Study of motor markers of decision urgency in pathological gamblers

Details

Supervisors

Duque, Julie

Faculty

Faculté de pharmacie et des sciences biomédicales

Degree label

Master [120] en sciences biomédicales, à finalité approfondie

Abstract

enRecent models of decision-making support the existence of an urgency signal, a time- dependent signal that increases over time and pushes us to commitment. A past study using Transcranial Magnetic Stimulation (TMS) has shown that urgency modulation could be assessed at the neural level through changes in motor-evoked potentials (MEPs): an MEP suppression in nearby irrelevant muscles, indicating surround inhibition, and an MEP increase in distant irrelevant muscles, indicating broad facilitation. Rather than being a fixed construct, urgency seems to be shaped by multiple influences, notably motivation by reward and inhibitory control. Reward is known to invigorate action and may therefore increase urgency, possibly through surround inhibition. In contrast, inhibitory control may counteract this effect, possibly by reducing broad facilitation. Interestingly, impulsive individuals, such as pathological gamblers, typically exhibit reduced inhibitory control and heightened reward sensitivity. Because these two influences also shape urgency, the aim of this study was to investigate impulsivity through the lens of urgency in pathological gamblers. We predicted that pathological gamblers would exhibit an abnormally elevated urgency, reflecting an imbalance between motivation by reward and inhibitory control, which will be observable both behaviorally and in urgency- related MEP markers. Twenty-four participants (9 pathological gamblers and 15 healthy participants) performed the Tokens task combined with single-pulse TMS. Reward motivation was manipulated via monetary precues (reward vs. no reward precues) and inhibitory control through task difficulty (Easy vs. Difficult blocks). On separate days, the TMS coil position was adapted to target either finger (to probe surround inhibition) or leg muscle representations (to probe broad facilitation). Preliminary results showed that, in healthy participants, urgency decreased with task difficulty, leading to slower but more accurate decisions, and increased with reward precues, leading to faster decisions without affecting accuracy. In contrast, pathological gamblers did not show modulation of urgency by task demands or reward cues, yet performance parameters followed similar patterns as in healthy participants. Overall, these encouraging preliminary results reveal effects of reward motivation and inhibitory control on performance in both groups, but effects on urgency-related measures were observed only in healthy participants. Increasing the sample size will be necessary to confirm these effects, clarify the trends observed in TMS data, and allow direct comparisons between pathological gamblers and healthy participants.