Artículos de revistas: "Lateral occipital cortex"

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Kaido, Takanobu, Tohru Hoshida, Toshiaki Taoka y Toshisuke Sakaki. "Retinotopy with coordinates of lateral occipital cortex in humans". Journal of Neurosurgery 101, n.º 1 (julio de 2004): 114–18. http://dx.doi.org/10.3171/jns.2004.101.1.0114.

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Object. The lateral occipital cortex in humans is known as the “extrastriate visual cortex.” It is, however, an unexplored field of research, and the anatomical nomenclature for its surface has still not been standardized. This study was designed to investigate whether the lateral occipital cortex in humans has retinotopic representation. Methods. Four right-handed patients with a diagnosis of intractable epilepsy from space-occupying lesions in the occipital lobe or epilepsy originating in the occipital lobe received permanently implanted subdural electrodes. Electrical cortical stimulation was applied directly applied to the brain through metal electrodes by using a biphasic stimulator. The location of each electrode was measured on a lateral skull x-ray study. Each patient considered a whiteboard with vertical and horizontal median lines. The patient was asked to look at the midpoint on the whiteboard. If a visual hallucination or illusion occurred, the patient recorded its outline, shape, color, location, and motion on white paper one tenth the size of, and with vertical and horizontal median lines similar to those on, the whiteboard. Polar angles and eccentricities of the midpoints of the phosphenes from the coordinate origin were measured on the paper. On stimulation of the lateral occipital lobe, 44 phosphenes occurred. All phosphenes were circular or dotted, with a diameter of approximately 1 cm, except one that was like a curtain in the peripheral end of the upper and lower visual fields on stimulation of the parietooccipital region. All phosphenes appeared in the visual field contralateral to the cerebral hemisphere stimulated. On stimulation of the lateral occipital lobe, 22 phosphenes moved centrifugally or toward a horizontal line. From three-dimensional scatterplots and contour maps of the polar angles and eccentricities in relation to the x-ray coordinates of the electrodes, one can infer that the lateral occipital cortex in humans has retinotopic representation. Conclusions. The authors found that phosphenes induced by electrical cortical stimulation of the lateral occipital cortex represent retinotopy. From these results one can assert that visual field representation with retinotopic relation exists in the extrastriate visual cortex.

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2

Appelbaum, L. G., J. M. Ales, B. Cottereau y A. M. Norcia. "Configural specificity of the lateral occipital cortex". Neuropsychologia 48, n.º 11 (septiembre de 2010): 3323–28. http://dx.doi.org/10.1016/j.neuropsychologia.2010.07.016.

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3

Tyler, C. W., L. T. Likova y A. R. Wade. "Properties of Object Processing in Lateral Occipital Cortex". Journal of Vision 4, n.º 8 (1 de agosto de 2004): 91. http://dx.doi.org/10.1167/4.8.91.

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4

Beer, Anton L., Tina Plank, Evangelia-Regkina Symeonidou, Georg Meyer y Mark W. Greenlee. "Combining fiber tracking and functional brain imaging for revealing brain networks involved in auditory–visual integration in humans". Seeing and Perceiving 25 (2012): 5. http://dx.doi.org/10.1163/187847612x646280.

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Previous functional magnetic resonance imaging (MRI) found various brain areas in the temporal and occipital lobe involved in integrating auditory and visual object information. Fiber tracking based on diffusion-weighted MRI suggested neuroanatomical connections between auditory cortex and sub-regions of the temporal and occipital lobe. However, the relationship between functional activity and white-matter tracks remained unclear. Here, we combined probabilistic tracking and functional MRI in order to reveal the structural connections related to auditory–visual object perception. Ten healthy people were examined by diffusion-weighted and functional MRI. During functional examinations they viewed either movies of lip or body movements, listened to corresponding sounds (phonological sounds or body action sounds), or a combination of both. We found that phonological sounds elicited stronger activity in the lateral superior temporal gyrus (STG) than body action sounds. Body movements elicited stronger activity in the lateral occipital cortex than lip movements. Functional activity in the phonological STG region and the lateral occipital body area were mutually modulated (sub-additive) by combined auditory–visual stimulation. Moreover, bimodal stimuli engaged a region in the posterior superior temporal sulcus (STS). Probabilistic tracking revealed white-matter tracks between the auditory cortex and sub-regions of the STS (anterior and posterior) and occipital cortex. The posterior STS region was also found to be relevant for auditory–visual object perception. The anterior STS region showed connections to the phonological STG area and to the lateral occipital body area. Our findings suggest that multisensory networks in the temporal lobe are best revealed by combining functional and structural measures.

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5

Taylor, John C. y Paul E. Downing. "Division of Labor between Lateral and Ventral Extrastriate Representations of Faces, Bodies, and Objects". Journal of Cognitive Neuroscience 23, n.º 12 (diciembre de 2011): 4122–37. http://dx.doi.org/10.1162/jocn_a_00091.

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The occipito-temporal cortex is strongly implicated in carrying out the high-level computations associated with vision. In human neuroimaging studies, focal regions are consistently found within this broad region that respond strongly and selectively to faces, bodies, or objects. A notable feature of these selective regions is that they are found in pairs. In the posterior-lateral occipito-temporal cortex, focal selectivity is found for faces (occipital face area), bodies (extrastriate body area), and objects (lateral occipital). These three areas are found bilaterally and at close quarters to each other. Likewise, in the ventro-medial occipito-temporal cortex, three similar category-selective regions are found, also in proximity to each other: for faces (fusiform face area), bodies (fusiform body area), and objects (posterior fusiform). Here we review some of the extensive evidence on the functional properties of these areas with two aims. First, we seek to identify principles that distinguish the posterior-lateral and ventro-medial clusters of selective regions but that apply generally within each cluster across the three stimulus kinds. Our review identifies and elaborates several principles by which these relationships hold. In brief, the posterior-lateral representations are more primitive, local, and stimulus-driven relative to the ventro-medial representations, which in contrast are more invariant to visual features, global, and linked to the subjective percept. Second, because the evidence base of studies that compare both posterior-lateral and ventro-medial representations of faces, bodies, and objects is still relatively small, we seek to provoke more cross-talk among the research strands that are traditionally separate. We identify several promising approaches for such future work.

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6

Carlson, Thomas A., Robert Rauschenberger y Frans A. J. Verstraten. "No Representation Without Awareness in the Lateral Occipital Cortex". Psychological Science 18, n.º 4 (abril de 2007): 298–302. http://dx.doi.org/10.1111/j.1467-9280.2007.01892.x.

