Scientific Understanding of Consciousness
Dopaminergically Mediated Reward in Somatosensory Decision-Making
PLoS Biol 7(7): e1000164. doi:10.1371/journal.pbio.1000164
Influence of Dopaminergically Mediated Reward on Somatosensory Decision-Making.
Pleger B, Ruff CC, Blankenburg F, Klöppel S, Driver J, et al. (2009)
1 Wellcome Trust Centre for Neuroimaging at UCL, London, United Kingdom, 2 Department of Cognitive Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 3 UCL Institute of Cognitive Neuroscience, London, United Kingdom, 4 Laboratory for Social and Neural Systems Research (SNS), Institute for Empirical Research in Economics, University of Zurich, Switzerland, 5 Department of Neurology and Bernstein Center for Computational Neuroscience, Charité, Berlin, Germany, 6 Department of Psychiatry and Psychotherapy, University of Freiburg, Freiburg, Germany
The rewards one receives during decision-making has a profound impact on learning. Much recent interest has focused on the role of the neurotransmitter dopamine in the basal ganglia for influencing learning and behaviour. Here, we ask whether reward can influence low-level sensory processing, for instance in primary sensory cortex, and how dopamine mediates this process. We show in humans that dopamine level, as manipulated with a dopamine agonist and antagonist in a double-blind placebo-controlled design, is involved in reward modulation of primary somatosensory cortex. Higher anticipated reward improved tactile decisions, and receipt of visual reward signals reactivated primary somatosensory cortex for the judged hand as measured using functional neuroimaging. After receiving a higher reward on one trial, somatosensory activations and decisions were enhanced on the next trial, suggesting that reward outcome provides a form of teaching signal that may be fed back to task-relevant sensory cortex. All these behavioural and neural effects of reward on somatosensory decision-making were strongly modulated by the availability of dopamine as the mediating neurotransmitter. These findings raise the tantalising new possibility that reward manipulations in conjunction with dopaminergic drugs might be used to enhance pathologically deficient or lapsed sensory processes, analogous to how rewards can be used to shape or correct behaviour.
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