Monocular Cells Without Ocular Dominance Columns

Adams, Daniel L.; Horton, Jonathan C.

doi:10.1152/jn.00131.2006

Cited by 24 publications

(14 citation statements)

References 66 publications

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“…The dotted line indicates V2/V3 border. ton and Hocking, 1996a; Adams and Horton, 2006b). In the portion of the human mosaic in which the columns looked like squirrel monkey columns, there was no spatial correlation between patches and columns (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, the center alone is less useful for defining the location of a patch than an algorithm that incorporates information about the entire structure. For this reason, we performed a spatial correlation to quantify the relationship between patches and ocular dominance columns (Lia and Olavarria, 1996;Boyd and Casagrande, 1999;Adams and Horton, 2006b). To define patches, a single CO section was high-pass Fourier filtered to correct for global changes in section density (attributable to small differences in layer 3 depth).…”

Section: Methodsmentioning

confidence: 99%

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Complete Pattern of Ocular Dominance Columns in Human Primary Visual Cortex

Adams¹,

Sincich²,

Horton³

2007

J. Neurosci.

196

206

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The occipital lobes were obtained after death from six adult subjects with monocular visual loss. Flat-mounts were processed for cytochrome oxidase (CO) to reveal metabolic activity in the primary (V1) and secondary (V2) visual cortices. Mean V1 surface area was 2643 mm 2 (range, 1986 -3477 mm 2 ). Ocular dominance columns were present in all cases, having a mean width of 863 m. There were 78 -126 column pairs along the V1 perimeter. Human column patterns were highly variable, but in at least one person they resembled a scaled-up version of macaque columns. CO patches in the upper layers were centered on ocular dominance columns in layer 4C, with one exception. In this individual, the columns in a local area resembled those present in the squirrel monkey, and no evidence was found for column/patch alignment. In every subject, the blind spot of the contralateral eye was conspicuous as an oval region without ocular dominance columns. It provided a precise landmark for delineating the central 15°of the visual field. A mean of 53.1% of striate cortex was devoted to the representation of the central 15°. This fraction was less than the proportion of striate cortex allocated to the representation of the central 15°in the macaque. Within the central 15°, each eye occupied an equal territory. Beyond this eccentricity, the contralateral eye predominated, occupying 63% of the cortex. In one subject, monocular visual loss began at age 4 months, causing shrinkage of ocular dominance columns. In V2, which had a larger surface area than V1, CO stripes were present but could not be classified as thick or thin.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Complete Pattern of Ocular Dominance Columns in Human Primary Visual Cortex

Adams¹,

Sincich²,

Horton³

2007

J. Neurosci.

196

206

View full text Add to dashboard Cite

show abstract

“…However, the presence of ocular preference in neurons from areas not organized in ocular dominance maps raised the question of the benefit of function maps in neuronal selectivity (Drager, 1975; Weber et al, 1977; Hollander and Halbig, 1980; Adams and Horton, 2003, 2006). Alike, comparable orientation selectivity was found in V1 neurons from animals with and without orientation maps (Tiao and Blakemore, 1976; Murphy and Berman, 1979; Blasdel and Salama, 1986; Grinvald et al, 1986; Metin et al, 1988; Bosking et al, 1997; Girman et al, 1999; Ohki et al, 2005; Van Hooser et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

Surround suppression maps in the cat primary visual cortex

Vanni

Casanova

2013

Front. Neural Circuits

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In the primary visual cortex and higher-order areas, it is well known that the stimulation of areas surrounding the classical receptive field of a neuron can inhibit its responses. In the primate area middle temporal (MT), this surround suppression was shown to be spatially organized into high and low suppression modules. However, such an organization has not been demonstrated yet in the primary visual cortex. Here, we used optical imaging of intrinsic signals to spatially evaluate surround suppression in the cat visual cortex. The magnitude of the response was measured in areas 17 and 18 for stimuli with different diameters, presented at different eccentricities. Delimited regions of the cortex were revealed by circumscribed stimulations of the visual field (“cortical response field”). Increasing the stimulus diameter increased the spread of cortical activation. In the cortical response field, the optimal stimulation diameter and the level of suppression were evaluated. Most pixels (≥3/4) exhibited surround suppression profiles. The optimal diameter, corresponding to a population of receptive fields, was smaller in area 17 (22°) than in area 18 (36°) in accordance with electrophysiological data. No difference in the suppression strength was observed between both areas (A17: 25%, A18: 21%). Further analysis of our data revealed the presence of surround modulation maps, organized in low and high suppression domains. We also developed a statistical method to confirm the existence of this cortical map and its neuronal origin. The organization for center/surround suppression observed here at the level of the primary visual cortex is similar to those found in higher order areas in primates (e.g., area MT) and could represent a strategy to optimize figure ground discrimination.

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“…Location within VPm was verified electrophysiologically during the experiment (Diamond et al 1992) and checked by histological identification of the recording site (Yu et al 2006). Recording sites were marked by electrolytic lesions: 5-10 A for 20 s at 50 kHz (Adams and Horton 2006). After perfusion with 10% formalin, sites were identified by staining 50-m coronal sections with cresyl violet.…”

Section: Electrophysiologymentioning

confidence: 99%

Role of Precise Spike Timing in Coding of Dynamic Vibrissa Stimuli in Somatosensory Thalamus

Montemurro

Panzeri²,

Maravall³

et al. 2007

Journal of Neurophysiology

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Rats discriminate texture by whisking their vibrissae across the surfaces of objects. This process induces corresponding vibrissa vibrations, which must be accurately represented by neurons in the somatosensory pathway. In this study, we investigated the neural code for vibrissa motion in the ventroposterior medial (VPm) nucleus of the thalamus by single-unit recording. We found that neurons conveyed a great deal of information (up to 77.9 bits/s) about vibrissa dynamics. The key was precise spike timing, which typically varied by less than a millisecond from trial to trial. The neural code was sparse, the average spike being remarkably informative (5.8 bits/spike). This implies that as few as four VPm spikes, coding independent information, might reliably differentiate between 10(6) textures. To probe the mechanism of information transmission, we compared the role of time-varying firing rate to that of temporally correlated spike patterns in two ways: 93.9% of the information encoded by a neuron could be accounted for by a hypothetical neuron with the same time-dependent firing rate but no correlations between spikes; moreover, > or =93.4% of the information in the spike trains could be decoded even if temporal correlations were ignored. Taken together, these results suggest that the essence of the VPm code for vibrissa motion is firing rate modulation on a submillisecond timescale. The significance of such a code may be that it enables a small number of neurons, firing only few spikes, to convey distinctions between very many different textures to the barrel cortex.

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Monocular Cells Without Ocular Dominance Columns

Cited by 24 publications

References 66 publications

Complete Pattern of Ocular Dominance Columns in Human Primary Visual Cortex

Complete Pattern of Ocular Dominance Columns in Human Primary Visual Cortex

Surround suppression maps in the cat primary visual cortex

Role of Precise Spike Timing in Coding of Dynamic Vibrissa Stimuli in Somatosensory Thalamus

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