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ROBERT P. ERICKSON 



impossible to devise a strictly continuous baseline out of a series of diverse 

 anions. These could, at best, designate points on a discontinuous baseline.) 

 Therefore, the first conclusion that can be drawn about the nature of the 

 sensory neural message for taste quality is that there are many fiber types 

 representing gustatory quality as for pitch discrimination, rather than a 

 few fiber types as in color vision. 



MODEL AND METHOD TO DETERMINE SIGNIFICANT 

 ASPECT OF AFFERENT MESSAGE 



How might the fiber types in taste be classified ? Let receptor 3 in 

 Fig. 1 now be labeled a " red " receptor. This is a somewhat misleading 

 label because, although it has its maximum sensitivity in the red region 

 of the spectrum, it responds to a wide range of stimuli, and in concert 

 with the other receptor types, is probably responsible for signaling many 



y 



Fig. 2. Receptor profiles analogous to those shown in Fig. I b. Recordings 



obtained from single neurons in the nucleus of the solitary tract of the rat. 



Bar heights indicate number of impulses recorded in the first second of evoked 



activity. Small triangles indicate spontaneous level of activity. 



wavelengths. To label a taste fiber a " salt " fiber because it is maximally 

 sensitive to salts likewise may be misleading because it, as the red receptor, 

 is probably responsible for signaling a number of stimuli. Actually, 

 until the stimulus dimensions for taste quality are established, a fiber's 

 point of maximum sensitivity cannot readily be established. Because of 

 the possibility of a very large number of fiber " groups " as in audition, 

 it is incorrect to categorize these fibers in a few groups unless such groups 

 are estabUshed as indicated in Fig. 1b. 



