Dopamine Acts as the Brake for Human Inhibitory Control
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1
The University of Queensland , Queensland Brain Institute and The Prince Charles Hospital, Australia
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2
The University of Melbourne, Department of Psychology, Australia
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3
University of Cambridge, Department of Psychiatry, United Kingdom
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4
Monash University, School of Psychology, Psychiatry and Psychological Medicine, Australia
Response inhibition is a prototypical executive function of considerable clinical relevance, yet our understanding of its neurochemistry, particularly with regard to monoamines remains limited. We utilized the most selective and clinically relevant agents available for human use to modify dopaminergic, noradrenergic and serotonergic systems, and compared their effects on response inhibition with placebo. A randomized, double-blind, placebo-controlled, cross-over design with an acute dose of methylphenidate (30mg), atomoxetine (60mg), citalopram (30mg) and placebo (dextrose) was employed in 24 healthy males. Participants performed the stop-signal task in which participants were required to make a manual response to a frequent ‘go’ signal but cancel this response to an infrequent ‘stop’ signal. Speed of inhibition was indexed by the stop-signal reaction time (SSRT). Methylphenidate reduced SSRTs indicating enhanced response inhibition compared with all other conditions. Crucially, the enhancement of response inhibition by methylphenidate occurred without concomitant changes in overall response speed, as there was no effect on mean reaction time. No significant differences between atomoxetine and placebo, citalopram and placebo or between atomoxetine and citalopram were found. Optimum response inhibition is achieved when sub-cortical dopamine systems are able to amplify top-down catecholamine signals in order to exert greater control over voluntary action.
Keywords:
Dopamine,
Humans,
SSRT,
Methylphenidate,
monoamines
Conference:
The 20th Annual Rotman Research Institute Conference, The frontal lobes, Toronto, Canada, 22 Mar - 26 Mar, 2010.
Presentation Type:
Poster Presentation
Topic:
Neuropharmacology
Citation:
Bellgrove
MA,
Cummins
T,
Hester
R,
Mattingley
JB,
Nandam
LS,
Nathan
PJ and
Wagner
J
(2010). Dopamine Acts as the Brake for Human Inhibitory Control.
Conference Abstract:
The 20th Annual Rotman Research Institute Conference, The frontal lobes.
doi: 10.3389/conf.fnins.2010.14.00051
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Received:
28 Jun 2010;
Published Online:
28 Jun 2010.
*
Correspondence:
Mark A Bellgrove, The University of Queensland, Queensland Brain Institute and The Prince Charles Hospital, Brisbane, Australia, mark.bellgrove@monash.edu