHEX, EXT2, IGF2BP2, CDKN2B, LOC387761, and FTO were associated with risk for type 2 diabetes in Caucasians. We investigated the association of these single nucleotide polymorphisms (SNPs) and some additional tag SNPs with type 2 diabetes and related quantitative traits in Pima Indians. RESEARCH DESIGN AND METHODS—Forty-seven SNPs were genotyped in 3,501 Pima Indians informative for type 2 diabetes and BMI, among whom 370 had measures of quantitative traits. RESULTS—FTO provided the strongest evidence for replication, where SNPs were associated with type 2 diabetes (odds ratio = 1.20 per copy of the risk allele, P = 0.03) and BMI (P = 0.002). None of the other previously reported SNPs were associated with type 2 diabetes; however, associations were found between CDKAL1 and HHEX variants and acute insulin response (AIR), where the Caucasian risk alleles for type 2 diabetes were associated with reduced insulin secretion in normoglycemic Pima Indians. Multiallelic analyses of carrying risk alleles for multiple genes showed correlations between number of risk alleles and type 2 diabetes and impaired insulin secretion in normoglycemic subjects (P = 0.006 and 0.0001 for type 2 diabetes and AIR, respectively), supporting the hypothesis that many of these genes influence diabetes risk by affecting insulin secretion. CONCLUSIONS—Variation in FTO impacts BMI, but the implicated common variants in the other genes did not confer a significant risk for type 2 diabetes in Pima Indians. However, confidence intervals for their estimated effects were consistent with the small effects reported in Caucasians, and the multiallelic “genetic risk profile” identified in Caucasians is associated with diminished early insulin secretion in Pima Indians.

Rong, Rong; Hanson, Robert L.; Ortiz, Daniel; Wiedrich, Christopher; Kobes, Sayuko; Knowler, William C.; Bogardus, Clifton; Baier, Leslie J.

2009-01-01

393

Specificity and randomness in the visual cortex.  

PubMed

Research on the functional anatomy of visual cortical circuits has recently zoomed in from the macroscopic level to the microscopic. High-resolution functional imaging has revealed that the functional architecture of orientation maps in higher mammals is built with single-cell precision. By contrast, orientation selectivity in rodents is dispersed on visual cortex in a salt-and-pepper fashion, despite highly tuned visual responses. Recent studies of synaptic physiology indicate that there are disjoint subnetworks of interconnected cells in the rodent visual cortex. These intermingled subnetworks, described in vitro, may relate to the intermingled ensembles of cells tuned to different orientations, described in vivo. This hypothesis may soon be tested with new anatomic techniques that promise to reveal the detailed wiring diagram of cortical circuits. PMID:17720489

Ohki, Kenichi; Reid, R Clay

2007-08-27

394

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

395

Microglia in the cerebral cortex in autism.  

PubMed

We immunocytochemically identified microglia in fronto-insular (FI) and visual cortex (VC) in autopsy brains of well-phenotyped subjects with autism and matched controls, and stereologically quantified the microglial densities. Densities were determined blind to phenotype using an optical fractionator probe. In FI, individuals with autism had significantly more microglia compared to controls (p = 0.02). One such subject had a microglial density in FI within the control range and was also an outlier behaviorally with respect to other subjects with autism. In VC, microglial densities were also significantly greater in individuals with autism versus controls (p = 0.0002). Since we observed increased densities of microglia in two functionally and anatomically disparate cortical areas, we suggest that these immune cells are probably denser throughout cerebral cortex in brains of people with autism. PMID:22466688

Tetreault, Nicole A; Hakeem, Atiya Y; Jiang, Sue; Williams, Brian A; Allman, Elizabeth; Wold, Barbara J; Allman, John M

2012-12-01

396

Social Distance Evaluation in Human Parietal Cortex  

PubMed Central

Across cultures, social relationships are often thought of, described, and acted out in terms of physical space (e.g. “close friends” “high lord”). Does this cognitive mapping of social concepts arise from shared brain resources for processing social and physical relationships? Using fMRI, we found that the tasks of evaluating social compatibility and of evaluating physical distances engage a common brain substrate in the parietal cortex. The present study shows the possibility of an analytic brain mechanism to process and represent complex networks of social relationships. Given parietal cortex's known role in constructing egocentric maps of physical space, our present findings may help to explain the linguistic, psychological and behavioural links between social and physical space.

