The effects of repetitive transcranial magnetic stimulation over the lateral parietal region on episodic future thinking and episodic memory

The left angular gyrus (AG) has been implicated in the level of detail elicited during both episodic memory (EM) and episodic future thinking (EFT). This study aimed to investigate whether repetitive transcranial magnetic stimulation (rTMS) over the left lateral parietal region consistent with left AG targeting influences the level of detail reported during elicitations of EM and EFT. Thirty-six healthy adults (41.7% female, mean age = 25.36 years ± 2.52) attended four experimental sessions corresponding to four different conditions: facilitatory (20 Hz) rTMS, inhibitory (1 Hz) rTMS, active-control rTMS, and sham rTMS. Following rTMS, participants completed EM and EFT tasks. In these tasks, participants verbally detailed personal memories or future scenarios. Participants also completed a free associates task, operating as a non-episodic control. Results demonstrated a significant difference in both EM and EFT across conditions. Post-hoc analyses showed that when compared to the active-control and sham conditions, inhibitory rTMS significantly reduced the mean number of episodic details and significantly increased the mean number of external details elicited during both EM and EFT. However, there was no significant difference between the facilitatory, active-control, and sham rTMS conditions on the detail elicited in both EM and EFT tasks. Analyses also demonstrated no significant differences on the free associates task across all conditions. This study supports the role of the left lateral parietal region in the generation of episodic detail in both EM and EFT, with the potential for inhibitory rTMS to modulate both EM and EFT in healthy populations.