Vestibulo-Ocular Responses, Visual Field Dependence, and Motion Sickness in Aerobatic Pilots

BACKGROUND: Aerobatic flight is a challenge for the vestibular system, which is likely to lead to adaptive changes in the vestibular responses of pilots. We investigated whether aerobatic pilots, as individuals who experience intense vestibular stimulation, present modifications of the vestibular-ocular reflex, motion sickness susceptibility and intensity, visual vertical estimation, and visual dependence as compared to normal volunteers.METHODS: To evaluate vestibulo-ocular reflexes, eye movements were recorded with videonystagmography while subjects were rotated on a rotatory chair with the axis of rotation being vertical (canal-ocular reflex) or inclined to 17° (otolith-ocular reflex). Motion sickness was evaluated after the rotatory test using the Graybiel diagnostic criteria. General motion sickness susceptibility and visual field dependence were also evaluated.RESULTS: Averaged data did not show significant difference in canal-ocular reflex and otolith ocular-reflex between groups. However, a significant asymmetry in otolith-driven ocular responses was found in pilots (CW 0.50 ± 1.21° · s−1 vs. CCW 1.59 ± 1.12° · s−1), though visual vertical estimation was not altered in pilots and both groups were found field independent. Pilots were generally less susceptible to motion sickness (MSSQ scores: 2.52 ± 5.59 vs. 13.5 ± 11.36) and less affected by the nauseogenic stimulation (Graybiel diagnostic criteria 3.36 ± 3.81 vs. 8.39 ± 7.01).DISCUSSION: We did not observe the expected habituation in the group of aerobatic pilots. However, there was a significant asymmetry in the otolith-driven ocular responses in pilots, but not in the controls, which may result from the asymmetry in piloting protocols.Kuldavletova O, Tanguy S, Denise P, Quarck G. Vestibulo-ocular responses, visual field dependence, and motion sickness in aerobatic pilots. Aerosp Med Hum Perform. 2020; 91(4):326–331.

Assessment of visual field dependence: Comparison between the mechanical 3D rod-and-frame test developed by Oltman in 1968 with a 2D computer-based version

The identification of subject’s perceptual style regarding multisensory integration is a central issue for spatial perception and sensorimotricity. In spatial orientation studies, the weighting of visual frame of reference (visual field dependence) is classically assessed by using verticality perception tasks, and especially the mechanical 3D rod-and-frame test (3D RFT). The validation of a 2D computer-based version of the RFT by virtue of its portability would facilitate the identification of modes of spatial referencing for the design and evaluation of sensory and motor rehabilitation programs. We question here whether the computerized 2D RFT yields frame effects similar (in amplitude, direction) and correlated to those induced by the mechanical 3D RFT. In both devices, 35 young and healthy males’ subjects were seated and tasked with aligning a rod to the gravity vertical within a square frame that was tilted at 18Âř. The results showed significantly larger rod deviations from the verticality in the 3D RFT. 3D and 2D RFT errors significantly correlated but shared a small amount of common variance ( r 2 = 0.35). In addition, left-right tilt asymmetry changes from one device to another. These results suggest that the mechanical 3D RFT for verticality perception remains a more robust test for identifying the subject’s perceptual style.