In nature, animals normally perceive sensory information on top of backgrounds. Thus, the neural substrate to perceive under background conditions is inherent in all sensory systems. Where and how sensory systems process backgrounds is not fully understood. In olfaction, just a few studies have addressed the issue of odor coding on top of continuous odorous backgrounds. Here, we tested how background odors are encoded by mitral cells (MCs) in the olfactory bulb (OB) of male mice. Using in vivo two-photon calcium imaging, we studied how MCs responded to odors in isolation versus their responses to the same odors on top of continuous backgrounds. Weshow that MCs adapt to continuous odor presentation and that mixture responses are different when preceded by background. In a subset of odor combinations, this history-dependent processing was useful in helping to identify target odors over background. Other odorous backgrounds were highly dominant such that target odors were completely masked by their presence. Our data are consistent in both low and high odor concentrations and in anesthetized and awake mice. Thus, odor processing in the OB is strongly influenced by the recent history of activity, which could have a powerful impact on how odors are perceived.
Bibliographical noteFunding Information:
Received March 19, 2017; revised Sept. 15, 2017; accepted Oct. 22, 2017. Author contributions: A.V., Y.L., and A.M. designed research; A.V. performed research; A.V. analyzed data; A.V. and A.M. wrote the paper. This work was supported by an Israel Science Foundation grant (#107/11) and an European Research Council consolidator grant (#616063) to A.M., as well as contributions from the Gatsby Charitable Foundation. We thank Yoav Adam for technical help with the imaging and Yishai Elyada for help with data analysis. We thank Dan Rokni and members of the Mizrahi laboratory for comments and discussions. The authors declare no competing financial interests. Correspondence should be addressed to Adi Mizrahi at the above address. E-mail: firstname.lastname@example.org. DOI:10.1523/JNEUROSCI.0755-17.2017 Copyright © 2017 Vinograd et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License Creative Commons Attribution 4.0 International, which permits unrestricted use, distribution and reproduction in anymediumprovidedthattheoriginalworkisproperlyattributed.
© 2017 Vinograd et al.
- Olfactory bulb
- Olfactory coding
- Two-photon calcium imaging