Relating the Neural Representation and Perceptual Quality of Olfactory Stimuli

Abstract

Event Abstract Back to Event Relating the Neural Representation and Perceptual Quality of Olfactory Stimuli John P. McGann1* 1 Rutgers University, Department of Psychology, United States The mouse olfactory bulb provides a powerful system for exploring the olfactory system because it permit the direct observation of physiological responses to odorants on both the population and single-cell levels while relating those responses to the corresponding perception of the odorant using behavioral olfactory psychophysical experimentation. Fig. 1A shows a fluorescence image of the right olfactory bulb of an anesthetized mouse expressing the exocytosis indicator synaptopHluorin [1] in the axon terminals of its olfactory receptor neurons (ORNs). The image shows the dorsal surface of the bulb visualized in vivo through a cranial window. Note that individual olfactory bulb glomeruli are visible in both the lower (left) and higher (right) magnification views. Fig. 1B (left) illustrates how the presentation of the odorant methyl valerate induces an increase in fluorescence (indicating transmitter release from ORN terminals) in a subset of the glomeruli shown in 1A (right). This pattern of response is odorant-specific, thus serving as the primary sensory representation of the odorant. In this session I will show how changes in this sensory representation may be induced experimentally, though pharmacological manipulation or sensory experience, and how these changes can be linked to olfactory perception. Fig. 1B illustrates how the application of the GABAB receptor antagonist CGP35348 (which blocks the GABA-mediated presynaptic inhibition of neurotransmitter release from ORN terminals) alters the representation of methyl valerate by increasing the magnitude of odor-evoked synaptic input without changing the relative responses across glomeruli [2]. In separate behavioral experiments, mice received bilateral infusions of CGP while performing behavioral tasks designed to quantify their perception of odor intensity and to evaluate their ability to discriminate between chemically similar odorants. The results demonstrate that CGP infusion produces changes in olfactory perceptions that are predictable from its effects on the neurophysiology of odorant responses. These experiments show how this combination of experimental techniques can successfully link the neural representation of odorants with the behaviorally-observed perception of odor intensity and quality. fig1