Stochastic noise application for the assessment of medial vestibular nucleus neuron sensitivity in vitro

Galvanic vestibular stimulation (GVS) has been shown to improve balance measures in individuals with balance or vestibular impairments. This is proposed to be due to the stochastic resonance (SR) phenomenon, which is defined as application of a low-level/subthreshold stimulus to a non-linear system to increase detection of weaker signals. However, it is still unknown how SR exhibits its positive effects on human balance. This is one of the first demonstrations of the effects of sinusoidal and stochastic noise on individual neurons. Using whole-cell patch clamp electrophysiology, sinusoidal and stochastic noise can be applied directly to individual neurons in the medial vestibular nucleus (MVN) of C57BL/6 mice. Here we demonstrate how to determine the threshold of MVN neurons in order to ensure the sinusoidal and stochastic stimuli are subthreshold and from this, determine the effects that each type of noise has on MVN neuronal gain. We show that subthreshold sinusoidal and stochastic noise can modulate the sensitivity of individual neurons in the MVN without affecting basal firing rates. The video component of this article can be found at https://www.jove.com/video/60044