Yamakawa, Yoshinori; Kanai, Ryota; Matsumura, Michikazu; Naito, Eiichi

2009-01-01

397

Reconstructing Speech from Human Auditory Cortex  

PubMed Central

How the human auditory system extracts perceptually relevant acoustic features of speech is unknown. To address this question, we used intracranial recordings from nonprimary auditory cortex in the human superior temporal gyrus to determine what acoustic information in speech sounds can be reconstructed from population neural activity. We found that slow and intermediate temporal fluctuations, such as those corresponding to syllable rate, were accurately reconstructed using a linear model based on the auditory spectrogram. However, reconstruction of fast temporal fluctuations, such as syllable onsets and offsets, required a nonlinear sound representation based on temporal modulation energy. Reconstruction accuracy was highest within the range of spectro-temporal fluctuations that have been found to be critical for speech intelligibility. The decoded speech representations allowed readout and identification of individual words directly from brain activity during single trial sound presentations. These findings reveal neural encoding mechanisms of speech acoustic parameters in higher order human auditory cortex.

Pasley, Brian N.; David, Stephen V.; Mesgarani, Nima; Flinker, Adeen; Shamma, Shihab A.; Crone, Nathan E.; Knight, Robert T.; Chang, Edward F.

2012-01-01

398

Neural representations of contextual guidance in visual search of real-world scenes.  

PubMed

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

2013-05-01

399

Strategy Switching and the Rat Prefrontal Cortex  

Microsoft Academic Search

The prefrontal cortex (PFC) is important for cognitive flexibility - the PFC appears to be involved whenever a novel strategy\\u000a has to be adopted or a switch from an old to a new strategy is needed. A serial reversal (Acquisition-Reversal-Extinction)\\u000a task was used to study when and how the rat PFC is involved in various phases of this task. Each

Matthijs G. P. Feenstra; Jan P. C. de Bruin

400

Propagating Waves in Human Motor Cortex  

PubMed Central

Previous studies in non-human primates (NHPs) have shown that beta oscillations (15–30 Hz) of local field potentials (LFPs) in the arm/hand areas of primary motor cortex (MI) propagate as traveling waves across the cortex. These waves exhibited two stereotypical features across animals and tasks: (1) The waves propagated in two dominant modal directions roughly 180° apart, and (2) their propagation speed ranged from 10 to 35 cm/s. It is, however, unknown if such cortical waves occur in the human motor cortex. This study shows that the two properties of propagating beta waves are present in MI of a tetraplegic human patient while he was instructed to perform an instruction delay center-out task using a cursor controlled by the chin. Moreover, we show that beta waves are sustained and have similar properties whether the subject was engaged in the task or at rest. The directions of the successive sustained waves both in the human subject and a NHP subject tended to switch from one dominant mode to the other, and at least in the NHP subject the estimated distance traveled between successive waves traveling into and out of the central sulcus is consistent with the hypothesis of wave reflection between the border of motor and somatosensory cortices. Further, we show that the occurrence of the beta waves is not uniquely tied to periods of increased power in the beta frequency band. These results demonstrate that traveling beta waves in MI are a general phenomenon occurring in human as well as NHPs. Consistent with the NHP data, the dominant directions of the beta LFP waves in human aligned to the proximal to distal gradient of joint representations in MI somatotopy. This consistent finding of wave propagation may imply the existence of a hardwired organization of motor cortex that mediates this spatiotemporal pattern.

