504 BRAIN MECHANISMS AND LEARNING 



solving occurs after corpus callosum section in the chimpanzee (Mvcrs, i960). The 

 accumulation of information thus far seems to indicate, rather definitely, a tactile 

 gnostic intercommunicative function for the corpus callosmn similar to that seen 

 for visual gnosis. 



RosvOLD. Did you ever test for the locus of tactile functions in the corpus 

 callosum ? 



Myers. No. 



RosvoLD. Have you any inkling of what function the anterior corpus callosum 

 may have. Wc have some suspicion that it enters into delayed response behaviour, 

 hi some animals with anterior section only, there seems to be an impairment of 

 memory function. 



Myers. No, I have no information specifically related to anterior corpus callosum 

 function. 



Segundo. Would Dr Myers comment on the publications of Akelaitis who, 

 with the purpose of avoiding generalization of epileptic seizures, sectioned the 

 corpus callosum in a number of patients (Akelaitis, 1941). Were those patients 

 studied as to their discriminative capacities, and, if so, which were the results of this 

 analysis ? 



Myers. These patients were subjected to a host ot examinations exploring their 

 sensory, motor, and intellectual capacities both pre- and post-operatively. Accord- 

 ing to these tests the corpus callosum transection resulted in no clear-cut and 

 consistent deficits. But I believe there is no conflict between these apparently 

 negative human results and the results we have reported here. Akelaitis tested 

 visual function in his patients by testing recognition of different visual objects in 

 opposite homonymous fields of the same eye thus separately testing visual recogni- 

 tion through the separate hemispheres. Such recognition was found to be bilater- 

 ally undisturbed and he concluded that corpus callosum did not function in visual 

 recognition. However, he failed to take into account the tact that past experience 

 through each hemisphere's own afferent sensory systems could independently have 

 established the basis for recognition of those common objects in each homonymous 

 field apart from presence or absence of corpus callosum. Had we taught our 

 chiasma-sectioned, callosum-sectioned cats, their visual response without a mask 

 and later tested first through one and then through the other eye for recognition of 

 the discriminanda I doubt whether the cats would have had difficulty in responding 

 correctly through either eye. The central point to be made is that for cross recogni- 

 tion tests to be critical as tests of corpus callosum function the situation or experi- 

 ence to be tested must be, in some sense or other, novel or imflimiliar to the subject. 



Olds. About the last experiment, is it possible that the animal did not learn the 

 discrimination you thought he learned — you assume he learned that when the 

 vertical bar was solid it was positive and when it was split it was negative. It 

 seems the animal might have learned that when the patch is on one eye vertical is 

 positive and when the patch is on the other eye vertical is negative. Does that seem 

 a possible interpretation? 



Myers. That must be considered a definite possibility against which no ultimate 

 control can be conceived, bound as one is in this experiment to use two different 

 receptive fields. However, the slight interference with transfer seen with mildly 

 conflicting discriminations would be hard to explain on this basis. The configura- 

 tion of results of later experiments not vet published also speak against the idea of the 



