Orientation sensitive properties of visually driven neurons in extrastriate area 21a of cat cortex.

Orientation sensitive properties of extrastriate area 21a neurons were investigated. Special attention was paid to the qualitative characteristics of neuron responses to the different orientations of visual stimulus motion across neuron classical receptive fields (CRF). The results of experiments have shown that a group of neurons (31%) in area 21a with specialized responses to moving visual stimuli changed their direction selective (DS) characteristics depending on the orientation of the stimulus movement.

Spatial summation processes in the receptive fields of visually driven neurons of the cat's cortical area 21a.

The spatial summation in receptive fields (RF) of single neurons in cat's extrastriate area 21a was investigated as a basic neurophysiological substrate for central integration processing of visual information. The results showed that the majority of investigated neurons changed their response patterns with gradual increase of applied stimulus size. In approximately 82% of cases the suppression of neuron discharges was observed when the length of the moving strip exceeded that of the RF.

[Receptive fields of lateral suprasylvian neurons in the cat].

The receptive field structure of single neurons in lateral suprasylvian area was investigated in cat. Receptive fields were of larger sizes comparing with visual cortex (up to 2000 sq. deg.

Effects of background illumination of visually evoked responses of neurons in the Clare-Bishop area of the cat.

Functional properties of visually driven neurons were investigated at various levels of background illumination. Roughly 50 percent of the investigated cells inhibited their responses to stationary flash lights after background illumination, about 25 percent did not show any difference and 25 percent were facilitated. The increase of the background illumination influenced the movement evoked responses in various ways.