title: Rule learning enhances structural plasticity of long-range axons in frontal cortex.
abstract: Rules encompass cue-action-outcome associations used to guide decisions and strategies in a specific context. Subregions of the frontal cortex including the orbitofrontal cortex (OFC) and dorsomedial prefrontal cortex (dmPFC) are implicated in rule learning, although changes in structural connectivity underlying rule learning are poorly understood. We imaged OFC axonal projections to dmPFC during training in a multiple choice foraging task and used a reinforcement learning model to quantify explore-exploit strategy use and prediction error magnitude. Here we show that rule training, but not experience of reward alone, enhances OFC bouton plasticity. Baseline bouton density and gains during training correlate with rule exploitation, while bouton loss correlates with exploration and scales with the magnitude of experienced prediction errors. We conclude that rule learning sculpts frontal cortex interconnectivity and adjusts a thermostat for the explore-exploit balance.
authors.affiliation: UCSF Neuroscience Graduate Program, University of California San Francisco, San Francisco, California 94158, USA.
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Johnson
authors.affiliation: Department of Psychology, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Hannah
authors.initials: H
authors.lastname: Peckler
authors.affiliation: Department of Psychology, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Lung-Hao
authors.initials: LH
authors.lastname: Tai
authors.affiliation: Department of Psychology, University of California Berkeley, Berkeley, California 94720, USA.|Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Wilbrecht
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D002755:Choice Behavior; D006801:Humans; D007858:Learning; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D017397:Prefrontal Cortex / Q000502:physiology*; D012201:Reward