title: Prefrontal cortex mediates extinction of responding by two distinct neural mechanisms in accumbens shell.
abstract: Suppression of ill-timed or competing actions optimizes goal-directed behaviors. Diminished inhibitory control over such actions is a central feature of such disorders as impulsivity, obesity, and drug addiction. The ventromedial prefrontal cortex (vmPFC) is involved in suppression of unreinforced actions. Using reversible inactivation in rats, we demonstrate that vmPFC activity is also required for inhibition of unreinforced actions extinguished during learning of a cued appetitive task and that behavioral disinhibition following vmPFC inactivation depends on dopamine signaling in nucleus accumbens shell (NAcS). Combining electrophysiological recording in NAcS with vmPFC inactivation in rats reveals two neural mechanisms by which vmPFC inhibits unreinforced actions. The first is by suppressing phasic excitations that promote behavioral cue responding. The second is by increasing the basal firing of NAcS neurons that tonically inhibit reward seeking. These results identify the vmPFC and the NAcS as critical elements of the circuits relevant to suppression of inappropriate actions.
authors.affiliation: Ernest Gallo Clinic and Research Center, Wheeler Center for the Neurobiology of Addiction, Department of Neurology, University of California, San Francisco, Emeryville, California 94608, USA. ali.ghazizadehehsaei@nih.gov
authors.forename: Ali
authors.initials: A
authors.lastname: Ghazizadeh
authors.forename: Frederic
authors.initials: F
authors.lastname: Ambroggi
authors.forename: Naomi
authors.initials: N
authors.lastname: Odean
authors.forename: Howard L
authors.initials: HL
authors.lastname: Fields
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D005108:Extinction, Psychological / Q000502:physiology*; D008297:Male; D008959:Models, Neurological; D009714:Nucleus Accumbens / Q000166:cytology / Q000502:physiology*; D017397:Prefrontal Cortex / Q000166:cytology / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans