ACHEMS 2019
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SPLTRAK Abstract Submission
Decoding Olfactory Stimulus Strength from Olfactory Bulb LFP Oscillations
Justin T. Losacco & Diego Restrepo
University of Colorado Anschutz Medical Campus, Aurora, CO, United States

The perception of odor concentration is vital for survival. Since increased concentration reduces firing latency for mitral cells in the olfactory bulb (OB), firing phase with respect to the low frequency oscillation (LFO: respiration, theta local field potential) may convey stimulus strength. This signal can be read out via single cell firing, through aggregate neuronal activity patterns in the local field potential (LFP), and through the interaction between these phenomena—through spike-field coherence. While the representation of stimulus strength in mitral cell firing has been studied in vitro, markedly less is known about how the network of principal cells in OB conveys this information. Here, I implanted tetrodes into the mitral cell layer of the dorsomedial OB of C57BL/6 mice. Single-unit activity and the LFP were recorded while the mice performed two variants of the behavioral go no-go task, discriminating between odor identity—and separately—odor concentration. All mice learned both tasks within a few days of training. LFP power (all bands) increased for rewarded stimuli and decreased for unrewarded stimuli over task acquisition in both paradigms (identity and concentration). In the concentration task, LFP power correlated with the rewarded odors irrespective of concentration. Phase amplitude coupling (PAC), or the relationship between the oscillatory phase of the LFO and the power of a higher frequency gamma oscillation (from coherent mitral cell firing) was stronger for the identity task than the concentration task. Additional work using discriminant analysis will determine whether LFP power or PAC are able to decode which stimulus was presented in both the identity and concentration paradigms.