My Editor’s Choice

Professor Ulf Ziemann,Editor-in-Chief, Clinical Neurophysiology

Professor Ulf Ziemann
Editor-in-Chief, Clinical Neurophysiology

The Editor’s Choice—

Frequency-dependent tuning of the human vestibular "sixth sense" by transcranial oscillatory currents. Clinical Neurophysiology

Clinical Neurophysiology Volume 153 (September 2023)

Rossi S, Cinti A, Viberti F, Benelli A, Neri F, De Monte D, Giannotta A, Romanella S, Smeralda C, Donniacuo A, Prattichizzo D, Pasqualetti P, Santarnecchi E, Mandalà M. Clinical Neurophysiology 2023;153:123-132.

Vestibular information is often referred to as the sixth sense. Motion sickness, the most frequent vestibular disturbance, is caused by low-frequency motion and associated with slow-frequency EEG oscillations in the delta range, mainly in temporoparietal cortex. The vestibular cortex is a multisensory associative region, located in the mid-posterior Sylvian fissure and the posterior insular cortex. While low-frequency (1-2 Hz) alternating current stimulation of vestibular afferents causes motion sickness, it is unclear if the same is true with directly stimulating vestibular cortex. Rossi and colleagues demonstrated that transcranial alternating current stimulation (tACS) of bilateral vestibular cortex at 1 and 2 Hz induced symptoms of motion sickness, oscillopsia and postural instability, as measured by posturographic sway recordings, while 10 Hz and sham-tACS did not. The effects at 1-2 Hz were also obtained in a rare patient with bilateral peripheral vestibular deafferentation, indicating that current spread to peripheral vestibular afferents cannot explain the findings. In contrast, 10 Hz-tACS significantly reduced the chronic vestibular symptoms in the patient. These findings are important as they demonstrate that weak electrical oscillations in a frequency range corresponding to the physiological vestibular cortical activity can cause motion sickness, while higher stimulation frequencies may be useful to treat motion sickness, and possibly other forms of vertigo.

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