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7

Larsson, J. y D. J. Heeger. "Two Retinotopic Visual Areas in Human Lateral Occipital Cortex". Journal of Neuroscience 26, n.º 51 (20 de diciembre de 2006): 13128–42. http://dx.doi.org/10.1523/jneurosci.1657-06.2006.

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8

Zeng, Hang, Gereon R. Fink y Ralph Weidner. "Visual Size Processing in Early Visual Cortex Follows Lateral Occipital Cortex Involvement". Journal of Neuroscience 40, n.º 22 (29 de abril de 2020): 4410–17. http://dx.doi.org/10.1523/jneurosci.2437-19.2020.

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9

Wurm, Moritz F., D. Yves Cramon y Ricarda I. Schubotz. "The Context–Object–Manipulation Triad: Cross Talk during Action Perception Revealed by fMRI". Journal of Cognitive Neuroscience 24, n.º 7 (julio de 2012): 1548–59. http://dx.doi.org/10.1162/jocn_a_00232.

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To recognize an action, an observer exploits information about the applied manipulation, the involved objects, and the context where the action occurs. Context, object, and manipulation information are hence expected to be tightly coupled in a triadic relationship (the COM triad hereafter). The current fMRI study investigated the hemodynamic signatures of reciprocal modulation in the COM triad. Participants watched short video clips of pantomime actions, that is, actions performed with inappropriate objects, taking place at compatible or incompatible contexts. The usage of pantomime actions enabled the disentanglement of the neural substrates of context–manipulation (CM) and context–object (CO) associations. There were trials in which (1) both manipulation and objects, (2) only manipulation, (3) only objects, or (4) neither manipulation nor objects were compatible with the context. CM compatibility effects were found in an action-related network comprising ventral premotor cortex, SMA, left anterior intraparietal sulcus, and bilateral occipito-temporal cortex. Conversely, CO compatibility effects were found bilaterally in lateral occipital complex. These effects interacted in subregions of the lateral occipital complex. An overlap of CM and CO effects was observed in the occipito-temporal cortex and the dorsal attention network, that is, superior frontal sulcus/dorsal premotor cortex and superior parietal lobe. Results indicate that contextual information is integrated into the analysis of actions. Manipulation and object information is linked by contextual associations as a function of co-occurrence in specific contexts. Activation of either CM or CO associations shifts attention to either action- or object-related relevant information.

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10

Read, Jenny C. A., Graeme P. Phillipson, Ignacio Serrano-Pedraza, A. David Milner y Andrew J. Parker. "Stereoscopic Vision in the Absence of the Lateral Occipital Cortex". PLoS ONE 5, n.º 9 (7 de septiembre de 2010): e12608. http://dx.doi.org/10.1371/journal.pone.0012608.

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11

Betts, L., S. Rainville y H. Wilson. "Adaptation to radial frequency patterns in the lateral occipital cortex". Journal of Vision 8, n.º 6 (29 de marzo de 2010): 723. http://dx.doi.org/10.1167/8.6.723.

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12

Scholte, H. S., S. Ghebreab, A. Smeulders y V. Lamme. "Lateral Occipital cortex responsive to correlation structure of natural images". Journal of Vision 10, n.º 7 (17 de agosto de 2010): 1363. http://dx.doi.org/10.1167/10.7.1363.

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13

Palejwala, Ali H., Kyle P. O’Connor, Panayiotis Pelargos, Robert G. Briggs, Camille K. Milton, Andrew K. Conner, Ty M. Milligan, Daniel L. O’Donoghue, Chad A. Glenn y Michael E. Sughrue. "Anatomy and white matter connections of the lateral occipital cortex". Surgical and Radiologic Anatomy 42, n.º 3 (16 de noviembre de 2019): 315–28. http://dx.doi.org/10.1007/s00276-019-02371-z.

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14

Erdogan, Goker, Quanjing Chen, Frank E. Garcea, Bradford Z. Mahon y Robert A. Jacobs. "Multisensory Part-based Representations of Objects in Human Lateral Occipital Cortex". Journal of Cognitive Neuroscience 28, n.º 6 (junio de 2016): 869–81. http://dx.doi.org/10.1162/jocn_a_00937.

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The format of high-level object representations in temporal-occipital cortex is a fundamental and as yet unresolved issue. Here we use fMRI to show that human lateral occipital cortex (LOC) encodes novel 3-D objects in a multisensory and part-based format. We show that visual and haptic exploration of objects leads to similar patterns of neural activity in human LOC and that the shared variance between visually and haptically induced patterns of BOLD contrast in LOC reflects the part structure of the objects. We also show that linear classifiers trained on neural data from LOC on a subset of the objects successfully predict a novel object based on its component part structure. These data demonstrate a multisensory code for object representations in LOC that specifies the part structure of objects.

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15

Wiggett, Alison J. y Paul E. Downing. "Representation of Action in Occipito-temporal Cortex". Journal of Cognitive Neuroscience 23, n.º 7 (julio de 2011): 1765–80. http://dx.doi.org/10.1162/jocn.2010.21552.

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A fundamental question for social cognitive neuroscience is how and where in the brain the identities and actions of others are represented. Here we present a replication and extension of a study by Kable and Chatterjee [Kable, J. W., & Chatterjee, A. Specificity of action representations in the lateral occipito-temporal cortex. Journal of Cognitive Neuroscience, 18, 1498–1517, 2006] examining the role of occipito-temporal cortex in these processes. We presented full-cue movies of actors performing whole-body actions and used fMRI to test for action- and identity-specific adaptation effects. We examined a series of functionally defined regions, including the extrastriate and fusiform body areas, the fusiform face area, the parahippocampal place area, the lateral occipital complex, the right posterior superior temporal sulcus, and motion-selective area hMT+. These regions were analyzed with both standard univariate measures as well as multivoxel pattern analyses. Additionally, we performed whole-brain tests for significant adaptation effects. We found significant action-specific adaptation in many areas, but no evidence for identity-specific adaptation. We argue that this finding could be explained by differences in the familiarity of the stimuli presented: The actions shown were familiar but the actors performing the actions were unfamiliar. However, in contrast to previous findings, we found that the action adaptation effect could not be conclusively tied to specific functionally defined regions. Instead, our results suggest that the adaptation to previously seen actions across identities is a widespread effect, evident across lateral and ventral occipito-temporal cortex.

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16

Silvanto, J., D. S. Schwarzkopf, S. Gilaie-Dotan y G. Rees. "Differing causal roles for lateral occipital cortex and occipital face area in invariant shape recognition". European Journal of Neuroscience 32, n.º 1 (28 de junio de 2010): 165–71. http://dx.doi.org/10.1111/j.1460-9568.2010.07278.x.

