Cognitive control and binding in context-based decision-making : normal and dopamine deviant populations

Top-down guidance of behavior in a complex and dynamically changing world is often based on information held in working memory. Such guidance serves to bias decision-making processes in directions consistent with externally set rules or internally maintained intentions. Orthogonal to this goal-driven guidance, decisions may be biased also by stimulus-driven factors, such as the automatic reactivation of episodic associations that accompanied the current stimulus in a previous instance. We investigated whether top-down and bottom-up processes account for variation in context based decision making as measured by the AX-CPT in a behavioral [1] and fMRI study [2]. Moreover, several behavioural studies have indicated that transiently induced positive affect modulates control processes in context-based decision making, generally leading to enhanced flexibility. Using ERPs in a classic AX-CPT, we studied the temporal dynamics of a positive affect induction on control processes in context-based decision making [3]. Additionally, we studied learning the associations between a situation, the response to it, and the outcome of that decision and the effect of basal ganglia modulations on this learning process by means of a Parkinson’s patient study. Studies [1] and [2] pointed out that in decisions with rapidly changing environmental demands, goal-driven preparation is often beneficial but may also hamper performance which can be overcome by applying increased control. Moreover, this top-down bias is regulated more efficiently when the specific stimulus is presented in the same context it was previously associated with, compared to when it is presented in a new and unusual context. Additionally, fMRI study shed light on the way these stimulus-driven performance changes may be represented in the brain. Study [3] showed that a positive affect induction influenced reactive and evaluative components of control (indexed by the N2 elicited by the target, and by the Error-Related Negativity elicited after incorrect responses) in an AX-CPT task, whereas cue-induced preparation and maintenance processes remained largely unaffected (as reflected in the P3b and the Contingent Negative Variation components of the ERP). The patient studies suggest that moderate dopaminergic medication and STN stimulation in Parkinson’s patients [chapter 5,6] both improve learning functions relying on caudate and putamen. However, the improvement induced by dopaminergic medication largely depended on individual patient characteristics.LEI Universiteit LeidenNWO, LUF, KNAWFSW - Action Control - Ou

The Allure of High-Risk Rewards in Huntington’s disease

Objectives: Huntington’s disease (HD) is a neurodegenerative disorder that produces a bias toward risky, reward-driven decisions in situations where the outcomes of decisions are uncertain and must be discovered. However, it is unclear whether HD patients show similar biases in decision-making when learning demands are minimized and prospective risks and outcomes are known explicitly. We investigated how risk decision-making strategies and adjustments are altered in HD patients when reward contingencies are explicit. Methods: HD (N=18) and healthy control (HC; N=17) participants completed a risk-taking task in which they made a series of independent choices between a low-risk/low reward and high-risk/high reward risk options. Results: Computational modeling showed that compared to HC, who showed a clear preference for low-risk compared to high-risk decisions, the HD group valued high-risks more than low-risk decisions, especially when high-risks were rewarded. The strategy analysis indicated that when high-risk options were rewarded, HC adopted a conservative risk strategy on the next trial by preferring the low-risk option (i.e., they counted their blessings and then played the surer bet). In contrast, following a rewarded high-risk choice, HD patients showed a clear preference for repeating the high-risk choice. Conclusions: These results indicate a pattern of high-risk/high-reward decision bias in HD that persists when outcomes and risks are certain. The allure of high-risk/high-reward decisions in situations of risk certainty and uncertainty expands our insight into the dynamic decision-making deficits that create considerable clinical burden in HD

Proactive control and episodic binding in context processing effects

Decision making often involves using prior contextual information to evaluate relevant events. A laboratory equivalent of context processing situations, the AX-Continuous Performance Task (AX-CPT), yields errors when a target probe appears in a nontarget context, or when a nontarget probe appears in a target context. According to goal-driven accounts, context information is used for top-down preparation towards processing of context-appropriate information. Performance costs in nontarget trials are attributed to inefficient cognitive control. In contrast, the episodic binding account predicts that prior experiences with combinations of a context, probe, and response are bound in episodic memory and thus bias future actions. Performance costs in this view are caused by the need to overrule prepotent associations. The current experiments tested the relative importance of proactive cognitive control versus episodic learning of appropriate stimulus-response relations for CPT performance. Support was obtained for both contributions

Positive affect modulates flexibility and evaluative control

The ability to interact with a constantly changing environment requires a balance between maintaining the currently relevant working memory content and being sensitive to potentially relevant new information that should be given priority access to working memory. Mesocortical dopamine projections to frontal brain areas modulate working memory maintenance and flexibility. Recent neurocognitive and neurocomputational work suggests that dopamine release is transiently enhanced by induced positive affect. This ERP study investigated the role of positive affect in different aspects of information processing: in proactive control (context maintenance and updating), reactive control (flexible adaptation to incoming task-relevant information), and evaluative control in an AX-CPT task. Subjects responded to a target probe if it was preceded by a specific cue. Induced positive affect influenced the reactive and evaluative components of control (indexed by the N2 elicited by the target and by the error-related negativity elicited after incorrect responses, respectively), whereas cue-induced proactive preparation and maintenance processes remained largely unaffected (as reflected in the P3b and the contingent negative variation components of the ERP)

Effect of beta and gamma neurofeedback on memory and intelligence in the elderly

Recent research showed a correlation between cognitive decline and a decrease of EEG gamma activity. In the present double-blind randomized control study, we investigated whether gamma and beta neurofeedback protocols, that have been shown to modulate performance on cognitive control and memory in young adults, also leads to increased brain activity and cognitive performance in elderly. Twenty older adults either performed eight 30-min gamma neurofeedback session or beta neurofeedback session within a period of 21 days. Cognitive performance was determined before and after the training through an IQ and memory task and we added a subjective well-being questionnaire. Both neurofeedback training protocols resulted in a significant increase of the brain activity within each training session, suggesting that the aging brain is still trainable. However, we found no effects on cognitive performance or transfer of the feedback beyond the trainings. We discuss several possible reasons for the lack of training on rest measurements and cognition and ways to improve the feedback protocols for future studies. © 2013 Elsevier B.V

The role of dopamine in action control: Insights from medication effects in Parkinson’s disease

Health and self-regulatio