Presentation Information
[P2-10]Role of Supplementary Motor Areas in temporal estimation using tDCS.
*Claire TERRAN1, Laurence CASINI1 (1. CRPN - Centre for Research in Psychology and Neuroscience, AMU, CRNS (France))
Keywords:
Timing,tDCS,SMA,Duration range,Bisection task
Time is a fundamental aspect of life, orchestrating a wide array of behaviours in our daily activities. Multiple models explaining the mechanisms of temporal estimation coexist, attributing this function to different neural structures. A key distinction is often made between sub-second and supra-second intervals: durations under one second are thought to be prosessed primarly via a cortico-thalamo-cerebellar network, while longer intervals are believed to rely on a cortico-thalamo-striatal circuit. However, evidence also suggests the possibility of shared mechanisms across these time scales. We chose to anchor this study within the internal clock model, more specifically the pacemaker-accumulator framework, to investigate: (1) whether the supplementary motor areas (SMA) could serve as a substrate for the accumulation process and, (2) whether judgments of both short and long durations rely on an accumulation process. Using transcranial Direct Current Stimulation (tDCS), we modulated the activity of the SMA and subsequently assessed its role on temporal estimation using a temporal bisection task. Participants’ performance provided insights into two key parameters of temporal estimation: precision and variability. Preliminary results reveal that SMA modulation affects temporal estimation differently depending on the duration range. Specifically, tDCS significantly impacted the variability of long-duration judgments, whereas it affected the accuracy of estimations in the short-duration range. Interpreted within the pacemaker-accumulator model, these findings support the hypothesis that the SMA may act as the neurobiological substrate for the accumulation process, one of the internal clock’s critical components. Overall, this study enhances our understanding of the neural mechanisms underlying temporal estimation and highlights the pivotal role of the SMA in the estimation of both short and long durations.