Characterizing Brain Activation and Postural Response During Concurrent Cognitive Tasks in the Presence of Optic Flow Stimulation: A Functional Near-Infrared Spectroscopy Study

项目摘要 人体姿势控制涉及来自视觉、躯体感觉和前庭输入的多个感觉整合。 由于随着年龄的增长，躯体感觉和前庭功能下降， 用于维持老年人平衡的感觉输入。研究使用光流（OF）来检查效果 视觉输入对姿势控制的影响。而光流刺激可以通过传统的PC显示器呈现 随着消费级虚拟现实（VR）头戴式显示器的出现，提供了新的选择。一个 沉浸式VR环境是有利，因为它可以提供OF刺激以引起自运动错觉 这会引起姿势反应，同时也会将受试者与外界刺激隔离开来。除了视觉 注意力对于老年人保持良好的平衡至关重要。研究使用了双重任务 范例，例如执行与平衡任务沿着的认知任务，以检查 与姿势控制相关的需求。然而，感觉统合加工的机制和 在真实的平衡任务中， 并发认知任务。一种新的神经成像方法，功能近红外光谱（fNIRS）， 为我们提供了探索人脑中姿势控制的潜在机制的机会。的 本研究的目的是调查生理限制时，处理的信息和观察 双任务条件下的神经资源分配。在这项研究中，健康的年轻人（年龄25-45岁， n = 24），健康的老年人（年龄65-85岁，n = 24），以及基于STEADI有跌倒风险的老年人 和临床平衡/步态评估（年龄65-85岁，n = 24）将被招募。在首次访视中，受试者将 要求佩戴VR头戴式显示器，该显示器将呈现OF刺激。粒子运动速度将 在六个级别之间变化，0 m/s（静态）、5 m/s、10 m/s、15 m/s、20 m/s和25 m/s。非静态OF速度将 在块体设计（A1-B-A2）中收缩到静态OF（0 m/s），总共六种条件。每个块将 持续30秒。在第二次访视中，受试者将在接受 以5 m/s和20 m/s的速度进行OF刺激。在两次研究访视期间，将使用fNIRS测量 感兴趣区域（ROI）中的脑活动，包括双侧前额叶皮质、上级颞区和 颞顶交界处我们将比较ROI中的组、性别和半球差异。一 重复测量方差分析将用于分析反应时间和姿势摇摆数据，以检查 组（年轻人、老年人和有跌倒风险的老年人）、OF速度（6种OF速度）、块（A1、B和 A2）以及它们之间的相互作用。

PROJECT SUMMARY Human postural control involves multiple sensory integrations from visual, somatosensory, and vestibular inputs. Due to a decline in somatosensation and vestibular function that occurs with aging, vision becomes the dominant sensory input used to maintain balance in elderly adults. Studies have used optic flow (OF) to examine the effect of visual input on postural control. While optic flow stimulus can be presented through traditional PC monitor setups, the advent of consumer grade virtual reality (VR) head mounted displays has provided new options. An immersive VR environment is advantageous because it can provide OF stimulus to induce a self-motion illusion that provokes postural responses while also isolating the subject from outside stimuli. In addition to visual information, attention is critical for older individuals to maintain good balance. Studies have used dual-task paradigms, such as performing a concurrent cognitive task along with a balance task, to examine the cognitive demands associated with postural control. However, the mechanisms of sensory integration processing and neural resource allocation in the human brain have not been fully investigated in real balance tasks with concurrent cognitive tasks. A novel neuroimaging method, functional near-infrared spectroscopy (fNIRS), provides us the opportunity to explore the underlying mechanism of postural control in the human brain. The purpose of this research is to investigate physiological limitations when processing OF information and observe the neural resource allocation during dual-task conditions. In this study, healthy younger adults (aged 25-45 y.o., n = 24), healthy older adults (aged 65-85 y.o., n = 24), and older adults at risk of falling based on the STEADI and clinical balance/gait assessments (aged 65-85 y.o., n = 24) will be recruited. In the first visit subjects will be asked to wear a VR head mounted display that will present the OF stimulation. Particle movement speed will vary between six levels, 0 m/s (static), 5m/s, 10 m/s, 15 m/s, 20 m/s, and 25 m/s. The nonstatic OF speeds will be contracted to the static OF (0 m/s) in a block design, (A1-B-A2), for a total of six conditions. Each block will last for 30 seconds. In the second visit, the subjects will perform two auditory reaction time tasks while receiving OF stimulation at the speeds of 5 m/s and 20 m/s. During the two study visits fNIRS will be used to measure brain activity in regions of interest (ROIs) including the bilateral prefrontal cortices, superior temporal areas, and temporoparietal junctions. We will compare the group, gender, and hemisphere differences in the ROIs. A repeated measure ANOVA will be used to analyze the reaction time and postural sway data to examine the effects of Group (younger, older, and older adults with fall risks), OF speed (six OF speeds), Block (A1, B, and A2), and their interactions.