PT  - JOURNAL ARTICLE
AU  - Elena Kudryavitskaya
AU  - Eran Marom
AU  - David Pash
AU  - Adi Mizrahi
TI  - Flexible Representations of Odour Categories in the Mouse Olfactory Bulb
AID  - 10.1101/2020.03.21.002006
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.03.21.002006
4099  - http://biorxiv.org/content/early/2020/03/24/2020.03.21.002006.short
4100  - http://biorxiv.org/content/early/2020/03/24/2020.03.21.002006.full
AB  - The ability to group sensory stimuli into categories is crucial for efficient interaction with a rich and ever-changing environment. In olfaction, basic features of categorical representation of odours were observed as early as in the olfactory bulb (OB). Categorical representation was described in mitral cells (MCs) as sudden transitions in responses to odours that were morphed along a continuum. However, it remains unclear to what extent such response dynamics actually reflects perceptual categories and decisions therein. Here, we tested the role of learning on category formation in the mouse OB, using in vivo two-photon calcium imaging and behaviour. We imaged MCs responses in naïve mice and in awake behaving mice as they learned two tasks with different classification logic. In one task, a 1-decision boundary task, animals learned to classify odour mixtures based on the dominant compound in the mixtures. As expected, categorical representation of close by odours, which was evident already in naïve animals, further increased following learning. In a second task, a multi-decision boundary task, animals learned to classify odours independent of their chemical similarity. Rather, odour discrimination was based on the meaning ascribed to them (either rewarding or not). Following the second task, odour representations by MCs reorganized according to the odour value in the new category. This functional reorganization was also reflected as a shift from predominantly excitatory odour responses to predominantly inhibitory odour responses. Our data shows that odour representations by MCs is flexible, shaped by task demands, and carry category-related information.