Effects of theta burst stimulation on vmHRV
To analyze the effects of cTBS and iTBS compared to sham stimulation on vmHRV, we performed three linear regression models in R Studio (R Core Team, 2022). In the respective models, changes in resting vmHRV, on-task vmHRV, and vmHRV reactivity scores were included as outcome variables. These changes were operationalized as change scores calculated by subtracting the respective RMSSD values from the pre-stimulation periods from the respective post-stimulation values. As such, positive/negative change scores reflect increases/decreases of vmHRV following stimulation for resting vmHRV and on-task vmHRV. For vmHRV reactivity, positive change scores indicate a shift in vmHRV reactivity (i.e., vmHRV changes from rest to ESST performance) towards greater increase/lesser decrease during the post-stimulation period and vice versa. Participants’ age and sex were included as covariates in all models. As it has been demonstrated that individual levels of state anxiety may influence the effects of TBS on vmHRV (Poppa et al., 2020), we included the results of the STAI-S as an additional covariate.