The authors tested the spatial generalization of shape and color discriminations in 2 monkeys, in which 3 visual field quadrants were affected, respectively, by lesions in area V4, TEO, or both areas combined. The fourth quadrant served as a normal control. The monkeys were trained to discriminate stimuli presented in a standard location in each quadrant, followed by tests of discrimination per...

Vision in humans and in non-human primates is mediated by a constellation of hierarchically organized visual areas. One important area is V4 which has highly nonlinear response properties. To better understand the filtering properties of V4 neurons we recorded from 71 well isolated cells stimulated with 4000-12000 static grayscale natural images. We fit predictive models of neuron spike rates u...

Ghose, Geoffrey M. and Daniel Y. Ts’o. Form processing modcaca fascicularis were anesthetized by continuous intravenous infusion of sufentanil citrate (3–8 mgrkgrh) , paralyzed (vercules in primate area V4. J. Neurophysiol. 77: 2191–2196, 1997. Area V4 occupies a central position among the areas of the primate uronium bromide, 100 mgrkgrh) , and artificially respirated. The level of anesthesia ...

A biologically-based neural network simulation is used to analyze the contributions to color perception of each of several processing steps in the visual system from the retina to cortical area V4. We consider the effects on color constancy and color induction of adaptation, spectral opponency, non-linearities including saturation and rectification, and spectrally-specific long-range inhibition...

The F1- and F2-polypeptide components of the fusion proteins and the hemagglutinin/neuraminidase proteins of the avirulent Queensland (V4) and virulent Australia-Victoria (AuV) strains of Newcastle disease virus have been isolated and subjected to extensive primary structural analysis including amino-terminal sequence analysis and fast atom bombardment-mass spectrometry mapping. Nucleotide sequ...

The visually driven responses of macaque area V4 neurons are modulated during the preparation of saccadic eye movements, but the relationship between presaccadic modulation in area V4 and saccade preparation is poorly understood. Recent neurophysiological studies suggest that the variability across trials of spiking responses provides a more reliable signature of motor preparation than mean fir...

Previous transcranial magnetic stimulation (TMS) studies suggested that feedback from higher to lower areas of the visual cortex is important for the access of visual information to awareness. However, the influence of cortico-cortical feedback on awareness and the nature of the feedback effects are not yet completely understood. In the present study, we used electrical microstimulation in the ...