Joint experience-dependent representations of odors and temporal context in the zebrafish homolog of piriform cortex

Intelligent behavior requires experience-dependent internal representations of relevant information. We examined representational learning in telencephalic area pDp of adult zebrafish, the homolog of piriform cortex. Activity was measured by multiphoton imaging through a prism in head-fixed fish trained in an odor discrimination task. Population dynamics could be decomposed into independent modes, each consisting of distributed activity across mixed-selectivity neurons, that encoded odor identity, novelty, and the progression of time. Training sharpened novelty detection, strengthened odor-specific response components, and geometrically untangled representational manifolds. Experience-driven plasticity generalized across chemically related stimuli. Main observations could be reproduced phenomenologically by a model assuming linear interactions between novelty-, identity- and time-encoding activity modes. We conclude that pDp jointly represents olfactory and temporal information relevant for episodic memory. Experience enhances the accessibility and generalization of information, indicating that pDp supports brain-wide learning by geometrically organizing olfactory and time-related information on neural manifolds.