SPATIO-TEMPORAL CODING OF ODOR

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Perhaps the most important debate in olfactory neuroscience is whether the temporal transformation of olfactory input mediates the perception of odor. Confounding this debate is the observation that dynamic odor plume structure produces temporal responses that also affect odor discrimination. Our long term goals focus on understanding the functional role of the antennal lobe (AL) local circuitry in establishing temporally patterned output from the AL and how these spatio-temporal representations affect odor perception. These issues are central to basic understanding of normal olfactory function in humans. However, the experiments required to gain this understanding are invasive, thus, we the Sphinx Moth as a model system. The current proposal seeks to first characterize and control for stimulus dynamics (which include non-molecular properties of odor stimuli, such as stimulus concentration, duration and intermittency) that can affect both spatio-temporal responses from the AL and sensory perceptions. Our approach will use behavioral assays to characterize olfactory discrimination and under systematically varying stimulus conditions. Here we will establish the concentration thresholds below which animals are unable to: 1) detect odorants; and 2) discriminate between odorants. Next, we will quantify the effects of stimulus duration and intermittency on discrimination thresholds. This behavioral work establishes the stimulus dynamics parameters under which normal olfactory behaviors are produced and will provide reference data with which we can replicate stimulus conditions and use neurophysiological methods to characterize AL population responses. Here we will use established methods to quantify how uniquely a recorded neural population responds to different odorants across response time as a function of varying stimulus dynamics. The final aim of the proposal seeks to assess the relative contributions of two known temporal components to AL responses, slow patterns of neural bursting and silence and local field potential oscillations. We propose 3 methods to disrupt the relationship between the oscillations and the neural spiking activity and quantify the effect on our population measures of uniqueness of odor-driven responses.