抄録
During the past ten years, electrophysiological studies on the peripheral olfactory nervous systems have been advanced by several investigators. Among them, however, only a few experiments are concerned wirh the mammalian olfaction. The present works were undertaken to study the electrical activity of the olfactory and trigeminal nerves, and of the single olfactory receptor cell in the guinea pig. Odors used in this experiment were selected from Amoore's classification table (1962). The following results were obtained :
1. The olfactory nerve responses of the guinea pigs are bigger to putrid and ethereal odors than to floral and musky ones.
2. When compared among many separated olfactory nerve twigs of the guinea pigs, the responses showed striking difference in magnitude depending upon the odorous substances used. Similar differences were already found among the kinds of animals (Shibuya, 1967). It was inferred that these two, differences in the magnitude of the response are due to the uneven distribution in the olfactory epithelium of the olfactory cells which have different selective sensitivity to various odours,
3. This concept was supported by a more direct experimental fisnding by a microelectrode that there exstas an olfactory cell which has sensitivity to amyl acetate, but not to menthone,
4. It was found that the magniutde of the olfactory nerve response declined initially during repeatcd stimulation but then it usually remained beyond a level, bigger than about 50% of the original one. The finding indicates that a greater part of the olfactory fatigue may occur in the central nervous system.
5. Response patterns of the olfactory nerve twigs werc different to different odours.
6. It was shown that the trigeminal nerve distributed in the nasal cavity has good sensistivity to many kinds of odors. Therefore, it is suggested that the trigeminal nerve plays an important role in the olfactory sensation.
