Introduction
Neuroimaging studies have provided convincing evidence that frequencies generated in the brain are not just a cumulative sum of underlying neural activity but rather represent fundamental mechanisms that drive various functions in the brain (Sejnowski and Paulsen DLPFC is one of the most crucial brain regions involved in cognitive functions and is often the target in stimulation studies (Dedoncker et al. Our study builds on these behavioral and neuroimaging findings to investigate whether the effect of multiple-session stimulation along with arithmetic training can induce a significant impact on resting-state brain networks. The DMN, the frontoparietal network (FPN), and the salience network are crucial brain networks involved in cognitive processing (Sridharan et al. Besides, numerous research studies utilizing diffusion tensor imaging (DTI) analysis have consistently demonstrated a correlation between performance on arithmetic assessments and measurements of fractional anisotropy (FA) in white matter (WM) pathways that connect the fronto-parietal and cortico-subcortical regions of the brain (Peters and De Smedt In addition, brain structure and function vary greatly between individuals (Forkel et al. In summary, the objective of the study was to understand if multiple sessions of individually adjusted theta band stimulation over the L-DLPFC along with arithmetic training can induce changes in resting-state functional connectivity and white matter structural integrity. During the 5 days of experiment, participants received intensive arithmetic training with personalized theta tACS over the L-DLPFC for 3 days (Day 2 to Day 4). Baseline assessments and post-stimulation assessments were carried out on Day 1 and Day 5. We hypothesized that electrical stimulation would influence resting-state grey matter networks as well as cause modifications in white matter structural integrity.