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Kable, Joseph W., Jessica Lease-Spellmeyer y Anjan Chatterjee. "Neural Substrates of Action Event Knowledge". Journal of Cognitive Neuroscience 14, n.º 5 (1 de julio de 2002): 795–805. http://dx.doi.org/10.1162/08989290260138681.

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Human concepts can be roughly divided into entities (prototypically referred to in language by nouns) and events (prototypically referred to in language by verbs). While much work in cognitive neuroscience has investigated how the brain represents different categories of entities, less attention has been given to the more basic distinction between entities and events. We used functional magnetic resonance imaging to examine brain activity while subjects performed a conceptual matching task that required them to access knowledge of objects and actions, using either pictures or words. Since action events involve movement through space, we hypothesized that accessing knowledge of actions would cause greater activation in brain regions involved in motion or spatial processing. In comparison to objects, accessing knowledge of actions through pictures was accompanied by increased activity bilaterally in the human MT/MST and nearby regions of the lateral temporal cortex. Accessing knowledge of actions through words activated areas just anterior and dorsal to area MT/MST on the left, within the posterior aspect of the middle and superior temporal gyri. We propose that the lateral occipital temporal cortex contains a mosaic of neural regions that processes different kinds of motion, ranging from the perception of objects moving in the world to the conception of movement implied in action verbs. The lateral occipital temporal cortex mediates the perceptual and conceptual features of action events, similar to the way that the ventral occipital temporal cortex processes the perceptual and conceptual features of entities.

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18

Plewan, Thorsten, Ralph Weidner, Simon B. Eickhoff y Gereon R. Fink. "Ventral and Dorsal Stream Interactions during the Perception of the Müller-Lyer Illusion: Evidence Derived from fMRI and Dynamic Causal Modeling". Journal of Cognitive Neuroscience 24, n.º 10 (octubre de 2012): 2015–29. http://dx.doi.org/10.1162/jocn_a_00258.

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The human visual system converts identically sized retinal stimuli into different-sized perceptions. For instance, the Müller-Lyer illusion alters the perceived length of a line via arrows attached to its end. The strength of this illusion can be expressed as the difference between physical and perceived line length. Accordingly, illusion strength reflects how strong a representation is transformed along its way from a retinal image up to a conscious percept. In this study, we investigated changes of effective connectivity between brain areas supporting these transformation processes to further elucidate the neural underpinnings of optical illusions. The strength of the Müller-Lyer illusion was parametrically modulated while participants performed either a spatial or a luminance task. Lateral occipital cortex and right superior parietal cortex were found to be associated with illusion strength. Dynamic causal modeling was employed to investigate putative interactions between ventral and dorsal visual streams. Bayesian model selection indicated that a model that involved bidirectional connections between dorsal and ventral stream areas most accurately accounted for the underlying network dynamics. Connections within this network were partially modulated by illusion strength. The data further suggest that the two areas subserve differential roles: Whereas lateral occipital cortex seems to be directly related to size transformation processes, activation in right superior parietal cortex may reflect subsequent levels of processing, including task-related supervisory functions. Furthermore, the data demonstrate that the observer's top–down settings modulate the interactions between lateral occipital and superior parietal regions and thereby influence the effect of illusion strength.

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19

Cattaneo, Zaira, Silvia Bona, Andrea Ciricugno y Juha Silvanto. "The chronometry of symmetry detection in the lateral occipital (LO) cortex". Neuropsychologia 167 (marzo de 2022): 108160. http://dx.doi.org/10.1016/j.neuropsychologia.2022.108160.

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20

Sayres, Rory y Kalanit Grill-Spector. "Relating Retinotopic and Object-Selective Responses in Human Lateral Occipital Cortex". Journal of Neurophysiology 100, n.º 1 (julio de 2008): 249–67. http://dx.doi.org/10.1152/jn.01383.2007.

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What is the relationship between retinotopy and object selectivity in human lateral occipital (LO) cortex? We used functional magnetic resonance imaging (fMRI) to examine sensitivity to retinal position and category in LO, an object-selective region positioned posterior to MT along the lateral cortical surface. Six subjects participated in phase-encoded retinotopic mapping experiments as well as block-design experiments in which objects from six different categories were presented at six distinct positions in the visual field. We found substantial position modulation in LO using standard nonobject retinotopic mapping stimuli; this modulation extended beyond the boundaries of visual field maps LO-1 and LO-2. Further, LO showed a pronounced lower visual field bias: more LO voxels represented the lower contralateral visual field, and the mean LO response was higher to objects presented below fixation than above fixation. However, eccentricity effects produced by retinotopic mapping stimuli and objects differed. Whereas LO voxels preferred a range of eccentricities lying mostly outside the fovea in the retinotopic mapping experiment, LO responses were strongest to foveally presented objects. Finally, we found a stronger effect of position than category on both the mean LO response, as well as the distributed response across voxels. Overall these results demonstrate that retinal position exhibits strong effects on neural response in LO and indicates that these position effects may be explained by retinotopic organization.

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21

Mullin, C. y J. Steeves. "Transcranial magnetic stimulation to lateral occipital cortex disrupts object ensemble processing". Journal of Vision 11, n.º 11 (23 de septiembre de 2011): 890. http://dx.doi.org/10.1167/11.11.890.

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22

Guo, Jiahui, Tirta Susilo y Bradley Duchaine. "Decreased activation to faces in lateral occipital cortex in acquired prosopagnosia". Journal of Vision 15, n.º 12 (1 de septiembre de 2015): 1204. http://dx.doi.org/10.1167/15.12.1204.

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23

Sayres, R. y K. Grill-Spector. "Retinal position and object category effects in human lateral occipital cortex". Journal of Vision 8, n.º 6 (2 de abril de 2010): 82. http://dx.doi.org/10.1167/8.6.82.

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24

Sathian, K. "Analysis of haptic information in the cerebral cortex". Journal of Neurophysiology 116, n.º 4 (1 de octubre de 2016): 1795–806. http://dx.doi.org/10.1152/jn.00546.2015.

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

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25

Silvanto, J., D. S. Schwarzkopf, S. Gilaie-Dotan, G. D. Geraint y G. Rees. "State-dependent TMS reveals rotation-invariant shape representations in Lateral Occipital Cortex and Occipital Face Area". Journal of Vision 10, n.º 7 (13 de agosto de 2010): 1011. http://dx.doi.org/10.1167/10.7.1011.

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26

Batista, Alana X., Paulo R. Bazán, Adriana B. Conforto, Maria da Graça M. Martin, Sharon S. Simon, Benjamin Hampstead, Eberval Gadelha Figueiredo y Eliane C. Miotto. "Effects of Mnemonic Strategy Training on Brain Activity and Cognitive Functioning of Left-Hemisphere Ischemic Stroke Patients". Neural Plasticity 2019 (9 de mayo de 2019): 1–16. http://dx.doi.org/10.1155/2019/4172569.

