[Inhibitory reactions of the motor cortex neurons in the triggering of conditioned reflex organization in cats].

The neuronal impulse reactions of the motor cortex neurons (field 4) which are involved in the reflex realization were studied on the awakening cats trained to perform conditioned movement after the influence of two stimuli (the preliminary and the conditional). Slow cortex potential in vertex was registered simultaneously. It was established that before the response to the triggering signal (interstimuli period) high amplitude negative shift in the slow cortex potential is present.

Modulation of the spike activity of neocortex neurons during a conditioned reflex.

Experiments were conducted on cats to study the effects of iontophoretic application of glutamate and a number of modulators on the spike activity of neurons in the sensorimotor cortex during a conditioned reflex. These studies showed that glutamate, as well as exerting a direct influence on neuron spike activity, also had a delayed facilitatory action lasting 10-20 min after iontophoresis was finished. Adrenomimetics were found to have a double modulatory effect on intracortical glutamate connections: inhibitory and facilitatory effects were mediated by beta1 and beta2 adrenoceptors respectively.

[The modulation of the pulse activity of neocortical neurons during a conditioned reflex].

Spontaneous and evoked activity of neurons in the sensorimotor cortex was recorded in cats with learned conditioned placing reaction before, during, and after the iontophoretic application of synaptically active substances. It was shown that apart from direct excitatory effect on the cortical neurons during its application, glutamate (Glu) exerted some modulatory influence on unit activity in subsequent 20 min. Noradrenaline suppressed the background and evoked activity through beta 1 adrenoreceptors.

Interaction between dopamine and glutamate in the sensorimotor cortex during conditioned placing reaction.

Changes in impulse activity of sensorimotor cortex neurons associated with interaction of glutamate and dopamine during conditioned placing reaction were investigated in experiments on cats. Application of either glutamate or levodopa as a dopamine precursor increased background and evoked impulse activity in many of sensorimotor cortex neurons. It occurred occasionally that an increased impulse activity of cortical neurons produced by joint application of glutamate and levodopa could be much more intense than that produced by one of these substances.

[Variations of neuronal responses in cat cerebral cortex to somatic stimulation in the presence of additional stimulants].

Neuronal responses (areas 3, 4, 5) were registered in awake cats after electric stimulation of the contralateralis limb. External stimuli, food and defensive motivation inhibit short-latency neuronal reactions which were registered in control. When in the experiment there was electric stimulation of another limb instead of an external stimuli the neuronal reaction did not change.