T. PINTO HAMUY 60I 



as a whole, but the specific cortex would also matter. One could suggest that lesions 

 placed outside the specific cortex have to be of a certain extent in order to deter- 

 mine an impairment similar to a smaller lesion placed in the specific cortex. 



RosvOLD. What did the rats do when they did not movef 



Pinto-Hamuy. When the shock began they ran to the other compartment. And 

 even that sort of 'unconditioned' response needed a certain learning after ablation 

 of the neocortex. 



Hebb. Do I assume that the rats were all reared in small cages? The reason for my 

 asking is a fact which has puzzled us very much ; if rats are reared in a small cage, 

 lesions of the anterior part of the brain will have an equal effect with lesions in the 

 posterior part, in complex learning situations. If rats are reared in a large cage with 

 a number of objects, so that they have a naturalistically normal experience during 

 growth, they show a very different picture. The animals with anterior lesions now 

 show little effect. An equal lesion in the posterior part of the cortex (it does not 

 have to be visual cortex) will produce gross defects. Here is another case, when we 

 are talking about the mode of physiological organization of the brain, where we 

 must take into account (as a possible source of variability between experiments) the 

 conditions of rearing and the past history of the animal. 



Pinto. I do not think our cages were particularly small; our animals had space to 

 move around. They measured 45 X 15 X 28.5 centimetres. 



CoviAN. Have you observed differences with just unilateral neodecortication? 



Pinto. We did not study that kind of preparation because we had previous 

 experience with discrimination learning following a unilateral lesion; very obvious 

 changes were not found in this type of learning with unilateral lesion. 



