[Changes in the functional characteristic of motor cortex neurons following their rhythmic polarization]

The study was devoted to the effect of rhythmical extracellular activating polarization on spontaneous and evoked (by stimulation of the ventroposterolateral nucleus of the thalamus) unit activity of the motor cortex, preliminarily sensitized by application of an epileptigen (penicillin or strychnine solution). The experiments were carried out on alert unrestrained rabbits. A 3-5 minutes rhythmical polarization of the neurons (0,12, 0, 10 c/s, 200-600 msec pulse duration) resulted in following aftereffects: 1) changes in the mean spike frequency in 58% of neurons; 2) increase of grouping of firing in units with an initial group-type spontaneous activity (21%); 3) assimilation of the polarizing rhythm (10%); 4) facilitation of excitatory phases of thalamically evoked unit responses that occured simultaneously with an increase of mean discharge frequency (18%). The results are discussed from the point of view of the hypothesis of excitatory reverberation in the microsystem of interconnected neurons.