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ROBERT M. BENJAMIN 



rat where the results, at least at one time, seemed clear and consistent, and 

 secondly, in the squirrel monkey where they are not. 



The results of electrical stimulation of the nerves in the rat are sum- 

 marized in Fig. 12 (Benjamin and Pfaflfmann, 1955). The evoked responses, 

 slow waves recorded from the brain surface with a gross electrode, were 

 confined to these two small areas, one for each nerve. Maps from six of 

 these experiments were combined to produce the composite area outlined 

 in the lower diagram. 



200mV 



Fig. 12. Above : Cortical areas in the rat activated by electrical stimulation of 



chorda tympani and the lingual branch of the IXth nerve. Below : " the 



composite taste nerve area " compiled from six such recording experiments. 



From Benjamin and Akert, 1959. 



The gustatory function of this composite taste nerve area was estabhshed 

 by ablation experiments. Bilateral removal of the composite area pro- 

 duced impairment of taste discrimination as measured both by preference 

 (Benjamin and Pfafifmann, 1955; Benjamin and Akert, 1959; Benjamin, 

 1959) and conditioning techniques (Benjamin, 1960). Conversely, removal 

 of all of the rest of the neocortex sparing the composite area left discrimina- 

 tion normal. These two types of lesions localized taste impairment to the 

 composite area. Further parcellation established that the ventral part of 

 this total area was the most crucial for normal taste behavior. Some 

 sample lesions and the associated thalamic degeneration diagrammed in 

 Fig. 13 illustrate this point. At the top is a lesion of the whole composite 

 area which produced degeneration of the whole subnucleus of the ventralis 



