RESPONSES TO ODORANTS 



57 



Phasic olfactory responses are graphed as a function of flow rate for 

 two odorants in Fig. 13. Periodic testing with amyl acetate showed that 

 the olfactory accessibility was considerably greater during collection of the 

 benzyl amine data than it was for the amyl acetate run. Thus, the curves 



10 



< -0.3 



\ \ ^ 





10 



' \ 



vvwWiV**v«^w\ 



"^Vy 



AMYL ACETATE 10 



10 



i\ 



>^ 



'^ U U ^H*v^>l««s"^ 









Fig. 12. Comparison of integrated olfactory responses, recorded simultaneously 



from two nerve twigs, for variation of nasal flow and concentration of amyl 



acetate. The unit of concentration is saturation at 20°C. Stimulation procedure 



was odor on 5 sec of every 20 sec followed by 1 min on. 



for benzyl amine would be shifted to the right if the accessibility were re- 

 duced to the level that existed during the amyl acetate run. The maximal 

 response to benzyl amine is sizably greater than that to amyl acetate. By 

 contrast, the maximal response that can be obtained with butyric acid is 

 much smaller than either of these. For a sufficiently low concentration of 

 amyl acetate, the response as a function of nasal flow rate reaches a maxi- 

 mum that is less than the characteristic maximal value. 



Plateauing of the olfactory response with nasal flow rate, in the range 

 that is physically possible, appears to correlate with low aqueous solubility 

 of odorants, although only a few have been examined. Response depend- 

 ence on the flow rate clearly reflects the need to deliver odorant molecules 

 to the receptor sites. The solubility relation suggests that plateauing is 



