[The effect of 2-amino-5-phosphopentanoic acid (AP5)--a NMDA glutamate receptor blocker--on the neuronal activity of the motor cortex in a cat performing the conditioned reflex of placing its paw on a lever].

During cats' performance of the forepaw placing reaction, which was conditioned by a short electrical stimulation (4 msec, 500 Hz) of the contralateral parietal cortex (area 5), two types of stimulus-related responses could be recorded in the contralateral motor cortex. The primary short-latency responses (peak latency about 10 msec, duration up to 30-50 msec) were little sensitive to the application of AP5, a glutamate-NMDA-receptor blocker. The secondary long-latency responses (peak latency 65 msec, duration up to 150-200 msec) were suppressed in 44% of cases of AP5 application. The excitatory movement-related responses were suppressed by AP5 in 18% of cases. An increase in the latency of the conditioned movement itself was observed in 19% of cases. AP5 caused a decrease in the background firing in 46% of spontaneously active neurons. The number of cases of enhancement of separate response components and background neuronal activity and the number of cases of a decrease in the movement latency under the action of AP5 did not exceed those expected at random data distribution.