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Memory dysfunction is one of the main cognitive impairments caused by stroke, especially associative memory. Therefore, cognitive training, such as face-name mnemonic strategy training, could be an important intervention for this group of patients. The goal of this study was to evaluate the behavioral effects of face-name mnemonic strategy training, along with the neural substrate behind these effects, in the left frontoparietal lobe stroke patients. Volunteers underwent 2 sessions of functional magnetic resonance imaging (fMRI) during face-name association task: one prior and the other after the cognitive training. The fMRI followed a block design task with three active conditions: trained face-name pairs, untrained face-name pairs, and a couple of repeated face-name pairs. Prior to each fMRI session, volunteers underwent neuropsychological assessment. Training resulted in better performance on delayed memory scores of HVLT-R, and on recognition on a generalization strategy task, as well as better performance in the fMRI task. Also, trained face-name pairs presented higher activation after training in default-mode network regions, such as the posterior cingulate cortex, precuneus, and angular gyrus, as well as in lateral occipital and temporal regions. Similarly, untrained face-name pairs also showed a nonspecific training effect in the right superior parietal cortex, right supramarginal gyrus, anterior intraparietal sulcus, and lateral occipital cortex. A correlation between brain activation and task performance was also found in the angular gyrus, superior parietal cortex, anterior intraparietal sulcus, and lateral occipital cortex. In conclusion, these results suggest that face-name mnemonic strategy training has the potential to improve memory performance and to foster brain activation changes, by the recruitment of contralesional areas from default-mode, frontoparietal, and dorsal attention networks as a possible compensation mechanism.

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Dormal, Giulia, Maxime Pelland, Mohamed Rezk, Esther Yakobov, Franco Lepore y Olivier Collignon. "Functional Preference for Object Sounds and Voices in the Brain of Early Blind and Sighted Individuals". Journal of Cognitive Neuroscience 30, n.º 1 (enero de 2018): 86–106. http://dx.doi.org/10.1162/jocn_a_01186.

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Sounds activate occipital regions in early blind individuals. However, how different sound categories map onto specific regions of the occipital cortex remains a matter of debate. We used fMRI to characterize brain responses of early blind and sighted individuals to familiar object sounds, human voices, and their respective low-level control sounds. In addition, sighted participants were tested while viewing pictures of faces, objects, and phase-scrambled control pictures. In both early blind and sighted, a double dissociation was evidenced in bilateral auditory cortices between responses to voices and object sounds: Voices elicited categorical responses in bilateral superior temporal sulci, whereas object sounds elicited categorical responses along the lateral fissure bilaterally, including the primary auditory cortex and planum temporale. Outside the auditory regions, object sounds also elicited categorical responses in the left lateral and in the ventral occipitotemporal regions in both groups. These regions also showed response preference for images of objects in the sighted group, thus suggesting a functional specialization that is independent of sensory input and visual experience. Between-group comparisons revealed that, only in the blind group, categorical responses to object sounds extended more posteriorly into the occipital cortex. Functional connectivity analyses evidenced a selective increase in the functional coupling between these reorganized regions and regions of the ventral occipitotemporal cortex in the blind group. In contrast, vocal sounds did not elicit preferential responses in the occipital cortex in either group. Nevertheless, enhanced voice-selective connectivity between the left temporal voice area and the right fusiform gyrus were found in the blind group. Altogether, these findings suggest that, in the absence of developmental vision, separate auditory categories are not equipotent in driving selective auditory recruitment of occipitotemporal regions and highlight the presence of domain-selective constraints on the expression of cross-modal plasticity.

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Hasson, Uri, Galia Avidan, Leon Y. Deouell, Shlomo Bentin y Rafael Malach. "Face-selective Activation in a Congenital Prosopagnosic Subject". Journal of Cognitive Neuroscience 15, n.º 3 (1 de abril de 2003): 419–31. http://dx.doi.org/10.1162/089892903321593135.

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Congenital prosopagnosia is a severe impairment in face identification manifested from early childhood in the absence of any evident brain lesion. In this study, we used fMRI to compare the brain activity elicited by faces in a congenital prosopagnosic subject (YT) relative to a control group of 12 subjects in an attempt to shed more light on the nature of the brain mechanisms subserving face identification. The face-related activation pattern of YT in the ventral occipito-temporal cortex was similar to that observed in the control group on several parameters: anatomical location, activation profiles, and hemispheric laterality. In addition, using a modified vase – face illusion, we found that YT's brain activity in the face-related regions manifested global grouping processes. However, subtle differences in the degree of selectivity between objects and faces were observed in the lateral occipital cortex. These data suggest that face-related activation in the ventral occipito-temporal cortex, although necessary, might not be sufficient by itself for normal face identification.

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Bentley, Paul, Patrik Vuilleumier, Christiane M. Thiel, Jon Driver y Raymond J. Dolan. "Effects of Attention and Emotion on Repetition Priming and Their Modulation by Cholinergic Enhancement". Journal of Neurophysiology 90, n.º 2 (agosto de 2003): 1171–81. http://dx.doi.org/10.1152/jn.00776.2002.

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We examined whether behavioral and neural effects of repeating faces are modulated by independent factors of selective attention, emotion, and cholinergic enhancement, during functional MRI. Face repetition occurred either between task-relevant (spatially attended) or task-irrelevant (unattended) stimuli; faces could be fearful or neutral; subjects received either placebo or physostigmine. Under placebo, a reaction time advantage occurred with repetition (i.e., priming) that did not differ between levels of attention, but was attenuated with emotion. Inferior temporo-occipital cortex demonstrated repetition decreases to both attended and unattended faces, and showed either equivalent or greater repetition decreases with emotional compared with neutral faces. By contrast, repetition decreases were attenuated for emotional relative to neutral faces in lateral orbitofrontal cortex. These results distinguish automatic repetition effects in sensory cortical regions from repetition effects modulated by emotion in orbitofrontal cortex, which parallel behavioral effects. Under physostigmine, unlike placebo, behavioral repetition effects were seen selectively for attended faces only, whereas emotional faces no longer impaired priming. Physostigmine enhanced repetition decreases in inferior occipital cortex selectively for attended faces, and reversed the emotional interaction with repetition in lateral orbitofrontal cortex. Thus we show that cholinergic enhancement both augments a neural signature of priming and modulates the effects of attention and emotion on behavioral and neural consequences of repetition.

