Toward a theoretical role for tonic norepinephrine in the orbitofrontal cortex in facilitating flexible learning.
To adaptively respond in a complex, changing world, animals need to flexibly update their understanding of the world when their expectations are violated. Though several brain regions in rodents and primates have been implicated in aspects of this updating, current models of orbitofrontal cortex (OFC) and norepinephrine neurons of the locus coeruleus (LC-NE) suggest that each plays a role in responding to environmental change, where the OFC allows updating of prior learning to occur without overwriting or unlearning one's previous understanding of the world that changed, while elevated tonic NE allows for increased flexibility in behavior that tracks an animal's uncertainty. In light of recent studies highlighting a specific LC-NE projection to the OFC, in this review we discuss current models of OFC and NE function, and their potential synergy in the updating of associations following environmental change.
Intramural Research Program of the National Institute on Drug Abuse, NIH, United States. Electronic address: brian.sadacca@nih.gov.
Brian F
BF
Sadacca
Intramural Research Program of the National Institute on Drug Abuse, NIH, United States.
Andrew M
AM
Wikenheiser
Intramural Research Program of the National Institute on Drug Abuse, NIH, United States; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, United States; Department of Neuroscience, Johns Hopkins School of Medicine, United States. Electronic address: schoenbaum@nih.gov.
Geoffrey
G
Schoenbaum
D000818:Animals; D056344:Executive Function / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000378:metabolism*
D009638:Norepinephrine
ensemble states; flexible learning; norepinephrine; orbitofrontal cortex; reinforcement learning