Functional Brain Activation in Response to a Clinical Vestibular Test Correlates with Balance

Abstract

The current study characterizes brain fMRI activation in response to two modes of vestibular stimulation: Skull tap and auditory tone burst. The auditory tone burst has been used in previous studies to elicit either a vestibulo-spinal reflex [saccular-mediated colic Vestibular Evoked Myogenic Potentials (cVEMP)], or an ocular muscle response [utricle-mediated ocular VEMP (oVEMP)]. Research suggests that the skull tap elicits both saccular and utricle-mediated VEMPs, while being faster and less irritating for subjects than the high decibel tones required to elicit VEMPs. However, it is not clear whether the skull tap and auditory tone burst elicit the same pattern of brain activity. Previous imaging studies have documented activity in the anterior and posterior insula, superior temporal gyrus, inferior parietal lobule, inferior frontal gyrus, and the anterior cingulate cortex in response to different modes of vestibular stimulation. Here we hypothesized that pneumatically powered skull taps would elicit a similar pattern of brain activity as shown in previous studies. Our results provide the first evidence of using pneumatically powered skull taps to elicit vestibular activity inside the MRI scanner. A conjunction analysis revealed that skull taps elicit overlapping activation with auditory tone bursts in the canonical vestibular cortical regions. Further, our postural control assessments revealed that greater amplitude of brain activation in response to vestibular stimulation was associated with better balance control for both techniques. Additionally, we found that skull taps elicit more robust vestibular activity compared to auditory tone bursts, with less reported aversive effects, highlighting the utility of this approach for future clinical and basic science research.

Vestibular brain changes within 70 days of head down bed rest

“…All the reported voxels are significant at p < .001. We observed brain activation in the bilateral insula, superior temporal, and supramarginal cortices while subjects were receiving vestibular stimulation, and deactivation in cerebellar, somatosensory and motor cortices versus rest; these findings are consistent with our previous work using this mode of vestibular stimulation (Noohi et al, ).…”

“…Meanwhile, relative to rest, deactivation was found in the cerebellum, cingulate, superior frontal, superior parietal, precuneus, paracentral, somatosensory, and motor cortices. These results are consistent with the existing literature (Noohi et al, ; Schlindwein et al, ), including activation of the vestibular cortex (Lopez, Blanke, & Mast, ; zu Eulenburg, Caspers, Roski, & Eickhoff, ). Declines in visual and somatosensory activation during vestibular stimulation versus rest likely reflect increased attention to, or weighting of, vestibular inputs (Schlindwein et al, ).…”

“…We have recently shown that this approach is well tolerated by subjects, it activates vestibular cortical regions, it results in vestibular evoked myogenic potentials in eye muscles, and it does not evoke excessive head motion (Noohi et al, ). We also found that pneumatically powered skull taps elicited overlapping activation with auditory tone bursts in the vestibular networks (Noohi et al, ). Thus, the skull tap is a validated method for studying vestibular brain activity in the MRI context.…”

Effect of Selected Vestibular Exercises on Postural Stability in Elderly Women with Type 2 Diabetes

“…Further, it was reported that vestibular stimulation integrates the cortical structures through its connections and helps to overcome postural difficulties [18]. Vestibular stimulation integrates the midbrain structures like inferior colliculus, red nucleus and periaqueductal gray matter and interstitial nucleus of Cajal and maintains the balance [19,20]. Vestibular stimulation also integrates at the level of the spinal cord through its descending pathways [21].…”

Vestibular modulation of postural stability: An update

“…These structures are reported to receive maximum number of projections from the vestibular system [33]. Vestibular stimulation results in activation of brain with higher amplitude which was reported to be essential for postural control [34].…”