[Program and feedback in the systems organization of a motor act]

Abstract

After simultaneous visual dereceptation, aimed jumps in cats, reinforced by electric shocks, are restored, while those with food reward are irreversibly lost. Yet, after a two-stage dereceptation, the aimed jumps reappeared even in case when they had food reinforcement. The adequacy of their performance depended on the stability of the distance between the starting sites. The possibility of local cortical control of motor units was demonstrated which is considered as a component of the general mechanism of urgent identification of the motor system state, via somatic afferent pathways. The ablation of their higher link (the medial lemniscus) at the level where it enters the thalamus, disturbs the biomechanics of the aimed jump, increasing the number of multisensory responses of single sensorimotor cortical units. It is suggested that the motivation and the program of the movement corrected by feedback, provide for its adaptive character.