Responses of Neurons in the Middle Temporal Visual Area After Long-Standing Lesions of the Primary Visual Cortex in Adult New World Monkeys

In the marmoset Callithrix jacchus, ocular dominance columns (ODC) have been reported to be present in young animals, but absent in adults (Spatz, 1989). We have studied in juvenile and adult animals the postnatal organization of the retino-geniculo-cortical afferents by means of transneuronal labeling. We show in the present work that ODC are present in the primary visual cortex of Callithrix jacchus, both in the adult and in the juvenile animal. The present work confirms the presence of ODC in the visual cortex of juvenile marmoset before the end of the first postnatal month. In 2-month-old animals, ODC are well demarcated in IVcα and IVcβ. In the adult marmosets, the present data clearly show that the primary visual cortex is also organized with ODC. In horizontal sections, they form a mosaic through the ventral and dorsal calcarine cortex and through the dorso-lateral occipital part of the striate cortex. In frontal sections, their presence is manifest in IVcβ within the calcarine cortex and they only faintly appear in IVcα. These new findings are important since they underline the usefulness of the adult New World Monkeys as a model in visual research.

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The Effect of Attention on Neuronal Responses to High and Low Contrast Stimuli

Journal of Neurophysiology ◽

10.1152/jn.01019.2009 ◽

2010 ◽

Vol 104 (2) ◽

pp. 960-971 ◽

Cited By ~ 24

Author(s):

Joonyeol Lee ◽

John H. R. Maunsell

Keyword(s):

Cerebral Cortex ◽

Visual Cortex ◽

Rhesus Monkeys ◽

Receptive Fields ◽

Visual Area ◽

Neuronal Responses ◽

Attentional Modulation ◽

Low Contrast ◽

Middle Temporal ◽

Visual Area Mt

It remains unclear how attention affects the tuning of individual neurons in visual cerebral cortex. Some observations suggest that attention preferentially enhances responses to low contrast stimuli, whereas others suggest that attention proportionally affects responses to all stimuli. Resolving how attention affects responses to different stimuli is essential for understanding the mechanism by which it acts. To explore the effects of attention on stimuli of different contrasts, we recorded from individual neurons in the middle temporal visual area (MT) of rhesus monkeys while shifting their attention between preferred and nonpreferred stimuli within their receptive fields. This configuration results in robust attentional modulation that makes it possible to readily distinguish whether attention acts preferentially on low contrast stimuli. We found no evidence for greater enhancement of low contrast stimuli. Instead, the strong attentional modulations were well explained by a model in which attention proportionally enhances responses to stimuli of all contrasts. These data, together with observations on the effects of attention on responses to other stimulus dimensions, suggest that the primary effect of attention in visual cortex may be to simply increase the strength of responses to all stimuli by the same proportion.

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Faculty Opinions recommendation of Submillimeter fMRI reveals a layout of dorsal visual cortex in macaques, remarkably similar to New World monkeys.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.734905991.793564771 ◽

2019 ◽

Author(s):

Marcello Rosa

Keyword(s):

Visual Cortex ◽

New World ◽

New World Monkeys

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Projections from primary visual cortex to cytochrome oxidase thin stripes and interstripes of macaque visual area 2

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0402052101 ◽

2004 ◽

Vol 101 (18) ◽

pp. 7147-7151 ◽

Cited By ~ 27

Author(s):

Y. Xiao ◽

D. J. Felleman

Keyword(s):

Visual Cortex ◽

Cytochrome Oxidase ◽

Primary Visual Cortex ◽

Visual Area

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Shape Processing Area LO and Illusory Contours

Perception ◽

10.1068/p6388 ◽

2009 ◽

Vol 38 (8) ◽

pp. 1260-1263 ◽

Cited By ~ 7

Author(s):

Lee H de-Wit ◽

Robert W Kentridge ◽

A David Milner

Keyword(s):

Visual Cortex ◽

Functional Mri ◽

Primary Visual Cortex ◽

Visual Illusions ◽

Visual Area ◽

Illusory Contours ◽

Feedback Effects ◽

Shape Representations ◽

Shape Processing

Recent functional MRI has demonstrated that illusory contours can activate the primary visual cortex. Our investigation sought to demonstrate whether this correlation reflects computations performed in the primary visual cortex or feedback effects from shape processing area LO. We explored this in a patient who has a bilateral lesion to LO, but a functionally spared V1. Our data indicate that illusory contours are unable to influence behaviour without visual area LO. Whilst we would not claim that our data provide evidence for the ‘cognitive’ nature of illusory contours, they certainly suggest that illusory contours are dependent upon the computations involved in extracting shape representations in LO. Our data highlight the importance of neuropsychological research in interpreting the role of feedforward and feedback effects in the generation of visual illusions.

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Resolving the organization of the third tier visual cortex in primates: A hypothesis-based approach

Visual Neuroscience ◽

10.1017/s0952523815000073 ◽

2015 ◽

Vol 32 ◽

Cited By ~ 25

Author(s):

ALESSANDRA ANGELUCCI ◽

MARCELLO G.P. ROSA

Keyword(s):

Visual Cortex ◽

Experimental Evidence ◽

Visual Processing ◽

New World ◽

Dorsal Stream ◽

Macaque Monkey ◽

New World Monkeys ◽

New World Primates ◽

Developmental Context ◽

The Third

AbstractAs highlighted by several contributions to this special issue, there is still ongoing debate about the number, exact location, and boundaries of the visual areas located in cortex immediately rostral to the second visual area (V2), i.e., the “third tier” visual cortex, in primates. In this review, we provide a historical overview of the main ideas that have led to four models of third tier cortex organization, which are at the center of today's debate. We formulate specific predictions of these models, and compare these predictions with experimental evidence obtained primarily in New World primates. From this analysis, we conclude that only one of these models (the “multiple-areas” model) can accommodate the breadth of available experimental evidence. According to this model, most of the third tier cortex in New World primates is occupied by two distinct areas, both representing the full contralateral visual quadrant: the dorsomedial area (DM), restricted to the dorsal half of the third visual complex, and the ventrolateral posterior area (VLP), occupying its ventral half and a substantial fraction of its dorsal half. DM belongs to the dorsal stream of visual processing, and overlaps with macaque parietooccipital (PO) area (or V6), whereas VLP belongs to the ventral stream and overlaps considerably with area V3 proposed by others. In contrast, there is substantial evidence that is inconsistent with the concept of a single elongated area V3 lining much of V2. We also review the experimental evidence from macaque monkey and humans, and propose that, once the data are interpreted within an evolutionary-developmental context, these species share a homologous (but not necessarily identical) organization of the third tier cortex as that observed in New World monkeys. Finally, we identify outstanding issues, and propose experiments to resolve them, highlighting in particular the need for more extensive, hypothesis-driven investigations in macaque and humans.

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