Posterior insula activity is associated with VR sickness severity after prolonged immersion: a resting-state fMRI study

The neural mechanisms underlying virtual reality (VR) sickness remain poorly understood. This study explored neural alterations following prolonged VR immersion and their associations with VR sickness severity using resting-state functional magnetic resonance imaging (fMRI). Fractional amplitude of low-frequency fluctuations (fALFF) was calculated and used as an index to reveal local activity features of brain regions at rest. Resting-state functional imaging data were acquired following approximately 7.5-hour experimental duration under either a head-mounted display (HMD) or a conventional computer monitor (LCD) condition. Regional fALFF values were compared between the two display conditions to identify regions showing significant differences. Associations between fALFF values in the identified regions and individual differences in sickness severity were subsequently examined. Compared with the LCD condition, prolonged HMD exposure was associated with significantly lower fALFF in the right posterior insula. Moreover, under the HMD condition, lower posterior insula fALFF was significantly associated with greater VR sickness severity, whereas no significant association was observed under the LCD condition. These findings suggest that the right posterior insula may represent a candidate neural correlate of sickness following prolonged HMD exposure.