Motor priming is associated with widespread recruitment into neural ensembles and more rapid ensemble transitions

Repetition priming is a ubiquitous form of implicit learning in which repetition leads to increased performance. We investigated egestive priming of feeding behavior in Aplysia californica using an isolated cerebral and buccal ganglia preparation and recorded the activities of numerous neurons by using voltage-sensitive dye (VSD) imaging. The high-dimensional VSD data were subjected to tensor component analysis, which characterized three neuronal ensembles with distinct spatial and temporal domains. The activities of these ensembles corresponded to three motor phases: radula protraction, early retraction, and late retraction. Priming resulted in repetition enhancement characterized by increased neural activity during early retraction (i.e., gain modulation), as well as a more rapid transition into the late retraction ensemble. In addition, priming recruited previously inactive neurons into the protraction and early retraction ensembles. These results indicate that priming-induced neural plasticity is multifaceted, operating across multiple axes of plasticity, and each axis modifies specific subsets of ensembles.