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Demeyere, Nele, Pia Rotshtein y Glyn W. Humphreys. "The Neuroanatomy of Visual Enumeration: Differentiating Necessary Neural Correlates for Subitizing versus Counting in a Neuropsychological Voxel-based Morphometry Study". Journal of Cognitive Neuroscience 24, n.º 4 (abril de 2012): 948–64. http://dx.doi.org/10.1162/jocn_a_00188.

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This study is the first to assess lesion–symptom relations for subitizing and counting impairments in a large sample of neuropsychological patients (41 patients) using an observer-independent voxel-based approach. We tested for differential effects of enumerating small versus large numbers of items while controlling for hemianopia and visual attention deficits. Overall impairments in the enumeration of any numbers (small or large) were associated with an extended network, including bilateral occipital and fronto-parietal regions. Within this network, severe impairments in accuracy when enumerating small sets of items (in the subitizing range) were associated with damage to the left posterior occipital cortex, bilateral lateral occipital and right superior frontal cortices. Lesions to the right calcarine extending to the precuneus led to patients serially counting even small numbers of items (indicated by a steep response slope), again demonstrating an impaired subitizing ability. In contrast, impairments in counting large numerosities were associated with damage to the left intraparietal sulcus. The data support the argument for some distinctive processes and neural areas necessary to support subitization and counting with subitizing relying on processes of posterior occipital cortex and with counting associated with processing in the parietal cortex.

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Pundik, Svetlana, Aleka Scoco, Margaret Skelly, Jessica P. McCabe y Janis J. Daly. "Greater Cortical Thickness Is Associated With Enhanced Sensory Function After Arm Rehabilitation in Chronic Stroke". Neurorehabilitation and Neural Repair 32, n.º 6-7 (junio de 2018): 590–601. http://dx.doi.org/10.1177/1545968318778810.

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Objective. Somatosensory function is critical to normal motor control. After stroke, dysfunction of the sensory systems prevents normal motor function and degrades quality of life. Structural neuroplasticity underpinnings of sensory recovery after stroke are not fully understood. The objective of this study was to identify changes in bilateral cortical thickness (CT) that may drive recovery of sensory acuity. Methods. Chronic stroke survivors (n = 20) were treated with 12 weeks of rehabilitation. Measures were sensory acuity (monofilament), Fugl-Meyer upper limb and CT change. Permutation-based general linear regression modeling identified cortical regions in which change in CT was associated with change in sensory acuity. Results. For the ipsilesional hemisphere in response to treatment, CT increase was significantly associated with sensory improvement in the area encompassing the occipital pole, lateral occipital cortex (inferior and superior divisions), intracalcarine cortex, cuneal cortex, precuneus cortex, inferior temporal gyrus, occipital fusiform gyrus, supracalcarine cortex, and temporal occipital fusiform cortex. For the contralesional hemisphere, increased CT was associated with improved sensory acuity within the posterior parietal cortex that included supramarginal and angular gyri. Following upper limb therapy, monofilament test score changed from 45.0 ± 13.3 to 42.6 ± 12.9 mm ( P = .063) and Fugl-Meyer score changed from 22.1 ± 7.8 to 32.3 ± 10.1 ( P < .001). Conclusions. Rehabilitation in the chronic stage after stroke produced structural brain changes that were strongly associated with enhanced sensory acuity. Improved sensory perception was associated with increased CT in bilateral high-order association sensory cortices reflecting the complex nature of sensory function and recovery in response to rehabilitation.

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32

Nakao, Naoyuki. "Retractorless surgery for a pineal region tumor through an occipital transtentorial approach". Neurosurgical Focus 40, videosuppl1 (enero de 2016): 1. http://dx.doi.org/10.3171/2016.1.focusvid.15412.

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This video demonstrates surgical techniques of the occipital transtentorial approach to a pineal region tumor without using a fixed brain retractor, which may cause functional impairment or even tissue injury to the occipital visual cortex. There are several ways to facilitate retractorless surgery through this approach. A lateral-semiprone positioning of the patient can induce gravity retraction. The brain is relaxed by draining CSF fluid through lumbar drainage or lateral ventricular tap in the case of obstructive hydrocephalus. Dynamic retraction with handheld instruments after extensive dissection of the deep venous system, including basal veins, can provide a sufficient working space.The video can be found here: https://youtu.be/kQvEHiNcRow.

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Bona, Silvia, Zaira Cattaneo y Juha Silvanto. "The Causal Role of the Occipital Face Area (OFA) and Lateral Occipital (LO) Cortex in Symmetry Perception". Journal of Neuroscience 35, n.º 2 (14 de enero de 2015): 731–38. http://dx.doi.org/10.1523/jneurosci.3733-14.2015.

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Aly, Mariam, Charan Ranganath y Andrew P. Yonelinas. "Neural Correlates of State- and Strength-based Perception". Journal of Cognitive Neuroscience 26, n.º 4 (abril de 2014): 792–809. http://dx.doi.org/10.1162/jocn_a_00532.

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Perceptual judgments can be based on two kinds of information: state-based perception of specific, detailed visual information, or strength-based perception of global or relational information. State-based perception is discrete in the sense that it either occurs or fails, whereas strength-based perception is continuously graded from weak to strong. The functional characteristics of these types of perception have been examined in some detail, but whether state- and strength-based perception are supported by different brain regions has been largely unexplored. A consideration of empirical work and recent theoretical proposals suggests that parietal and occipito-temporal regions may be differentially associated with state- and strength-based signals, respectively. We tested this parietal/occipito-temporal state/strength hypothesis using fMRI and a visual perception task that allows separation of state- and strength-based perception. Participants made same/different judgments on pairs of faces and scenes using a 6-point confidence scale where “6” responses indicated a state of perceiving specific details that had changed, and “1” to “5” responses indicated judgments based on varying strength of relational match/mismatch. Regions in the lateral and medial posterior parietal cortex (supramarginal gyrus, posterior cingulate cortex, and precuneus) were sensitive to state-based perception and were not modulated by varying levels of strength-based perception. In contrast, bilateral fusiform gyrus activation was increased for strength-based “different” responses compared with misses and did not show state-based effects. Finally, the lateral occipital complex showed increased activation for state-based responses and additionally showed graded activation across levels of strength-based perception. These results offer support for a state/strength distinction between parietal and temporal regions, with the lateral occipital complex at the intersection of state- and strength-based processing.

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Dricot, Laurence, Bettina Sorger, Christine Schiltz, Rainer Goebel y Bruno Rossion. "Evidence for Individual Face Discrimination in Non-Face Selective Areas of the Visual Cortex in Acquired Prosopagnosia". Behavioural Neurology 19, n.º 1-2 (2008): 75–79. http://dx.doi.org/10.1155/2008/561476.