Takahashi, Kazutaka; Saleh, Maryam; Penn, Richard D.; Hatsopoulos, Nicholas G.

2011-01-01

401

The prefrontal cortex: categories, concepts and cognition  

Microsoft Academic Search

The ability to generalize behaviour-guiding principles and concepts from experience is key to intelligent, goal-directed behaviour. It allows us to deal efé ciently with a complex world and to adapt readily to novel situations. We review evidence that the prefrontal cortex—the cortical area that reaches its greatest elaboration in primates—plays a central part in acquiring and representing this information. The

Earl K. Miller; David J. Freedman; Jonathan D. Wallis

2002-01-01

402

Domain specificity in the primate prefrontal cortex  

Microsoft Academic Search

Experimental studies in nonhuman primates and functional imaging studies in humans have underlined the critical role played\\u000a by the prefrontal cortex (PFC) in working memory. However, the precise organization of the frontal lobes with respect to the\\u000a different types of information operated upon is a point of controversy, and several models of functional organizations have\\u000a been proposed. One model, developed

Lizabeth M. Romanski

2004-01-01

403

The Auditory Cortex: The Final Frontier  

Microsoft Academic Search

\\u000a The auditory cortex consists of 10–15 interconnected areas or fields whose neurons receive a modest input from the thalamus\\u000a and about 10–100 times more input from other auditory cortical areas and nonauditory cortical fields from the same and contralateral\\u000a hemisphere. Modeling this conglomerate as a black box functional network model is potentially doable (Stephan et al. 2000),\\u000a but that does

Jos J. Eggermont

404

Viscoelastic response of human hair cortex  

Microsoft Academic Search

The present study describes a new methodological approach which allows the separate analysis and quantitative determination\\u000a of the viscous and elastic components of human hair using a computerised experimental system. In a first series of experiments\\u000a subsequent to the estimation of the cross-sectional surface area of the cuticle, the cortex and the medulla, the viscoelastic\\u000a response of hair (considered as

G. Nikiforidis; C. Balas; D. Tsambaos

1992-01-01

405

Whole-brain haemodynamic after-effects of 1-Hz magnetic stimulation of the posterior superior temporal cortex during action observation.  

PubMed

The posterior superior temporal sulcus (pSTS) is active when observing biological motion. We investigated the functional connections of the pSTS node within the action observation network by measuring the after-effect of focal repetitive transcranial magnetic stimulation (rTMS) with whole-brain functional magnetic resonance imaging (fMRI). Participants received 1-Hz rTMS over the pSTS region for 10 min and underwent fMRI immediately after. While scanned, they were shown short video clips of a hand grasping an object (grasp clips) or moving next to it (control clips). rTMS-fMRI was repeated for four consecutive blocks. In two blocks we stimulated the left pSTS region and in the other two the right pSTS region. For each side TMS was applied with an effective intensity (95 % of motor threshold) or with ineffective intensity (50 % of motor threshold). Brain regions showing interactive effects of (clip type) × (TMS intensity) were identified in the lateral temporo-occipital cortex, in the anterior intraparietal region and in the ventral premotor cortex. Remote effects of rTMS were mostly limited to the stimulated hemisphere and consisted in an increase of blood oxygen level-dependent responses to grasp clips compared to control clips. We show that the pSTS occupies a pivotal relay position during observation of goal-directed actions. PMID:22772359

Arfeller, Carola; Schwarzbach, Jens; Ubaldi, Silvia; Ferrari, Paolo; Barchiesi, Guido; Cattaneo, Luigi

2012-07-08

406

Human left ventral premotor cortex mediates matching of hand posture to object use.  

