(PS6-85) Preliminary analysis on behavioral and resting state connectivity data following theta burst stimulation

Recent neuromodulation studies have shown compelling evidence that theta burst stimulation (TBS) of the dorsolateral prefrontal cortex (dlPFC) is involved with the cognitive process of emotion regulation, an underlying mechanism crucial to the treatment of mental illnesses. However, it is not yet explained how specific mechanistic changes in the brain contribute to this finding. This study aims to determine both resting state connectivity and behavioral changes in task performance following two patterns of stimulation: intermittent (iTBS) and continuous (cTBS). We hypothesized that iTBS would increase the functional connectivity between the left dlPFC and downstream regions and improve task performance while cTBS would decrease such connectivity.

Our study aims to enroll 200 total participants to complete 3 sessions of either iTBS or cTBS, with functional scans performed about 24 hours after each TMS session. Participants are instructed to complete a variation of the Sternberg letter memory task while in the scan, for both TMS targeting and functional connectivity analyses. The task requires participants to either sort or maintain the letter presentation every trial. Participants are required to attend six visits in total (including consent) throughout the study. This poster aims to present preliminary analysis of task performance in response to each visit and TMS frequency (n=85).

For both sort and maintain trials, we analyzed the effects of TMS frequency (iTBS and cTBS) and visit on accuracy and reaction time using a two-way ANOVA. For sort trials, the analysis revealed that there was not a significant interaction between the effects of TMS frequency and visit for accuracy (F(1,3) =1.63, p = 0.18). However, simple main effects were found with both TMS frequency (p< 0.001) and visit (p< 0.01). Additionally, a significant interaction was found between TMS frequency and visit for reaction time (F(1,3) = 3.61, p = 0.013). Simple main effects were found with visit (p< 0.001), but not with TMS frequency (p = 0.815). Results regarding maintain trials will be included on the poster.

The results supports our hypotheses with expected interaction found between TMS frequency, visit, accuracy, and reaction time. More detailed results and indications regarding both behavioral and e-field data will be presented at the conference. With TBS being increasingly applied in the treatment of mental illness, it will be important to understand how TBS modulates network connectivity. As we understand more about the underlying mechanisms of the relationship between specific brain regions and emotion regulation, TBS can be widely applied to various mental illnesses in clinical treatment.