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Visual Areas (visual + area)
Selected AbstractsCortical sources of the early components of the visual evoked potentialHUMAN BRAIN MAPPING, Issue 2 2002Francesco Di Russo Abstract This study aimed to characterize the neural generators of the early components of the visual evoked potential (VEP) to isoluminant checkerboard stimuli. Multichannel scalp recordings, retinotopic mapping and dipole modeling techniques were used to estimate the locations of the cortical sources giving rise to the early C1, P1, and N1 components. Dipole locations were matched to anatomical brain regions visualized in structural magnetic resonance imaging (MRI) and to functional MRI (fMRI) activations elicited by the same stimuli. These converging methods confirmed previous reports that the C1 component (onset latency 55 msec; peak latency 90,92 msec) was generated in the primary visual area (striate cortex; area 17). The early phase of the P1 component (onset latency 72,80 msec; peak latency 98,110 msec) was localized to sources in dorsal extrastriate cortex of the middle occipital gyrus, while the late phase of the P1 component (onset latency 110,120 msec; peak latency 136,146 msec) was localized to ventral extrastriate cortex of the fusiform gyrus. Among the N1 subcomponents, the posterior N150 could be accounted for by the same dipolar source as the early P1, while the anterior N155 was localized to a deep source in the parietal lobe. These findings clarify the anatomical origin of these VEP components, which have been studied extensively in relation to visual-perceptual processes. Hum. Brain Mapping 15:95,111, 2001. © 2001 Wiley-Liss, Inc. [source] Brain potentials associated with the onset and offset of rapid eye movement (REM) during REM sleepPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 3 2002KEIKO OGAWA Abstract The relationship between dreaming and rapid eye movements (REM) during REM sleep is still controversial. This study records the brain potentials time-locked to the onset and offset of REM in 11 healthy young volunteers. Before the onset of REM, no presaccadic readiness potential was found. Conversely, two positive potentials (P1 and P2) appeared following the offset of REM. The latter potentials were dominant in the parieto-occipital area. These findings suggest that REM is initiated without preparation but elicits some information-processing activities that were speculated to occur in the cortical visual area. The data support the activation,synthesis or association hypothesis of dreaming rather than the scanning hypothesis. [source] Guanosine-Induced Synaptogenesis in the Adult Brain In VivoTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 12 2009Inmaculada Gerrikagoitia Abstract Astrocytes release factors like cholesterol, apoE, and pleiotropic molecules that influence synaptogenesis in the central nervous system. In vitro studies have shown that guanosine elicits the production and further release of these synaptogenic factors. To demonstrate that such astrocytic factors are synaptogenic in vivo, osmotic pumps were implanted in primary visual cortex (VC) of Sprague-Dawley rats to deliver guanosine. Simultaneous injection of dextran amine as an anterograde tracer at the same site where the osmotic pumps were implanted enabled the morphology of the fibers emerging from the VC to be visualized as well. The guanosine-treated efferent connections from these animals showed a significant increase in the number and size of synaptic boutons along the efferent fibers when compared with controls. A similar increase in the number and size of synaptic boutons was also detected when the cortico,cortical connection to the lateral secondary visual area was studied in more detail. The ensuing morphological changes to the synapses did not show a clear preference for any particular type or site of the axonal branches that integrates this cortical connection. Moreover, the distribution of boutons along the fibers was clearly stochastic according to their size. Thus, guanosine administration appears to open up the possibility of manipulating connections to compensate for total or partial denervation. Anat Rec, 292:1968,1975, 2009. © 2009 Wiley-Liss, Inc. [source] Evidence regarding the integrity of the posterior medial lateral suprasylvian visual area in the catTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 16 2010Helen Sherk Abstract Among the areas of lateral suprasylvian visual cortex in cats defined by Palmer et al. (J Comp Neurol [1978] 177:237,256), PMLS (posterior lateral suprasylvian area) has been the most studied. Although PMLS has strong and well-documented connections with area 17, it is unclear whether these connections extend to its upper visual field representation. We asked what cortical areas send input to the upper field representation in PMLS by making tracer injections in areas 17, 19, and posterior suprasylvian cortex. Tracer injections made in area 17's upper field representation in 15 cats failed to label the corresponding region in PMLS. Instead, they showed that area 17 is strongly connected with the posterior bank of the posterior suprasylvian sulcus (pSS), a region attributed by Palmer et al. to area 21a. Injections in area 19 had the same outcome. We consider this posterior upper field representation plus the lower field representation in PMLS to belong to a single area, LS (lateral suprasylvian visual area). Our data suggest that the upper field representation in PMLS belongs to a different area, most likely AMLS (anterior medial lateral suprasylvian area). J. Comp. Neurol. 