PubMed

Visuomotor transformations for grasping have been associated with a fronto-parietal network in the monkey brain. The human homologue of the parietal monkey region (AIP) has been identified as the anterior part of the intraparietal sulcus (aIPS), whereas the putative human equivalent of the monkey frontal region (F5) is located in the ventral part of the premotor cortex (vPMC). Results from animal studies suggest that monkey F5 is involved in the selection of appropriate hand postures relative to the constraints of the task. In humans, the functional roles of aIPS and vPMC appear to be more complex and the relative contribution of each region to grasp selection remains uncertain. The present study aimed to identify modulation in brain areas sensitive to the difficulty level of tool object - hand posture matching. Seventeen healthy right handed participants underwent fMRI while observing pictures of familiar tool objects followed by pictures of hand postures. The task was to decide whether the hand posture matched the functional use of the previously shown object. Conditions were manipulated for level of difficulty. Compared to a picture matching control task, the tool object - hand posture matching conditions conjointly showed increased modulation in several left hemispheric regions of the superior and inferior parietal lobules (including aIPS), the middle occipital gyrus, and the inferior temporal gyrus. Comparison of hard versus easy conditions selectively modulated the left inferior frontal gyrus with peak activity located in its opercular part (Brodmann area (BA) 44). We suggest that in the human brain, vPMC/BA44 is involved in the matching of hand posture configurations in accordance with visual and functional demands. PMID:23936212

Vingerhoets, Guy; Nys, Jo; Honoré, Pieterjan; Vandekerckhove, Elisabeth; Vandemaele, Pieter

2013-07-30

407

Spatial processing in the primate auditory cortex.  

PubMed

Spatial localization of auditory stimuli is dependent on the cerebral cortex, yet it remains unclear how cortical activity gives rise to spatial percepts. It has recently been proposed that spatial information is processed serially within the primate auditory cortex, initially in the primary auditory cortex (AI) through the auditory areas caudal to AI, particularly the caudomedial (CM) and caudolateral fields, and onward to the parietal lobe. The activity of single neurons in AI and CM supports this hypothesis, where a greater percentage of CM neurons are sensitive to the spatial location of acoustic stimuli than AI neurons, and the spatial sensitivity of CM neurons extends across a broader range of the stimulus spectrum compared to AI neurons. Further, populations of CM neurons are better able to predict sound localization ability than are populations of AI neurons. We have recently explored the effects of stimulus intensity on both sound localization performance and the spatial sensitivity of auditory cortical neurons. The preliminary results of these experiments again indicate that spatial information is serially processed between AI and the caudal fields. The effects of visual stimulation on auditory localization have also been investigated. Under the appropriate circumstances, visual stimuli can "capture" the spatial location of auditory stimuli in both humans and monkeys. This perceptual illusion suggests that there is a plastic shift in auditory spatial perception. Where the representation of this shift resides is unknown, although two likely candidates are the multimodal regions of the parietal lobe and the superior temporal sulcus. PMID:11694723

Recanzone, G H

408

Exploring the pulvinar path to visual cortex.  

PubMed

The primary pathway for visual signals from the retina to cerebral cortex is through the lateral geniculate nucleus of the thalamus to primary visual cortex. A second visual pathway has been postulated to pass through the thalamic pulvinar nucleus and to project to multiple regions of visual cortex. We have explored this second visual pathway using a method that allows us to identify the inputs and outputs of pulvinar neurons. Specifically, we applied microstimulation in the superficial layers of superior colliculus (SC) to test for orthodromic activation of pulvinar neurons receiving input from SC. We also microstimulated the cortical motion area MT and tested for antidromic activation of pulvinar to identify neurons projecting to MT (and to determine the presence of orthodromic input back to pulvinar). In this initial report, we concentrate on two observations. First, we find that there are clusters of neurons in the pulvinar that receive input from SC along with neurons that project to MT or receive input from MT. Second, we find that neurons with input from SC have characteristics of the SC superficial layers: they respond to visual stimuli but do not discharge before saccadic eye movements. Neurons projecting to MT respond similarly to these SC-input neurons, while those receiving input from MT more frequently show directional selectivity as does MT. These findings indicate the visual nature of the signals conveyed in this pathway and shed light on the functional role of the thalamus in a possible second visual pathway. PMID:18718342

