Olfactory and nonolfactory odor detection in pigeons: elucidation by a cardiac acceleration paradigm.

A technique for the Pavlovian conditioning of cardiac acceleration in response to odorants was developed and used to compare the sensitivity of pigeons to four odorants before and after resection of the olfactory nerves. This method provided quite reliable psychophysical functions yet required relatively little training time. Thresholds of normal pigeons to n-amyl acetate, n-butyl acetate, benzaldehyde and butanol were approximately 10(-4), 10(-5), 10(-3.3) and 10(-4.3) of vapor saturation, respectively. Following resection surgery, sensitivity decreased by 2 to 4 log units. When transection of the ophthalmic branch of the trigeminal nerve was combined with olfactory nerve resection, little evidence of a further decline in odor sensitivity was seen. Based on these results each of these compounds could be used, at concentrations below the postoperative threshold, to study, in isolation, both normal and reconstituting olfactory systems in the pigeon.