SOME THALAMIC AND CORTICAL MECHANISMS OF TASTE 325 



lower diagram which served as a guide for lesions. If our hypothesis was 

 correct, ablation of the black cortex should produce taste deficits and 

 degeneration of the thalamic taste cells in the ventromedial complex. 



The situation no longer seems to be black and white. Thus far, Blomquist 

 and I have removed the black area in five monkeys and produced only one 

 small taste deficit, removed all of the areas both black and white in three 

 animals and produced no deficits, and finally, in three animals, removed all 

 of these areas and in addition, the fronto-parietal operculum and part of 

 the insula producing only one slightly deficient monkey. This was dis- 

 turbing. The typical degeneration picture, as seen in Fig. 15, was even 



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Fig. 15. Retrograde degeneration in the ventrobasal nuclear complex of 



the squirrel monkey resulting from the cortical lesion in Fig. 16. Arrow 



marks some undegenerated cells in the posterior ventromedial nuclear 



complex presumably belonging to the taste system. 



more disturbing. The degeneration extends from the lateral border of the 

 centrum medianum toward the tip of the ventromedial complex, but leaves 

 a little clump of normal cells right where the microelectrode results would 

 locate taste. Not only did these cortical lesions fail to produce consistent 

 taste impairment, but they apparently did not produce degeneration of all 



23 