518:3343,3358, 2010. © 2010 Wiley-Liss, Inc. [source] Receptive-field properties of V1 and V2 neurons in mice and macaque monkeysTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 11 2010Gert Van den Bergh Abstract We report the results of extracellular single-unit recording experiments where we quantitatively analyzed the receptive-field (RF) properties of neurons in V1 and an adjacent extrastriate visual area (V2L) of anesthetized mice with emphasis on the RF center-surround organization. We compared the results with the RF center-surround organization of V1 and V2 neurons in macaque monkeys. If species differences in spatial scale are taken into consideration, mouse V1 and V2L neurons had remarkably fine stimulus selectivity, and the majority of response properties in V2L were not different from those in V1. The RF center-surround organization of mouse V1 neurons was qualitatively similar to that for macaque monkeys (i.e., the RF center is surrounded by extended suppressive regions). However, unlike in monkey V2, a significant proportion of cortical neurons, largely complex cells in V2L, did not exhibit quantifiable RF surround suppression. Simple cells had smaller RF centers than complex cells, and the prevalence and strength of surround suppression were greater in simple cells than in complex cells. These findings, particularly on the RF center-surround organization of visual cortical neurons, give new insights into the principles governing cortical circuits in the mouse visual cortex and should provide further impetus for the use of mice in studies on the genetic and molecular basis of RF development and synaptic plasticity. J. Comp. Neurol. 518:2051,2070, 2010. © 2010 Wiley-Liss, Inc. [source] Thirty years of a very special visual area, Area V5THE JOURNAL OF PHYSIOLOGY, Issue 1 2004S. Zeki No abstract is available for this article. [source] The representation of Kanizsa illusory contours in the monkey inferior temporal cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2008Gy. Sįry Abstract Stimulus reduction is an effective way to study visual performance. Cues such as surface characteristics, colour and inner lines can be removed from stimuli, revealing how the change affects recognition and neural processing. An extreme reduction is the removal of the very stimulus, defining it with illusory lines. Perceived boundaries without physical differences between shape and background are called illusory (or subjective) contours. Illusory and real contours activate early stages of the macaque visual pathway in similar ways. However, data relating to the processing of illusory contours in higher visual areas are scarce. We recently reported how illusory contours based on abutting-line gratings affect neurones in the monkey inferotemporal cortex, an area essential for object and shape vision. We now present data on how inferotemporal cortical neurones of monkeys react to another type of shapes, the Kanizsa figures. A set of line drawings, silhouettes, their illusory contour-based counterparts, and control shapes have been presented to awake, fixating rhesus monkeys while single-cell activity was recorded in the anterior part of the inferotemporal cortex. Most of the recorded neurones were responsive and selective to shapes presented as illusory contours. Shape selectivity was proved to be different for line drawings and illusory contours, and also for silhouettes and illusory contours. Neuronal response latencies for Kanizsa figures were significantly longer than those for line drawings and silhouettes. These results reveal differences in processing for Kanizsa figures and shapes having real contours in the monkey inferotemporal cortex. [source] The fidelity of the cortical retinotopic map in human amblyopiaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007Xingfeng Li Abstract To delineate the fidelity of the functional cortical organization in humans with amblyopia, we undertook an investigation into how spatial information is mapped across the visual cortex in amblyopic observers. We assessed whether the boundaries of the visual areas controlled by the amblyopic and fellow fixing eye are in the same position, the fidelity of the retinotopic map within different cortical areas and the average receptive field size in different visual areas. The functional organization of the visual cortex was reconstructed using a fMRI phase-encoded retinotopic mapping analysis. This method sequentially stimulates each point in the visual field along the axes of a polar-coordinate system, thereby reconstructing the representation of the visual field on the cortex. We found that the cortical areas were very similar in normals and amblyopes, with only small differences in boundary positions of different visual areas between fixing and fellow amblyopic eye activation. Within these