Distinct Characteristics of Odor-evoked Calcium and Electrophysiological Signals in Mitral/Tufted Cells in the Mouse Olfactory Bulb

Fiber photometry is a recently-developed method that indirectly measures neural activity by monitoring Ca2+ signals in genetically-identified neuronal populations. Although fiber photometry is widely used in neuroscience research, the relationship between the recorded Ca2+ signals and direct electrophysiological measurements of neural activity remains elusive. Here, we simultaneously recorded odor-evoked Ca2+ and electrophysiological signals [single-unit spikes and local field potentials (LFPs)] from mitral/tufted cells in the olfactory bulb of awake, head-fixed mice. Odors evoked responses in all types of signal but the response characteristics (e.g., type of response and time course) differed. The Ca2+ signal was correlated most closely with power in the beta-band of the LFP. The Ca2+ signal performed slightly better at odor classification than high-gamma oscillations, worse than single-unit spikes, and similarly to beta oscillations. These results provide new information to help researchers select an appropriate method for monitoring neural activity under specific conditions.

Automated summary

By recording odor-evoked Ca2+ and electrophysiological signals simultaneously in awake, head-fixed mice, researchers found that Ca2+ signals were most closely correlated with beta-band power in the LFP. The study provided new insights into the relationship between different types of neural signals and their performance in odor classification.