scholarly journals The organization of chromatic and spatial interactions in the primate striate cortex

1988 ◽  
Vol 8 (5) ◽  
pp. 1712-1727 ◽  
Author(s):  
DY Ts'o ◽  
CD Gilbert
Keyword(s):  
Striate Cortex ◽  
Spatial Interactions

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

scholarly journals Modelling the contribution of short-range atmospheric and hydrological transfers to nitrogen fluxes, budgets and indirect emissions in rural landscapes

2012 ◽  
Vol 9 (5) ◽  
pp. 1647-1660 ◽  
Author(s):  
J.-L. Drouet ◽  
S. Duretz ◽  
P. Durand ◽  
P. Cellier
Keyword(s):  
Short Range ◽  
Landscape Scale ◽  
Soil Conditions ◽  
N2o Emissions ◽  
Spatial Interactions ◽  
Rural Landscapes ◽  
Environmental Threats ◽  
Spatially Distributed ◽  
Simulation Results ◽  
Oligotrophic Ecosystems

Abstract. Spatial interactions within a landscape may lead to large inputs of reactive nitrogen (Nr) transferred from cultivated areas and farms to oligotrophic ecosystems and induce environmental threats such as acidification, nitric pollution or eutrophication of protected areas. The paper presents a new methodology to estimate Nr fluxes at the landscape scale by taking into account spatial interactions between landscape elements. This methodology includes estimates of indirect Nr emissions due to short-range atmospheric and hydrological transfers. We used the NitroScape model which integrates processes of Nr transformation and short-range transfer in a dynamic and spatially distributed way to simulate Nr fluxes and budgets at the landscape scale. Four configurations of NitroScape were implemented by taking into account or not the atmospheric, hydrological or both pathways of Nr transfer. We simulated Nr fluxes, especially direct and indirect Nr emissions, within a test landscape including pig farms, croplands and unmanaged ecosystems. Simulation results showed the ability of NitroScape to simulate patterns of Nr emissions and recapture for each landscape element and the whole landscape. NitroScape made it possible to quantify the contribution of both atmospheric and hydrological transfers to Nr fluxes, budgets and indirect Nr emissions. For instance, indirect N2O emissions were estimated at around 21% of the total N2O emissions. They varied within the landscape according to land use, meteorological and soil conditions as well as topography. This first attempt proved that the NitroScape model is a useful tool to estimate the effect of spatial interactions on Nr fluxes and budgets as well as indirect Nr emissions within landscapes. Our approach needs to be further tested by applying NitroScape to several spatial arrangements of agro-ecosystems within the landscape and to real and larger landscapes.

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.

Functional connectivity between simple cells and complex cells in cat striate cortex

10.1038/1609 ◽  
1998 ◽  
Vol 1 (5) ◽  
pp. 395-403 ◽  
Author(s):  
Jose-Manuel Alonso ◽  
Luis M. Martinez
Keyword(s):  
Functional Connectivity ◽  
Striate Cortex ◽  
Simple Cells ◽  
Complex Cells ◽  
Cat Striate Cortex

A Phenomenological Theory of Socioeconomic Systems with Spatial Interactions

1982 ◽  
Vol 14 (7) ◽  
pp. 869-888 ◽  
Author(s):  
P F Lesse
Keyword(s):  
Lagrange Multipliers ◽  
Average Cost ◽  
Phenomenological Theory ◽  
Traffic Flows ◽  
Spatial Interactions ◽  
Practical Application ◽  
Density Distributions ◽  
Expected Values ◽  
Probability Density Distributions ◽  
The Relationship

This paper deals with a class of models which describe spatial interactions and are based on Jaynes's principle. The variables entering these models can be partitioned in four groups: (a) probability density distributions (for example, relative traffic flows), (b) expected values (average cost of travel), (c) their duals (Lagrange multipliers, traffic impedance coefficient), and (d) operators transforming probabilities into expected values. The paper presents several dual formulations replacing the problem of maximizing entropy in terms of the group of variables (a) by equivalent extreme problems involving groups (b)-(d). These problems form the basis of a phenomenological theory. The theory makes it possible to derive useful relationships among groups (b) and (c). There are two topics discussed: (1) practical application of the theory (with examples), (2) the relationship between socioeconomic modelling and statistical mechanics.

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.

Sign in / Sign up

Export Citation Format

Share Document