Background: Emerging evidence indicates an association between vestibular dysfunction and Depersonalization/Derealization (DD) symptoms. However, substantial heterogeneity in the studied populations, experimental paradigms, and assessment methodologies limits clear conclusions regarding the involvement of the vestibular system in the onset of DD symptoms. Objective: To clarify the contribution of the vestibular system to DD symptoms in vestibular patients and healthy individuals undergoing vestibular stimulation. Methods: Following PRISMA guidelines, we reviewed studies examining: (1) DD symptoms in vestibular patients, and (2) DD symptoms in healthy individuals during vestibular stimulation. Results: Twenty-three studies met the inclusion criteria. Among these, 86.9% reported DD symptoms either in patients with vestibular disorders (14/15) or in healthy individuals during vestibular stimulations (6/8). Additionally, 82.61% of the studies identified an association between DD symptoms and anxiety or spatial disorientation. Conclusions: Together, these findings indicate that vestibular alterations may contribute to the emergence of DD symptoms. Anxiety and spatial disorientation were found to frequently co-occur suggesting an interaction between vestibular processing, affective regulation, and spatial cognition. This association can be interpreted within a neurofunctional framework, which posits that vestibular alterations disrupt multisensory integration in parietotemporal, insular, and hippocampal regions, contributing to the core phenomenology of DD.

The vestibular system is increasingly recognized for its role in higher-order cognitive functions, including bodily self-representation. However, its involvement in self-face representation remains unexplored. In the present study, we investigated whether artificial modulation of the vestibular system via Galvanic Vestibular Stimulation (GVS) can influence the representation of one's own and others' faces. Fifty healthy individuals performed two face-recognition tasks (explicit and implicit) while receiving sinusoidal bipolar GVS or Sham stimulation. During tasks, images of faces belonging to Self (S), Familiar-Others (FO), and Stranger-Others (SO) were presented. Participants were randomly assigned to one of two groups according to GVS polarity: left-anodal/right-cathodal (L-GVS) or right-anodal/left-cathodal (R-GVS). In both tasks, a robust Self Advantage (SA) emerged, with faster reaction times (RTs) for self-faces than familiar-other and stranger-other faces. Interestingly, an interaction between Identity, Stimulation, and GVS polarity was observed only in the explicit task. Specifically, R-GVS slowed recognition of self-faces relative to Sham. In contrast, L-GVS slowed recognition of stranger-other faces while facilitating recognition of familiar-other faces. Notably, under L-GVS RTs for self-faces no longer differ from those of familiar-other faces, effectively shifting the SA toward a more general familiarity advantage. Galvanic Vestibular Stimulation modulates face recognition and self-other distinction, in a polarity-dependent manner, providing causal evidence for vestibular involvement in self-face representation and identity processing.

The vestibular system contributes to cardiovascular regulation during changes in gravitational load (e.g., postural transitions, microgravity), in vestibular disorders, and during vestibular stimulations. Studies employing sinusoidal galvanic vestibular stimulation (GVS) reported conflicting autonomic responses, and recent evidence suggests that vestibular afferents encode GVS in a non-linear fashion. Whether this non-linear encoding results in polarity-dependent autonomic responses and whether such responses interact with concurrent cognitive demand remains unknown. To investigate these issues, we used sinusoidal GVS to modulate vestibular input in 35 healthy individuals while physiological signals were recorded using a wearable device. Participants completed a working memory task, preceded and followed by rest periods, under three counterbalanced conditions: right-anodal/left-cathodal GVS (RGVS), left-anodal/right-cathodal GVS (LGVS), and Sham GVS. Perceived stress was repeatedly assessed. During task performance, heart rate increased with RGVS and decreased with LGVS relative to Sham (p = 0.001) and perceived stress increased across all conditions (p < 0.001). Post-task, heart rate remained elevated in RGVS compared to LGVS (p = 0.006), and stress ratings decreased in LGVS compared to the other conditions (p < 0.01). These findings indicate that sinusoidal GVS induces polarity-dependent autonomic effects, primarily during concurrent cognitive demand. This pattern may reflect non-linear vestibular encoding, with its emergence being potentially modulated by attentional shifts.