Abstract: Nine rats with permanent paired electrodes implanted in differentsubcortical regions, such as n. amygdaloideus centralis, area amygdaloideaanterior, hippocampus ventralis, n. caudatus-putmen, fimbria hippocampi,area between n. amygdaloidus corticalis and amygdaloideus medialis, areabetween capsula interna and globus pallidus, and pedenculus cerebri, werestimulated with 50Hz, 50 microamp. current at 24hrs. interval. No kindling effect had ever developed since the stimulations oftenresulted in flattening of EEGs recorded from the stimulated regions. Thepatterns of the EEG flattening after stimulation were very similar to thoseobserved by Shao and Valenstein in the kindled rats when a series ofsubthreshold brain stimulations Were administered, Reserpine injectioncompletely dispelled this effect. It was concluded that this phenomenon reflects an inhibitory effect ofthe subcortical brain stimulation and depends not upon the location of thestimulation but upon the functional state of the neurons during stimulation.

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