Directional effects of whole-body spinning and visual flow in virtual reality on vagal neuromodulation

Abstract

BACKGROUND: Neural circuits allow whole-body yaw rotation to modulate vagal parasympathetic activity, which alters beat-to-beat variation in heart rate. The overall output of spinning direction, as well as vestibular-visual interactions on vagal activity still needs to be investigated. OBJECTIVE: This study investigated direction-dependent effects of visual and natural vestibular stimulation on two autonomic responses: heart rate variability (HRV) and pupil diameter. METHODS: Healthy human male subjects (n = 27) underwent constant whole-body yaw rotation with eyes open and closed in the clockwise (CW) and anticlockwise (ACW) directions, at 90°/s for two minutes. Subjects also viewed the same spinning environments on video in a VR headset. RESULTS: CW spinning significantly decreased parasympathetic vagal activity in all conditions (CW open p = 0.0048, CW closed p = 0.0151, CW VR p = 0.0019,), but not ACW spinning (ACW open p = 0.2068, ACW closed p = 0.7755, ACW VR p = 0.1775,) as indicated by an HRV metric, the root mean square of successive RR interval differences (RMSSD). There were no direction-dependent effects of constant spinning on sympathetic activity inferred through the HRV metrics, stress index (SI), sympathetic nervous system index (SNS index) and pupil diameter. Neuroplasticity in the CW eyes closed and CW VR conditions post stimulation was observed. CONCLUSIONS: Only one direction of yaw spinning, and visual flow caused vagal nerve neuromodulation and neuroplasticity, resulting in an inhibition of parasympathetic activity on the heart, to the same extent in either vestibular or visual stimulation. These results indicate that visual flow in VR can be used as a non-electrical method for vagus nerve inhibition without the need for body motion in the treatment of disorders with vagal overactivity. The findings are also important for VR and spinning chair based autonomic nervous system modulation protocols, and the effects of motion integrated VR.

Machine learning methods for the study of cybersickness: a systematic review

“…With regard to comparing EEG studies, vestibular stimuli and visual stimuli used to induce motion sickness activates a vast array of different cortical areas in the brain [ 37 , 53 – 62 ]. Previous research has also found that certain movements of visual scenes inside VR can alter HRV [ 8 , 63 ]. Constant clockwise rotation of the visual environment has been found to inhibit cardiac parasympathetic activity [ 8 ].…”

“…Previous research has also found that certain movements of visual scenes inside VR can alter HRV [ 8 , 63 ]. Constant clockwise rotation of the visual environment has been found to inhibit cardiac parasympathetic activity [ 8 ]. Root mean square of successive differences of R-R intervals (RMSSD) and standard deviation of R-R intervals (SDRR), measures of parasympathetic activity, were also found to be decreased in forward visual movement compared to backward visual movement during VR immersion in a rollercoaster ride [ 63 ].…”

“…VR can also be used for planning cost-effective architectural designs [ 4 ]. Moreover, there is potential for VR well-being applications in high-stress reduction [ 5 ], exposure therapy to reduce anxiety and trauma [ 6 , 7 ] and health-related interventions using VR neuromodulation [ 8 ]. The importance of VR is further highlighted in environments with restricted social interactions such as those imposed by the recent COVID-19 pandemic, allowing people to connect despite physical boundaries [ 9 ].…”

Both whole-body rotation and visual flow induce cardiovascular autonomic response in Human, but visual response is overridden by vestibular stimulation

“…Finally, the fact that visual stimulus was able to modulate only the cardiac response, but not the arterial pressure, may indicate that the autonomic response is driven by the parasympathetic system. Accordingly, recent data demonstrates parasympathetic activation by visual rotation in healthy male subjects 34 .…”

Vestibular-autonomic interactions: beyond orthostatic dizziness

“…The vestibular-autonomic reflexes encompass numerous pathways triggered by vestibular activation, resulting in changes in sympathetic or parasympathetic outflows [4,5 vestibular nucleus to the parabrachial complex [6], which sends projections to brainstem and forebrain areas integrating vestibular sensation and autonomic control, and cerebellar modulation of brainstem areas mediating autonomic output [1,[7][8][9][10][11][12][13]. Various sites within the cerebellum (anterior lobe, rostral posterior lobe, caudal posterior lobe-nodulus) demonstrate the ability to influence sympathetic and parasympathetic reflexes [14][15][16]17 && ]. The central vestibular sensation and autonomic control systems are highly interconnected and converge within the insular cortex.…”