4.7. Limitations and future directions
While the current dose-response relationship studies exploring the associations between EFs and brain functions show promise, there are several areas that require further investigation. Integrating head models with fMRI is still a relatively new approach in tES studies, and although previous works have reported novel findings, replication studies are necessary to establish a comprehensive understanding of the relationship between EF distribution patterns and changes in BOLD signals.The complexity of the underlying biophysical processes and the diverse nature of neural responses make it difficult to directly link electric field distribution patterns to the efficacy of tDCS. The predictive value of integrating EF distribution with fMRI data in determining treatment outcomes requires further investigation. To drive the field forward, several important steps should be considered. First, future research should focus on elucidating the biophysical mechanisms underlying the effects of EF distribution on neural responses [Theoretically, the polarization of neuronal membranes correlates linearly with the electric field they’re exposed to [The emergence of closed-loop tES-fMRI studies, where fMRI and tES are performed simultaneously, opens up exciting possibilities for real-time integration of personalized ongoing brain function with EFs [