Evaluation of Cerebral Blood Flow While Viewing 3D Video Clips

The technology provides an enhanced visual experience with realistic scene portrayal, but is known to cause motion sickness when stereoscopic video clips of rotating or blurred images are viewed. Viewers complain of symptoms such as eye fatigue, nausea, and dizziness. The underlying cause of these symptoms has not been identified; therefore, an investigation to determine the mechanism for the motion sickness is necessary. Previous stabilometry studies have reported that 3D sickness is induced by a peripheral viewing of stereoscopic video clips as opposed to the visual pursuit. In this study, the author investigated the influence of 3D recognition on brain activity. Functional near-infrared imaging (fNIRS) was used to determine if either peripheral viewing or visual pursuit changes brain activity. Stabilograms and eye movement were simultaneously recorded while the subject viewed video clips to confirm that the actual visual recognition method in use corresponded to our instructions. Using the fNIRS technique, cerebral blood flow was measured while the subject viewed stereoscopic video clips with and without a background. Following a preliminary test with the subject’s eyes closed (baseline), changes in the concentration of oxygenated hemoglobin were measured. This test was performed for 70 s, with and without backgrounds, while the subject peripherally viewed a moving sphere. Compared to the baseline test, the concentration of oxygenated hemoglobin in the occipital lobe increased significantly during a viewing for both background cases. The result is consistent with both visual recognition methods. Furthermore, for both background cases, the concentration in the upper occipital lobe significantly increased during peripheral viewing versus visual pursuit. Peripheral viewing might enhance the activity in the dorsal stream, which could serve as an indication to the mechanism causing 3D sickness.