BRAIN-WIDE NETWORKS OF CATEGORY LEARNING IN THE MOUSE

Learning to categorize objects and experiences is a fundamental cognitive process that enables flexible behavior in complex environments. Multiple regions in the neocortex, hippocampus and subcortex have been implicated in category learning across species. However, most of these studies, especially in animal models, have focused on single brain regions or pairwise interactions, highlighting the need for an unbiased investigation of brain-wide spatial and temporal interactions.
Here, we employ functional ultrasound imaging to record whole-brain dynamics while mice perform a category learning task in a head-fixed 2- alternative forced choice paradigm. Using this approach, we aim to characterize the learning-related recruitment of brain regions that constitute functional networks processing visual categories.
Whole-brain trial-averaged activity revealed three phases: early stimulus-related activity, followed by later choice- and reward-related activity. K-means clustering identified groups of brain areas that changed their activity with learning, each group confined to a single phase, indicating trial phase-specific functional reorganization. Ridge regression showed that early-phase clusters, including dorsal caudoputamen, lateral dorsal nucleus of the thalamus, pontine nuclei and insula, increased stimulus encoding after initial learning, demonstrating their involvement in the stimulus-processing network.
Across category learning, global trial-evoked activity decreased, yet regional activation patterns and stimulus encoding remained largely stable. Category tuning index analysis revealed regions selectively modulated by visual categories, including infralimbic cortex, entorhinal cortex, dorsal caudoputamen, medial hippocampus, pontine nuclei and insula.
These combined results provide brain-wide maps of functional networks dissociating category learning from visual operant learning, highlighting candidate regions for future targeted circuit investigations in mice.