Midline Head Tap to Image the Human Vestibular Cortex on fMRI

A simple head tap can stimulate inner ear otolith organ activation. In this pilot proof‐of‐concept study, midline forehead taps were delivered in the magnetic resonance imaging (MRI) scanner to elicit an observable response in the areas most suspected of representing a vestibular cortex. In three right‐handed and three left‐handed healthy adult volunteers, manual midline forehead taps delivered in the fMRI scanner gave consistent brain responses at the temporoparietal junctions, although there was not an intensity correlation with handedness. Five of six showed an expected somatosensory response. In a further three participants, two profoundly deaf, there were activations; specifically, these results suggest a vestibular response and not an auditory response. Based on a positron emission tomography (PET) scan study employing ‘natural' vestibular stimuli with no likelihood of artefact responses, the fMRI scan data was analysed for the presence of insula and Heschl's gyrus responses, which were found. The insular cortex, particularly the posterior insula, is the most frequently responding structure in all vestibular imaging studies and appears to be the most important as being, or as constituting part of, the vestibular cortex. This fMRI technique is simple, noninvasive and could be automated by compressed air.