Galvanic Effects on the Human Vestibuloocular Reflex

电流对人类前庭眼反射的影响

• 批准号: 7086166
• 负责人: AMERICO A MIGLIACCIO
• 金额: $ 7.98万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7086166
• 关键词: afferent nerve; clinical research; electrical conductance; electrodes; electrostimulus; gentamicins; head movements; human subject; motion perception; neurophysiology; smooth pursuit eye movement; vestibular nerve; vestibuloocular reflex; vision; vision tests; visual stimulus; visual tracking

DESCRIPTION (provided by applicant): The long-term objectives of this project are to better understand the contribution of irregular vestibular nerve afferent fibers to the human vestibulo-ocular reflex (VOR), and to understand the functional impact of gentamicin's preferential toxicity on the region of the crista where irregular afferents predominate. During rapid head rotations, while viewing a near target, the VOR gain must increase to account for translation of the eyes with respect to the target. The neural substrate underlying these changes in VOR gain is unclear; however, the observation that this vergence-mediate gain increase is absent for ipsilesional head rotations in patients treated unilaterally with intratympanic gentamicin suggests that irregular vestibular nerve afferents may play a role in active modification of VOR gain (Migliaccio et al., 2004). Unlike regular vestibular afferents, irregular afferents are particularly sensitive to externally applied direct currents and their firing rate can be reduced by galvanic stimulation (Goldberg et al., 1984). Chen-Huang & McCrea (1998) showed in monkeys that when irregular afferents are galvanically inhibited, vergence-mediated modulation of the VOR is also reduced; however, the VOR gain during far viewing is unaffected by galvanic stimulation (Minor and Goldberg, 1991; Karlberg et al., 2000). The first goal of this project is to examine the effects of galvanic inhibition of irregular afferents on the human vergence-mediated VOR gain in normal subjects. If the vergence-mediated VOR gain is reduced during galvanic inhibition, then this would indicate that irregular afferents play an important role in increasing the VOR gain during near viewing. Our second goal is to repeat this experiment in patients treated with intratympanic gentamicin. If during rapid head rotations towards the gentamicin treated ear the vergence-mediated VOR is unaffected by galvanic inhibition, but is increased by galvanic excitation, then this would suggest that modulation of VOR gain by vergence depends upon irregular afferents that are preferentially affected by gentamicin and by galvanic stimuli.

描述(申请人提供)：本项目的长期目标是更好地了解不规则前庭神经传入纤维对人类前庭-眼反射(VOR)的贡献，并了解庆大霉素的优先毒性对不规则传入占主导地位的眉骨区域的功能影响。在快速头部旋转期间，当观看近目标时，必须增加VOR增益以考虑眼睛相对于目标的平移。这些VOR增益变化背后的神经基础尚不清楚；然而，观察到在单侧接受鼓室内庆大霉素治疗的患者的自身头部旋转中，这种收敛中介的增益增加是不存在的，这表明不规则的前庭神经传入可能在主动改变VOR增益中发挥作用(Migliaccio等人，2004年)。与规则的前庭传入不同，不规则传入对外部施加的直流电特别敏感，它们的放电频率可以通过电刺激来降低(Goldberg等人，1984)。Chen-Huang&McCrea(1998)在猴子身上表明，当不规则传入被电流抑制时，收敛介导的VOR调制也会减少；然而，远距离观看时的VOR增益不受电流刺激的影响(Minor and Goldberg，1991；Karlberg等人，2000)。这个项目的第一个目标是检验电抑制不规则传入对正常受试者人类收敛介导的VOR增益的影响。如果在电流抑制过程中，会聚调节的VOR增益降低，那么这表明不规则传入在增加近距离观察时的VOR增益中起着重要作用。我们的第二个目标是在鼓室内注射庆大霉素的患者中重复这一实验。如果在快速旋转头部朝向庆大霉素治疗的耳朵时，收敛介导的VOR不受电流抑制的影响，但被电流兴奋所增加，那么这表明收敛对VOR增益的调制依赖于不规则的传入，而不规则的传入优先受庆大霉素和电刺激的影响。