corresponding visual areas, we did find anomalies in retinotopy in some but not all amblyopes that were not simply a consequence of the poorer functional responses and affected central and peripheral field regions. Only a small increase in the average (or collective) receptive field size was found for full-field representation in amblyopes and none at all for central field representation. The former may simply be a consequence of the poorer functional responses. [source] Heteromodal connections supporting multisensory integration at low levels of cortical processing in the monkeyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2005Céline Cappe Abstract While multisensory integration is thought to occur in higher hierarchical cortical areas, recent studies in man and monkey have revealed plurisensory modulations of activity in areas previously thought to be unimodal. To determine the cortical network involved in multisensory interactions, we performed multiple injections of different retrograde tracers in unimodal auditory (core), somatosensory (1/3b) and visual (V2 and MT) cortical areas of the marmoset. We found three types of heteromodal connections linking unimodal sensory areas. Visuo-somatosensory projections were observed originating from visual areas [probably the ventral and dorsal fundus of the superior temporal area (FSTv and FSTd), and middle temporal crescent (MTc)] toward areas 1/3b. Somatosensory projections to the auditory cortex were present from S2 and the anterior bank of the lateral sulcus. Finally, a visuo-auditory projection arises from an area anterior to the superior temporal sulcus (STS) toward the auditory core. Injections in different sensory regions allow us to define the frontal convexity and the temporal opercular caudal cortex as putative polysensory areas. A quantitative analysis of the laminar distribution of projecting neurons showed that heteromodal connections could be either feedback or feedforward. Taken together, our results provide the anatomical pathway for multisensory integration at low levels of information processing in the primate and argue against a strict hierarchical model. [source] Functional neuroanatomy of the human near/far response to blur cues: eye-lens accommodation/vergence to point targets varying in depthEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2004Hans O. Richter Abstract The purpose of this study was to identify the networks involved in the regulation of visual accommodation/vergence by contrasting the cortical functions subservient to eye-lens accommodation with those evoked by foveal fixation. Neural activity was assessed in normal volunteers by changes in rCBF measured with PET. Thirteen right-handed subjects participated in three monocular tasks: (i) resting with eyes closed; (ii) sustained foveal fixation upon a LED at 1.2 m (0.83 D); and (iii) accommodating alternately on a near (24 cm, 4.16 D) vs. a far (3.0 m, 0.33 D) LED alternately illuminated in sequential 2 s epochs. The contrast between the conditions of near/far accommodation and of constant foveal fixation revealed activation in cerebellar hemispheres and vermis; middle and inferior temporal cortex (BA 20, 21, 37); striate cortex and associative visual areas (BA 17/18). Comparison of the condition of constant fixation with the condition of resting with closed eyes indicated activation of cerebellar hemispheres and vermis; visual cortices (BA 17/18); a right hemisphere dominant network encompassing prefrontal (BA 6, 9, 47), superior parietal (BA 7), and superior temporal (BA 40) cortices; and bilateral thalamus. The contrast between the conditions of near/far accommodation with closed-eye rest reflected an incremental summation of the activations found in the previous comparisons (i.e. activations associated with constant fixation). Neural circuits activated selectively during the near/far response to blur cues over those during constant visual fixation, occupy posterior structures that include occipital visual regions, cerebellar hemispheres and vermis, and temporal cortex. [source] Primary and multisensory cortical activity is correlated with audiovisual perceptsHUMAN BRAIN MAPPING, Issue 4 2010Margo McKenna Benoit Abstract Incongruent auditory and visual stimuli can elicit audiovisual illusions such as the McGurk effect where visual /ka/ and auditory /pa/ fuse into another percept such as/ta/. In the present study, human brain activity was measured with adaptation functional magnetic resonance imaging to investigate which brain areas support such audiovisual illusions. Subjects viewed trains of four movies beginning with three congruent /pa/ stimuli to induce adaptation. The fourth stimulus could be (i) another congruent /pa/, (ii) a congruent /ka/, (iii) an incongruent stimulus that evokes the McGurk effect in susceptible individuals (lips /ka/ voice /pa/), or (iv) the converse combination that does not cause the McGurk effect (lips /pa/ voice/ ka/). This paradigm was predicted to show increased release from adaptation (i.e. stronger brain activation) when the fourth movie and the related percept was increasingly different from the three previous movies. A stimulus change in either the auditory or the visual stimulus from /pa/ to /ka/ (iii, iv) produced within-modality and cross-modal responses in primary auditory and visual areas. A greater release from adaptation was observed for incongruent non-McGurk (iv) compared to incongruent McGurk (iii) trials. A network including the primary auditory and visual cortices, nonprimary auditory cortex, and several multisensory areas (superior temporal sulcus, intraparietal sulcus, insula, and pre-central cortex) showed a correlation between perceiving the McGurk effect and the fMRI signal, suggesting that these areas support the audiovisual illusion. