Nerve impulse sequences correlated with the four primary taste qualities in rat

Neural correlates of the taste qualities must be contained in transient impulse trains across many nerve fibres. In the present study, ten chemicals with primary tastes were used in two or three concentrations. Gustatory impulses were recorded from thin strands, consisting of one or at most three functional nerve fibres, dissected out of the chorda tympani nerve of twelve Wistar albino rats, and their numbers in every successive 50 msec were counted for 500 msec period after gustatory stimulus onset. The results obtained were as follows (pless than0.05): 1) Nerve impulse sequence produced by substances of the salty quality were different from those elicited by chemicals of the other three qualities in 250-300 msec after stimulus onset. 2) The same was true in the case of sour and sweet qualities provided that they became dissimilar to each other in 250 msec after stimulation. 3) No difference could be recognized between impulse trains of bitter and sour solutions as well as between those of bitter and sweet ones.