ϒ Spike-Field Coherence in a Population of Olfactory Bulb Neurons Differentiates between Odors Irrespective of Associated Outcome

Balancing the Robustness and Efficiency of Odor Representations during Learning

“…On average, 41.6 ± 7.5 % of the imaged mitral cell population exhibited significant changes in fluorescence to at least one odorant during the odor period. The odorant responses included both increases and decreases in fluorescence (Day 1, 72.3 ± 9.0 % of responses were increases and 27.7 ± 9.0 % were decreases; Day 7, 72.2 ± 7.0 % of responses were increases and 27.8 ± 7.0 % were decreases), consistent with previous reports (Bathellier et al, 2008; Davison and Katz, 2007; Doucette and Restrepo, 2008; Fuentes et al, 2008; Gschwend et al, 2012; Kato et al, 2012; Kollo et al, 2014; Li et al, 2015; Nagayama et al, 2004; Rinberg and Gelperin, 2006; Shusterman et al, 2011; Yokoi et al, 1995). Additionally, a large fraction of the responsive mitral cells exhibited divergent responses between the two odorants on Day 1 (Figures 2B-D and Figure S1).…”

“…Our study contributes to the mounting evidence supporting the olfactory bulb as an important locus for learning- related activity changes (Abraham et al, 2014; Doucette and Restrepo, 2008; Doucette et al, 2011; Li et al, 2015). It is noteworthy that one previous study described that olfactory perceptual learning, similar to the difficult discrimination task used here, resulted in increased pattern separation in anterior piriform cortical ensembles but not in mitral cells (Chapuis and Wilson, 2012).…”

“…Over a week, mice repeatedly experienced a similar or dissimilar odorant pair in a discrimination task or passive exposure. We acknowledge that it is becoming increasingly clear that fine temporal features of mitral cell spiking, which are not accessible with the temporal resolution of our imaging approach, can carry important information about odorant identity (Bathellier et al, 2008; Blauvelt et al, 2013; Blumhagen et al, 2011; Cury and Uchida, 2010; Friedrich et al, 2004; Gschwend et al, 2012; Lepousez and Lledo, 2013; Li et al, 2015; Shusterman et al, 2011). It has also been shown that the reaction time in olfactory discrimination tasks can be as short as a couple hundred milliseconds (Abraham et al, 2004; Resulaj and Rinberg, 2015; Uchida and Mainen, 2003), indicating that mitral cell responses within this time window must contain sufficient information for discrimination at least in certain contexts.…”

“…Previous studies have described learning-related plasticity at multiple levels within the olfactory system (Abraham et al, 2014; Chapuis and Wilson, 2012; Doucette and Restrepo, 2008; Doucette et al, 2011; Kass et al, 2013, 2016; Li et al, 2015; Shakhawat et al, 2014; Wachowiak et al, 2005). Our study contributes to the mounting evidence supporting the olfactory bulb as an important locus for learning- related activity changes (Abraham et al, 2014; Doucette and Restrepo, 2008; Doucette et al, 2011; Li et al, 2015).…”

“…These modulatory functions are sensitive to brain states, as neural activity in the olfactory bulb during the awake state has been shown to be dramatically different from the anesthetized state (Blauvelt et al, 2013; Kato et al, 2012; Kollo et al, 2014; Rinberg and Gelperin, 2006). Recent studies in awake behaving animals are beginning to shed light on the way olfactory experience and learning alters the dynamics of olfactory circuits (Abraham et al, 2014; Doucette and Restrepo, 2008; Doucette et al, 2011; Li et al, 2015; Shakhawat et al, 2014). However, a comprehensive understanding of how different types of experience affect odor representations in the early stages of processing is still lacking.…”