[Prolonged negative potentials of the surface of the sensomotor cortex of the cat and responses of neural and glial cells].

In acute experiments on immobilized cats, potentials evoked by stimulation of the ventrolateral and intralaminar thalamic nuclei, of the surface of the sensorimotor cortex and pyramidal pathways as well as the corresponding postsynaptic responses of pyramidal neurons, were studied. A negative shift of potential in response to tetanic stimulation of the cortical surface or thalamic nucleus occurred on the cortical surface. Concominantly, intracellular recording of the glial-cell activity was performed. Superficial application of strychnine induced the suppression of the slow-negative potential arising during direct cortical and primary responses and the corresponding slow potentials of IPSP. The effects of iontophoretic application of strychnine on IPSP of pyramidal neurons and cortical glial-cell response were also studied. Both ways of application appeared to block mainly the early component of IPSP during which the input resistance was significantly lesser than that of the late component, pointing to the difference in their genesis. The findings indicate that slow-negative potentials reflect hyperpolarization of pyramidal neurons, while the separate components of responses have common genesis.