Amplification of Olfactory Transduction Currents Implements Sparse Stimulus Encoding.

Sensory systems must perform the dual and opposing tasks of being sensitive to weak stimuli while also maintaining information content in dense and variable sensory landscapes. This occurs in the olfactory system, where olfactory sensory neurons (OSNs) are highly sensitive to low concentrations of odors and maintain discriminability in complex odor environments. How OSNs maintain both sensitivity and sparsity is poorly understood. Here, we investigated whether the calcium-activated chloride channel, TMEM16B, may support these dual roles in OSNs in both male and female mice. We used multiphoton microscopy to image the stimulus-response density of OSNs in the olfactory epithelium. In TMEM16B knock-out mice, we found that sensory representations were denser, and the magnitude of OSN responses was increased. Behaviorally, these changes in sensory representations were associated with an increased aversion to the odorant trimethylamine, which switches perceptual valence as its concentration increases, and a decreased efficiency of olfactory-guided navigation. Our results indicate that the calcium-activated chloride channel TMEM16B sparsens sensory representations in the peripheral olfactory system and contributes to efficient integrative olfactory-guided behaviors.