Abstract
The anterior olfactory nucleus (AON) is the initial recipient of odour information from the olfactory bulb, and the target of dense innervation conveying spatiotemporal cues from the hippocampus. We hypothesized that the AON detects the coincidence of these inputs, generating patterns of activity reflective of episodic odour engrams. Using activity-dependent tagging combined with neural manipulation techniques, we reveal that contextually-relevant odour engrams are stored within the AON and that their activity is necessary and sufficient for the behavioural expression of odour memory. Our findings offer a new model for studying the mechanisms underlying memory representations.
Highlights
The anterior olfactory nucleus (AON) is the initial recipient of odour information from the olfactory bulb, and the target of dense innervation conveying spatiotemporal cues from the hippocampus
FosCreER mice were infused with an adeno-associated virus (AAV) vector carrying a Credependent reporter (AAV9-CAG-FLEX-GFP) into the AON
We observed a high density of GFPlabelled cells within the AON in animals exposed to an odourcontext pairing, yet neither stimulus alone increased the number of labelled cells compared to homecage and vehicle-only conditions (Supplementary Fig. 1a, b)
Summary
The anterior olfactory nucleus (AON) is the initial recipient of odour information from the olfactory bulb, and the target of dense innervation conveying spatiotemporal cues from the hippocampus. We hypothesized that the AON detects the coincidence of these inputs, generating patterns of activity reflective of episodic odour engrams. Using activity-dependent tagging combined with neural manipulation techniques, we reveal that contextually-relevant odour engrams are stored within the AON and that their activity is necessary and sufficient for the behavioural expression of odour memory. Engrams can be later recalled when their activity is triggered by external cues, informing the animal on behaviourally relevant stimuli[6,7]. We determined the necessity of hippocampal-AON projections for recollecting spatiotemporal aspects of odour memory and identified a coincidence detection property for the AON27. Our results establish the AON as a cortical repository for odour memory representations
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