Fiber connections of the temporal lobe with the corpus striatum and related structures in the cat

Fiber connections of the ventral portions of the posterior sylvian and ectosylvian gyri of the cat were studied after lesions of either or both of these regions using the Fink-Heimer method. Massive terminal degeneration was observed throughout the ventromedial aspect of the head and entire body of the caudate nucleus on the ipsilateral side. Terminal degeneration was also observed in other nuclei associated with the basal ganglia: putamen; globus pallidus; subthalamic nucleus; and substantia nigra. Also, large quantities of degeneration were traced to the dorsomedial nucleus, posterior thalamic nuclei, and to auditory relay nuclei. In other cats degenerative changes after similarily placed lesions in the ventral posterior sylvian and ectosylvian gyri were studied by electron microscopy. The EM observations confirmed the light microscopic findings. In the ventromedial aspect of the head of the caudate nucleus large quantities of degenerating boutons were observed to form synaptic contacts, principally upon dendritic spines. Lesions were also placed in the substantia nigra using a contralateral approach. Degenerating axons were traced from the site of the lesion into the head of the caudate nucleus and putamen. The largest quantities of terminal degeneration in the caudate nucleus were located in its ventromedial aspect. These findings suggest an anatomical basis by which both the temporal lobe and substantia nigra could separately regulate the activity of neurons in the ventromedial portion of the head of the caudate nucleus.