[Neurophysiological correlates of visual perception].

Abstract

Structural organization of simple and complex receptive fields of the visual cortex was studied. The bidimensional weight function of the field determining its main properties as a filter of spatial frequencies (the space-frequency and the orientation sensitivity), was investigated. Two types of modules are discussed: the cylinders of cortical neurons whose receptive fields are oriented towards a single area of the visual field and adjusted for different spatial frequencies and orientations. One type of the modules contains neurons whose receptive fields describe the amplitude and phase of a visual signal and give the Fourier-description of a portion of picture; the second type's receptive fields describe the amplitude alone and give the power spectra. Comparison with psychophysical data suggests that the second type serves for texture description. Inhibition in the receptive field induced by frequencies which are lateral in respect to the optimal frequency and by orientations which are perpendicular in respect to the optimal orientation, reveals the mutually inhibiting influences among the module's neurons. Significance of this type of organization for visual perception is discussed.