Center for Social and Affective Neuroscience, Linköping University, Sweden.
Center for Social and Affective Neuroscience, Linköping University, Sweden.
Neuroscience. 2021 Jun 1;464:53-58. doi: 10.1016/j.neuroscience.2021.02.015. Epub 2021 Feb 17.
Ageing is accompanied by a steady decline in touch sensitivity and acuity. Conversely, pleasant touch, such as experienced during a caress, is even more pleasant in old age. There are many physiological changes that might explain these perceptual changes, but researchers have not yet identified any specific mechanisms. Here, we review both the perceptual and structural changes to the touch system that are associated with ageing. The structural changes include reduced elasticity of the skin in older people, as well as reduced numbers and altered morphology of skin tactile receptors. Effects of ageing on the peripheral and central nervous systems include demyelination, which affects the timing of neural signals, as well as reduced numbers of peripheral nerve fibres. The ageing brain also undergoes complex changes in blood flow, metabolism, plasticity, neurotransmitter function, and, for touch, the body map in primary somatosensory cortex. Although several studies have attempted to find a direct link between perceptual and structural changes, this has proved surprisingly elusive. We also highlight the need for more evidence regarding age-related changes in peripheral nerve function in the hairy skin, as well as the social and emotional aspects of touch.
随着年龄的增长，触觉的敏感性和敏锐度会逐渐下降。相反，愉快的触觉，如抚摸时所体验到的，在老年时更加令人愉悦。有许多生理变化可以解释这些感知变化，但研究人员尚未确定任何特定的机制。在这里，我们回顾了与衰老相关的触觉系统的感知和结构变化。结构变化包括老年人皮肤弹性降低，以及皮肤触觉感受器数量减少和形态改变。衰老对周围和中枢神经系统的影响包括脱髓鞘，这会影响神经信号的定时，以及外周神经纤维数量减少。衰老的大脑在血流、代谢、可塑性、神经递质功能以及触觉方面，在初级体感皮层中的身体图也会发生复杂的变化。尽管有几项研究试图找到感知和结构变化之间的直接联系，但这一联系却出人意料地难以捉摸。我们还强调了需要更多关于毛发皮肤外周神经功能与年龄相关变化以及触觉的社会和情感方面的证据。
