[The effect of a microinjection of atropine into the rat motor cortex on the acquisition of a motor skill].

Atropine is known to impede the acquisition of conditioned responses by neurons of the motor cortex. Does atropine exert influence (and of what kind) on acquisition of local movements controlled by neurons of the motor cortex? In the present study we examined the influence of atropine microinjections on acquisition of reaching movement in freely moving rats. The intracortical pressure injections of atropine (5 mcg and 15 mcg/0,6 mcl/40 s) were made unilaterally into the forearm area of the motor cortex in adult mongrel rats. Hungry rats learned to reach sunflower seeds form a horizontal tube by using the forelimb contralateral to the injected site. Atropine exerted dose-dependent influence of the acquisition of the motor skill. All the tested doses depressed the inhibition of concurrent movements during learning. In addition, the higher dose of atropine inhibited the initiation of the reaching movements. A hypothesis was proposed to explain these differences.