[Functional characteristics of the orientation-selective neurons in the frontal visual field of the striate cortex in...

The extracellular activity of 150 neurons (field 17) from binocular region of the visual cortex in the Siberian chipmunk was investigated. 65% of neurons proved to be selective to orientation and selective (but differently) to the direction of movements of the contrast boundaries and light. 18% of neurons were nonselective to the orientation and direction of the stimulus movement. 17% of neurons were activated only with the total illumination of the receptive field. Out of 39 orientation-selective neurons investigated by the moving and stationary stimuli 16 neurons reacted only to the moving stimuli: 13 neurons responded to exposure to stationary bars with prolonged tonic activation, 7 neurons showed a short phasic response and 3 neurons--a phasically-tonic response. All the phasic neurons were a maximally activated at higher movement velocities compared with the tonic neurons. The possible analogy between fast-phasic and slow-tonic neurons and Y- and X-systems is discussed.