Visual receptive field properties of neurons in the caudate nucleus.

Visual single-unit activity was recorded in the caudate nucleus of halothane-anaesthetized, immobilized, artificially respirated cats. Visually sensitive neurons were found in the dorsolateral part of the caudate body. A majority of the units responded optimally to small spot-like stimuli moving with velocities between 30 and 120 degrees /s. The receptive field of these units is large: it covers a major part of both the contra- and ipsilateral visual hemifields. No signs of retinotopy were observed. Most of the neurons display directional selectivity and are narrowly tuned to the direction of the moving stimulus. These physiological properties are consistent with recent morphological results that reveal multiple connections of the caudate nucleus with the superior colliculus through tecto-extrageniculo-thalamic pathways in the mammalian brain.