During the course of this project, we have implemented a state-of-the-art method to monitor and analyze sniffing in freely moving mice with a high level of precision (thanks to miniaturized ultra-light pressure sensors), establishing the methodological framework for studies on social odor neuronal processing, and leading to new discoveries on the link between respiration and brain activity in the context of memory function (Casali et al., accepted in Nature Communications) and olfaction (Terral et al., Nature Communications 2024).
Combining this approach with advanced computational methods and cutting-edge technologies that enable recording large neuronal ensembles in freely moving mice, we have shed light on the mechanisms of memory consolidation during sleep: we found that these are strongly linked to bodily functions and in particular, the way the animal breath (Casali et al., accepted). This work yielded a machine-learning-based toolbox which can predict brain states (sleep states, wakefulness) solely based on the respiration signal. This toolbox will be shared with the community through an open-access platform.
We also uncovered that neurons in the olfactory piriform cortex replay past activity patterns after an olfactory learning task when the animal is asleep. Activity in this sensory cortex correlates with neuronal activity in the hippocampus and could therefore potentially instruct memory networks during memory consolidation (Moore, Terral et al., manuscript in preparation). Our results indeed show that the odors sampled during wakefulness, when mice explore two distinct territories, shape hippocampal activity both during wake and sleep (Moore, Ravassard et al., manuscript in preparation).
Finally, we have tracked the brain substrates of individuals’ identity in mice and studied the role of a pro-social neuropeptide, oxytocin, in the olfactory piriform cortex in the context of social behaviors.
Overall, this program has taken full advantage of advanced technologies to dissect the neural bases of functions with fundamental ecological relevance: the capacity to remember a path leading to vital resources (spatial/olfactory memory) and the capacity to remember or interact with others (social behaviors).
