[Plasticity of reactions of the sensomotor cortex to sound combined with electrophoretic application of acetylcholine].

Reactivity to sound and electrophoretic application of acetylcholine-chloride (ACH) was studied in 170 sensorimotor units of non-anaesthetized rats. Reactivity to sound was found in 60 per cent of the cells, and to ACH, in 83 per cent. Plasticity of the reaction to sound ("conditioned stimulus") was studied in 44 units, when it was presented jointly with ACH ("unconditioned stimulus"). After pairing, the reaction to sound changed in 14 units out of 36 (40%). In the control procedures of pseudoconditioning, reactivity to sound changed in four units out of 15 (27%). Pseudoconditioning and stimuli pairing was successively carried out in seven units: four units manifested plasticity of their reactivity, two of them changed the response to sound both during pseudoconditioning and subsequent pairing of stimuli. It is assumed that the plastic properties of the examined neurones are determined by the integrative activity of the cell micropool with a radius of 70 to 150 mu.