scholarly journals Myelin densities in retinotopically defined dorsal visual areas of the macaque

2021 ◽  
Author(s):  
Xiaolian Li ◽  
Qi Zhu ◽  
Wim Vanduffel
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Cortical Thickness ◽  
New World Monkeys ◽  
Isotropic Resolution ◽  
Density Mapping ◽  
Area V2 ◽  
Visual Areas ◽  
Density Results

AbstractThe visuotopic organization of dorsal visual cortex rostral to area V2 in primates has been a longstanding source of controversy. Using sub-millimeter phase-encoded retinotopic fMRI mapping, we recently provided evidence for a surprisingly similar visuotopic organization in dorsal visual cortex of macaques compared to previously published maps in New world monkeys (Zhu and Vanduffel, Proc Natl Acad Sci USA 116:2306–2311, 2019). Although individual quadrant representations could be robustly delineated in that study, their grouping into hemifield representations remains a major challenge. Here, we combined in-vivo high-resolution myelin density mapping based on MR imaging (400 µm isotropic resolution) with fine-grained retinotopic fMRI to quantitatively compare myelin densities across retinotopically defined visual areas in macaques. Complementing previously documented differences in populational receptive-field (pRF) size and visual field signs, myelin densities of both quadrants of the dorsolateral posterior area (DLP) and area V3A are significantly different compared to dorsal and ventral area V3. Moreover, no differences in myelin density were observed between the two matching quadrants belonging to areas DLP, V3A, V1, V2 and V4, respectively. This was not the case, however, for the dorsal and ventral quadrants of area V3, which showed significant differences in MR-defined myelin densities, corroborating evidence of previous myelin staining studies. Interestingly, the pRF sizes and visual field signs of both quadrant representations in V3 are not different. Although myelin density correlates with curvature and anticorrelates with cortical thickness when measured across the entire cortex, exactly as in humans, the myelin density results in the visual areas cannot be explained by variability in cortical thickness and curvature between these areas. The present myelin density results largely support our previous model to group the two quadrants of DLP and V3A, rather than grouping DLP- with V3v into a single area VLP, or V3d with V3A+ into DM.

Pontine projection from striate and prestriate visual cortex in the macaque monkey: An anterograde study

1990 ◽  
Vol 4 (3) ◽  
pp. 205-216 ◽  
Author(s):  
W. Fries
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Striate Cortex ◽  
Macaque Monkey ◽  
Field Of View ◽  
Central Visual Field ◽  
Tracer Techniques ◽  
Visual Areas ◽  
Visual Cortical ◽  
Anterograde Tracer

AbstractThe projection from striate and prestriate visual cortex to the pontine nuclei has been studied in the macaque monkey by means of anterograde tracer techniques in order to assess the contribution of anatomically and functionally distinct visual cortical areas to the cortico-ponto-cerebellar loop. No projection to the pons was found from central or paracentral visual-field representations of V1 (striate cortex) or prestriate visual areas V2, and V4. Small patches of terminal labeling occurred after injections of tracer into more peripheral parts of V1, V2 and V3, and into V3A. The terminal fields were located most dorsolaterally in the anterior to middle third of the pons and were quite restricted in their rostro-caudal extent. Injections of V5, however, yielded substantial terminal labeling, stretching longitudinally throughout almost the entire pons. This projection could be demonstrated to arise from parts of V5 receiving input from central visual-field representations of striate cortex, whereas parts of V4 receiving similarly central visual-field input had no detectable projection to the pons. Its distribution may overlap to a large extent with the termination of tecto-pontine fibers and with the termination of fibers from visual areas in the medial bank (area V6 or P0) and lateral bank (area LIP) of the intraparietal sulcus, as well as from frontal eye fields (FEF). It appears that the main information relayed to the cerebellum by the visual corticopontine projection is related to movement in the field of view.

Residual Vision in a Subject with Damaged Visual Cortex

1999 ◽  
Vol 11 (5) ◽  
pp. 502-510 ◽  
Author(s):  
Heinz Schärli ◽  
Alison M. Harman ◽  
John H. Hogben
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Target Stimulus ◽  
Striate Cortex ◽  
Light Flash ◽  
Black And White ◽  
Confidence Levels ◽  
Residual Vision ◽  
Visual Areas ◽  
The Subject

