The cortical visual area V6: brain location and visual topography

Galletti, Claudio; Fattori, Patrizia; Gamberini, Michela; Kutz, Dieter F.

doi:10.1046/j.1460-9568.1999.00817.x

Cited by 208 publications

(283 citation statements)

References 19 publications

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“…In the monkey V6 (22), the representations of the upper and lower visual fields are clearly distinct, and in part even in different walls of the parieto-occipital sulcus, with a trend of more anterior locations for upper than lower visual field representations. Interestingly, the mean current directions at the cuneus source were opposite during the upper and lower visual field responses (Fig.…”

Section: Resultsmentioning

confidence: 96%

“…14 and 25) should have pushed the functional area V6 from the medial fundus of the parieto-occipital sulcus in monkeys (22) to the upper posterior wall of the parietooccipital sulcus and thus to the anteromedial cuneus in humans. The neurons of V6 have large receptive fields (22), and lack enhanced foveal magnification both in monkeys (22) and humans (26), and the area has been suggested to participate in visuospatial analysis of environment for arm reaching and eye movements (27,28). The human anteromedial cuneus could also contain an area or multiple areas with no equivalent in the macaque brain.…”

Section: Resultsmentioning

confidence: 99%

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Coinciding early activation of the human primary visual cortex and anteromedial cuneus

Vanni¹,

Tanskanen²,

Seppä³

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

195

125

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Proper understanding of processes underlying visual perception requires information on the activation order of distinct brain areas. We measured dynamics of cortical signals with magnetoencephalography while human subjects viewed stimuli at four visual quadrants. The signals were analyzed with minimum current estimates at the individual and group level. Activation emerged 55-70 ms after stimulus onset both in the primary posterior visual areas and in the anteromedial part of the cuneus. Other cortical areas were active after this initial dual activation. Comparison of data between species suggests that the anteromedial cuneus either comprises a homologue of the monkey area V6 or is an area unique to humans. Our results show that visual stimuli activate two cortical areas right from the beginning of the cortical response. The anteromedial cuneus has the temporal position needed to interact with the primary visual cortex V1 and thereby to modify information transferred via V1 to extrastriate cortices.A natomy of connections between primate visual cortices suggests a hierarchical organization of signal processing (1). However, the order of processes at different functional areas cannot be directly deduced from the anatomical hierarchy without relevant timing information. In monkeys, several areas become active immediately after the primary visual cortex (V1), while another set of areas is active at clearly longer latencies (2, 3). The areas showing early responses, such as V5͞middle temporal area (MT), medial superior temporal area, and frontal eye field, are specialized in analyzing dynamical visual information and in visuomotor transformation (for reviews, see refs. 4 and 5). The areas with longer latencies, such as V4, are sensitive to object form and color and participate in object recognition (6, 7). The dissimilarities in activation latencies and functional properties of these areas suggest diversity in the type and amount of necessary input and preprocessing before activation. Given the differences between monkey and human visual cortices (for a review, see ref. 8), we aimed to explore the dynamics and distribution of early cortical activation in humans. Neuromagnetic signals were recorded while the subjects viewed pattern reversal or luminance stimuli at the four visual quadrants. The signals were analyzed with minimum current estimates (MCEs), which require minimal human intervention for determining the location and orientation of the cortical currents (9). The individual three-dimensional estimates were aligned with a nonlinear transformation according to individual brain shapes (10, 11), and both the individual and group average MCEs were compared with the existing maps of human visual cortices (12-16). Materials and MethodsSubjects and Stimuli. We studied five female and five male subjects (mean age 27 years, range 20-42 years). The stimuli were generated with a Macintosh computer and presented with a dataprojector (VistaPro, Electrohome Ltd., Ontario, Canada) on a back projection screen, with viewing d...

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Coinciding early activation of the human primary visual cortex and anteromedial cuneus

Vanni¹,

Tanskanen²,

Seppä³

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

195

125

View full text Add to dashboard Cite

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“…Rather than indicating the existence of subdivisions within DM, these gradients most likely reflect the distinct ways that primates use information contained in different parts of the visual field (Gattass et al, 1997;Ungerleider et al, 2008). The robust input from early ventral stream areas to the representations of paracentral visual field can be linked to a form-processing capacity, which has been proposed for one of the most likely Old World monkey homologs of DM (V6; see below) in the context of performing quick analyses for guidance of grasping and reaching (Galletti et al, 1999). Given the long latency of skeletomotor activity, connections from ventral stream areas could be relevant to updating and refining computations of object shape and size performed by DM, in time for midtrajectory corrections.…”

Section: Discussionmentioning

confidence: 99%

Connections of the Dorsomedial Visual Area: Pathways for Early Integration of Dorsal and Ventral Streams in Extrastriate Cortex

Palmer²,

et al. 2009

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The dorsomedial area (DM), a subdivision of extrastriate cortex characterized by heavy myelination and relative emphasis on peripheral vision, remains the least understood of the main targets of striate cortex (V1) projections in primates. Here we placed retrograde tracer injections encompassing the full extent of this area in marmoset monkeys, and performed quantitative analyses of the numerical strengths and laminar patterns of its afferent connections. We found that feedforward projections from V1 and from the second visual area (V2) account for over half of the inputs to DM, and that the vast majority of the remaining connections come from other topographically organized visual cortices. Extrastriate projections to DM originate in approximately equal proportions from adjacent medial occipitoparietal areas, from the superior temporal motion-sensitive complex centered on the middle temporal area (MT), and from ventral stream-associated areas. Feedback from the posterior parietal cortex and other association areas accounts for Ͻ10% of the connections. These results do not support the hypothesis that DM is specifically associated with a medial subcircuit of the dorsal stream, important for visuomotor integration. Instead, they suggest an early-stage visual-processing node capable of contributing across cortical streams, much as V1 and V2 do. Thus, although DM may be important for providing visual inputs for guided body movements (which often depend on information contained in peripheral vision), this area is also likely to participate in other functions that require integration across wide expanses of visual space, such as perception of self-motion and contour completion.

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“…Dorsal is up, and caudal is right. Scale bars: C, 5 mm; photomicrographs, 200 m. Cin, Cingulate sulcus; Cal, calcarine fissure; Cs, central sulcus; IPs, intraparietal sulcus; Ls, lunate sulcus; POs, parietooccipital sulcus; STs, superior temporal sulcus; A, anterior; V, ventral; L, lateral; P, posterior; MIP, medial intraparietal area (Colby et al, 1988); PE, area PE (Pandya and Seltzer, 1982); PGm, medial area PG (Pandya and Seltzer, 1982); V6, area V6 (Galletti et al, 1999b); V6A, area V6A (Galletti et al, 1999a). vigorously during an instructed-delay reaching task performed in darkness when the hand was retracted from the visual target and moved toward the animal's body (Fig.…”

Section: Other Functional Properties Of Pec Somatosensory Cellsmentioning

confidence: 99%