Enhanced motivation of cognitive control in Parkinson's disease

Abstract

Motor and cognitive deficits in Parkinson's disease (PD) have been argued to reflect motivational deficits. In prior work, however, we have shown that motivation of cognitive control is paradoxically potentiated rather than impaired in Parkinson's disease. This is particularly surprising given the fact that Parkinson's disease is often accompanied by depression, a prototypical disorder of motivation. To replicate our previous finding and assess the effects of depression, we investigated performance of PD patients with (n = 22) and without depression (history) (n = 23) and age‐matched healthy controls (n = 23) on a task specifically designed to measure the effect of reward motivation on task‐switching. We replicated previous findings by showing contrasting effects of reward motivation on task‐switching in PD patients and age‐matched healthy controls. While the promise of high versus low reward improved task‐switching in PD, it tended to impair task‐switching in age‐matched healthy controls. There were no effects of a depression (history) diagnosis in PD patients. These findings reinforce prior observations that Parkinson's disease is accompanied by enhanced incentive motivation of cognitive control and highlight the potential of incentive motivational strategies for overcoming cognitive deficits in Parkinson's disease.

The cognitive effects of a promised bonus do not depend on dopamine synthesis capacity

“…Thus, the current study cannot refute hypothesized correlations between motivational effects on cognitive control and other measures of dopamine function. For example, the current design does not disconfirm previously demonstrated and replicated links between motivation, cognitive control and polymorphisms in the dopamine transporter gene 3 , 14 , 18 , dopamine release 37 or dopamine-related disease status 13 , 38 , 39 . Similarly, the current failure to replicate does not undermine other studies demonstrating a link between dopamine synthesis capacity and cognitive motivation indexed with other tasks, such as delay discounting 40 , cognitive effort discounting 23 , 24 or reward-based reversal learning 41 .…”

Dopamine Promotes Cognitive Effort by Biasing the Benefits Versus Costs of Cognitive Work

“…Converging evidence from research on Parkinson's disease (13)(14)(15)(16)(17), showing dopaminedependent changes in cognitive motivation, provides an initial basis for this conjecture. 35 Moreover, catecholamine-enhancing psychostimulants alter cognitive effort-based choice in both rodents (10) and humans (18).…”

“…In cortico-striatal loops governing action selection, dopamine has opponent effects on D1 and D2expressing medium spiny neurons, which are thought to modulate the relative sensitivity to the benefits versus the costs of actions (5). Given that similar mechanisms are thought to govern 30 cognitive action selection (6-8), we hypothesized that striatal dopamine could promote willingness to exert cognitive effort, boosting motivated cognitive control for attention, planning, and decision-making (9-12).Converging evidence from research on Parkinson's disease (13)(14)(15)(16)(17), showing dopaminedependent changes in cognitive motivation, provides an initial basis for this conjecture. 35 Moreover, catecholamine-enhancing psychostimulants alter cognitive effort-based choice in both rodents (10) and humans (18).…”

Chemistry of the Adaptive Mind: Lessons from Dopamine

“…Two separate lines of evidence provide tantalizing evidence for the proposal that cognitive task valuation depends on striatal dopamine. First, there is ample evidence for altered effects of incentives on cognitive control task performance, measured with rewarded task-switching or Stroop tasks, as a function of (striatal dopamine cell loss in) PD patients (Aarts et al, 2012;Timmer et al, 2018), dopaminergic medication in PD (Manohar et al, 2015), individual differences in striatal dopamine synthesis capacity (Aarts et al, 2014), and individual variation in a striatal dopamine transporter gene (Aarts et al, 2010). Moreover, striatal dopamine genetic variation is associated with altered (effects of methylphenidate on) striatal BOLD signal during incentivized cognitive control task performance (Aarts et al, 2010).…”