Strong magnetic fields induce dizziness, vertigo, and nystagmus due to Lorentz forces acting on the cupula in the semi-circular canals (Roberts et al. 2012). Studies using passive motion, galvanic or caloric vestibular stimulation have shown that vestibular information can interfere with cognitive tasks with spatial components (e.g., Falconer & Mast, 2012). In this study, we were interested if magnetic vestibular stimulation (MVS) in a 7 Tesla MRI scanner influences performance in cognitive tasks with spatial components. 30 participants solved a mental rotation task in a 7T MR scanner with an egocentric and an allocentric strategy. The findings of previous studies suggest that only the egocentric strategy should be affected by altered vestibular information. The allocentric strategy served as a control condition. The strength of MVS was manipulated within participants by letting them solve the task inside the bore with two different head positions, resulting in a stronger and a weaker stimulation condition (Wyssen et al., in press). Response time analyses showed that overall participants responded slower under stronger stimulation than under weaker stimulation. This effect of magnetic vestibular stimulation on response times was only present in the egocentric mental rotation task but not when participants used the allocentric strategy. However, participants showed inter-individual differences, and the strength of the individual effect could not be linked to the individual stimulation strength quantified by nystagmus. The findings of our study suggest that MVS could influence cognitive tasks with spatial components in MRI scanners. The effect of magnetic vestibular stimulation should be considered in fMRI studies using ultra-high magnetic fields using spatial tasks, as it could be a possible confounder. In the future magnet ic vestibular stimulation could serve as a tool to investigate the interrelation of vestibular information and spatial cognition. References: (1) Roberts, D. C., Marcelli, V., Gillen, J. S., Carey, J. P., Della Santina, C. C., & Zee, D. S. (2011). MRI magnetic field stimulates rotational sensors of the brain. Curr. Biol., 21(19), 1635-1640. (2) Falconer C. J., Mast F.W. (2012). Balancing the mind: vestibular induced facilitation of egocentric mental transformations. Exp. Psychol., 59(6):332-9. (3) Wyssen, G., Morrison, M., Korda, A., Wimmer, W., Otero-Millan, J., Ertl, M., Szukics, A.A., Wyss, T., Wagner, F., Caversaccio, M.D., Mantokoudis, G., Mast, F.W. (in press). Measuring the Influence of Magnetic Vestibular Stimulation on Nystagmus, Self-Motion Perception, and Cognitive Performance in a 7T MRT. J. Vis. Exp., e64022.
