Motivation-cognition interaction: how feedback processing changes in healthy ageing and in Parkinson's disease

Several studies have investigated the interaction between motivation and cognition in both young and older adults, but with inconsistent results. A recent hypothesis suggests exploring the role of dopamine to study this interaction.

To explore how different motivational states can modulate cognitive control, as well as investigate the hypothesis of a dopaminergic role in this phenomenon.

27 young subjects, 15 healthy old subjects, and 15 Parkinson's disease (PD) patients took part in this study. The motivational Simon task-a new paradigm in which rewards and punishments are delivered to promote fast and accurate responses-was employed. The participants' performance was evaluated by analysing their reaction times and accuracy, while employing a diffusion model analysis.

The employment of positive and negative feedback significantly modulated performance in a conflict task. In both, the young and older participants, the speed-accuracy trade-off significantly changed in response to different motivational incentives (p < .005), although in opposite ways. On the contrary, PD patients showed an absence of performance modulation in response to positive and negative feedback.

In normal conditions, motivation interacts with cognitive control to modulate decisional aspects of a response in a conflict task. The elderly modulate their performance in response to positive and negative feedback differently from young adults, showing a classical positivity effect. The impairment manifested by PD patients, which is compatible with the literature about feedback processing deficits in this clinical condition, can support the hypothesis that the interaction between motivation and cognitive control is mediated by dopaminergic functionality.