Neurobiological Substrates of Visual-Somatosensory Integration in Aging

摘要 一个迅速发展的被称为多感觉整合(MSI)的认知神经科学领域正在研究 同时处理感官信息的复杂性。首先，对MSI进行了调查 三种主要感官(即视觉、听觉和体感系统)的配对，这三种感官通常是 称为：听觉-躯体感觉(AS)、听觉-视觉(AV)和视觉-躯体感觉(VS)。 组合。跨多个感觉通道的并发信息的成功集成对于 在现实世界中运作，完成日常生活活动，以及行动能力。 到目前为止，只有很少的研究研究了老年人的多感官加工，并且主要是 重点关注影音互动。将MSI与现实世界活动联系起来的人仍然很少。一项研究的结果 在我们实验室进行的研究表明，与年轻人相比，老年人表现出 在处理并发信息与信息时，反应时获益显著更大；两种感觉模式 这显然对日常步态和平衡起着重要作用。此外，我们最新的研究表明 衰老时多感觉加工的不同模式，其中较大(即较差)的个体与 多感官效应表现出更差的静态平衡，报告更多的跌倒，并支持更少的参与 与老年人相比，体力活动对MSI的影响较小。这些结果支持了这一观点 行为测量的VS整合可能反映了与年龄相关的单一感觉的生理衰退 正在处理。 VS对老年人信息处理的促进作用具有重大的公共卫生影响 由于单感视觉和躯体感觉障碍与功能衰退有关，增加了 跌倒的风险，步态速度变慢，生活质量变差。此外，MSI的影响也被归因于 衰老过程中神经元结构的基本退行性变化；然而，这一推测 解释还有待经验性的检验。此外，功能和结构上的神经联系 VS在衰老中的整合尚未建立--VS神经生物学底物的确定 老年人衰老的整合及其与各种运动结果的关联 将在某一天帮助确定引入认知和物理补救的机会是至关重要的 合并VS增强策略以努力保持功能独立性的计划。

ABSTRACT A rapidly growing field of cognitive neuroscience referred to as multisensory integration (MSI) investigates the complexities of processing simultaneous sensory information. Primarily, MSI has been investigated in pairings of the three “major” senses (i.e., visual, auditory, and somatosensory systems), which are typically referred to as: auditory-somatosensory (AS), auditory-visual (AV), and visual-somatosensory (VS) combinations. Successful integration of concurrent information across multiple sensory modalities is crucial for functioning in the real world, completion of activities of daily living, and mobility. To date, only few studies have investigated multisensory processing in older adults and have predominately focused on AV interactions. Fewer still have related MSI to real world activities. Results from a study conducted in our laboratory revealed that compared to younger adults, older adults demonstrated a significantly larger reaction time benefit when processing concurrent VS information; two sensory modalities that clearly play an important role in everyday gait and balance. Further, our most recent work indicates differential patterns of multisensory processing in aging where individuals with larger (i.e., worse) VS multisensory effects manifested worse static balance, reported more falls, and endorsed less engagement in physical activities compared to elders with smaller MSI effects. These results provide support for the notion that VS integration measured behaviorally might reflect age-related physiological declines in unisensory processing. The facilitative benefit of VS information processing in older adults has major public health implications since unisensory visual and somatosensory impairments have been linked to functional decline, increased risks of falls, slower gait velocity, and poorer quality of life. Additionally, the effect of MSI has been attributed to basic degenerative changes in neuronal architecture during the aging process; however, this speculative interpretation has yet to be empirically tested. Furthermore, the functional and structural neural correlates of VS integration in aging have not been established - determining the neurobiological substrates of VS integration in aging and the association of such enhancement with various motor outcomes in older adults would be paramount to one day help identify opportunities to introduce cognitive and physical remediation programs that incorporate VS enhancement strategies in an effort to maintain functional independence.