Plastic reorganizations of the receptive fields of neurons of the auditory cortex and the medial geniculate body induced by microstimulation of the auditory cortex.

The receptive fields of neurons (RFs) whose activity was simultaneously recorded at several loci of the auditory cortex (AC) and in the medial geniculate body (MGB) were investigated before and after intracortical microstimulation (ICMS). Three types of neurons of the AC and MGB were distinguished on the basis of the character of the RFs: mono-, bi-, and polymodal. The RFs of the neighboring neurons in the AC (or in the MGB) could differ, while the RFs of remote neurons of the AC could be similar. The microstimulation of the AC could lead to changes in the RFs of neurons in the stimulated locus and neighboring loci of the AC, as well as in the loci of the MGB tonotopically associated with them. It is hypothesized that long-term modification of the efficiency of synaptic transmission between different elements of the cortex-thalamus-cortex circuit which arises as the result of the circulation of impulses along this chain during ICMS may be the mechanism underlying the observed changes in the RFs of AC and MGB neurons.