It is known that 30% of aircraft accidents are caused by 'spatial disorientation,' in which pilots lose their sense of direction and are unable to accurately perceive the attitude and position of the aircraft. Specifically, there is a phenomenon called 'somatogravic illusion,' where a pilot may perceive the aircraft as climbing at an angle when it is actually accelerating forward. This is believed to be caused by the otolith organs, which are acceleration sensors in the inner ear, being unable to distinguish between linear acceleration and the tilt relative to gravity. Spatial disorientation is also believed to be a cause of motion sickness in passengers, not just pilots. However, the detailed neural mechanisms behind it remain unclear, and effective methods for preventing its onset have not been identified.
A research team led by Professor Yutaka Hirata, and his graduate student Shin Tadokoro at Chubu University Graduate School of Engineering, focused on goldfish, which are known to have neural mechanisms for eye movement based on spatial orientation similar to those in humans. The research team developed a system to provide goldfish with translational and tilt motions and visual stimuli and discovered that spatial disorientation occurs as in humans by evaluating a reflexive eye movement called the "vestibulo-ocular reflex." It was also confirmed that goldfish, which had entered a state of spatial disorientation in a dark environment where they couldn't see ahead, were able to overcome this disorientation within three hours when they were exposed to a visible forward landscape and trained. After the training, the goldfish were returned to the dark environment again, but they did not develop spatial disorientation.
The research team has also constructed a mathematical model that reproduces the development of spatial disorientation and the subsequent recovery process and has proposed a computational theory for spatial orientation formation in the brain. The findings obtained in this study are expected to contribute to establishing methods for preventing aircraft pilots from developing spatial disorientation and passengers from experiencing motion sickness and falls.
Spatial disorientation in humans and goldfish and eye movements in goldfish
