[Cortical neuron activity in the presence of sound combined with electrophoretic application of L-glutamate].

Unit activity in the sensorimotor cortex of rats immobilized by d-tubocurarine, was studied at random and paired presentations of sound and microionophoretic application of L-glutamate. 54% of the studied units exhibited specific plastic changes of spike activity in the course of the pairings; the changes were manifested in a significant increase or modification of the initial response to the sound. These activity reorganizations differed from those appearing during pseudoconditioning. Simultaneous records of the activity of two units have revealed that a micropool of units manifesting specific plastic properties is restricted to a sphere with a radius of up to 200 micronm. It has been assumed that one of the conditions of formation of plasticity in the activity of individual units is the regularity and intensity of the response to the unconditioned stimulus.