PLASTIC REORGANIZATION OF RECEPTIVE-FIELD S OF AUDITORY-CORTEX AND MEDIAL GENICULATE-BODY NEURONS INDUCED BY INTRACORTICAL MICROSTIMULATION

The effects of intracortical microstimulation (ICMS) on receptive fiel ds (RFs) of simultaneously recorded auditory cortex (A1) and medial ge niculate body (MGB) neurons were examined in rats under ketamine. Thre e types of neurons were distinguished according to the configuration o f their RFs: mono-, be-, and polymodal. It was shown that RFs of adjac ent neurons may be different and Rfs of distant (up to 1 mm in rostro- caudal direction) neurons may be similar. ICMS was able to produce cha nges in RF structure of A1 neurons at and near the stimulation side an d also in homotopically related regions of MGB. RFs of homotopically r elated A1 and MGB neurons mostly changed in a similar way after ICMS. We suggest that the mechanism underlying the observed RF changes of A1 and MGB neurons in related to ICMS-induced long-term changes (LTP and LTD) in synaptic efficacy of the cortex-thalamus-cortex loop.