CORTICOCAUDATOTHALAMIC INTERACTIONS IN EXPERIMENTAL FOCAL EPILEPSY IN THE CAT

Corticocaudatothalamic network dynamics were studied in cats with seizures induced by the injection of tungstic acid into the pericruciate gyrus. The discharge patterns of neurons and concomitant slow-wave activity in the lateral, rostral portion of the head of the caudate nucleus were compared to similar activity in the medial, rostral portion of the ipsilateral head of the caudate nucleus and the ipsilateral ventral anterior thalamus. In the preictal phase, activation of neurons in the lateral caudate followed burst activity recorded at the focus whereas there was no detectable effect on activity recorded in the medial caudate. The amplitude of the propagated slow waves was also greater in the lateral segment of the caudate, somatotopically related to the cortical focus. The spread of ictal activity followed a stereotyped pattern; activation of the ipsilateral thalamus followed cortical seizure activity in sequential spread subsequently occurring to the lateral caudate head and finally to the medial caudate head. The findings suggest that seizure afterdischarge may be transferred from one segment of the caudate nucleus to another by external synaptic connections. © 1979.