Magnetic Resonance Imaging-Guided Temporal Interference Stimulation of the Cerebellar Fastigial Nucleus in Stroke Patients for Balance.

Lower limb motor and balance impairments are common dysfunctions after stroke. Although non-invasive brain stimulation has shown promise as an adjunct to neurorehabilitation, it remains limited to superficial cortical regions, instead of deep brain targets such as the cerebellar fastigial nucleus, which contributes to posture control and motor coordination. Temporal interference stimulation represents an emerging strategy for non-invasive brain stimulation for targeting deep neural structures. It delivers two high-frequency electric fields with slightly different carrier frequencies through the scalp. Computational models and early experimental studies suggest that temporal interference stimulation may preferentially modulate deep targets while reducing stimulation of superficial tissues. In this study, we introduce a standardized, image-guided protocol for cerebellar fastigial nucleus temporal interference stimulation in stroke patients. The protocol combines high-resolution structural magnetic resonance imaging, individualized electric field modelling, and computational optimization to design subject-specific electrode montages focusing toward the cerebellar fastigial nucleus. This protocol provides a reproducible framework for studying deep cerebellar neuromodulation and may support future mechanistic and rehabilitation studies of post-stroke motor and balance dysfunction.