J. C. ECCLES 



345 



tion is that the partial dcaftercntation had thrown more mechanical stress 

 on the remaining stretch-receptors of the weight-supporting extensors, 

 with the consequence that there was nicreased activity of their synapses, 



JJJJJUJL BICEPS- SEMI TENDINOSUS 

 >■-« (CONTROL) 



T ^"^ A 



•L'^\J—LLL LATERAL GASTROCNEMIUS 



"""" (EXCESS USEi 



lJ\^ 



T smV A 



.\_\_\_\_\_ DEEP PERONEAL NERVE 



iniMC (CONTROL) 



L6 



T 



T Jmv A 



normol side ' -. cut side 



L7 



X, 



u 



~rrrrr flexor digitorum longus 

 -"•« (EXCESS USE) 



NORMAL SIDE 



CUT SIDE 



L7 



JV_ IJU 



Fig. 5 

 Monosynaptic reflexes recorded in the Lg, L, or Si ventral roots in response to maximum 

 group la afferent volleys from the four muscles as specified. On the left side of the figure, the 

 biceps-semitendinosus and deep peroneal volleys served to control the symmetry of the 

 preparation, there being approximate equality of the reflexes into comparable ventral roots 

 on the two sides. Each of the reflexes is shown before (A) and during maximum post-tetanic 

 potentiation (T). On the right side of the figure the monosynaptic reflexes from the two other 

 muscles arc similarly assembled, but each of these muscles on the cut side had been subjected 

 to excess use as described in the text. Note that, in response to a lateral gastrocnemius afferent 

 volley, both A and T reflexes are larger into the Sj and L^ ventral roots on the cut side. This is 

 also seen for the flexor digitorum longus reflex into L- (reproduced by permission ot R. M. 

 Eccles and Westerman (1959) and of the Editors of Nature). 



the excess use giving an enhanced function. Of less significance in relation 

 to learning is the finding that functionally over-loaded muscles have 

 hypertrophied nerve fibres (Edds, 1950). 



