Molecular, physiological and ethologial perspectives
on insect olfaction

B.H. Smith

Department of Entomology, 1735 Neil Ave., Ohio State University, Columbus, OH 43210-1220, USA

Research on insect olfaction has made significant progress on a number of fronts. Recent advances highlight the molecular and biochemical bases for transduction of chemical information into signals projected to the CNS. Further work has revealed the bases for processing those signals and integrating them with motor systems. Finally, work under both laboratory and field conditions have revealed behavioral mechanisms that insects use to approach or avoid important odors. Even in the case of pheromonal systems, these behavioral mechanisms always involve reasonably stereotypical responses to odors that can be modified by one or another learning process. In many cases important correlations have been established across molecular, physiological and behavioral levels of analysis. For example, odor stimulation activates defined spatial and temporal activity patterns that are characteristic for different odorants. More recently, several lines of evidence have revealed synaptic plasticity in the antennal lobes, which are the first-order processing centers for olfactory information in the brain. This plasticity is correlated to learned recognition of the association of odors to food reinforcement. Yet there have only been a few attempts to establish a causal link between any these neural events and behavior, and these attempts have met with limited success. Thus causal relationships are bound to be complex. The seminar will briefly review what has been done to link olfactory processing across different levels of analysis and highlight the need for these kinds of studies in the near future.

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