Long-term changes in the efficiency of excitatory and inhibitory connections in neuronal micronetworks of the motor cortex induced by tetanization of the thalamic nuclei and the sensory cortex.

Tetanization of the ventrolateral nucleus of the thalamus, the red nucleus, and the sensory cortex produced long-term potentiation and depression of the efficiency of both excitatory and inhibitory connections in the neuronal micronetworks of the motor cortex in the cat. Rhythmic stimulation of various structures produced a variety of stable patterns of interneuronal connections in micronetworks. In monosynaptic excitation and disynaptic inhibition, the efficiency of inhibitory transmission was potentiated simultaneously with depression of the efficiency of excitatory transmission in the same post-synaptic cell. The efficiencies of synapses formed by axon collaterals of a given cell on its neighboring cells could change in different directions. These results may indicate that the sign (positive or negative) of modification may be determined by the activity of both cells, i.e., the pre- and post-synaptic cells.