Activity of Vestibular Nuclei Neurons During Vestibular and Optokinetic Stimulation in the Alert Mouse

Abstract

As a result of the availability of genetic mutant strains and development of noninvasive eye movements recording techniques, the mouse stands as a very interesting model for bridging the gap among behavioral responses, neuronal response dynamics studied in vivo, and cellular mechanisms investigated in vitro. Here we characterized the responses of individual neurons in the mouse vestibular nuclei during vestibular (horizontal whole body rotations) and full field visual stimulation. The majority of neurons (∼2/3) were sensitive to vestibular stimulation but not to eye movements. During the vestibular-ocular reflex (VOR), these neurons discharged in a manner comparable to the “vestibular only” (VO) neurons that have been previously described in primates. The remaining neurons [eye-movement-sensitive (ES) neurons] encoded both head-velocity and eye-position information during the VOR. When vestibular and visual stimulation were applied so that there was sensory conflict, the behavioral gain of the VOR was reduced. In turn, the modulation of sensitivity of VO neurons remained unaffected, whereas that of ES neurons was reduced. ES neurons were also modulated in response to full field visual stimulation that evoked the optokinetic reflex (OKR). Mouse VO neurons, however, unlike their primate counterpart, were not modulated during OKR. Taken together, our results show that the integration of visual and vestibular information in the mouse vestibular nucleus is limited to a subpopulation of neurons which likely supports gaze stabilization for both VOR and OKR.

Loss of -Calcitonin Gene-Related Peptide ( CGRP) Reduces the Efficacy of the Vestibulo-ocular Reflex (VOR)

“…Quantification of the VOR and main sequence. The surgical preparation for head implant surgery and experimental setup have been previously described (Vidal et al, 2004;Beraneck and Cullen, 2007). Eye movement data were recorded using an infrared video system (ISCAN) with optics modified for the mouse.…”

“…Eye-and head-movement data were digitally low-pass filtered using a 51st-order finite-impulse-response filter (cutoff frequency ϭ 40 Hz), and eye position data were differentiated to obtain velocity traces. VOR gain and phase were determined by the leastsquares optimization (Beraneck et al, 2008) and are plotted as mean Ϯ SD across animals. All mice (n ϭ 16) were tested at each frequency.…”

“…To test our proposal that ␣CGRP is critical for ensuring VOR efficacy, we quantified VOR response dynamics over the range of natural head movements. During exploratory activity, mice produce head movements for which component frequencies are mostly Յ4 Hz (Beraneck et al, 2008). Thus, we applied sinusoidal rotations over this frequency range.…”

Rotational Responses of Vestibular–Nerve Afferents Innervating the Semicircular Canals in the C57BL/6 Mouse

“…In addition to these studies of the VOR, the responses of central vestibular neurons to rotations have been investigated in mice (Beraneck and Cullen 2007). Studies of vestibular hair cells in mice have defined the role of specific ion channels in sensory transduction (Rüsch and Eatock 1996; Eatock et al…”

Galvanic stimulation of the vestibular periphery in guinea pigs during passive whole body rotation and self-generated head movement

“…Unlike primates, they do not produce smooth pursuit eye movements (Marlinsky and Kröller 2000), which, in monkeys, share the central pathways that process signals related to the VOR (Roy and Cullen 2002). Furthermore, in the mouse, another afoveate species, Beraneck and Cullen (2007) showed that putative secondary vestibular neurons with eye position sensitivity ("ES neurons") encode a signal correlated with eye velocity during optokinetic nystagmus (OKN). However, in contrast to previous findings in primates (Blazquez and Highstein 2007;Waespe and Henn 1979), mouse vestibular-only cells ("VO neurons") do not exhibit activity related to either the visual motion stimulus or eye movement during OKN.…”