Olfactory system electrophysiology

In particular, the importance of chirality in diverse pheromone systems has been reviewed recently (Mori, 1998). For example, olive fruit flies (Bactrocera oleae) emit racemic 2 the males detect the R enantiomer, while females detect the S (Haniotakis et al., 1986). The sex pheromone of the Osaka beetle (Anomala osakana) is 4a, while the closely related Japanese beetle (Popilia japonica) uses 4b (Table 16.1). Interestingly, 4a is a powerful behavioral antagonist in P. japonica (Tumlinson et al., 1977). The hemlock looper, Lambdina fiscellaria, responds only to (5R, 1 S)-5,I I -dimethylheptadecane. The enantiomer or the R/R or S/S diastereomers do not elicit electrophysiological or behavioral responses (Li et al., 1993). Table 16.1 gives an overview of those species where proteins from the pheromone olfactory system have been identified. 

Scott, J.W. (1981) Electrophysiological identification of mitral and tufted cells and distribution of their axons in the olfactory system of the rat. J. Neurophysiol., 46, 918-931. 

This fact prompted the question how these animals detect odors. By using electrophysiology (see above) we could show that odor molecules were detected on the first antenna, and more specifically on the final segment. We screened a number of synthetic volatile compounds, and noted that the crabs olfactory system readily could detect and differentiate between these compounds. After establishing the olfactory sensitivity to these synthetic stimuli, we next wanted to establish if they were indeed behaviorally active in themselves, and if... 

Silver W (1982) Electrophysiological responses from the peripheral olfactory system of the American eel, Anguilla rostrata. J Comp Physiol A Sens Neural Behav Physiol 148 379-388... 

The relationship between chemical structure and perceived odor has been studied by electrophysiological, chemical-analytical, and psychophysical techniques. Certain odorants in addition to being detected by the olfactory system evoke specific behavioral responses. Recent studies on various mammalian species have attempted to equate specific odor sources with behavioral patterns and to profile the odorants in hopes of Identifying the biologically active components ( ). In addition, studies on human odor suggest similarities in odor sources and types with other mammalian species and also suggest some of these odors may be reflective of internal body processes. 

Another stimulus which generated interest was the progress in understanding the physiology of olfactory systems for which we are indebted to such workers as E. D. Adrian, C. Pfaffmann and Y. Zotterman. The availability of electrophysiological techniques, which allowed the measurement of the electrical responses of the olfactory bulbs and peripheral olfactory systems to odour stimulation, promised easier experimentation. 

During the first ISOT, only Jacques LeMagnen, the founder of the field of olfactory-endocrine relationships, whose later work linked animal and human studies, hinted at future developments. In his paper he remarked that. .. Electrophysiological investigation of olfactory and gustatory afferent fibres does not allow us to analyse the discriminatory process itself. Only behavioural data can actually reveal the differential effects of the given stimuli on the olfactory system. Thanks however to the work of Adrian, Pfaffman and of the Swedish and other workers, modern electrophysiological... 

Hara, T. J., 1967, Electrophysiological studies on the olfactory system of the goldfish, Carassius auratus L. III. Effects of sex steroids on olfactory activity. Comp. Biochem. Physiol.. 22 209. 

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