Vestibular Evoked Myographic Correlation

Abstract

This work started from the hypothesis that the physiological processes giving rise to the vestibular evoked myogenic potential (VEMP) can be induced not only by transient sounds but also by a continuous stimulation with a stochastic signal. The hypothesis is based on the idea that the number of motor unit action potentials (MUAPs) decreases after a momentary amplitude increase of the effective stimulus, whereas a momentary amplitude decrease has the opposite effect. This concept was theoretically analyzed by assuming that the effective stimulus is closely related to the envelope of the stimulus actually presented. The analysis led to the prediction that the cross-correlation function of the effective stimulus and the measured electromyogram (EMG) has VEMPlike properties. Experiments confirmed this prediction, thus providing evidence of a novel electrophysiological response: the vestibular evoked myographic correlation (VEMCorr). The methodological approach corresponded to a conventional VEMP study, except that the stimulus (delivered with a hand-held minishaker) comprised not only a series of 500-Hz tone pulses (classical VEMP measurement, for comparison) but also sequences of narrow-band noise with a center frequency of 500 Hz (VEMCorr measurement). Each of the 12 test persons showed a clear VEMCorr. Moreover, VEMP and VEMCorr largely resembled each other, as predicted. Apparently they are two different expressions of a more general mechanism that leads to a roughly linear relationship between stimulus envelope and expectation of the EMG. Future applications of the VEMCorr could exploit that a continuous-stimulation paradigm allows for varying the center frequency of the stimulus without changing the relative bandwidth.

Temporal Modulation Transfer Functions of Amplitude-Modulated Cervical Vestibular-Evoked Myogenic Potentials in Young Adults

“…These waveforms are consistent with increases in stimulus level over an AM cycle resulting in inhibitory activity, a positive peak followed by a negative peak, while decreases in stimulus level over an AM cycle resulting in excitatory activity, an initial negative peak followed by a positive peak. Few published studies have evaluated cVEMP offset responses, but these AMcVEMP offset responses are consistent with the limited literature (Ciardo et al 2016; Lütkenhöner 2019).…”

Effects of Stimulus Polarity on Amplitude-Modulated Cervical Vestibular-Evoked Myogenic Potentials

“…Otolith hair cells are known to act as half-wave rectifiers 24 25 26 and this rectification would be expected to enhance the temporal envelope in cVEMPs. 27 ASSRs share a similar mechanism related to the half-wave rectification of inner hair cells, 28 and these responses to amplitude-modulated tones are present at modulation frequencies. Harmonic distortion products of the modulation frequency were observed in the present study ( Fig.…”

Weak Vestibular Response in Persistent Developmental Stuttering

“…In modelling studies, the VEMP represents a superposition of motor unit action potentials occurring at irregular time intervals ( Wit and Kingma, 2006 ), with generation of motor unit action potentials being inhibited following presentation of sound or vibration. The VEMP can be described by two mathematical functions: one specifies the mean number of motor unit action potentials per unit of time, and the other describes the time course of an individual motor unit action potential ( Lütkenhöner, 2019 ). As such, the VEMP does not correspond directly to neural firing rates of interest in the current study (i.e., those along the VIII cranial nerve or within vestibular nuclei).…”