This study uses a multimodal VR platform (BioVRSea) synchronized with EEG to show that PD patients exhibit challenge-dependent increases in delta-theta and alpha-beta spectral power during postural perturbations versus controls, indicating impaired sensorimotor integration.

Offers a translational, ecologically valid EEG biomarker method to detect and quantify PD-related postural control dysfunction for diagnosis, stratification, and treatment monitoring, though it lacks direct mechanistic or therapeutic targets.

Disrupted postural control (PC), a hallmark of neurological conditions such as Parkinson's disease (PD) and mild traumatic brain injury (mTBI), is associated with altered neural oscillatory dynamics measured using electroencephalography (EEG). However, few studies have employed ecologically valid paradigms to assess these dynamics. In this study, we utilized BioVRSea, a multimodal virtual reality (VR) platform combining realistic postural perturbations with real-time EEG to examine cortical responses to multisensory stimulation. We tested whether EEG time-frequency representations could differentiate pathological PC responses in PD and mTBI from normative function in matched healthy controls (HC). Motion sickness susceptibility and symptom changes were evaluated using the Motion Sickness Susceptibility Questionnaire (MSSQ) and the Motion Sickness Symptoms Scale. In HC, only the older subgroup exhibited a significant increase in low-frequency (delta-theta, $\approx 1$ -7 Hz) power at 50% perturbation intensity and during the post-perturbation phase (cluster-level p <0.05). Compared with matched controls, PD participants showed increased spectral power in both the delta-theta ( $\approx 1$ -7 Hz) and alpha-beta ( $\approx 10$ -30 Hz) ranges (cluster-level p <0.05), particularly at higher perturbation intensities, suggesting impaired sensorimotor integration. In contrast, no significant EEG differences were observed between the mTBI group and matched controls (p > 0.05). These findings demonstrate the feasibility of synchronized VR-EEG paradigms for capturing challenge-dependent neural signatures of postural control dysfunction. Further validation is warranted to determine their potential clinical utility in neurological assessment.