[Excitatory interactions in the nerve nets switching on the cells of the auditory cortex and the medial geniculate body].

Crosscorrelation method was used for revealing effective monosynaptic excitatory interactions in neural networks containing simultaneously recorded neurons from different loci of auditory cortex (A1) and medial geniculate body (MGB). It was shown that (a) there were effective reciprocal excitatory connections between neurons in different loci of A1 and MGB; (b) connections between neurons in tonotopic loci of A1 and MGB and in adjacent cortical loci were the most effective; (c) connections were "divergent", i.e., one neuron in A1 (MGB) excited neurons in different loci of A1 and MGB simultaneously; (d) connections were "convergent", i. e., one neuron in A1 (MGB) was excited by neurons from different loci of A1 and MGB simultaneously. We suggest that this principles of organization of excitatory connections in thalamo-cortical networks promoted the induction of long-term changes (LTP and LTD) in excitatory synaptic efficacy and that this mechanism underlie the observed changes of receptive fields of A1 and MGB neurons induced by intracortical microstimulation.