Control of chronic experimental focal epilepsy by feedback caudatum stimulations.

The effects of feedback caudate nucleus (CN) stimulations (5 cycles/s, 0.3 ms, 1-5 V, 1-3 s) on the interictal spiking activity of epileptic foci automatically detected by a neuroanalyzer were followed in adult cats during 2-3 weeks of training. Spike depression occurred instantly after the onset of feedback stimulation, became stable after 3-4 days of operant training, and persisted with very little current reinforcement in a daily training schedule. No comparable effects were obtained either by random CN stimulation or by contingent stimulations of other subcortical structures such as the thalamus, the mesencephalic reticular formation, or the hypothalamus. A recovery of recurrent inhibitory caudate-cortical loops is presumed to contribute to the progressive normalization of cortical excitability obtained by training.