REINNERVATED MUSCLES FAIL TO PRODUCE STRETCH REFLEXES

1. We studied the stretch-evoked reflex organization of hind limb musc les in two decerebrate cats 36 mo after unilateral section and immedia te surgical repair of the common nerve supplying the lateral gastrocne mius (LG) and soleus (S) muscles. 2. The production of considerable re flex force by innervated muscles in response to electrical stimulation of uninjured nerves indicated substantial functional recovery of moto r units. However, reduction in the responsiveness of reinnervated musc les to stretch of the untreated medial gastrocnemius (MG) muscle indic ated some deficit in recovery of normal synaptic integration. 3. Stret ch failed to elicit autogenic excitation of the reinnervated S and LG. This failure was observed whether the reinnervated muscles were quies cent or contracting in other reflexes. 4. The heterogenic reflex organ ization of reinnervated muscles was abnormal. Stretch of the reinnerva ted S failed to evoke heterogenic reflexes both in the untreated MG an d in the reinnervated LG. Stretch of the reinnervated LG failed to pro duce excitation of MG. 5. These findings demonstrate deficiencies in p roprioceptive feedback from reinnervated muscles and lead us to expect incomplete recovery of motor function after nerve section.