156 



MASAYASU SATO 



X 1/1 28 M HCl 



-♦- 1/256M » 



• 1/51 2M ^ 

 O Ringer 



O ♦4«C 



e - 2«c 



O * O'C 



-8 -4 M ♦S 



Temperature change CO 



5 10 



Concentration (mM) 



Fig. 6. Relationship between the magnitude of the integrated response and 



temperature change at the tongue produced by HCl solutions (A) and that 



between response magnitude and HCl concentration at varying temperatures 



(B). From Nagaki, Sato and Yamashita, unpublished. 



PROPERTIES OF SINGLE TASTE UNITS 



Impulse discharge of 29 single nerve fibres was recorded from 24 cats. 

 A majority of single taste fibres of the chorda tympani was found to res- 

 pond not only to more than two kinds of taste stimuli but also to both 

 taste and temperature stimuli of the tongue. In Table 1 units obtained are 

 classified according to their responsiveness to taste and thermal stimuli. It 

 is seen from this table that about 50 per cent of units obtained responded to 

 warming, cooling and taste stimuli, 30 per cent to cooling and taste, 10 

 per cent to taste stimuli only and another 10 per cent to temperature change 

 only. In addition, we have also obtained mechanosensitive units, which 

 showed larger spike height than that of other fibres. 



Typical examples of the response of four types of units to taste and 

 temperature stimuli are shown in Fig. 7. The unit shown in Fig. 7a res- 

 ponds to warming, cooling and taste stimuli and may be called the warm- 

 taste unit. The warm fibre in the chorda tympani and described by Dodt 

 and Zotterman (1952) is probably nothing but the warm-taste unit. The 

 unit shown in b responds to cooling and taste stimuli and may be called the 

 cold-taste unit. The unit shown in c responds very little to thermal change, 

 but it still shows a small increase in the impulse number when the tempera- 



