Anodal transcranial direct current stimulation of cerebellum relieves motion sickness by reducing the release of acetylcholine

Motion sickness (MS) is a condition caused by conflicts between motion sensors and past visual or motion memories, leading to discomfort with symptoms like hypolocomotion, low body temperature, poor appetite, and nausea. Previous studies have shown that the cerebellum is closely related to the occurrence of MS. In the present study, we aimed to evaluate the potential therapeutic effects of transcranial direct current stimulation (tDCS) of cerebellum on MS. The motion sickness index and the rotarod motor performance test were used to assess the motion sickness symptoms and motor learning in mice. Our results showed that tDCS was effective in reducing the motion sickness index in rotation-induced MS mice, as well as in reversing the rotation-induced impairment in rotarod motor learning. To understand the potential underlying mechanism, we used two-photon microimaging to monitor the release of acetylcholine in the cerebellum. Our results showed a significant increase in acetylcholine release in the cerebellum after rotation. Furthermore, anodal tDCS (a-tDCS) not only counteracted rotation-induced increase of acetylcholine in MS mice but also reduced the level of acetylcholine in static control mice. Together, these findings indicate that anodal transcranial direct current stimulation alleviates symptoms associated with motion sickness, which may be related to the reduction of acetylcholine release in the cerebellum.