THE TARGET-REACHING AND FOOD-TAKING BEHAVIOR IN THE CAT - A MODEL FORTHE INVESTIGATION OF RECOVERY OF MOTOR FUNCTIONS

The recovery of motor functions after CNS lesions is a complex action with several restitutional processes occurring in parallel. To describ e the function-oriented phenomena and to understand the organisational changes within the neuronal systems in question there is the urgent n eed for investigations relating the impairment of defined neuronal sys tems with quantitative and qualitative changes of a behavioural motor paradigm. The system of the C3-C4 propriospinal neurones in the cat is one of the models which could serve such a purpose. It relays disynap tic excitation from several supraspinal motor centres to forelimb moto neurones, parallel to the input to the motoneurones from the same cent res via the segmental reflex apparatus. Behavioural studies indicate t hat the motor command for reaching towards a target with the forelimb is to a large extent mediated in the C3-C4 propriospinal system, where as the command for taking of the object seems to be organised in the i nterneuronal systems of the forelimb segments, not depending on an int egration in the C3-C4 propriospinal relay. The paper reviews different studies which have analysed the effects of lesions of various motor c entres and tracts on this behavioural paradigm. It becomes evident tha t different components of the motor behaviour have different restituti onal capacities. The quantitative analysis of the various dimensions o f the cat forelimb together with the possibility to perform localised lesions within defined neuronal systems make this experimental approac h suited for the investigation of integrative aspects related to the r estitution of function within systems organising motor behaviour.