R. HERNANDEZ-PEON AND H. BRUST-CARMONA 



401 



habituation at the spinal cord in mcscnccphahc cats depends on that 

 descending influence. 



From the prececiing experiments it is evident that brain stem structures 

 participate in spinal habituation. However, those experiments do not 

 preclude the possibility that the isolated spinal cord might also be capable 

 of performing that function. Whether the spinal cord is able to learn is a 



DECEREBRATED 



SPINAL 







15 



20 



7\A^ 



vvr^sA 



5 msec. 



Fig. 6 

 Tactile cviiked potenti.ils recorded frcnn the latcr.d column of 

 the spinal cord. The left column shows the decrement observed 

 in a decerebrate cat during a series of twenty cutaneous shocks 

 delivered at a rate of i/sec. The responses of the right column 

 were obtained in the same animal immediately after transect- 

 ing the spinal cord above the recording site. 



question whose answer is of considerable importance to the conceptualiza- 

 tion of integrative levels of the C.N.S. in learning processes. 



Our spinal preparation pcrnntted us to investigate this question. It was 

 found that repetition of tactile stimuli in spinal cats also led to a progressive 

 decline of the corresponding evoked potentials (Fig. 6). And, as happens 

 in intact animals, a transient increase in the intensity of the stimulus caused 

 the diminished responses to have a greater amplitude after the disrupting 