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Two areas in the human occipito-temporal cortex respond preferentially to faces: ‘the fusiform face area’ (‘FFA’) and the ‘occipital face area’ (‘OFA’). However, it is unclear whether these areas have an exclusive role in processing faces, or if sub-maximal responses in other visual areas such as the lateral occipital complex (LOC) are also involved. To clarify this issue, we tested a brain-damaged patient (PS) presenting a face-selective impairment with functional magnetic resonance imaging (fMRI). The right hemisphere lesion of the prosoagnosic patient encompasses the ‘OFA’ but preserves the ‘FFA’ and LOC [14,16]. Using fMRI-adaptation, we found a larger response to different faces than repeated faces in the ventral part of the LOC both for normals and the patient, next to her right hemisphere lesion. This observation indicates that following prosopagnosia, areas that do not respond preferentially to faces such as the ventral part of the LOC (vLOC) may still be recruited to subtend residual perception of individual faces.

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Heun, Reinhard, Frank Jessen, Uwe Klose, Michael Erb, Dirk-Oliver Granath y Wolfgang Grodd. "Response-related fMRI of veridical and false recognition of words". European Psychiatry 19, n.º 1 (enero de 2004): 42–52. http://dx.doi.org/10.1016/j.eurpsy.2003.09.005.

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AbstractObjectives. – Studies on the relation between local cerebral activation and retrieval success usually compared high and low performance conditions, and thus showed performance-related activation of different brain areas. Only a few studies directly compared signal intensities of different response categories during retrieval. During verbal recognition, we recently observed increased parieto-occipital activation related to false alarms. The present study intends to replicate and extend this observation by investigating common and differential activation by veridical and false recognition.Methods. – Fifteen healthy volunteers performed a verbal recognition paradigm using 160 learned target and 160 new distracter words. The subjects had to indicate whether they had learned the word before or not. Echo-planar MRI of blood-oxygen-level-dependent signal changes was performed during this recognition task. Words were classified post hoc according to the subjects’ responses, i.e. hits, false alarms, correct rejections and misses. Response-related fMRI-analysis was used to compare activation associated with the subjects’ recognition success, i.e. signal intensities related to the presentation of words were compared by the above-mentioned four response types.Results. – During recognition, all word categories showed increased bilateral activation of the inferior frontal gyrus, the inferior temporal gyrus, the occipital lobe and the brainstem in comparison with the control condition. Hits and false alarms activated several areas including the left medial and lateral parieto-occipital cortex in comparison with subjectively unknown items, i.e. correct rejections and misses. Hits showed more pronounced activation in the medial, false alarms in the lateral parts of the left parieto-occipital cortex.Conclusions. – Veridical and false recognition show common as well as different areas of cerebral activation in the left parieto-occipital lobe: increased activation of the medial parietal cortex by hits may correspond to true recognition, increased activation of the parieto-occipital cortex by false alarms may correspond to familiarity decisions. Further studies are needed to investigate the reasons for false decisions in healthy subjects and patients with memory problems.

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Li, Kaiming, John A. Sweeney y Xiaoping P. Hu. "Context-dependent dynamic functional connectivity alteration of lateral occipital cortex in schizophrenia". Schizophrenia Research 220 (junio de 2020): 201–9. http://dx.doi.org/10.1016/j.schres.2020.03.020.

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Eštočinová, Jana, Emanuele Lo Gerfo, Chiara Della Libera, Leonardo Chelazzi y Elisa Santandrea. "Augmenting distractor filtering via transcranial magnetic stimulation of the lateral occipital cortex". Cortex 84 (noviembre de 2016): 63–79. http://dx.doi.org/10.1016/j.cortex.2016.08.012.

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Harley, E. M., W. B. Pope, J. P. Villablanca, J. Mumford, R. Suh, J. C. Mazziotta, D. Enzmann y S. A. Engel. "Engagement of Fusiform Cortex and Disengagement of Lateral Occipital Cortex in the Acquisition of Radiological Expertise". Cerebral Cortex 19, n.º 11 (25 de marzo de 2009): 2746–54. http://dx.doi.org/10.1093/cercor/bhp051.

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40

Dennis, M. M., L. K. Pearce, R. W. Norrdin y E. J. Ehrhart. "Bacterial Meningoencephalitis and Ventriculitis Due to Migrating Plant Foreign Bodies in Three Dogs". Veterinary Pathology 42, n.º 6 (noviembre de 2005): 840–44. http://dx.doi.org/10.1354/vp.42-6-840.

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Regional suppurative meningoencephalitis and ventriculitis of variable chronicity was diagnosed in three young dogs residing in Colorado. Grass awns were grossly identified in the right occipital cortex of one dog and in the right lateral ventricle of another. Intralesional plant material was microscopically evident in the dura mater overlying the right occipital cortex of the third dog. One grass awn was identified as a floret of Hordeum jabatum. In each case, aerobic culture of brain tissue identified multiple isolates of bacteria. The dogs presented with clinically variable, rapidly progressive neurologic dysfunction, including tetraplegia, depressed mentation, and episodic extensor rigidity, ataxia, circling, stupor, vocalization, and head-pressing. Encephalitis due to bacteria introduced from migrating plant foreign material is a potential sequela of intranasal, periocular, or pharyngeal foreign bodies.

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41

Tatlı, S. Z., E. Özkan, M. Araz, M. İ. Erden y V. Şentürk Cankorur. "Evaluation of Brain Functions in Conversion Disorder with PET/MRI". European Psychiatry 65, S1 (junio de 2022): S220. http://dx.doi.org/10.1192/j.eurpsy.2022.573.

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Introduction Since there is no objective criteria, unique clinical symptom or laboratory test to make the diagnosis of conversion disorder; its diagnosis and treatment is challenging which leads to a poor prognosis. Objectives The aim of this study is to investigate the brain metabolic activity of patients with conversion disorder with PET/MRI. Methods 12 conversion disorder patients were included. Somatosensory Amplification Scale, Somatoform Dissociation Scale, Patient Health Questionnaire-15, Toronto Alexithymia Scale were filled in by the participants. Neurological, mental status examinations, Wechsler Adult Intelligence Scale-Revised Form (WAIS-R) and brain F18-FDG-PET/MRI were performed. Structured Clinical Interview for DSM-5, Hamilton Depression and Anxiety Scales were administered. Results 83% of the patients were female, the mean age was 33 years and average education period was 10,2 years. WAIS-R total scores were consistent with low avarage intelligence level.Cerebral hypermetabolism was detected in the primary visual cortex. Average regional brain metabolic activity had a tendency to increase in bilateral prefrontal, right sensorimotor (SM),cingulate,right inferior parietal,occipital lateral,right temporal lateral cortices and cerebellum. Each region was metabolically correlated with the homologous contralateral regions. Significant correlations in the same direction was found between frontal and occipital lateral & primary visual cortices; cerebellum and left sensorimotor cortex; anterior cingulate cortex(ACC) and superior parietal cortex & cerebellum. No correlations were found between ACC and left SM cortex. Conclusions Findings of our study indicate that there are moderate changes in regional brain metabolic activities and inter-regional correlations in patients with conversion disorder. In order to confirm these findings, furter functional neuroimaging studies are needed. Disclosure No significant relationships.