It is well known that a lesion in the optic radiation or striate cortex leads to blind visual regions in the retinotopically corresponding portion of the visual field. However, various studies show that some subjects still perceive certain stimuli even when presented in the “blind” visual field. Such subjects either perceive stimuli abnormally or only certain aspects of them (residual vision) or, in some cases, deny perception altogether even though visual performance can be shown to be above chance (blindsight). Research on monkeys has suggested a variety of parallel extrastriate visual pathways that could bypass the striate cortex and mediate residual vision or blindsight. In the present study, we investigated a subject with perimetrically blind visual areas caused by bilateral brain damage. Black and white stimuli were presented at many locations in the intact and affected areas of the visual field. The subject's task was to state, using confidence levels, whether the target stimulus was black or white. The results revealed an area in the “blind” visual field in which the subject perceived a light flash when the experimental black stimulus was presented. We hypothesize that a spared region in the visual cortex most likely accounts for these findings.

scholarly journals Visual field representations and locations of visual areas V1/2/3 in human visual cortex

2003 ◽  
Vol 3 (10) ◽  
pp. 1 ◽  
Author(s):  
Robert F. Dougherty ◽  
Volker M. Koch ◽  
Alyssa A. Brewer ◽  
Bernd Fischer ◽  
Jan Modersitzki ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Human Visual Cortex ◽  
Visual Areas

scholarly journals A twisted visual field map in the primate cortex predicted by topographic continuity

2019 ◽  
Author(s):  
Hsin-Hao Yu ◽  
Declan P. Rowley ◽  
Nicholas S.C. Price ◽  
Marcello G.P. Rosa ◽  
Elizabeth Zavitz
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Receptive Fields ◽  
Electrode Array ◽  
Extrastriate Cortex ◽  
Complex Type ◽  
Retinotopic Maps ◽  
Visual Areas ◽  
Array Recordings ◽  
Retinotopic Map

AbstractAdjacent neurons in visual cortex have overlapping receptive fields within and across area boundaries, an arrangement which is theorized to minimize wiring cost. This constraint is thought to create retinotopic maps of opposing field sign (mirror and non-mirror representations of the visual field) in adjacent visual areas, a concept which has become central in current attempts to subdivide the cortex. We modelled a realistic developmental scenario in which adjacent areas do not mature simultaneously, but need to maintain topographic continuity across their borders. This showed that the same mechanism that is hypothesized to maintain topographic continuity within each area can lead to a more complex type of retinotopic map, consisting of sectors with opposing field sign within a same area. Using fully quantitative electrode array recordings, we then demonstrate that this type of map exists in the primate extrastriate cortex.

scholarly journals Area-specific mapping of binocular disparity across mouse visual cortex

2019 ◽  
Author(s):  
Alessandro La Chioma ◽  
Tobias Bonhoeffer ◽  
Mark Hübener
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Binocular Disparity ◽  
Receptive Fields ◽  
Natural Image ◽  
Lower Visual Field ◽  
Natural Image Statistics ◽  
Visual Areas ◽  
The Difference ◽  
Mouse Visual Cortex

SummaryBinocular disparity, the difference between left and right eye images, is a powerful cue for depth perception. Many neurons in the visual cortex of higher mammals are sensitive to binocular disparity, with distinct disparity tuning properties across primary and higher visual areas. Mouse primary visual cortex (V1) has been shown to contain disparity-tuned neurons, but it is unknown how these signals are processed beyond V1. We find that disparity signals are prominent in higher areas of mouse visual cortex. Preferred disparities markedly differ among visual areas, with area RL encoding visual stimuli very close to the mouse. Moreover, disparity preference is systematically related to visual field elevation, such that neurons with receptive fields in the lower visual field are overall tuned to near disparities, likely reflecting an adaptation to natural image statistics. Our results reveal ecologically relevant areal specializations for binocular disparity processing across mouse visual cortex.

scholarly journals Higher-order visual areas broaden stimulus responsiveness in mouse primary visual cortex

2021 ◽  
Author(s):  
Matthijs N. oude Lohuis ◽  
Alexis Cerván Cantón ◽  
Cyriel M. A. Pennartz ◽  
Umberto Olcese
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Higher Order ◽  
The Past ◽  
Early Visual Processing ◽  
Visual Areas ◽  
Sensory Evoked ◽  
Prevailing View