Berman, Rebecca A; Wurtz, Robert H

2008-01-01

409

Hemispherical map for the human brain cortex  

NASA Astrophysics Data System (ADS)

Understanding the function of the human brain cortex is a primary goal in human brain mapping. Methods to unfold and flatten the cortical surface for visualization and measurement have been described in previous literature; but comparison across multiple subjects is still difficult because of the lack of a standard mapping technique. We describe a new approach that maps each hemisphere of the cortex to a portion of a sphere in a standard way, making comparison of anatomy and function across different subjects possible. Starting with a three-dimensional magnetic resonance image of the brain, the cortex is segmented and represented as a triangle mesh. Defining a cut around the corpus collosum identifies the left and right hemispheres. Together, the two hemispheres are mapped to the complex plane using a conformal mapping technique. A Mobius transformation, which is conformal, is used to transform the points on the complex plane so that a projective transformation maps each brain hemisphere onto a spherical segment comprising a sphere with a cap removed. We determined the best size of the spherical cap by minimizing the relative area distortion between hemispherical maps and original cortical surfaces. The relative area distortion between the hemispherical maps and the original cortical surfaces for fifteen human brains is analyzed.

Tosun, Duygu; Prince, Jerry L.

2001-07-01

410

The motor cortex and amyotrophic lateral sclerosis.  

PubMed

On theoretical grounds, abnormalities of the motor cortex in patients with amyotrophic lateral sclerosis (ALS) could lead to anterograde ("dying-forward") transneuronal degeneration of the anterior horn cells as suggested by Charcot. Conversely, retrograde ("dying-back") degeneration of the corticospinal tracts could affect the motor cortex. Evidence derived from clinical, neuropathological, static, and functional imaging, and physiological studies, favors the occurrence of anterograde degeneration. It is hypothesized that transneuronal degeneration in ALS is an active excitotoxic process in which live but dysfunctional corticomotoneurons, originating in the primary motor cortex, drive the anterior horn cell into metabolic deficit. When this is marked, it will result in more rapid and widespread loss of lower motor neurons. In contrast, slow loss of corticomotoneurons, as occurs in primary lateral sclerosis (PLS), precludes excitotoxic drive and is incompatible with anterograde degeneration. Preservation of slow-conducting non-M1 direct pathways in PLS is not associated with excitotoxicity, and anterior horn cells survive for long periods of time. PMID:11268031

Eisen, A; Weber, M

2001-04-01

411

Verifying LOC based functional and performance constraints  

Microsoft Academic Search

In the era of billion-transistor design, it is critical to establish effective verification methodologies from the system level all the way down to the implementations. Assertion languages (e.g. IBM's Sugar2.0, Synopsys's OpenVera) have gained wide acceptance for specifying functional properties for automatic validation. They are, however, based on linear temporal logic (LTL), and hence have certain limitations. Logic of constraints

Xi Chen; Harry Hsieh; Felice Balarin; Yosinori Watanabe

2003-01-01

412

Chemical and biological differentiation of Cortex Phellodendri Chinensis and Cortex Phellodendri Amurensis.  

PubMed

The Chinese herbal drug Cortex Phellodendri is derived from two species of PHELLODENDRON, P. CHINENSIS Schneid. and P. AMURENSE Rupr. Traditionally, Cortex Phellodendri Chinensis (CPC) and Cortex Phellodendri Amurensis (CPA) are used interchangeably because they are believed to share the same clinical efficacy. Berberine has been believed to be the active ingredient of the herbs. However, recent studies have shown that the content of berberine is much higher in CPC than in CPA. Interestingly, the majority of researches deal with CPA, the one with lower content of berberine. These observations provoke us to reconsider the active ingredients of Cortex Phellodendri. In this study, two traditional usages (antidiarrheal and antibacterial) of Cortex Phellodendri were compared with the chemical analysis of the two herb species used in its formulation. The results suggest that berberine is one of the active ingredie