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source] A double dissociation between striate and extrastriate visual cortex for pattern motion perception revealed using rTMSHUMAN BRAIN MAPPING, Issue 10 2009Benjamin Thompson Abstract The neural mechanisms underlying the integration and segregation of motion signals are often studied using plaid stimuli. These stimuli consist of two spatially coincident dynamic gratings of differing orientations, which are either perceived to move in two unique directions or are integrated by the visual system to elicit the percept of a checkerboard moving in a single direction. Computations pertaining to the motion of the individual component gratings are thought to take place in striate cortex (V1) whereas motion integration is thought to involve neurons in dorsal stream extrastriate visual areas, particularly V5/MT. By combining a psychophysical task that employed plaid stimuli with 1 Hz offline repetitive transcranial magnetic stimulation (rTMS), we demonstrated a double dissociation between striate and extrastriate visual cortex in terms of their contributions to motion integration. rTMS over striate cortex increased coherent motion percepts whereas rTMS over extrastriate cortex had the opposite effect. These effects were robust directly after the stimulation administration and gradually returned to baseline within 15 minutes. This double dissociation is consistent with previous patient data and the recent hypothesis that both coherent and transparent motion percepts are supported by the visual system simultaneously and compete for perceptual dominance. Hum Brain Mapp 2009. © 2009 Wiley-Liss, Inc. [source] Neural substrates of tactile object recognition: An fMRI studyHUMAN BRAIN MAPPING, Issue 4 2004Catherine L. Reed Abstract A functional magnetic resonance imaging (fMRI) study was conducted during which seven subjects carried out naturalistic tactile object recognition (TOR) of real objects. Activation maps, conjunctions across subjects, were compared between tasks involving TOR of common real objects, palpation of "nonsense" objects, and rest. The tactile tasks involved similar motor and sensory stimulation, allowing higher tactile recognition processes to be isolated. Compared to nonsense object palpation, the most prominent activation evoked by TOR was in secondary somatosensory areas in the parietal operculum (SII) and insula, confirming a modality-specific path for TOR. Prominent activation was also present in medial and lateral secondary motor cortices, but not in primary motor areas, supporting the high level of sensory and motor integration characteristic of object recognition in the tactile modality. Activation in a lateral occipitotemporal area associated previously with visual object recognition may support cross-modal collateral activation. Finally, activation in medial temporal and prefrontal areas may reflect a common final pathway of modality-independent object recognition. This study suggests that TOR involves a complex network including parietal and insular somatosensory association cortices, as well as occipitotemporal visual areas, prefrontal, and medial temporal supramodal areas, and medial and lateral secondary motor cortices. It confirms the involvement of somatosensory association areas in the recognition component of TOR, and the existence of a ventrolateral somatosensory pathway for TOR in intact subjects. It challenges the results of previous studies that emphasize the role of visual cortex rather than somatosensory association cortices in higher-level somatosensory cognition. Hum. Brain Mapping 21:236,246, 2004. © 2004 Wiley-Liss, Inc. [source] Rollvection versus linearvection: Comparison of brain activations in PETHUMAN BRAIN MAPPING, Issue 3 2004Angela Deutschländer Abstract We conducted a PET study to directly compare the differential effects of visual motion stimulation that induced either rollvection about the line of sight or forward linearvection along this axis in the same subjects. The main question was, whether the areas that respond to vection are identical or separate and distinct for rollvection and linearvection. Eleven healthy volunteers were exposed to large-field (100° × 60°) visual motion stimulation consisting of (1) dots accelerating from a focus of expansion to the edge of the screen (forward linearvection) and (2) dots rotating counterclockwise in the frontal plane (clockwise rollvection). These two stimuli, which induced apparent self-motion in all subjects, were compared to each other and to a stationary visual pattern. Linearvection and rollvection led to bilateral activations of visual areas including