[Effect of iontophoretically administered L-DOPA and ketamin on the impulse activity of the somatomotor cortex neurons during the conditioned placing movements].

Interactions between the neuronal dopamine and NMDA glutamate receptors were investigated by iontophoresis of L-DOPA and ketamin to 19 single cortical neurons of the somatomotor cortex neurons in cats performing the operant reflex. L-DOPA producing bursts of 8-12 impulses that led to the significant increase of the total number of spikes related to the movements and insignificant decreased the power or the average number of spikes in a conditional response. Effects of ketamin on impulse activity were multidirectional resulting in most cases (16 cells) in the significant increase of the response power and in other three cells producing the suppression of discharges related to movements. It is supposed that following the ketamin iontophoresis the facilitation of conditional responses was caused by the blocking of the NMDA-glutamatergic transmission to intracortical inhibitory neurons, whereas inhibition of conditioned responses of other cortical cells was produced by blocking NMDA-glutamatergic transmission to pyramidal neurons. The total number of spikes associated with the performance of movements following the joint application of L-DOPA and ketamin was significantly higher compared with the effect of the isolated L-DOPA iontophoresis. These data indicate the NMDA-glutamatergic transmission, which plays an important role in shaping the cortical neuron responses in the performance of behavioral reactions may be modulated by L-DOPA.