scholarly journals Metric reconstruction of human striate cortex: An average

2005 ◽  
Vol 5 (12) ◽  
pp. 84-84
Author(s):  
M. Schira
Keyword(s):  
Striate Cortex ◽  
Metric Reconstruction

Tetraploidy and the striate cortex

Pathology ◽  
1977 ◽  
Vol 9 (2) ◽  
pp. 99-104 ◽  
Author(s):  
C.L. Scholtz
Keyword(s):  
Striate Cortex

scholarly journals Collicular Vision Guides Nonconscious Behavior

2010 ◽  
Vol 22 (5) ◽  
pp. 888-902 ◽  
Author(s):  
Marco Tamietto ◽  
Franco Cauda ◽  
Luca Latini Corazzini ◽  
Silvia Savazzi ◽  
Carlo A. Marzi ◽  
...  
Keyword(s):  
Visual Experience ◽  
Striate Cortex ◽  
Visual Signals ◽  
Visually Guided ◽  
Visuomotor Integration ◽  
Motor Processing ◽  
Pupillary Responses ◽  
Cortex Area ◽  
Extrastriate Areas

Following destruction or deafferentation of primary visual cortex (area V1, striate cortex), clinical blindness ensues, but residual visual functions may, nevertheless, persist without perceptual consciousness (a condition termed blindsight). The study of patients with such lesions thus offers a unique opportunity to investigate what visual capacities are mediated by the extrastriate pathways that bypass V1. Here we provide evidence for a crucial role of the collicular–extrastriate pathway in nonconscious visuomotor integration by showing that, in the absence of V1, the superior colliculus (SC) is essential to translate visual signals that cannot be consciously perceived into motor outputs. We found that a gray stimulus presented in the blind field of a patient with unilateral V1 loss, although not consciously seen, can influence his behavioral and pupillary responses to consciously perceived stimuli in the intact field (implicit bilateral summation). Notably, this effect was accompanied by selective activations in the SC and in occipito-temporal extrastriate areas. However, when instead of gray stimuli we presented purple stimuli, which predominantly draw on S-cones and are thus invisible to the SC, any evidence of implicit visuomotor integration disappeared and activations in the SC dropped significantly. The present findings show that the SC acts as an interface between sensory and motor processing in the human brain, thereby providing a contribution to visually guided behavior that may remain functionally and anatomically segregated from the geniculo-striate pathway and entirely outside conscious visual experience.

scholarly journals Erratum: Corrigendum: Neuronal basis of perceptual learning in striate cortex

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Zhen Ren ◽  
Jiawei Zhou ◽  
Zhimo Yao ◽  
Zhengchun Wang ◽  
Nini Yuan ◽  
...  
Keyword(s):  
Perceptual Learning ◽  
Striate Cortex

Favored patterns in spike trains. II. Application

1983 ◽  
Vol 49 (6) ◽  
pp. 1349-1363 ◽  
Author(s):  
J. E. Dayhoff ◽  
G. L. Gerstein
Keyword(s):  
Striate Cortex ◽  
Biological Significance ◽  
Companion Paper ◽  
Spike Trains ◽  
Area 17 ◽  
Stimulus Information ◽  
Experimental Conditions ◽  
Cat Striate Cortex ◽  
Template Methods ◽  
Anesthetized Cat

In this paper we apply the two methods described in the companion paper (4) to experimentally recorded spike trains from two preparations, the crayfish claw and the cat striate cortex. Neurons in the crayfish claw control system produced favored patterns in 23 of 30 spike trains under a variety of experimental conditions. Favored patterns generally consisted of 3-7 spikes and were found to be in excess by both quantized and template methods. Spike trains from area 17 of the lightly anesthetized cat showed favored patterns in 16 of 27 cases (in quantized form). Some patterns were also found to be favored in template form; these were not as abundant in the cat data as in the crayfish data. Most firing of the cat neurons occurred at times near stimulation, and the observed patterns may represent stimulus information. Favored patterns generally contained up to 7 spikes. No obvious correlations between identified neurons or experimental conditions and the generation of favored patterns were apparent from these data in either preparation. This work adds to the existing evidence that pattern codes are available for use by the nervous system. The potential biological significance of pattern codes is discussed.

