Right‑DLPFC rTMS Transiently Modulates Risky Decision-Making and EEG Oscillatory Activity
Reza Kazemi1, Reza Rostami2, Maryam Majidinezhad3
1Faculty of Entrepreneurship, University of Tehran, Tehran, Iran.
Background:
Previous evidence suggests that inhibition of the right dorsolateral prefrontal cortex (DLPFC) increases risky decision-making, highlighting its role in cognitive control and risk aversion. However, it remains unclear whether excitatory stimulation of this region can reduce risky decision-making. Combining repetitive transcranial magnetic stimulation (rTMS) with Electroencephalography (EEG) provides an opportunity to examine neurophysiological correlates of stimulation-related changes in decision-making.
Objective:
This study aimed to examine whether high-frequency (20 Hz) rTMS applied over the right DLPFC influences decision-making performance and associated EEG measures in healthy adults.
Methods:
A within-subject, crossover design was employed. EEG recordings were obtained before and after stimulation, while the Iowa Gambling Task (IGT) was administered at three stages: baseline, during stimulation, and post-stimulation. EEG was recorded during both eyes-closed and task-performance conditions.
Results:
During active rTMS, participants showed reduced IGT performance, reflected by a decrease in advantageous card selections. Performance returned to baseline following stimulation, whereas no comparable changes were observed during sham stimulation. EEG analyses revealed a significant post-stimulation increase in β-band power following active stimulation. No stimulation-related effects were observed for frontal theta activity, theta/beta ratio (TBR), or frontal alpha asymmetry (FAA), although a reduction in frontal TBR was observed during the sham-task condition.
Conclusion:
The findings provide preliminary evidence that high-frequency rTMS over the right DLPFC can transiently influence adaptive decision-making performance and is associated with post-stimulation modulation of β-band activity. The dissociation between behavioral effects observed during stimulation and EEG changes measured after stimulation suggests that neurophysiological modulation may persist beyond the period of behavioral interference. Given the small sample size and exploratory nature of the analyses, these findings should be considered preliminary and require replication in larger samples.
