410 



BRAIN MECHANISMS AND LEARNING 



Hernandez-Peon. Were these animals unconscious after the lesion and how 

 long did they remain unconscious? 



Doty. They were certainly unconscious tor many days following surgcr)'. 



Hernandez-Peon. The point is that the lesions we made did not impair con- 

 sciousness. The animals awoke and were able to walk after the anaesthesia wore off. 

 In cats with larger lesions producing unconsciousness, the long period of recovery 

 probably involves several unknown processes which may mask completely the 

 immediate effects of the lesion, hi fact Dr Brust-Carmona reported in January of 

 this year that in cats with small reticular lesions leg withdrawal can be conditioned 



CAT 14, 13 JUNE 56 



CSh 



a. 



I Sec. 1 1 0.0 



CAT 14, 17 JULY56 



LEM. i/i. Ik ( • 



_i______;_-_j X- 



FiG. 3 

 EEG records from cat having lesions shown in Fig. D-8. (a) pre-operative record of condi- 

 tioned respiratory response and electrocortical arousal reaction to the CS. (/>) first CS presented 

 on the sixth post-operative day produces an arousal reaction and a respiratory CR. Note that 

 record /) is at double the gain of j; hence the post-operative electrical activity is remarkably 

 near normal. (From Doty, R. W., Beck, E. C. and Kooi, K. A., 1959. Effect of brain-stem 

 lesions on conditioned responses of cats. Experimeutal Neurology, i, 360.) 



I month after the lesion was made, but that lesions in the subthalamic region 

 (smaller than Doty's) definitely impaired this type of conditioning. 



Palestini. It is interesting that different afferent systems may habituate because 

 of participation of different strtictures placed at different levels of the reticular 

 formation. I want to mention yet another possibility, based on Moruzzi's observa- 

 tions. Since, the 'cerveau isole' also shows habituation we may infer that structures 

 placed rostrally to the mesencephalon would also be capable of inducing this 

 phenomenon. 



Buser. I already mentioned the observations made on the cat with an extensive 

 lesion on the medial thalamus. Training to the routine motor alimentary condi- 

 tioning (pressing lever for food at a given signal) was carried on post-opcrativcly 



