Research will be carried out on spinal cats to investigate mechanisms by which rearrangement of the group Ia fiber - alpha motoneuron connection occurs caudal to injury. Specific aims will include morphological analysis of HRP filled motoneurons to see whether any change in dendritic structure occurs. The role of the autonomic neurvous system in the strengthening of connections which occurs within hours of transection will be explored. The chronic changes which occur after transection will be studied to see whether motoneurons (small versus large; extensor versus flexon) exhibit a greater change. Physiological studies of the stochastic nature of EPSP production will be continued with the aim of being able to describe changes after transection more completely in terms of fundamental properties of synaptic transmission.