medial parieto-occipital (PO), occipito-temporal (MT/V5), and ventral occipital (fusiform gyri) cortical areas, as well as superior parietal sites. Activations in the polar visual cortex around the calcarine sulcus (BA 17, BA 18) were larger and more significant during linearvection. Temporo-parietal sites displayed higher activity levels during rollvection. Differential activation of PO or MT/V5 was not found. Both stimuli led to simultaneous deactivations of retroinsular regions (more pronounced during linearvection); this is compatible with an inhibitory interaction between the visual and the vestibular systems for motion perception. Hum. Brain Mapp. 21:143,153, 2004. © 2004 Wiley-Liss, Inc. [source] Neurogenic development of the visual areas in the Chinese softshell turtle (Pelodiscus sinensis) and evolutionary implicationsJOURNAL OF ANATOMY, Issue 5 2008Chao Xi Abstract To characterize the neurogenic development of the visual areas of the turtle (Pelodiscus sinensis) during embryogenesis, a single dose of [3H]-thymidine (10 µCi) was injected into egg yolks from stages S11~12 to S21. At hatching, localization of [3H]-thymidine incorporation was examined, and led to three main observations. (1) Neurogenesis occurred in the stratum griseum centrale of the tectum opticum from S11~12 to S16 with a peak at S12. No obvious gradients of neurogenesis were observed. (2) Neurogenesis in the nucleus rotundus (Rot) and in the dorsal lateral geniculate nucleus (GLd) occurred from S11~12 to S15. Gradients of neurogenesis were detected along ventral,dorsal and lateral,medial axes in the Rot, but only the latter neurogenic gradient occurred in the GLd. (3) In the visual region of the dorsal ventricular ridge, neurogenesis lasted from S11~12 to S16. Similarly, neurogenesis occurred from S11~12 to S16~17 in the dorsal cortex, with a peak at S12 for both telencephalic visual regions. Neurogenesis followed a ventrolateral to dorsomedial gradient in the visual region of the dorsal ventricular ridge, and a superficial to deep gradient in the caudal dorsal cortex. A significant number of neurons in the rostral dorsal cortex followed a deep (earlier arising) to superficial (later arising) pattern of neurogenesis, similar to that in the avian Wulst or in the mammalian isocortex. Finally, we compared the timing and development of neurogenesis in the turtle with birds and mammals to understand the evolutionary implications of these processes. [source] Distribution and regulation of substance P-related peptide in the frog visual systemMICROSCOPY RESEARCH AND TECHNIQUE, Issue 4 2001Elizabeth A. DebskiArticle first published online: 10 AUG 200 Abstract Modulation of visual signal activity has consequences for both signal processing and for activity-dependent structuring mechanisms. Among the neuromodulatory agents found in visual areas are substance P (SP)-related peptides. This article reviews what is known about these substances in the amphibian retina and optic tectum with special emphasis on the leopard frog, Rana pipiens. It is found that the distribution of these SP-related peptides is remarkably similar to that seen in mammals. This suggests that study of model amphibian systems may significantly enhance our understanding of how neuropeptides contribute to visual system function and organization. Microsc. Res. Tech. 54:220,228, 2001. © 2001 Wiley-Liss, Inc. [source] Early neural activity in Necker-cube reversal: Evidence for low-level processing of a gestalt phenomenonPSYCHOPHYSIOLOGY, Issue 1 2004Jürgen Kornmeier Abstract Normally we experience the visual world as stable. Ambiguous figures provide a fascinating exception: On prolonged inspection, the "Necker cube" undergoes a sudden, unavoidable reversal of its perceived front-back orientation. What happens in the brain when spontaneously switching between these equally likely interpretations? Does neural processing differ between an endogenously perceived reversal of a physically unchanged ambiguous stimulus and an exogenously caused reversal of an unambiguous stimulus? A refined EEG paradigm to measure such endogenous events uncovered an early electrophysiological correlate of this spontaneous reversal, a negativity beginning at 160 ms. Comparing across nine electrode locations suggests that this component originates in early visual areas. An EEG component of similar shape and scalp distribution, but 50 ms earlier, was evoked by an external reversal of unambiguous figures. Perceptual disambiguation seems to be accomplished by the same structures that represent objects per se, and to occur early in the visual stream. This suggests that low-level mechanisms play a crucial role in resolving perceptual ambiguity. [source] Variations in the structure of the prelunate gyrus in Old World monkeysTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2006Estel Van Der Gucht Abstract Anatomical and electrophysiological studies have revealed a complex organization in the macaque prelunate gyrus. We investigated the morphology and architecture of the prelunate gyrus in Old World monkeys. In Macaca nemestrina, we observed a sulcus crossing the prelunate gyrus within 2 mm of the vertical meridian representation. In other macaque species