10:00 - 12:00
Fri-S5
Goethe Hall
Chair/s:
Veronica Egger, Diego Restrepo
The sense of smell has the complicated task of processing qualitatively multidimensional sensory input conveyed by turbulent odor plumes and paced by the respiratory rhythm. In addition, signal processing of olfactory input takes place under drastically different contextual circumstances. Our symposium will bring together an exciting set of speakers using a variety of experimental approaches that will discuss how olfactory system oscillations are generated, how they entrain activity in non-olfactory brain regions, how distance and direction of an odor source is encoded, and how oscillations contribute to multidimensional circuit processing and integrate with contextual circuit modulation.
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Olfactory learning elicits changes in oscillations and dimensionality in neural activity in hippocampal CA1
Fri-S5-005
Presented by: Diego Restrepo
Diego Restrepo 1, 3, Daniel Ramirez-Gordillo 1, Andrew Parra 1, Fabio M. Simoes de Souza 1, 2, Ming Ma 1, Jose Riguero 1, Emily Gibson 3, 4
1 Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA, 2 Center for Mathematics, Computation and Cognition, Federal University of ABC, Sao Bernardo do Campo, SP, Brazil, 3 Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA, 4 Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
The hippocampus is classically associated with learning and memory, spatial navigation and sequence storage, but there is evidence for a role of CA1 neurons in olfactory associative learning. To explore encoding of olfactory identity by CA1 neurons, we performed tetrode recording of local field potential and 2-photon imaging in dorsal CA1 of mice exposed to odorants in passive and active tasks. A pseudorandom odorant sequence was presented to head-fixed mice without water reward in the passive task, while in the active task the head-fixed mouse performed go/no-go associative learning where they obtained a water reward when they licked on a spout in the presence of the rewarded odorant.

We found that as the animal learns to discriminate odorants in the go-no go task, the coupling of high frequency neural oscillations to the phase of theta oscillations (theta-referenced phase-amplitude coupling or tPAC) in dorsal CA1 changes in a manner that results in divergence between rewarded and unrewarded odorant-elicited changes in the theta-phase referenced power (tPRP) for beta and gamma oscillations. Furthermore, the changes in tPAC resulted in a marked increase in the accuracy for decoding contextual odorant identity from tPRP when the animal became proficient. Additionally, the identity of the odorants could be decoded from calcium responses in the active task. For the passive task only a small subset of the neurons contributed to successful decoding of the odorant and odorant prediction fluctuated between trials. In contrast, for the active task in the proficient animal a large fraction of neurons contributed to decoding and odorant prediction defaulted to the unrewarded odorant in between trials. Our findings are significant because they show that ensembles of neurons in dorsal CA1 represent stimuli in strikingly different manners under different behavioral conditions.

Funded by NIH DC000566, NSF BIO-1926676 and U01NS099577.
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