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42

Vermaercke, Ben, Florian J. Gerich, Ellen Ytebrouck, Lutgarde Arckens, Hans P. Op de Beeck y Gert Van den Bergh. "Functional specialization in rat occipital and temporal visual cortex". Journal of Neurophysiology 112, n.º 8 (15 de octubre de 2014): 1963–83. http://dx.doi.org/10.1152/jn.00737.2013.

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Recent studies have revealed a surprising degree of functional specialization in rodent visual cortex. Anatomically, suggestions have been made about the existence of hierarchical pathways with similarities to the ventral and dorsal pathways in primates. Here we aimed to characterize some important functional properties in part of the supposed “ventral” pathway in rats. We investigated the functional properties along a progression of five visual areas in awake rats, from primary visual cortex (V1) over lateromedial (LM), latero-intermediate (LI), and laterolateral (LL) areas up to the newly found lateral occipito-temporal cortex (TO). Response latency increased >20 ms from areas V1/LM/LI to areas LL and TO. Orientation and direction selectivity for the used grating patterns increased gradually from V1 to TO. Overall responsiveness and selectivity to shape stimuli decreased from V1 to TO and was increasingly dependent upon shape motion. Neural similarity for shapes could be accounted for by a simple computational model in V1, but not in the other areas. Across areas, we find a gradual change in which stimulus pairs are most discriminable. Finally, tolerance to position changes increased toward TO. These findings provide unique information about possible commonalities and differences between rodents and primates in hierarchical cortical processing.

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Zhao, Kevin, Joseph Quillin y James K. Liu. "Endoscopic-assisted parieto-occipital interhemispheric precuneal transtentorial approach for microsurgical resection of vermian arteriovenous malformation: operative video and technical nuances". Neurosurgical Focus: Video 4, n.º 1 (enero de 2021): V9. http://dx.doi.org/10.3171/2020.10.focvid2067.

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In this illustrative video, the authors demonstrate resection of a superior vermian arteriovenous malformation (AVM) using the endoscopic-assisted parieto-occipital interhemispheric precuneal transtentorial approach. Lateral positioning allows for gravity-assisted access to the interhemispheric fissure without retractors. The parieto-occipital trajectory is useful in patients who have a steep tentorial angle and avoids manipulation of the occipital lobe and visual cortex. In addition, the authors utilize an angled endoscope, which allows full inspection of the resection bed after AVM removal to visualize areas hidden from the microsurgical view to minimize the chance of residual disease in a deep corridor with multiple visual obstructions.The video can be found here: https://youtu.be/hk9nIIdtqbI

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Kaiser, Daniel, Christian Walther, Stefan R. Schweinberger y Gyula Kovács. "Dissociating the neural bases of repetition-priming and adaptation in the human brain for faces". Journal of Neurophysiology 110, n.º 12 (15 de diciembre de 2013): 2727–38. http://dx.doi.org/10.1152/jn.00277.2013.

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The repetition of a given stimulus leads to the attenuation of the functional magnetic resonance imaging (fMRI) signal compared with unrepeated stimuli, a phenomenon called fMRI adaptation or repetition suppression (RS). Previous studies have related RS of the fMRI signal behaviorally both to improved performance for the repeated stimulus (priming) and to shifts of perception away from the first stimulus (adaptation-related aftereffects). Here we used identical task (sex discrimination), trial structure [ stimulus 1 (S1): 3,000 ms, interstimulus interval: 600 ms, stimulus 2 (S2): 300 ms], and S2 stimuli (androgynous faces) to test how RS of the face-specific areas of the occipito-temporal cortex relates to priming and aftereffects. By varying S1, we could induce priming (significantly faster reaction times when S1 and S2 were identical compared with different images) as well as sex-specific aftereffect [an increased ratio of male responses if S1 was a female face compared with ambiguous faces or to Fourier-randomized noise (FOU) images]. Presenting any face as S1 led to significant RS of the blood oxygen level-dependent signal in the fusiform and occipital face areas as well as in the lateral occipital cortex of both hemispheres compared with FOU, reflecting stimulus category-specific encoding. Additionally, while sex-specific adaptation effects were only observed in occipital face areas, primed trials led to a signal reduction in both face-selective regions. Altogether, these results suggest the differential neural mechanisms of adaptation and repetition priming.

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Mancini, Flavia, Nadia Bolognini, Emanuela Bricolo y Giuseppe Vallar. "Cross-modal Processing in the Occipito-temporal Cortex: A TMS Study of the Müller-Lyer Illusion". Journal of Cognitive Neuroscience 23, n.º 8 (agosto de 2011): 1987–97. http://dx.doi.org/10.1162/jocn.2010.21561.

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The Müller-Lyer illusion occurs both in vision and in touch, and transfers cross-modally from vision to haptics [Mancini, F., Bricolo, E., & Vallar, G. Multisensory integration in the Müller-Lyer illusion: From vision to haptics. Quarterly Journal of Experimental Psychology, 63, 818–830, 2010]. Recent evidence suggests that the neural underpinnings of the Müller-Lyer illusion in the visual modality involve the bilateral lateral occipital complex (LOC) and right superior parietal cortex (SPC). Conversely, the neural correlates of the haptic and cross-modal illusions have never been investigated previously. Here we used repetitive TMS (rTMS) to address the causal role of the regions activated by the visual illusion in the generation of the visual, haptic, and cross-modal visuo-haptic illusory effects, investigating putative modality-specific versus cross-modal underlying processes. rTMS was administered to the right and the left hemisphere, over occipito-temporal cortex or SPC. rTMS over left and right occipito-temporal cortex impaired both unisensory (visual, haptic) and cross-modal processing of the illusion in a similar fashion. Conversely, rTMS interference over left and right SPC did not affect the illusion in any modality. These results demonstrate the causal involvement of bilateral occipito-temporal cortex in the representation of the visual, haptic, and cross-modal Müller-Lyer illusion, in favor of the hypothesis of shared underlying processes. This indicates that occipito-temporal cortex plays a cross-modal role in perception both of illusory and nonillusory shapes.

