Long-term recording of olfactory and vomeronasal stimulant-induced waves from the turtle main olfactory bulb and accessory olfactory bulb

Abstract

Recording of stimulant-induced waves (bulbar responses) from the main olfactory bulb is a useful tool for measuring quantitative stable olfactory responses. There is a good relationship between the olfactory bulbar response, olfactory nerve response and electroolfactogram (EOG), suggesting that the bulbar response reflects events in receptor cells [1, 4, 19]. The modern whole-cell recording technique offers direct information on olfactory transduction in single cells, but it requires long experimental periods and many animals. On the other hand, analysis of bulbar responses provides useful information and requires the use of few animals. For example, we found that cAMP-increasing and IP 3-increasing odorants were not distinctly received by the turtle olfactory organ by measuring olfactory bulbar responses and analyzed with a multidimensional scaling from about 60 animals [10]. However, to record similar odor responses from isolated turtle olfactory neurons, at least 200 animals would be necessary. Bulbar responses are recorded with electrodes implanted into or located on the main olfactory bulb. When electrodes are located on the olfactory bulb surface [3, 7–10, 17, 18], it is possible to record stable responses over a period of 3 days. These methods were applied successfully to the accessory olfactory bulb [5, 15, 16]. In this paper, we describe the protocols used for recording of the stimulant-induced waves from the main and accessory olfactory bulb.