Abstract
To investigate how pheromonal information is processed in the rat accessory olfactory bulb (AOB), we optically imaged intrinsic signals and obtained high-resolution maps of activation induced by urinary stimulation. Application of volatile components in male rat urine induced activation exclusively in the anterior AOB (aAOB), irrespective of the recorded rats, sex. Volatile components of female urine elicited activation not only in the aAOB but also to some extent in the caudal part of the posterior AOB (pAOB) of male rats, and no responses were recorded from female rats. Non-volatile components of both male and female rat urine induced activation mainly in the rostral part of the pAOB and to a lesser extent in the aAOB, irrespective of the recorded rats, sex. In the present study, we further carried out single-unit recordings in the active region of the aAOB, where optical response to volatile urine was observed. We analyzed the firing activity of 46 neurons obtained from in nine animals. Of 13 neurons that responded to volatile stimulation (5% male urine, 5% female urine and/or 0.3% 2-heptanone) by increasing their firing rate significantly, 11 neurons responded to only one type of stimulation and 2 neurons responded to both female urine and 2-heptanone. By combining electrophysiological and intrinsic optical imaging techniques, we confirmed that the aAOB is activated by volatile urinary components. [J Physiol Sci. 2007;57 Suppl:S101]
