Neural sources of urgency during decision making in typically developing adolescents

Details

Supervisors

Duque, Julie ; Fumery, Thibault

Faculty

Faculté de pharmacie et des sciences biomédicales

Degree label

Master [120] en sciences biomédicales, à finalité approfondie

Abstract

New models of decision making include an urgency signal, increasing over time and pushing to commit to a choice. We still know very little about what shapes this urgency signal. The present study aims to understand how the urgency signal is influenced by motivation by reward and inhibitory control. We hypothesise that motivation by reward increases urgency, inducing a speed-up of decision and movement duration, and that inhibitory control leads to a decrease in urgency and decision speed when the context requires it. To test this hypothesis, we compare an adolescent group, whose immature inhibitory control may lead to a generally higher urgency signal, to a healthy adult group. 14 adolescents and 16 adults performed the Tokens task divided into an easy and a difficult part, which required more inhibitory control. In those parts, their responses were either rewarded by 1 euro, calling for a high motivation, or nothing. Moreover, participants underwent Magnetic Resonance Imagery (IRM), allowing to visualise the integrity of the basal ganglia dopaminergic tracts, underpinning motivation, and the hyperdirect pathway, underpinning inhibitory control. This work focuses on the analysis of behavioural data given that the study, which is still ongoing, will need to reach a total of 80 participants to allow reliable correlations between behavioural and neuroimaging data. The preliminary results suggest that motivation by reward similarly accelerates decision and movement speed, highlighting a oosting effect. No effect of motivation on urgency has yet been observed. Conversely, urgency seems to decrease in contexts associated with greater inhibitory control inducing slower decisions. Moreover, adolescent seems to show a generally higher urgency signal compared to adults. These encouraging preliminary results already allow us to observe group differences and certain effects of motivation and inhibitory control on decision making characteristics. These effects will be analysed again once the aimed number of participants has been reached and neuroimaging data will be considered at that point to investigate the neural aspect of the sources of the urgency signal.