Mechanisms of Stochastic Resonance in Human Postural Control

将身体稳定在直立位置的复杂任务对于进行许多日常活动和避免跌倒至关重要。尽管这一点很重要，但平衡控制仍然没有被完全理解。最近，一种被称为随机共振的现象被用来深入了解和加强站立过程中的平衡控制。它描述了一种使用噪声来改进各种系统中弱信号的检测和传输的机制。随机共振是基于这样一个概念，即通过系统的信息流可以通过最佳的噪声水平最大化。虽然这种噪音对感觉系统的影响已经被记录在案，但它的好处在多大程度上延伸到大脑内的过程还不清楚。因此，在感觉噪声存在的情况下，改善平衡控制不仅是更好的信号检测的结果，也可能是大脑高级区域活动增加的结果。 根据我在平衡控制方面的经验，这个研究项目的长期目标是了解通过感觉噪音改善姿势的中枢和外周机制。为了达到这一目标，第一个目标是提供机械证据，证明感官噪声对处理速度的影响，这是平衡控制的关键因素。我们将使用一个简单的反应时间任务来确定噪音引起的反应时间变化与大脑活动的不同状态之间的关系。第二个目标是确定反应性平衡控制的生理和行为因素，这些因素会因感觉噪声而改变。与安静的直立不同，扰乱的站立范式将允许我们在中央处理的感觉和运动阶段分离噪音增强的活动。此外，来自反应性平衡控制的见解将为开发减少通过感觉噪声造成的平衡障碍的干预措施提供良好的科学基础。在这两项研究中，噪音引起的变化将通过生理和行为测量(大脑和肌肉活动、唤醒等)来捕捉。 感觉噪音对安静的直立站立的影响已经被记录在案。然而，我们对它对功能上更相关的任务，如无功平衡控制的影响的了解是有限的。与此同时，目前还不清楚噪音引起的变化是否与大脑高级区域活动增加有关。为了解决这些不足，我们将表征感官噪声对处理速度和反应平衡控制的其他因素的影响。我们期待在人类系统和职能领域做出重要贡献。首先，我们将确定是否可以通过感觉噪音来缩短反应时间，以及潜在的影响如何依赖于大脑内部的噪音。其次，大脑某些区域活动的变化将表明，感觉噪音不仅增强了感觉检测，而且还增强了与执行平衡反应相关的中央处理。最后，我们将表征感觉噪声对反应性姿势控制的影响，这取决于噪声通道及其在恢复任务中的参与。虽然预期的贡献在本质上是基本的，但它们也将对人类健康和绩效等应用领域产生重要影响。例如，年轻人和老年人之间的预期比较将成为机械知情研究的理想垫脚石，这些研究利用感官噪音来降低加拿大老年人跌倒的风险。高素质的人员将在多学科环境中接受培训，以建设应对未来医疗保健系统挑战的能力。

The complex task of stabilizing the body in an upright position is critical for performing many daily activities and avoiding falls. In spite of this importance, balance control is still not fully understood. Recently, a phenomenon called stochastic resonance has been used to gain insights into and enhance balance control during standing. It describes a mechanism that uses noise to improve the detection and transmission of weak signals in various systems. Stochastic resonance is based on the concept that the flow of information through a system can be maximized by an optimal level of noise. While the effect of such noise on the sensory system has been documented, it is unclear to what degree its benefits extend to processes within the brain. Accordingly, it is possible that improved balance control in the presence of sensory noise is a result not only of better signal detection, but also of increased activity in higher brain areas. Building upon my experience in balance control, the long-term objective of this research program is to understand the central and peripheral mechanisms that are responsible for postural improvements via sensory noise. To reach this goal, the first objective is to deliver mechanistic evidence for the effect of sensory noise on speed of processing, a key factor of balance control. We will use a simple reaction time task to determine the relationship between noise-evoked changes in reaction times and various states of brain activity. The second objective is to identify physiological and behavioural factors of reactive balance control that are changed by sensory noise. In contrast to quiet upright standing, a perturbed standing paradigm will allow us to isolate noise-enhanced activity at both the sensory and motor stages of central processing. In addition, insights from reactive balance control will provide a good scientific basis for developing interventions that reduce balance impairments via sensory noise. In both lines of research, noise-evoked changes will be captured by physiological and behavioural measures (brain and muscle activity, arousal, etc.). The effect of sensory noise on quiet upright standing has been documented. However, our understanding of its impact on functionally more relevant tasks such as reactive balance control is limited. At the same time, it is unclear if noise-induced changes are linked to increased activity of higher brain areas. To address these shortfalls, we will characterize the influence of sensory noise on speed of processing and other factors of reactive balance control. We expect to make important contributions in the area of human systems and functions. First, we will determine whether reaction times can be reduced via sensory noise and how a potential effect depends on internal noise within the brain. Second, changes to the activity in certain brain areas will indicate that sensory noise does not only enhance sensory detection, but also central processing associated with the execution of a balance response. Finally, we will characterize effects of sensory noise on reactive postural control in dependence of the noise modality and its involvement in the recovery task. While the expected contributions are fundamental in nature, they will also have important implications for applied fields such as human health and performance. For example, the intended comparison between young and elderly individuals will serve as an ideal stepping stone for mechanistically informed studies that use sensory noise to reduce fall risk in elderly Canadians. Highly qualified personnel will be trained in a multidisciplinary environment to build capacity for future challenges of our health care system.