[Prolonged potentiation of responses of the neocortex of the intact brain and in vitro cortical slices].

The field potentials (FPs) and neuronal responses evoked by stimulation of subcortical white matter were recorded in the sensorimotor cortex of intact brain in alert rabbits and in cortical slices. After a few short (500 msec) tetanizations (200 Hz) delivered via the stimulating electrodes, a long-term (several hours) increase of short-latency (1-3 msec) FP amplitude occurred in the brain as well as an increase of the same FP components in cortical slices. The probability of short-latency (up to 1.8 msec) unit discharges increased after the tetanization. Repetition of tetanic stimulation in the same experiment increased and prolonged potentiation in vivo though it had an opposite effect in vitro. The long-term potentiation of neocortical FP seems to be due to the potentiation in monosynaptic pathways.