Girard P, Jouffrais C, Arcizet F, Bullier J, 2003, "Neuronal basis of coding natural textures in area V4 of the awake monkey" Perception 32 ECVP Abstract Supplement
Neuronal basis of coding natural textures in area V4 of the awake monkey
P Girard, C Jouffrais, F Arcizet, J Bullier
Although objects in a visual scene are in three dimensions (3-D), it is possible to identify them on the basis of 2-D pictures. It is therefore obvious that the cues in static monocular pictures can be used for the recognition of 3-D shapes. Among these monocular cues, the texture of objects is an important source of information. Our study aimed to reveal coding specificities of natural textures by area V4 neurons in the awake macaque monkey. We trained a monkey to fixate a point on a screen during the presentation of a natural texture picture in the receptive field of a neuron. In each trial, the picture is chosen among a set of 12 textures lit under 3 different directions (36 stimuli) and their respective 36 controls (random Fourier phase). These stimuli come from the CURET (Columbia - Utrecht reflectance and texture) database. We tested 90 neurons with the 72 stimuli. 81% of the neurons have a selective response to the textures and 70% to illumination direction. A multi-dimensional scaling analysis shows that there may be clusters of neuronal responses related to a limited number of natural texture parameters. Whereas luminance or contrast cannot explain the selectivity of the whole population of cells, spatial parameters extracted from a pyramid of filters account for the clustering of some neuronal responses. These results show that V4 neurons participate in the coding of natural textures by extracting spatial parameters.
[Supported by Project INSIGHT2+ founded by IST.]
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