SOME THALAMIC AND CORTICAL MECHANISMS OF TASTE 321 



bottom plot shows a unit which responded to the two strongest concentra- 

 tions of sucrose. You can see why these dot patterns were shown after the 

 temperature units. The patterns are not distinctive, for most of these 

 thalamic taste units were very poor responders. 



At the top of Fig. 1 1 is a plot of a unit which discharged to both sucrose 

 and sodium chloride. Again the meager response is evident. Contrast 

 this with the vigorous response of the unit at the bottom. He was a posi- 

 tive fellow, isolated in the same puncture and activated by the same solu- 

 tions. If you are willing to entertain the notion that this positive unit is 



62-375- 20 



1.0 Sue 0.1 Sue .01 Sue 



1.0 NaCI 0.1 NaCI .01 NaCI 



62- 375- 15 



:^r']i> MMiiitri1llittr^iiitfrt<i ^-^ 



1.0 Sue 0.1 Sue 



250msec 



1.0 NaCI 0.1 NaCI i 1 



10 sec 



Fig. 11. See Fig. 10. 



indeed a fiber, and if you are willing to contemplate the possibility that he 

 may represent the input to thalamic cells such as the one above, then some- 

 thing drastic happens at this synapse. The output is severely reduced. 

 Perhaps this attenuation is due to the anesthetic (nembutal), perhaps it is 

 normal, but if it is repeated at subsequent synapses, at the cortex for 

 example, there would not be much response left to record. 



At least one generality is clear from these data. The sensory code at the 

 thalamus is complex. Other generalities are not immediately apparent. 



Now I would like briefly to consider the cortical taste system, first, in the 



