[Specifics of post-theta modification of synaptic transmission in thalamo-cortical input of the rat's barrel cortex]

The possibility of the development of either the long-term posttetanic potentiation or the depression of focal evoked potentials in identified columns of the barrel somatic cortex of unanaesthetized rats during stimulation of their specific thalamocortical afferent fibers was shown. Phase-dependent potentiation developed after burst tetanization with the frequency of theta rhythm at the negative phase of a theta wave, whereas the stimulation at the positive phase produced the depression. Potentiation after continuous tetanization was observed only at the optimal selection of stimuli amplitude and duration. Excessively intense tetanization more frequently caused the depression of tested responses probably due to the involvement of recurrent inhibition.