State-Dependent Modulation of Odour Valence and Decision Making
1 University of Bonn, Institute for Physiology II
Olfactory perception is crucial for survival of most animals. Of particular importance is odour valence, which describes the biological value of odours and elicits a contextually appropriate action (e.g., aversion to predator odour, approach to food odour). Interestingly, odour valence is significantly modulated by internal state, environmental stimuli and experience. This plays a particularly important role in natural situations, which often demand decision making in conflicting situations, e.g., when a hungry animal forages for food, but detects a predator. Despite this crucial function, the mechanisms underlying valence coding and modulation are poorly understood. Particularly, how innate odour valence is modulated by internal state remains largely elusive, since previous studies have almost exclusively focused on artificially assigned valence using conditioning. So far, it is unknown whether conditioned and innate valence are encoded and modulated in the same way. Here, we study how natural odour valence is encoded and modulated, and how this affects decision-making in conflicting situations. To this end, we develop a paradigm to assess how non-conditioned behavioural responses towards ethologically relevant odours are naturally modulated by internal state (i.e., metabolic and reproductive), with the goal to record neuronal activity and behaviour in freely moving mice. Specifically, mice in different metabolic or reproductive states are exposed simultaneously to appetitive (e.g., food or male odour) and aversive odours (e.g., predator) while tracking behavioural responses. Furthermore, to examine the molecular mechanisms underlying state-dependent modulation, we are currently establishing protocols to analyse gene expression changes in defined neuronal subtypes using RNA sequencing.