Olfactory receptor response characteristics: a factor analysis.

The responses to odor stimulation of 22 single olfactory units in the frog olfactory mucosa were recorded with metal filled micropipettes. Seven purified odorants matched in concentration and a pure air stimulus were administered. The change in firing frequency for each unit to each chemical was evaluated to determine: (1) whether the response patterns developed across all units are different from chemical to chemical and, (2) whether individual units can be grouped in terms of their similarity of their responses to all odorants. The results of a Bartlett Sphericity test suggest that each odorant produces an independent pattern of responses across units. To answer the second question, a factor analysis was employed. It examined the responses of each unit to all chemicals and yielded 7 out of a possible 22 independent factors, suggesting that there are 7 ways by which the units studied look at the odorant stimuli and an air control employed in this study. These analyses were evaluated and discussed in terms of previously published data suggesting receptor site specificity.