R. HERNANDEZ-PEON AND H. BRUST-CARMONA 



399 



Interruption of monotonous stimulation usually led to restoration of 

 the diminished response (dishabituation). But successive series of stimuli 

 elicited the same degree of response decrement with a lesser number of 

 stimuli than was required for the first series. Dishabituation of the tactile 



AWAKE 



S^S sS^m [S^& finsB 



B|^^^H ^^^^^H ^^^^^H ^^^^^H 



ANAESTHETISED 



[5O/UY 



Sm.sec 



Fig. 5 



Releasing etfccts of anaesthesia upon spinal tactile habituation. The upper two rows show the 

 reduction of the evoked potentials obtained after forty repetitions of the tactile stimulus in the 

 awake animal. Then the cat was anaesthetized with pentobarbital. The lower two rows show 

 the great stability of the potentials evoked by the same number of stimuli. 



spinal potentials was also observed by presenting an alerting acoustic 

 stimulus, or by a transient increase of the intensity or frequency of the 

 regular tactile stimuli. As has been observed in other sensory pathways, 

 recovery of the extinguished responses was obtained by central anaes- 

 thesia. The spinal evoked potentials were not only restored to their 



