MODIFICATION OF GROUP-I FIELD POTENTIALS IN THE INTERMEDIATE NUCLEUS OF THE CAT SPINAL-CORD AFTER CHRONIC AXOTOMY OF AN EXTENSOR NERVE

In walking decerebrate cats the influence of group I afferents from th e medial gastrocnemius (MG) and the lateral gastrocnemius/soleus (LGS) muscles on stance phase duration is altered after axotomy of the LGS nerve [Whelan, P.J., Hiebert, G.W. and Pearson, K.G., J. Neurophysiol. , 74 (1995) 2782-2787]. We examined whether a site for this plasticity is the connection from group I afferents onto spinal interneurons, Gr oup I field potentials from MG, LGS and plantaris (PL) muscle afferent s were recorded in the intermediate nucleus of the L6/L7 segments. Wit hin 5 days following the transection of the LGS nerve in one hind leg, the field potential amplitudes from LGS afferents were decreased, fro m MG increased and those from PL were unchanged, The changes in the fi eld potentials parallel modifications in the influence of group I affe rents from the MG and LGS muscles on stance phase duration during walk ing. (C) 1997 Elsevier Science Ireland Ltd.