title: Nucleus accumbens core and shell inactivation differentially affects impulsive behaviours in rats.
abstract: Impulsivity is a multifactorial phenomenon, determined by deficits in decision-making (impulsive choice) and impulse control (impulsive action). Recent findings indicate that impulsive behaviour is not only top-down controlled by cortical areas, but also modulated at subcortical level. The nucleus accumbens (NAc) might be a key substrate in cortico-limbic-striatal circuits involved in impulsive behaviour. Dissociable effects of the NAc subregions in various behavioural paradigms point to a potential functional distinction between NAc core and shell concerning different types of impulsivity. The present study used reversible inactivation of the rats' NAc core and shell via bilateral microinfusion of the GABAA receptor agonist muscimol (0.05μg/0.3μl) and fluorophore-conjugated muscimol (FCM, 0.27μg/0.3μl) in order to study their contribution to different aspects of impulse control in a 5-choice serial reaction time task (5-CSRTT) and impulsive choice in a delay-based decision-making T-maze task. Acute inactivation of NAc core as well as shell by muscimol increased impulsive choice, with higher impairments of the rats' waiting capacity in the T-maze following core injections compared to shell. Intra-NAc shell infusion of muscimol also induced specific impulse control deficits in the 5-CSRTT, while deactivation of the core caused severe general impairments in task performance. FCM did not affect animal behaviour. Our findings reveal clear involvement of NAc shell in both forms of impulsivity. Both subareas play a key role in the regulation of impulsive decision-making, but show functional dichotomy regarding impulse control with the core being more implicated in motivational and motor aspects.
authors.affiliation: Department of Neuropharmacology, Brain Research Institute, Center for Cognitive Sciences, University of Bremen, PO Box 330440, 28359 Bremen, Germany. Electronic address: malte.feja@gmx.de.
authors.forename: Malte
authors.initials: M
authors.lastname: Feja
authors.affiliation: Department of Neuropharmacology, Brain Research Institute, Center for Cognitive Sciences, University of Bremen, PO Box 330440, 28359 Bremen, Germany. Electronic address: linda.hayn@uni-bremen.de.
authors.forename: Linda
authors.initials: L
authors.lastname: Hayn
authors.affiliation: Department of Neuropharmacology, Brain Research Institute, Center for Cognitive Sciences, University of Bremen, PO Box 330440, 28359 Bremen, Germany. Electronic address: michael.koch@uni-bremen.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Koch
mesh_terms: D000818:Animals; D003657:Decision Making / Q000187:drug effects / Q000502:physiology*; D058785:GABA-A Receptor Agonists; D007175:Impulsive Behavior / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D009118:Muscimol / Q000494:pharmacology; D009483:Neuropsychological Tests; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013997:Time Factors
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol
keywords: 5-CSRTT; Decision-making; GABA(A) agonist; Impulse control; Muscimol–BODIPY; T-maze