and other cercopithecines, we observed substantial variations in sulcal morphology across the prelunate gyrus. We did not find a sulcus in all species, and the location and depth of that indentation on the gyrus varied among species. A deep sulcus was observed in all species that emerged earlier in evolution than macaques, such as guenons, baboons, and colobines. We analyzed the regional and parcellation features of the prelunate gyrus in three macaque species, M. maura, M. mulatta, and M. radiata, and in Erythrocebus patas, with emphasis on the relation of structure to the distribution of prelunate visual areas. Nonphosphorylated neurofilament protein immunoreactivity permitted the delineation of a novel area in the prelunate gyrus of Old World monkeys, located around the prelunate sulcus. Species-specific patterns were also observed in the prelunate gyrus of the patas monkey compared to macaques. These observations, as well as a cladistic analysis of the data, suggest an expanded and diversified organization of the prelunate gyrus in some cercopithecoids that may reflect adaptation to specific ecological environments. It was, however, progressively lost in most macaques, being retained only in species that diverged early in the evolution of the genus Macaca, such as M. nemestrina and M. maura. Anat Rec Part A, 288A:753,775, 2006. © 2006 Wiley-Liss, Inc. [source] Immunohistochemical parcellation of the ferret (Mustela putorius) visual cortex reveals substantial homology with the cat (Felis catus)THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 21 2010Jihane Homman-Ludiye Abstract Electrophysiological mapping of the adult ferret visual cortex has until now determined the existence of 12 retinotopically distinct areas; however, in the cat, another member of the Carnivora, 20 distinct visual areas have been identified by using retinotopic mapping and immunolabeling. In the present study, the immunohistochemical approach to demarcate the areal boundaries of the adult ferret visual cortex was applied in order to overcome the difficulties in accessing the sulcal surfaces of a small, gyrencephalic brain. Nonphosphorylated neurofilament (NNF) expression profiles were compared with another classical immunostain of cortical nuclei, Cat-301 chondroitin sulfate proteoglycan (CSPG). Together, these two markers reliably demarcated the borders of the 12 previously defined areas and revealed further arealization beyond those borders to a total of 19 areas: 21a and 21b; the anterolateral, posterolateral, dorsal, and ventral lateral suprasylvian areas (ALLS, PLLS, DLS, and VLS, respectively); and the splenial and cingulate visual areas (SVA and CVA). NNF expression profile and location of the newly defined areas correlate with previously defined areas in the cat. Moreover, NNF and Cat-301 together revealed discrete expression domains in the posteroparietal (PP) cortex, demarcating four subdivisions in the caudal lateral and medial domains (PPcL and PPcM) and rostral lateral and medial domains (PPrL and PPrM), where only two retinotopic maps have been previously identified (PPc and PPr). Taken together, these studies suggest that NNF and Cat-301 can illustrate the homology between cortical areas in different species and draw out the principles that have driven evolution of the visual cortex. J. Comp. Neurol. 518:4439,4462, 2010. © 2010 Wiley-Liss, Inc. [source] Neuroplasticity predicts outcome of optic neuritis independent of tissue damageANNALS OF NEUROLOGY, Issue 1 2010Thomas M. Jenkins MRCP Objectives To determine whether lateral occipital complex (LOC) activation with functional magnetic resonance imaging (fMRI) predicts visual outcome after clinically isolated optic neuritis (ON). To investigate the reasons behind good recovery following ON, despite residual optic nerve demyelination and neuroaxonal damage. Methods Patients with acute ON and healthy volunteers were studied longitudinally over 12 months. Structural MRI, visual evoked potentials (VEPs), and optical coherence tomography (OCT) were used to quantify acute inflammation, demyelination, conduction block, and later to estimate remyelination and neuroaxonal loss over the entire visual pathway. The role of neuroplasticity was investigated using fMRI. Multivariable linear regression analysis was used to study associations between vision, structure, and function. Results Greater baseline fMRI responses in the LOCs were associated with better visual outcome at 12 months. This was evident on stimulation of either eye (p = 0.007 affected; p = 0.020 fellow eye), and was independent of measures of demyelination and neuroaxonal loss. A negative fMRI response in the LOCs at baseline was associated with a relatively worse visual outcome. No acute electrophysiological or structural measures, in the anterior or posterior visual pathways, were associated with visual outcome. Interpretation Early neuroplasticity in higher visual areas appears to be an important determinant of recovery from ON, independent of tissue damage in the anterior or posterior visual pathway, including neuroaxonal loss (as measured by MRI, VEP, and OCT) and demyelination (as measured by VEP). ANN NEUROL 2010;67:99,113 [source] | |||||||||||||||||||||||||