| Abstract: | Single unit activity of olfactory neuroreceptors was recordedin frogs. Stimulations with 20 pure chemicals delivered at knownconcentrations elicited excitatory and/or inhibitory responsesin 60 of the 76 recorded units. The responses exhibited varioustime patterns, partly depending on stimulus intensity. Longlasting after-effects were observed. Out of a total of 1520odour trials, 317 excited and 33 inhibited the cells, leadingto a receptor overall responsiveness of 23%. Various degreesof individual selectivity were encountered in the receptors;the greatest number responded to seven of the 20 odorants. Amarked tendency to stimulate the same receptors was observedfor several odorants. Three groups could be evidenced: benzene,anisole, dichlorobenzene and bromobenzene; camphor and cineole;tert-butyl alcohol, cyclohexanone and cyclohexanol. Fatty acidstended to be grouped. Sulphurous compounds elicited few responses,except tiophenol. Most of the neuroreceptors responded to odorantsbelonging to more than one odour group. |
