With the development of electrical stimulation technology, especially the emergence of temporally interfering (TI) stimulation, it is necessary to discuss the influence of current frequency on stimulation intensity. Accurate skull modeling is important for transcranial current stimulation (tCS) simulation prediction because of its large role in dispersing current. In this study, we simulated different frequencies of transcranial alternating current stimulation (tACS) and TI stimulation in single‐layer and layered skull model, compared the electric field via error parameters such as the relative difference measure and relative magnification factor. Pearson correlation analysis and t‐test were used to measure the differences in envelope amplitude. The results showed that the intensity of electric field in the brain generated by per unit of stimulation current will increase with current frequency, and the layered skull model had a better response to frequency. An obvious pattern difference was found between the electric fields of the layered and single‐layer skull individualized models. For TI stimulation, the Pearson correlation coefficient between the envelope distribution of the layered skull model and the single‐layer skull was only 0.746 in the individualized model, which is clearly lower than the correlation coefficient of 0.999 determined from the spherical model. Higher carrier frequencies seemed to be easier to generate a large enough brain electric field envelope in TI stimulation. In conclusion, we recommend using layered skull models instead of single‐layer skull models in tCS (particularly TI stimulation) simulation studies in order to improve the accuracy of the prediction of stimulus intensity and stimulus target.

Objective: We investigated changes in cortico–subcortical spatiotemporal dynamics to explore the treatment mechanisms of transcranial alternating current stimulation (tACS) in patients with Parkinson’s disease (PD). Methods: Resting-state functional magnetic resonance imaging (rs-fMRI) data were collected from 20 patients with PD and 20 normal controls (NC). Each patient with PD received successive multidisciplinary intensive rehabilitation treatment and tACS treatment over a one-year interval. Individual functional brain network mapping and co-activation pattern (CAP) analysis were performed to characterize cortico–subcortical dynamics. Results: The same tACS electrode placement stimulated different proportions of functional brain networks across the participants. CAP analysis revealed that the visual network, attentional network, and default mode network co-activated with the thalamus, accumbens, and amygdala, respectively. The pattern characterized by the de-activation of the visual network and the activation of the thalamus showed a significantly low amplitude in the patients with PD than in NCs, and this amplitude increased after tACS treatment. Furthermore, the co-occurrence of cortico–subcortical CAPs was significantly higher in patients with PD than in NCs and decreased after tACS treatment. Conclusions: This study investigated cortico–subcortical spatiotemporal dynamics in patients with PD and further revealed the tACS treatment mechanism. These findings contribute to understanding cortico– subcortical dynamics and exploring noninvasive neuromodulation targets of cortico–subcortical circuits in brain diseases, such as PD, Alzheimer’s disease, and depression.

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