Ocular torsion induced by Coriolis stimulation.

OBJECTIVE: The present study aimed to observe and analyze the ocular movements induced by Coriolis stimulation (eccentric pitch while rotating: PWR) that induces Coriolis forces on the vestibular apparatus of healthy human individuals. METHODS: A total of 31 healthy subjects participated in the study. Eccentric PWR was performed on 27 subjects, by pitching the participants' heads forward and backward at an angle of 30° each on an axis parallel and 7 cm below inter-aural axis, at a frequency of 0.5 Hz while on a chair rotating at a constant angular velocity of 97.2°/s on the earth-vertical axis. Ocular movements during stimulation were recorded using three-dimensional video-oculography. As a subsidiary analysis, 0.5 Hz head roll tilt was used as another stimulus that also induced torsional ocular movements. The forces induced on the vestibular apparatus, and phases of ocular torsion against the stimulus were calculated from the observed data. RESULTS: In the Coriolis stimulation during rightward yaw rotation, a rightward ocular torsion of 4.8° on average, was observed when the head pitched forward, and the direction of ocular torsion reversed when the head pitched backward. During leftward yaw rotation, these relationships were reversed with an average amplitude of 4.7° The phase of ocular torsion preceded that of Coriolis force by 0.2 s during rightward rotation and 0.14 s during leftward rotation. There were no significant differences in amplitude or phase between the directions of rotation. The phase lead of 0.5 Hz roll-tilt was significantly smaller than that of Coriolis stimulation (p < 0.01). CONCLUSION: Coriolis stimulation induced a specific pattern of ocular torsion, where its direction and phase suggested that the mechanism likely involved both the otolith and semicircular canals. Further studies may provide a clue to the magnitude of the otolith and semicircular canal contributions.

Effect of Standardized Yelling on Subjective Perception and Autonomic Nervous System Activity in Motion Sickness.

This study investigated the effects of yelling intervention on symptoms and autonomic responses in motion sickness. Forty-two healthy participants were recruited, and they participated in Coriolis stimulation, a technique for inducing motion sickness. The experimental procedure comprised five 1-min rotating stimuli with 1-min rest after each stimulus. Then, the symptom severity was assessed using the Motion Sickness Symptom Rating (MSSR). The d2 Test of Attention scores and cardiovascular responses were recorded before and after Coriolis stimulation. The electrocardiogram results were documented to analyze heart rate variability (HRV). During Coriolis stimulus, the participants were required to yell 5-8 times in the experimental trial, and to keep quiet for each minute of rotation in the control trial. The yelling intervention significantly reduced the MSSR score (p < 0.001). Nevertheless, it did not significantly affect the d2 Test of Attention scores. Yelling while rotating did not significantly affect the heart rate nor blood pressure. However, it decreased the normalized low frequency of HRV (p = 0.036). Moreover, it improved motion sickness, but its effect on attention was not evident. Motion sickness could significantly affect cardiovascular responses and HRV. However, yelling did not affect cardiovascular response, and it reduced sympathetic nervous system activity.

Electroacupuncture Could Reduce Motion Sickness Susceptibility in Healthy Male Adults: A Double-Blinded Study.

Objective: Motion sickness is the main cause of nausea-related symptoms during passive motion in transportation. The aim of this study was to evaluate the effects of electroacupuncture (EA) for the reduction of motion sickness symptoms. Materials and Methods: Study participants were randomly assigned into three groups: Group A, therapeutic EA; Group B, sham EA; and group C, a control group. After an EA session, participants were exposed to a motion stimulus, using a rotating chair. Their symptoms were measured using the Greek version of the Gianaros Motion Sickness Assessment Questionnaire (MSAQ). Results: In this study 20 volunteers participated. All 3 groups of subjects showed increases in their motion sickness symptoms after exposure to the motion stimulus. The mean total symptom score for Group A was 59,375, for Group B it was 74,333, and in Group C was it 93,166. This difference is partially statistically significant when comparing Group A with Group C, especially in a peripheral group of symptoms, as measured by the Gianaros MSAQ. Conclusions: The results of the present study suggest that participants who received therapeutic EA prior to motion stimulation tended to have fewer motion sickness symptoms in comparison with their counterparts, who were not given any therapy.