Cerebral vestibular-evoked potentials depend on body orientation

Area of Science:

• Neuroscience
• Vestibular System
• Auditory Neuroscience

Background:

• Otolithic vestibular receptors are crucial for sensing linear acceleration and head orientation relative to gravity.
• The cerebral processing of otolithic information and its modulation by body posture are not well understood.

Purpose of the Study:

• To characterize vestibular-evoked potentials (vEPs) using sound-induced vestibular stimulation.
• To investigate how body orientation relative to gravity influences these vEPs.

Main Methods:

• Used electroencephalography (EEG) in human participants with sound-induced vestibular stimulation.
• Validated otolithic activation via cervical vestibular-evoked myogenic potentials.
• Employed a novel masked auditory stimulus to isolate vestibular responses.

Main Results:

• Sound stimulation elicited reliable short- and middle-latency vEPs.
• Middle-latency components (Na/Pa and N*/P*) showed reduced amplitudes in the supine versus upright positions.
• This orientation-dependent modulation was specific to otolithic stimuli, not auditory controls, and stronger for Na/Pa.

Conclusions:

• The findings establish Na/Pa and N*/P* as reliable cerebral markers for otolithic processing.
• Early cerebral vestibular responses are dynamically modulated by body orientation relative to gravity.
• Modulation reflects context-dependent cerebral processing of otolithic signals, not peripheral mechanisms.