Vestibular prepulse inhibition of the human blink reflex
ObjectiveAuditory and somatosensory prepulses are commonly used to assess prepulse inhibition (PPI). The effect of a vestibular prepulse upon blink reflex (BR) excitability has not been hitherto assessed.

MethodsTwenty-two healthy subjects and two patients with bilateral peripheral vestibular failure took part in the study. Whole body yaw rotation in the dark provided a vestibular inertial prepulse. BR was electrically evoked after the end of the rotation. The area-under-the-curve (area) of the BR responses (R1, R2, and R2c) was recorded and analysed.

ResultsA vestibular prepulse inhibited the R2 (p < 0.001) and R2c area (p < 0.05). Increasing the angular acceleration did not increase the R2/R2c inhibition (p>0.05). Voluntary suppression of the vestibular-ocular reflex did not affect the magnitude of inhibition (p>0.05). Patients with peripheral vestibular failure did not show any inhibition.

ConclusionsOur data support a vestibular-gating mechanism in humans.

SignificanceThe main brainstem nucleus mediating PPI - the pedunculopontine nucleus (PPN) - is heavily vestibular responsive, which is consistent with our findings of a vestibular-mediated PPI. Our technique may be used to interrogate the fidelity of brain circuits mediating vestibular-related PPN functions. Given the PPNs importance in human postural control, our technique may also provide a neurophysiological biomarker of balance.

HighlightsO_LIThis is the first report of a vestibular prepulse inhibition of the blink reflex.
C_LIO_LIA vestibular prepulse inhibits the R2/R2c area in healthy subjects but not in patients with bilateral peripheral vestibular failure.
C_LIO_LIVestibular PPI is a potential neurophysiological marker of vestibular-motor integration at the brainstem level.
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