Long-term changes in functional connectivity predict responses to intracranial stimulation of the human brain

TL;DR

This study shows that long-term changes in brain functional connectivity can predict how the human brain responds to intracranial electrical stimulation, aiding personalized neuromodulation therapies.

Contribution

It demonstrates that slow fluctuations in functional connectivity over days improve prediction of stimulation responses, advancing personalized brain stimulation approaches.

Findings

Long-term FC variability correlates with delta and theta power increases.

Long-term FC features improve response prediction beyond spatial predictors.

Results support personalized neuromodulation based on connectivity changes.

Abstract

Targeted electrical stimulation of the brain perturbs neural networks and modulates their rhythmic activity both at the site of stimulation and at remote brain regions. Understanding, or even predicting, this neuromodulatory effect is crucial for any therapeutic use of brain stimulation. To this end, we analyzed the stimulation responses in 131 stimulation sessions across 66 patients with focal epilepsy recorded through intracranial EEG (iEEG). We considered functional and structural connectivity features as predictors of the response at every iEEG contact. Taking advantage of multiple recordings over days, we also investigated how slow changes in interictal functional connectivity (FC) ahead of the stimulation relate to stimulation responses. The results reveal that, indeed, this long-term variability of FC exhibits strong association with the stimulation-induced increases in delta and theta band power. Furthermore, we show through cross-validation that long-term variability of FC improves prediction of responses above the performance of spatial predictors alone. These findings can enhance the patient-specific design of effective neuromodulatory protocols for therapeutic interventions.