56 



DON TUCKER 



at 20''C, but the temperatures of the preparation and of the gas delivered 

 to the naris were varied together. Over the range of 10-35 C the inte- 

 grated olfactory response increased slightly with decrease in temperature 

 for a constant mole fraction of amyl acetate. The response in terms of 

 nerve impulses per unit time might decrease with a decrease in tempera- 

 ture, since broadening of the impulses with cooling would cause greater 

 individual contributions to the integrator record. 



ROOM AIR 



j^^^mi^W" 



'UUl^ 



* ' ^ * V i Vv ^«'wAyNA*-^,vM-«*.,»yM 



OLFACTOMETER 



x..,,,,.^.^....,..,.^ 





Fig, 1 1 . Integrated olfactory responses recorded during free respiration, which 

 ■ was of intermittent nature. Between the first and second groups in the first trace 

 a cigar was fit and smoke was blown at the animal near the end of the second 

 group. In the second trace cleaned air and amyl acetate at lO"'-* of air saturated 

 with the odorant were delivered to the breathing chamber from the olfactometer. 



(b) Odorant, concentration, and nasal flow rate. Odorant species, odorant 

 concentration and volume flow rate of the odorous medium into the naris 

 are the important parameters, among those which can be specified external 

 to the nose, for determining the olfactory response. This is also true for the 

 other nasal sensory systems that respond to odorants. Figure 12 illustrates 

 flow rate and concentration dependence for the responses of two olfactory 

 twigs to amyl acetate. The figure also introduces an intranasal parameter 

 of importance for determining the response — position of receptors in the 

 olfactory organ. It need hardly be pointed out that Adrian (1956, 1951) 

 deduced from olfactory bulb recordings the variation of the stimulus over 

 the organ. One may say that the accessibility of odorant molecules to the 

 receptors is different for various locations in the organ. Matters are com- 

 plicated further by the finding that olfactory accessibility can be varied by 

 changes in the physical dimensions of the nasal cavities. 



