The effect of acetylcholine and cholinergic transmission blockers on the neuronal impulse activity of the cat motor cortex in a conditioned reflex

: Influence of acetylcholine, atropine, d-turbocurarine and hexonium on the background and evoked impulse activity of the motor cortex neurons was investigated in cat under instrumental placing reaction. Only those neurons were analyzed whose responses preceded conditional movement. It was shown that acetylcholine increased the background impulse activity in one group of cortical neurons and decreased it in the other neuronal group. During iontophoretic application of acetylcholine the background activity of some neurons declined in spite of the increase of their evoked conditional response. Atropine inhibited background impulse activity, the conditional impulse response being preserved. The background impulse activity increased and evoked conditional response was inhibited during iontophoretic application. Hexonium inhibited the background activity and conditional evoked impulse activity. It is suggested that cholinergic fibers in the natural state participate in supporting the background activity of cortical neurons by means of m-cholinoreceptors and at the sam time they evoke the impulse activity linked with conditional responses through n-cholinoreceptors.