[P1] Poster: Day 1

[P1-36] Uncovering the neuroanatomical substrates of impulsive behaviour induced by the temporal predictability of events: an fMRI-EMG investigation

*Inga Korolczuk^1,2, Boris Burle², Bruno Nazarian³, Marion Royer D’Halluin^2,4,5, Franck Vidal⁴, Jennifer T Coull² (1. Department of Psychology, Medical University of Lublin (Poland), 2. Centre for Research in Psychology and Neuroscience (UMR7077), Aix-Marseille University & CNRS (France), 3. Aix-Marseille Université, UMR 7289 CNRS, Institut de Neurosciences de la Timone, Marseille, Provence-Alpes-Côte d'Azur, 13005, France (France), 4. CHU Sainte-Justine Research Center, Montréal, Québec, Canada (Canada), 5. Department of Neurosciences, Université de Montréal, Montréal, Québec, Canada (Canada))

Keywords:

Temporal predictability,Impulsivity,EMG,fMRI,Response conflict

Previous research has revealed that the temporal predictability of events enhances response speed but exacerbates impulsive responses during conflict tasks. We used fMRI coupled with EMG to investigate the neuroanatomical correlates underlying this impulsivity 24 healthy participants performed a temporally cued Simon conflict task. Temporal predictability was manipulated by visual pre-cues that either indicated (temporal cue) or not (neutral cue) target onset time. Participants responded to target shape (+/x) with left- or right-hand responses. Critically, the spatial location of the targets (left/right) was either compatible or incompatible with the required response hand, inducing response conflict. Behavioural data replicated previous findings: temporal cues increased the number of fast impulsive errors to incompatible targets. FMRI analysis revealed that temporal predictability, activated left inferior parietal cortex (IPC) and left premotor cortex irrespective of response hand laterality or target (in)compatibility. Conversely, response incompatibility activated right putamen and right premotor cortex, independent of cue type. Notably, an interaction effect—reflecting increased impulsivity to temporally predictable targets—was associated with enhanced activation in left IPC. This region is implicated in temporal attention and sensorimotor integration, and may accelerate motor preparation based on temporal expectations, boosting activation of both correct and incorrect responses. This anticipatory mechanism likely sharpens readiness but also leaves the system vulnerable to prepotent, task-irrelevant activations. Indeed, behavioural errors represent only part of the underlying impulsive processes during conflict. EMG recordings revealed that 16% of correct responses to incompatible targets were preceded by subthreshold EMG bursts in the incorrect response hand—so-called 'partial errors' - which are rapidly suppressed. Temporal predictability heightened this covert motor activation, with partial errors occurring more often after temporal cues than neutral ones. Our next steps include identifying brain regions linked to these partial errors to understand how temporal predictability affects the neural circuits modulating covert impulsive actions.