Oscillatory neural responses evoked by natural vestibular stimuli in humans
While there have been numerous studies of the vestibular system in mammals, less is known about the brain mechanisms of vestibular processing in humans. In particular, of the studies that have been carried out in humans over the last 30 years, none have investigated how vestibular stimulation (VS) affects cortical oscillations. Here, we recorded high-density electroencephalography (EEG) in healthy human subjects and a group of bilateral vestibular loss patients (BVPs) undergoing transient and constant velocity passive whole body yaw rotations, focusing our analyses on the modulation of cortical oscillations in response to natural VS. The present approach overcame significant technical challenges associated with combining natural VS with human electrophysiology and reveals that both transient and constant velocity VS are associated with a prominent suppression of alpha power (8-13Hz). Alpha band suppression was localized over bilateral temporo-parietal scalp regions and these alpha modulations were significantly smaller in BVPs. We propose that suppression of oscillations in the alpha band over temporo-parietal scalp regions reflects cortical vestibular processing, potentially comparable with alpha and mu oscillations in the visual and sensorimotor systems respectively, opening the door to the investigation of human cortical processing under various experimental conditions during natural VS.