Characteristics of the post-tetanic modification of synaptic transmission in the thalamocortical input of the somatosensory cortex in rats.

The development of both long-term post-tetanic potentiation and depression of focal evoked potentials by identified columns in the somatosensory cortex of unanesthetized rats was shown to occur in conditions of stimulation of their thalamocortical afferents. Trains of theta stimulation induced the phase-dependent development of post-tetanic potentiation after tetanization on the negative phase of the theta wave, while depression occurred after stimulation on the positive phase. Continuous tetanization produced potentiation only with stimulation at optimum amplitude and duration; extremely strong tetanization generally induced depression of responses to test stimuli, evidently because of activation of recurrent inhibition.