[Electrophysiologic study of influences of the Pulvinar stimulation on the caudate nucleus neurons responding to...

Responses of caudate neurons to electrical stimulation of the afferent input from the thalamic nucleus pulvinar and to visual stimuli of various orientations were studied extracellularly in awake chronic cats. Activation responses dominated among reactions of these neurons. The response latencies have ranged from 4 to 85 ms for units with primary activation and from 20 to 150 ms for inhibited ones, the values are indicative of both rapidly and slowly conducting afferent pathways. A possibility of monosynaptic transmission in the pulvinar-caudate projections is also revealed. Stimulation of pulvinar is found to be efficient for the significant (more than 50%) number of caudate neurons responding to visual stimuli including orientation-selective cells. The mode of influences from other structures of the visual system (optic tract, area 17, the Clare-Bishop area) on caudate neurons, responding to pulvinar stimulation is described. The obtained data are discussed in the aspect of the possible role of cortical and subcortical projections of the visual system in the creation of sensory specific responses of the caudate nucleus.