X38 



BRAINS OF RATS AND MEN 



nuclei, and in reptiles and birds these thalamic nuclei 

 are well separated, each having its own characteristic 

 type of functional connections. This thalamus evi- 



pineol body 



epithalomus 



optic troct 



medial 



forcbrain 



bundle 



dorsal 

 thalamus 



ventral 

 thalamus 



white m otter 



ra\j motter 



preoptic nucleus 

 optic nerve 



Fig. 30. — Diagram of the structure of the diencephalon of Ambly- 

 stoma as seen in cross-section. The dorsal thalamus is a general sensory 

 correlation center, from which sensory radiations descend to the lateral 

 forebrain bundle within which they pass forward to the lateral wall of 

 the cerebral hemisphere. There are also connections (not drawn) from the 

 dorsal thalamus to the ventral thalamus, from which fibers go to the lower 

 motor centers. The medial forebrain bundle connects the preoptic nu- 

 cleus and the hypothalamus, which lies immediately behind it, with the 

 cerebral hemisphere. 



dently performs very complex local or intrinsic reflex 

 adjustments, and in addition the extensive sensory 

 radiations maintain intimate functional connection 

 between the thalamus and the lateral wall of the cere- 

 bral hemisphere. In birds (Ingvar, 1923) and in rep- 



