200 



BRAINS OF RATS AND MEN 



We know that visual discriminations of similar 

 sort can be acquired independently of the cerebral 

 cortex, for they are successfully done by invertebrates 

 and fishes (see, for example, Washburn and Bentley, 



tholamut 



Fig. 50. — Schemata of the brlghtness-discrimmatlon experiments. 

 I. Before training. II. Thalamic connections established during training. 

 III. Cortical connections established during training. 



1906, and White, 191 9). In the rat it is probably fun- 

 damentally thalamic, though we do not know whether 

 it can be acquired in the absence of all of the cortex. 

 It has been shown experimentally that such discrimi- 

 nations can be learned by rats in the absence of any 

 particular part of the cortex except the archipallium. 



