The vistibulo-ocular reflex (VOR) is critical for maintaining visual acuity during head movements. The VOR ensures stability of images on the retina during head movements by generating smooth eye movements that are equal and opposite in direction to head movements. After unilateral labyrinthectomy (UL), eye movements are initially no longer able to compensate for head movements. However adequate VOR function is restored within several weeks. Physiological changes in flocculus target neurons (FTNs) in the medial vestibular nucleus may play a role in adaptation of the VOR during recovery from UL. The goal of this project is to first characterize the spatial distribution, morphological characteristics, and spike generation properties of FTNs. We will then attempt to determine if changes in spike generation gain of FTNs underlie recovery of the VOR after UL. Spike generation gain is defined as the linear change in firing rate evoked by intracellular current injection into neurons. Regulation of spike generation gain is one mechanism that neurons could use to modulate their response to a given input. In order to determine if modulation of spike generation gain is associated with vestibular compensation of the VOR, gain will be measured in FTNs in mouse brain slices in vitro before or during recovery from unilateral labyrinthectomy using whole cell patch clamp techniques. Results from this study will provide valuable insight into the cellular mechanisms that govern adaptation of the VOR.
| Smith, Marianne R; Nelson, Alexandra B; Du Lac, Sascha (2002) Regulation of firing response gain by calcium-dependent mechanisms in vestibular nucleus neurons. J Neurophysiol 87:2031-42 |
