Distinct roles of dopamine and subthalamic nucleus in learning and probabilistic decision making

E J Coulthard, Rafal Bogacz, Shazia Javed, Lucy Mooney, Gillian Murphy, Sophie A Keeley, Alan L Whone

Research output: Contribution to journalArticle (Academic Journal)peer-review

51 Citations (Scopus)

Abstract

Even simple behaviour requires us to make decisions based on combining multiple pieces of learned and new information.Making such decisions requires both learning the optimal response to each given stimulus as well as combining probabilistic 20 information from multiple stimuli before selecting a response. Computational theories of decision making predict that learning individual stimulus–response associations and rapid combination of information from multiple stimuli are dependent on different components of basal ganglia circuitry. In particular, learning and retention of memory, required for optimal response choice, are significantly reliant on dopamine, whereas integrating information probabilistically is critically dependent upon functioning of the glutamatergic subthalamic nucleus (computing the ‘normalization term’ in Bayes’ theorem). Here, we test these theories
25 by investigating 22 patients with Parkinson’s disease either treated with both deep brain stimulation to the subthalamic nucleus and dopaminergic therapy or managed with dopaminergic therapy alone. We use computerized tasks that probe three cognitive functions—information acquisition (learning), memory over a delay and information integration when multiple pieces of sequentially
presented information have to be combined. Patients performed the tasks on or off deep brain stimulation and/or ON or OFF dopaminergic therapy. Consistent with the computational theories, we show that stopping dopaminergic therapy impairs 30 memory for probabilistic information over a delay, whereas deep brain stimulation to the region of the subthalamic nucleus disrupts decision making when multiple pieces of acquired information must be combined. Furthermore, we found that when participants needed to update their decision on the basis of the last piece of information presented in the decision-making task,
patients with deep brain stimulation of the subthalamic nucleus region did not slow down appropriately to revise their plan, a pattern of behaviour that mirrors the impulsivity described clinically in some patients with subthalamic nucleus deep brain 35 stimulation. Thus, we demonstrate distinct mechanisms for two important facets of human decision making: first, a role for dopamine in memory consolidation, and second, the critical importance of the subthalamic nucleus in successful decision making when multiple pieces of information must be combined.
Original languageEnglish
Pages (from-to)3721-3734
Number of pages14
JournalBrain
Volume135
DOIs
Publication statusPublished - 2012

Keywords

  • decision making; Parkinson’s disease; mathematical modelling; reasoning; memory

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