Self-sustained rhythmic spike and wave activity and response of glial and nerve cells in the cat sensorimotor cortex

During acute experiments on unanesthetized cats, immobilized with myorelaxants, it was found that during rhythmic stimulation (8–14 Hz, duration: 10 sec) of the ventroposterolateral thalamic nucleus brief hyperpolarization is succeeded by depolarization in the pyramidal neurons of the sensorimotor cortex. Following this depolarization, rhythmic (approximately 3 Hz) paroxysmal depolarizing shifts in membrane potential are produced by ending stimulation, succeeded by protracted hyperpolarization and termination of rhythmic wave activity. Depolarization only is observed in glial cells, however, while hyperpolarization sets in after hyperpolarization is completed in the neurons. It is suggested that long-term changes in the membrane potential of cortical cells could make some contribution to the setting up and termination of rhythmic spike and wave activity.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 18, No. 3, pp. 319–325, May–June, 1986.