Abstract: The recovery of motor functions after CNS lesions is a complex action with several restitutional processes occurring in parallel. To describe the function-oriented phenomena and to understand the organisational changes within the neuronal systems in question there is the urgent need for investigations relating the impairment of defined neuronal systems 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 disynaptic excitation from several supraspinal motor centres to forelimb motoneurones, parallel to the input to the motoneurones from the same centres via the segmental reflex apparatus. Behavioural studies indicate that the motor command for reaching towards a target with the forelimb is to a large extent mediated in the C3–C4 propriospinal system, whereas the command for taking of the object seems to be organised in the interneuronal systems of the forelimb segments, not depending on an integration in the C3–C4 propriospinal relay. The paper reviews different studies which have analysed the effects of lesions of various motor centres and tracts on this behavioural paradigm. It becomes evident that different components of the motor behaviour have different restitutional capacities. The quantitative analysis of the various dimensions of the cat forelimb together with the possibility to perform localised lesions within defined neuronal systems make this experimental approach suited for the investigation of integrative aspects related to the restitution of function within systems organising motor behaviour.
Keywords: C3-C4 propriospinal system, Forelimb movements, Motor behaviour, X-ray cinematography, Spinal cord lesions, Movement kinematics
