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.