| Abstract: | NaCl solutions were flowed over the anterolateral region ofthe tongue of laboratory albino rats to determine the effectsof stimulus flow duration upon muitiunit chorda tympani nerveresponses. Fifty-five msec flow duration ‘artificial licks’delivered 5µl, while 2000 msec flow duration stimuli delivered650µl. Resonses were summated, A/D converted, and averaged,with time to stimulus presentation onset, ± 1 msec, astrigger. It was found that the latency and slope of the initialsegment of the phasic response were independent of flow duration,but they changed systematically with NaCl concentration. Slopeof both premaximum and postmaximum response was insensitiveto flow duration. In contrast, the magnitude and duration ofall segments of the phasic response were dependent upon bothstimulus flow duration and concentration. The final rising slopeof the phasic response, and the maximum response magnitude attained,were smaller, and were reached sooner, for the shorter flow,lick-duration stimuli. All maximum magnitudes to lick-durationstimuli occurred 170 msec or less after stimulus on-set. Thisis similar to the interval between actual licks. The contributionto the observed response differences of total number of fungiformpapillae stimulated, total number of receptor sites available,and rate of stimulus spread, was estimated. |
