Humans perceive motion information using vestibular and visual organs. Conflicts in motion information perceived from the two systems have been investigated as the major cause of visually induced motion sickness (VIMS). However little is known in the brain hemodynamics responses associated with VIMS provoking stimuli. In particular, whether these brain responses differ between people with different susceptibility to motion sickness is unknown. Indeed, cortical brain response to real physical movement is also poorly documented. This study uses Near-infrared spectroscopy (NIRS) to study the cortical hemodynamic responses to circular vection when watching VIMS provoking stimuli. The research comprises three parts and five studies. First, the cortical areas responding to real physi...[ Read more ]

Humans perceive motion information using vestibular and visual organs. Conflicts in motion information perceived from the two systems have been investigated as the major cause of visually induced motion sickness (VIMS). However little is known in the brain hemodynamics responses associated with VIMS provoking stimuli. In particular, whether these brain responses differ between people with different susceptibility to motion sickness is unknown. Indeed, cortical brain response to real physical movement is also poorly documented. This study uses Near-infrared spectroscopy (NIRS) to study the cortical hemodynamic responses to circular vection when watching VIMS provoking stimuli. The research comprises three parts and five studies. First, the cortical areas responding to real physical motion are investigated. The purpose was to identify the cortical areas sensitive to vestibular stimuli. Results of studies 1 and 2 indicate that different cortical hemodynamics were found in response to different motion conditions (lateral, fore-aft and sway motion) and circular swaying motion produced the strongest hemodynamic responses. The relationships between VIMS susceptibility and patterns in brain hemodynamic responses during vection were studied in the second part. Results of studies 3 and 4 indicate that the upper lateral area in the right hemisphere and the occipital region of the brain were oxygenated during circular vection, while regions around intraparietal cortex were found to be significantly and consistently affected by motion sickness susceptibility. This is partially consistent with the reciprocal inhibition theory between the visual and vestibular cortices (Brandt et al., 1998). The third part of the research was a pilot study to examine the effects of adaptation on VIMS susceptibility and the regional brain hemodynamic responses. After 7-days desensitization training, the cortical hemodynamic responses of the motion sickness susceptible participant converged to those of non-susceptible participants in the cortical areas which have been identified to be significantly affected by motion sickness susceptibility. In summary, this thesis investigated human cortical regions which could respond to real physical motion and identified cortical responses which are highly correlated with motion sickness susceptibility.