Core Body Temperature Effects on the Mouse Vestibulo-ocular Reflex

Abstract

Core body temperature has been shown to affect vestibular end-organ and nerve afferents so that their resting discharge rate and sensitivity increase with temperature. Our aim was to determine whether these changes observed in extracellular nerve recordings of anaesthetized C57BL/6 mice corresponded to changes in the behavioural vestibulo-ocular reflex (VOR) of alert mice. The VOR drives eye rotations to keep images stable on the retina during head movements. We measured the VOR gain (eye velocity/head velocity) and phase (delay between vestibular stimulus and response) during whole-body sinusoidal rotations ranging 0.5-12 Hz with peak velocity 50 or 100 °/s in nine adult C57BL/6 mice. We also measured the VOR during whole-body transient rotations with acceleration 3000 or 6000 °/s reaching a plateau of 150 or 300 °/s. These measures were obtained while the mouse's core body temperature was held at either 32 or 37 °C for at least 35 min before recording. The temperature presentation order and timing were pseudo-randomized. We found that a temperature increase from 32 to 37 °C caused a significant increase in sinusoidal VOR gain of 17 % (P < 0.001). Temperature had no other effects on the behavioural VOR. Our data suggest that temperature effects on regularly firing afferents best correspond to the changes that we observed in the VOR gain.

Retinoic acid degradation shapes zonal development of vestibular organs and sensitivity to transient linear accelerations

“…Given the larger cell bodies, higher conduction velocities 53,54 , and greater phase advances of evoked firing 55–57 of irregular neurons in striolar/central zones than regular neurons in extrastriolar/peripheral zones, these regions have been postulated to be important for mediating short-latency vestibular reflexes 58 . The aVOR in mice is fast with a latency as low as <7 ms 59 . However, we did not detect any deficit in aVOR and OVAR in Cyp26b1 cKO mutants when lateral cristae and macular organs, respectively, were inertially stimulated, suggesting that the striolar/central zones of vestibular organs (innervated by irregular afferents) are dispensable for these functions, at least in the adults.…”

Angular vestibuloocular reflex responses in Otop1 mice. II. Otolith sensor input improves compensation after unilateral labyrinthectomy

“…Data acquisition. The method of recording three-dimensional (3D) binocular eye movements with the use of high-speed videooculography and the techniques used for the off-line analysis of VOR responses have been described previously (Hübner et al 2013(Hübner et al , 2014(Hübner et al , 2017a(Hübner et al , 2017bKhan et al 2017;Migliaccio et al 2005Migliaccio et al , 2010Migliaccio et al , 2011 In brief, the videooculography system tracks a marker array that is placed onto each eye, which allows accurate measurement of eye movement components in all three dimensions: horizontal, vertical, and torsional (about the line of site). All VOR data were recorded with two high-speed infrared-sensitive cameras (DX-COL-CS; Point Grey), each one operating at 200 frames/s to capture binocular 3D eye movements.…”

Angular vestibuloocular reflex responses in Otop1 mice. I. Otolith sensor input is essential for gravity context-specific adaptation

“…After VOR adaptation training, we measured the VOR in complete darkness with a binocular 3D videooculography system (Hübner et al 2013(Hübner et al , 2014(Hübner et al , 2017a(Hübner et al , 2017bKhan et al 2017;Migliaccio et al 2005Migliaccio et al , 2010Migliaccio et al , 2011. In brief, the videooculography system tracks a marker array that is placed onto each eye, which allows accurate measurement of eye movement components in all three dimensions: horizontal, vertical, and torsional (about the line-of-site).…”