SummaryOver the past few years, the various areas that surround the primary visual cortex in the mouse have been associated with many functions, ranging from higher-order visual processing to decision making. Recently, some studies have shown that higher-order visual areas influence the activity of the primary visual cortex, refining its processing capabilities. Here we studied how in vivo optogenetic inactivation of two higher-order visual areas with different functional properties affects responses evoked by moving bars in the primary visual cortex. In contrast with the prevailing view, our results demonstrate that distinct higher-order visual areas similarly modulate early visual processing. In particular, these areas broaden stimulus responsiveness in the primary visual cortex, by amplifying sensory-evoked responses for stimuli not moving along the orientation preferred by individual neurons. Thus, feedback from higher-order visual areas amplifies V1 responses to non-preferred stimuli, which may aid their detection.

scholarly journals Compressive spatial summation in human visual cortex

2013 ◽  
Vol 110 (2) ◽  
pp. 481-494 ◽  
Author(s):  
Kendrick N. Kay ◽  
Jonathan Winawer ◽  
Aviv Mezer ◽  
Brian A. Wandell
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Object Representation ◽  
Spatial Summation ◽  
Blood Oxygenation ◽  
Population Responses ◽  
Visual Areas ◽  
Oxygenation Level ◽  
Restricted Region ◽  
Extrastriate Areas

Neurons within a small (a few cubic millimeters) region of visual cortex respond to stimuli within a restricted region of the visual field. Previous studies have characterized the population response of such neurons using a model that sums contrast linearly across the visual field. In this study, we tested linear spatial summation of population responses using blood oxygenation level-dependent (BOLD) functional MRI. We measured BOLD responses to a systematic set of contrast patterns and discovered systematic deviation from linearity: the data are more accurately explained by a model in which a compressive static nonlinearity is applied after linear spatial summation. We found that the nonlinearity is present in early visual areas (e.g., V1, V2) and grows more pronounced in relatively anterior extrastriate areas (e.g., LO-2, VO-2). We then analyzed the effect of compressive spatial summation in terms of changes in the position and size of a viewed object. Compressive spatial summation is consistent with tolerance to changes in position and size, an important characteristic of object representation.

scholarly journals Top-down control of visual cortex by the frontal eye fields through oscillatory realignment

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Domenica Veniero ◽  
Joachim Gross ◽  
Stephanie Morand ◽  
Felix Duecker ◽  
Alexander T. Sack ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Visual Perception ◽  
Magnetic Stimulation ◽  
Single Pulse ◽  
Frontal Eye Fields ◽  
Phase Reset ◽  
Top Down ◽  
Visual Areas ◽  
Beta Frequency

AbstractVoluntary allocation of visual attention is controlled by top-down signals generated within the Frontal Eye Fields (FEFs) that can change the excitability of lower-level visual areas. However, the mechanism through which this control is achieved remains elusive. Here, we emulated the generation of an attentional signal using single-pulse transcranial magnetic stimulation to activate the FEFs and tracked its consequences over the visual cortex. First, we documented changes to brain oscillations using electroencephalography and found evidence for a phase reset over occipital sites at beta frequency. We then probed for perceptual consequences of this top-down triggered phase reset and assessed its anatomical specificity. We show that FEF activation leads to cyclic modulation of visual perception and extrastriate but not primary visual cortex excitability, again at beta frequency. We conclude that top-down signals originating in FEF causally shape visual cortex activity and perception through mechanisms of oscillatory realignment.

scholarly journals A direct interareal feedback-to-feedforward circuit in primate visual cortex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Caitlin Siu ◽  
Justin Balsor ◽  
Sam Merlin ◽  
Frederick Federer ◽  
Alessandra Angelucci
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Projection Neurons ◽  
V1 Neurons ◽  
Cortical Areas ◽  
Area V2 ◽  
Computational Work ◽  
Primate Visual Cortex ◽  
Similar Area ◽  
Hierarchical Computation

AbstractThe mammalian sensory neocortex consists of hierarchically organized areas reciprocally connected via feedforward (FF) and feedback (FB) circuits. Several theories of hierarchical computation ascribe the bulk of the computational work of the cortex to looped FF-FB circuits between pairs of cortical areas. However, whether such corticocortical loops exist remains unclear. In higher mammals, individual FF-projection neurons send afferents almost exclusively to a single higher-level area. However, it is unclear whether FB-projection neurons show similar area-specificity, and whether they influence FF-projection neurons directly or indirectly. Using viral-mediated monosynaptic circuit tracing in macaque primary visual cortex (V1), we show that V1 neurons sending FF projections to area V2 receive monosynaptic FB inputs from V2, but not other V1-projecting areas. We also find monosynaptic FB-to-FB neuron contacts as a second motif of FB connectivity. Our results support the existence of FF-FB loops in primate cortex, and suggest that FB can rapidly and selectively influence the activity of incoming FF signals.

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