The effects of contrast on visual orientation and spatial frequency discrimination: a comparison of single cells and behavior

1987 ◽  
Vol 57 (3) ◽  
pp. 773-786 ◽  
Author(s):  
B. C. Skottun ◽  
A. Bradley ◽  
G. Sclar ◽  
I. Ohzawa ◽  
R. D. Freeman
Keyword(s):  
Spatial Frequency ◽  
Striate Cortex ◽  
Frequency Tuning ◽  
Single Cells ◽  
Frequency Discrimination ◽  
Frequency Selectivity ◽  
Response Amplitude ◽  
Visual Orientation ◽  
Characteristic Analysis ◽  
Response Variance

We have compared the effects of contrast on human psychophysical orientation and spatial frequency discrimination thresholds and on the responses of individual neurons in the cat's striate cortex. Contrast has similar effects on orientation and spatial frequency discrimination: as contrast is increased above detection threshold, orientation and spatial frequency discrimination performance improves but reaches maximum levels at quite low contrasts. Further increases in contrast produce no further improvements in discrimination. We measured the effects of contrast on response amplitude, orientation and spatial frequency selectivity, and response variance of neurons in the cat's striate cortex. Orientation and spatial frequency selectivity vary little with contrast. Also, the ratio of response variance to response mean is unaffected by contrast. Although, in many cells, response amplitude increases approximately linearly with log contrast over most of the visible range, some cells show complete or partial saturation of response amplitude at medium contrasts. Therefore, some cells show a clear increase in slope of the orientation and spatial frequency tuning functions with increasing contrast, whereas in others the slopes reach maximum values at medium contrasts. Using receiver operating characteristic analysis, we estimated the minimum orientation and spatial frequency differences that can be signaled reliably as a response change by an individual cell. This analysis shows that, on average, the discrimination of orientation or spatial frequency improves with contrast at low contrasts more than at higher contrasts. Using the optimal stimulus for each cell, we estimated the contrast threshold of 48 neurons. Most cells had contrast thresholds below 5%. Thresholds were only slightly higher for nonoptimal stimuli. Therefore, increasing the contrast of sinusoidal gratings above approximately 10% will not produce large increases in the number of responding cells. The observed effects of contrast on the response characteristics of nonsaturating cortical cells do not appear consistent with the psychophysical results. Cells that reach their maximum response at low-to-medium contrasts may account for the contrast independence of psychophysical orientation and spatial frequency discrimination thresholds at medium and high contrasts.

Distribution of GABAergic neurons and axon terminals in the macaque striate cortex

1987 ◽  
Vol 264 (1) ◽  
pp. 73-91 ◽  
Author(s):  
D. Fitzpatrick ◽  
J. S. Lund ◽  
D. E. Schmechel ◽  
A. C. Towles
Keyword(s):  
Striate Cortex ◽  
Gabaergic Neurons ◽  
Axon Terminals

Harmonic basis functions for spatial coding in the cat striate cortex

1989 ◽  
Vol 3 (4) ◽  
pp. 351-363 ◽  
Author(s):  
V. D. Glezer ◽  
V. V. Yakovlev ◽  
V. E. Gauzelman
Keyword(s):  
Spatial Frequency ◽  
Striate Cortex ◽  
Weighting Function ◽  
Discrete Distribution ◽  
Basis Functions ◽  
Spatial Coding ◽  
Central Visual Field ◽  
Spatial Frequencies ◽  
The Absolute ◽  
Number Of Cycles

AbstractThe number of subregions in the activity profiles of simple cells varies in different cells from 2–8; that is, the number of cycles in the weighting function varies from 1–4. The distribution of receptive-field (RF) sizes at eccentricities of 0-6 deg are clustered at half-octave intervals and form a discrete distribution with maxima at 0.62, 0.9, 1.24, 1.8, 2.48, and 3.4 deg. The spatial frequencies to which the cells are tuned are also clustered at half-octave intervals, forming a discrete distribution peaking at 0.45, 0.69, 0.9, 1.35, 1.88, 2.7, 3.8, and 5.6 cycles/deg. If we divide the RF sizes by the size of the period of the subregions, then the average indices of complexity (really existing) or the number of cycles in the weighting function form (after normalization) the sequences: 1, 1.41, 2.0, 2.9, 4.15.The relation between the bandwidth of the spatial-frequency characteristic and the optimal spatial frequency is in accordance with predictions of the Fourier hypothesis. The absolute bandwidth does not change with the number of cycles/module. This means that inside the module the absolute bandwidth does not change with the number of the harmonic. The results allow us to suggest the following. A module of the striate cortex, which is a group of cells with RFs of equal size projected onto the same area of central visual field, accounts for the Fourier description of the image. The basis functions of the module are composed of four harmonics only, irrespective of size and position of the module.Besides linear cells (sinusoidal and cosinusoidal elements), the module contains nonlinear cells, performing a nonlinear summation of the responses of sinusoidal and cosinusoidal elements. Such cells are characterized by an index of complexity which is more than the number of cycles in the weighting function and by marked overlap of ON and OFF zones. The analysis of organization suggests that the cells can measure the amplitude and phase of the stimulus.

Interpretation of the function of the striate cortex

2000 ◽  
Author(s):  
Bernardette M. Garner ◽  
Andrew P. Paplinski
Keyword(s):  
Striate Cortex
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