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Mullin, Caitlin R. y Jennifer K. E. Steeves. "TMS to the Lateral Occipital Cortex Disrupts Object Processing but Facilitates Scene Processing". Journal of Cognitive Neuroscience 23, n.º 12 (diciembre de 2011): 4174–84. http://dx.doi.org/10.1162/jocn_a_00095.

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The study of brain-damaged patients and advancements in neuroimaging have lead to the discovery of discrete brain regions that process visual image categories, such as objects and scenes. However, how these visual image categories interact remains unclear. For example, is scene perception simply an extension of object perception, or can global scene “gist” be processed independently of its component objects? Specifically, when recognizing a scene such as an “office,” does one need to first recognize its individual objects, such as the desk, chair, lamp, pens, and paper to build up the representation of an “office” scene? Here, we show that temporary interruption of object processing through repetitive TMS to the left lateral occipital cortex (LO), an area known to selectively process objects, impairs object categorization but surprisingly facilitates scene categorization. This result was replicated in a second experiment, which assessed the temporal dynamics of this disruption and facilitation. We further showed that repetitive TMS to left LO significantly disrupted object processing but facilitated scene processing when stimulation was administered during the first 180 msec of the task. This demonstrates that the visual system retains the ability to process scenes during disruption to object processing. Moreover, the facilitation of scene processing indicates disinhibition of areas involved in global scene processing, likely caused by disrupting inhibitory contributions from the LO. These findings indicate separate but interactive pathways for object and scene processing and further reveal a network of inhibitory connections between these visual brain regions.

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James, Thomas W., Ryan A. Stevenson, Sunah Kim, Ross M. VanDerKlok y Karin Harman James. "Shape from sound: Evidence for a shape operator in the lateral occipital cortex". Neuropsychologia 49, n.º 7 (junio de 2011): 1807–15. http://dx.doi.org/10.1016/j.neuropsychologia.2011.03.004.

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48

Beauchamp, Michael S. "See me, hear me, touch me: multisensory integration in lateral occipital-temporal cortex". Current Opinion in Neurobiology 15, n.º 2 (abril de 2005): 145–53. http://dx.doi.org/10.1016/j.conb.2005.03.011.

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Burton, H., A. Z. Snyder, T. E. Conturo, E. Akbudak, J. M. Ollinger y M. E. Raichle. "Adaptive Changes in Early and Late Blind: A fMRI Study of Braille Reading". Journal of Neurophysiology 87, n.º 1 (1 de enero de 2002): 589–607. http://dx.doi.org/10.1152/jn.00285.2001.

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Braille reading depends on remarkable adaptations that connect the somatosensory system to language. We hypothesized that the pattern of cortical activations in blind individuals reading Braille would reflect these adaptations. Activations in visual (occipital-temporal), frontal-language, and somatosensory cortex in blind individuals reading Braille were examined for evidence of differences relative to previously reported studies of sighted subjects reading print or receiving tactile stimulation. Nine congenitally blind and seven late-onset blind subjects were studied with fMRI as they covertly performed verb generation in response to reading Braille embossed nouns. The control task was reading the nonlexical Braille string “######”. This study emphasized image analysis in individual subjects rather than pooled data. Group differences were examined by comparing magnitudes and spatial extent of activated regions first determined to be significant using the general linear model. The major adaptive change was robust activation of visual cortex despite the complete absence of vision in all subjects. This included foci in peri-calcarine, lingual, cuneus and fusiform cortex, and in the lateral and superior occipital gyri encompassing primary (V1), secondary (V2), and higher tier (VP, V4v, LO and possibly V3A) visual areas previously identified in sighted subjects. Subjects who never had vision differed from late blind subjects in showing even greater activity in occipital-temporal cortex, provisionally corresponding to V5/MT and V8. In addition, the early blind had stronger activation of occipital cortex located contralateral to the hand used for reading Braille. Responses in frontal and parietal cortex were nearly identical in both subject groups. There was no evidence of modifications in frontal cortex language areas (inferior frontal gyrus and dorsolateral prefrontal cortex). Surprisingly, there was also no evidence of an adaptive expansion of the somatosensory or primary motor cortex dedicated to the Braille reading finger(s). Lack of evidence for an expected enlargement of the somatosensory representation may have resulted from balanced tactile stimulation and gross motor demands during Braille reading of nouns and the control fields. Extensive engagement of visual cortex without vision is discussed in reference to the special demands of Braille reading. It is argued that these responses may represent critical language processing mechanisms normally present in visual cortex.

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50

Le, Tien V., Elias Dakwar, Shannon Hann, Euclides Effio, Ali A. Baaj, Carlos Martinez, Fernando L. Vale y Juan S. Uribe. "Computed tomography–based morphometric analysis of the human occipital condyle for occipital condyle–cervical fusion". Journal of Neurosurgery: Spine 15, n.º 3 (septiembre de 2011): 328–31. http://dx.doi.org/10.3171/2011.5.spine10778.

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Object Occipital condyle screws serve as an alternative fixation point in occipital-cervical fusion. Their placement requires a thorough understanding of the anatomy of the occipital condyles and associated structures. This study is a CT-based morphometric analysis of occipital condyles as related to occipital condyle–cervical fusion. Methods A total of 170 patients were examined with CT scans of the craniocervical junction at a single institution, for a total of 340 occipital condyles, between March 6, 2006, and July 30, 2006. All CT scans were negative for traumatic, degenerative, and neoplastic pathological entities. Condylar anteroposterior (AP) length, transverse width, height, projected screw angle, and projected screw lengths were measured on an EBW Portal 2.5 CT Viewer Workstation (Philips Electronics). The longest axis in the AP orientation of the occipital condyle was accepted as the length. The transverse width was a line perpendicular to the midpoint of the long axis. The height was measured in the coronal projection that had the thickest craniocaudal portion of the condyle. The screw trajectory started 5 mm lateral to the medial edge of the condyle and a line was directed anteromedially in the longest axis. The angle was measured relative to the sagittal midline. The screw length was measured from the outer cortex of the posterior wall to the outer cortex of the anterior wall. Results The mean ± SD values for occipital condyle measurements were as follows: AP length was 22.38 ± 2.19 mm (range 14.7–27.6 mm); width was 11.18 ± 1.44 mm (range 7.4–19.0 mm); height was 9.92 ± 1.30 mm (range 5.1–14.3 mm); screw angle was 20.30° ± 4.89° (range 8.0°–34.0°); and screw length was 20.30 ± 2.24 mm (range 13.0–27.6 mm). Conclusions These measurements correlate with previous cadaveric and radiographic studies of the occipital condyle, and emphasize the role of preoperative planning for the feasibility of placement of an occipital condyle screw.

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