Overlaps of fMRI activation patterns of the anxiety-emotional and the vestibular-sensory networks

Clinical and meta-analytic imaging data suggest a considerable overlap between vestibular-sensory and anxiety-emotional processing networks. We therefore examined functional MRI activation using galvanic vestibular stimulation (GVS) and a fear conditioning paradigm in the same 28 healthy individuals. This study was to proof the effects of both stimulations in the same individual whereas our earlier meta-analytical analysis compared groups of participants who had received only one or the other stimulation. In the actual study we further assessed subjective experience (expectancy ratings, questionnaires) and autonomic arousal (skin conductance response; SCR). Activation patterns during vestibular stimulation confirmed previous findings showing highest fMRI-activation in the parieto-insular vestibular cortex. Fear conditioning activated the anterior insula, secondary somatosensory cortex (S2) and thalamus. A conjunction of fMRI-activation maps for both stimulation paradigms revealed bilateral anterior and posterior insula, dorsolateral prefrontal cortex and S2 as well as cerebellar hemisphere fMRI-activation. Regression analyses showed a high positive association of left anterior insular activation during the fear extinction period with trait anxiety. The vestibular intensity during GVS was positively associated with right ventro-lateral prefrontal cortex (PFC) fMRI-activation. This is compatible with the earlier hypothesized top-down regulation of vestibular perception which involves the PFC beneficial for suppression of unusual vestibular excitation or vertigo related to vestibular disorders.