Effect of psychosocial stress on intrinsic activation of human motor neurons

社会心理压力对人类运动神经元内在激活的影响

• 批准号: 7251270
• 负责人: Katrina S. Monroe
• 金额: $ 19.87万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-24 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7251270
• 关键词: Anxiety; Area; Arousal; Behavior; Biomechanics; Brain Stem; Characteristics; Chronic Fatigue Syndrome; Clinical; Developed Countries; Development; Disease; Emotional; Epidemiologic Studies; Exposure to; Fire - disasters; Generations; Goals; Health; Human; Impairment; Individual; Individual Differences; Intervention; Investigation; Mediating; Mental Depression; Motor; Motor Neurons; Muscle; Musculoskeletal Diseases; Neck; Neuraxis; Neuromodulator; Patients; Pattern; Physiological; Play; Prevalence; Psychosocial Factor; Psychosocial Stress; Rate; Research; Rest; Risk; Risk Factors; Role; Shoulder; Sleep Deprivation; Source; Spinal; Spinal Cord; Stress; Synapses; Techniques; Testing; Time; Unit of Measure; Water; Work; Workplace; base; human subject; improved; musculoskeletal injury; neuromuscular function; novel; prevent; response; trait; trapezius muscle

DESCRIPTION (provided by applicant): Although biomechanical and psychosocial variables have been identified as independent risk factors in the development of musculoskeletal injury, physiologic mechanisms that underlie potential interactions among these risk factors remain poorly understood. Monoaminergic inputs to spinal motor neurons are correlated with levels of physiologic arousal and generate persistent inward currents (PICs) that function to amplify existing sources of excitatory synaptic input to the motor neuron pool. These findings suggest a novel mechanism of stress-related musculoskeletal injury in which heightened physiologic arousal is proposed to cause an increase in tonic excitability of spinal motor neurons that is mediated by the enhanced activation of persistent inward currents. Three specific aims will test this hypothesis using the paired motor unit analysis technique to estimate the magnitude of persistent inward currents in human subjects by comparing the discharge rates of a low threshold motor unit (control unit) measured at the time of recruitment and derecruitment of a slightly higher threshold motor unit (test unit). Aim 1 will compare the contribution of persistent inward currents to single motor unit activity during voluntary contractions of the upper trapezius muscle when subjects are exposed to low and high levels of psychosocial stress. To determine whether persistent inward currents contribute to patterns of muscle activation that have been shown to increase the risk of musculoskeletal injury, Aim 2 will determine the association between PIC estimates and sustained motor unit activity during intermittent rest breaks following exposure to low and high levels of psychosocial stress. Based on findings that some individuals are more susceptible to the negative effects of psychosocial stress on neuromuscular function, Aim 3 will determine the effect of individual differences in trait and state anxiety on stress-induced physiologic arousal and PIC contributions to motor unit activity. Findings from this research will provide the first evidence to support a functional role for intrinsic mechanisms in regulating the tonic excitability of spinal motor neurons with changes in arousal in human subjects.

描述（由申请人提供）：尽管生物力学和心理社会变量已被确定为肌肉骨骼损伤发展的独立风险因素，但对这些风险因素之间潜在相互作用的生理机制仍知之甚少。对脊髓运动神经元的单胺能输入与生理唤醒水平相关，并产生持续性内向电流（PIC），其作用是放大对运动神经元池的兴奋性突触输入的现有来源。这些研究结果表明，一种新的机制，压力相关的肌肉骨骼损伤，其中提出了提高生理唤醒引起的强直性兴奋性的脊髓运动神经元，这是介导的增强激活的持续性内向电流。三个具体目标将使用配对运动单位分析技术来检验该假设，通过比较在略高阈值运动单位（测试单位）的募集和去募集时测量的低阈值运动单位（对照单位）的放电率来估计人类受试者中持续内向电流的幅度。目标1将比较当受试者暴露于低水平和高水平的心理社会压力时，上斜方肌自主收缩期间持续内向电流对单个运动单位活动的贡献。为了确定持续的内向电流是否有助于已被证明会增加肌肉骨骼损伤风险的肌肉激活模式，目标2将确定暴露于低水平和高水平心理社会压力后间歇性休息期间PIC估计值与持续运动单位活动之间的关联。基于一些个体更容易受到心理社会应激对神经肌肉功能的负面影响的研究结果，目标3将确定特质和状态焦虑的个体差异对应激诱导的生理唤醒和PIC对运动单位活动的贡献的影响。这项研究的结果将提供第一个证据来支持内在机制在调节人类受试者觉醒变化的脊髓运动神经元的紧张性兴奋性中的功能作用。