Neuron
Volume 84, Issue 1, 1 October 2014, Pages 177-189
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Article
Overriding Phasic Dopamine Signals Redirects Action Selection during Risk/Reward Decision Making

https://doi.org/10.1016/j.neuron.2014.08.033Get rights and content
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Highlights

  • LHb suppresses burst firing of dopamine neurons driven by excitatory inputs

  • Outcome-related LHb or VTA stimulation redirects choice during decision making

  • Attenuation of prechoice dopamine bursts reduced selection of preferred reward

  • Phasic DA signals provide feedback about recent actions to guide subsequent decisions

Summary

Phasic increases and decreases in dopamine (DA) transmission encode reward prediction errors thought to facilitate reward-related learning, yet how these signals guide action selection in more complex situations requiring evaluation of different reward remains unclear. We manipulated phasic DA signals while rats performed a risk/reward decision-making task, using temporally discrete stimulation of either the lateral habenula (LHb) or rostromedial tegmental nucleus (RMTg) to suppress DA bursts (confirmed with neurophysiological studies) or the ventral tegmental area (VTA) to override phasic dips. When rats chose between small/certain and larger/risky rewards, LHb or RMTg stimulation, time-locked to delivery of one of these rewards, redirected bias toward the alternative option, whereas VTA stimulation after nonrewarded choices increased risky choice. LHb stimulation prior to choices shifted bias away from more preferred options. Thus, phasic DA signals provide feedback on whether recent actions were rewarded to update decision policies and direct actions toward more desirable reward.

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