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Adaptive aspects of impulsivity and interactions with effects of catecholaminergic agents in the 5-choice serial reaction time task: implications for ADHD.

Published version
Peer-reviewed

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Authors

Hervig, Mona El-Sayed 
Moazen, Parisa 
Parker, Maximilian G 
Dalley, Jeffrey W 

Abstract

BACKGROUND: Work in humans has shown that impulsivity can be advantageous in certain settings. However, evidence for so-called functional impulsivity is lacking in experimental animals. AIMS: This study investigated the contexts in which high impulsive (HI) rats show an advantage in performance compared with mid- (MI) and low impulsive (LI) rats. We also assessed the effects of dopaminergic and noradrenergic agents to investigate underlying neurotransmitter mechanisms. METHODS: We tested rats on a variable inter-trial interval (ITI) version of the 5-choice serial reaction time task (5CSRTT). Rats received systemic injections of methylphenidate (MPH, 1 mg/kg and 3 mg/kg), atomoxetine (ATO, 0.3 mg/kg and 1 mg/kg), amphetamine (AMPH, 0.2 mg/kg), the alpha-2a adrenoceptor antagonist atipamezole (ATI, 0.3 mg/kg) and the alpha-1 adrenoceptor agonist phenylephrine (PHEN, 1 mg/kg) prior to behavioural testing. RESULTS: Unlike LI rats, HI rats exhibited superior performance, earning more reinforcers, on short ITI trials, when the task required rapid responding. MPH, AMPH and ATI improved performance on short ITI trials and increased impulsivity in long ITI trials, recapitulating the behavioural profile of HI. In contrast, ATO and PHEN impaired performance on short ITI trials and decreased impulsivity, thus mimicking the behavioural profile of LI rats. The effects of ATO were greater on MI rats and LI rats. CONCLUSIONS: These findings indicate that impulsivity can be advantageous when rapid focusing and actions are required, an effect that may depend on increased dopamine neurotransmission. Conversely, activation of the noradrenergic system, with ATO and PHEN, led to a general inhibition of responding.

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Keywords

Amphetamine, Atipamezole, Atomoxetine, Impulsivity, Methylphenidate, Phenylephrine, Amphetamine, Animals, Attention Deficit Disorder with Hyperactivity, Choice Behavior, Impulsive Behavior, Rats, Reaction Time

Journal Title

Psychopharmacology (Berl)

Conference Name

Journal ISSN

0033-3158
1432-2072

Volume Title

238

Publisher

Springer Science and Business Media LLC
Sponsorship
Wellcome Trust (093875/Z/10/Z)
Medical Research Council (G1000183)