Electrophysiological evidence for the existence of caudate-caudate connections

Experiments were performed in cats unanesthetized and paralyzed with Flaxedil. The stimulation of the right caudate elicited in the contralateral nucleus, biphasic positive-negative field potentials with latencies between 11-20 msec and peak to peak amplitudes of 132-216 microv. These were the shortest latencies and the highest amplitudes for those potentials evoked by stimulation of the symmetrical positions to recording electrode. However, no responses could be evoked in the caudate tail by stimulation of any part of the opposite nucleus. Lesions of cerebral cortex (sensorimotor cortex or hemidecortication) and thalamus (center median-parafascicular complex and massa intermedia) left the evoked responses in the caudate nucleus unchanged. However, the evoked potentials were suppressed by section of the corpus callosum. Our results suggest direct connections between both caudates, through the corpus callosum.