Poster No:
900
Submission Type:
Abstract Submission
Authors:
Gizem Vural1,2, Natasha Katruss3, Alexander Soutschek4
Institutions:
1LMU Klinikum, Munich, Other, 2General and Experimental Psychology Ludwig-Maximilians-University, Munich, Germany, 3Department of Psychology/Neuro-Cognitive Psychology of the Ludwig-Maximilians-Universität München, Munich, Germany, 4Ludwig Maximilian University, Munich, Germany
First Author:
Gizem Vural
LMU Klinikum|General and Experimental Psychology Ludwig-Maximilians-University
Munich, Other|Munich, Germany
Co-Author(s):
Natasha Katruss
Department of Psychology/Neuro-Cognitive Psychology of the Ludwig-Maximilians-Universität München
Munich, Germany
Introduction:
The ability to delay gratification in intertemporal decision-making involves complex neural mechanisms that have not been fully elucidated. While most previous research focused on the role of the prefrontal control network for intertemporal decisions, our study investigated the roles of the pre-supplementary motor area (pre-SMA) and the posterior parietal cortex (PPC), two regions that were neglected by past research, for the decision process. Specifically, we used time-locked transcranial magnetic stimulation (TMS) in combination with a process model of intertemporal decision making (drift diffusion model, DDM) to investigate the contributions of the pre-SMA and the PPC to early versus late components of the choice process.
Methods:
The study enrolled 32 participants (mean age: 26, including 16 females) in a within-subject design, involving two experimental conditions as early and late phase of TMS along with no stimulation condition as a control. Before the experimental session, a Siemens Prisma 3-Tesla MRI scanner (Siemens AG, Munich, Germany) was used to acquire structural scans for identifying the targeted brain regions. The Brainsight neuronavigation software (Rogue Research Inc.) was then utilized to position the PowerMAG ppTMS stimulator, which is equipped with a flat, figure-eight PowerMAG double coil PMD70 (2 x 70mm diameter) (MAG & More). To manipulate early components of the decision process, early TMS was administered 100 ms after stimulus presentation. In contrast, late TMS was tailored to each participant's median decision times from previous decisions to target the evidence accumulation process. This approach allows for a precise examination of the early and late components of decision-making processes in the pre-SMA and PPC during the intertemporal decision-making task. In the decision task, participants made choices between smaller-sooner (SS) and larger-later (LL) monetary rewards delivered after varying temporal delays.
Results:
Analyses of the binary choice data (without considering the choice process) revealed a weaker preference for LL over SS rewards (stronger temporal discounting) following late-phase TMS of the pre-SMA. In contrast, early pre-SMA TMS reduced choice consistency rather than temporal discounting per se. However, these standard analyses do not provide insights into which subcomponents of the decision process underlie the observed TMS effects.
An analysis of the decision process with a hierarchical DDM indicated that early pre-SMA TMS reduced the influence of reward magnitudes on evidence accumulation. This informs the findings from the choice consistency analyses by suggesting that less consistent choices in the early pre-SMA TMS condition result from a weaker representation of rewards in the decision-making process.
Disruption of the PPC via both early and late TMS induced a tendency towards quicker, less cautious decision-making, implying a rise in rapid and impulsive choices compared to the control condition. Notably, the PPC stimulation did not significantly alter reward or delay drift rates, indicating its limited impact on the evidence accumulation process.
Conclusions:
The application of TMS to the pre-SMA disrupted both the preference for delayed rewards and choice consistency, leading to more impulsive decision-making favoring immediate gratification. The lower choice consistency can be explained by altered reward valuation during evidence accumulation. Conversely, PPC stimulation appears to affect the speed of decision-making without compromising the evidence accumulation process or altering the initial decision-making bias. Together, these findings contribute to our understanding of the neurobiological underpinnings of decision-making, highlighting the distinct roles of the pre-SMA and PPC in mediating the trade-off between immediate and delayed rewards.
Brain Stimulation:
Non-invasive Magnetic/TMS 2
Higher Cognitive Functions:
Decision Making 1
Modeling and Analysis Methods:
Bayesian Modeling
Keywords:
Transcranial Magnetic Stimulation (TMS)
Other - Intertemporal decision-making; pre-SMA; PPC
1|2Indicates the priority used for review
Provide references using author date format
Soutschek, A. (2023), "Toward a unifying account of dopamine’s role in cost-benefit decision making", Biological Psychiatry Global Open Science, 3(2), 179-186.