Age-related changes in brain function are complex. Although ageing is associated with a reduction in cerebral blood flow and neuronal activity, task-related processing is often correlated with an enlargement of the corresponding and additionally recruited brain areas. This supplemental employment is considered an attempt to compensate for deficits in the ageing brain. Although there are contradictory reports regarding the role of the primary somatosensory cortex (SI), currently, there is little knowledge about age-related functional changes in other brain areas in the somatosensory network (secondary somatosensory cortex (SII), and insular, anterior (ACC) and posterior cingulate cortices (PCC)). We investigated 16 elderly (age range, 62-71 years) and 18 young subjects (age range, 21-28 years) by determining the current perception threshold (CPT) and applying functional magnetic resonance imaging (fMRI) using a 3.0 Tesla scanner under tactile stimulation of the right hand. CPT was positively correlated with age. fMRI analysis revealed significantly increased activation in the contralateral SI and ipsilateral motor cortex in elderly subjects. Furthermore, we demonstrated age-related reductions in the activity in the SII, ACC, PCC, and dorsal parts of the corpus callosum. Our study revealed dramatic age-related differences in the processing of a simple tactile stimulus in the somatosensory network. Specifically, we detected enhanced activation in the contralateral SI and ipsilateral motor cortex assumingly caused by deficient inhibition and decreased activation in later stages of somatosensory processing (SII, cingulate cortex) in elderly subjects. These results indicate that, in addition to over-activation to compensate for impaired brain functions, there are complex mechanisms of modified inhibition and excitability involved in somatosensory processing in the ageing brain.

译文

与年龄相关的脑功能变化是复杂的。尽管衰老与脑血流量和神经元活动减少有关,但与任务相关的处理通常与相应和额外招募的大脑区域的扩大有关。这种补充就业被认为是弥补大脑老化缺陷的一种尝试。尽管关于初级体感皮层 (SI) 的作用有相互矛盾的报道,但目前,关于体感网络中其他大脑区域 (次级体感皮层 (SII) 和岛状,前部 (ACC) 和后部扣带回 (PCC))。我们通过确定当前感知阈值 (CPT) 并使用3.0特斯拉扫描仪在右手的触觉刺激下应用功能磁共振成像 (fMRI),调查了16位老年人 (年龄范围,62-71岁) 和18位年轻受试者 (年龄范围,21-28岁)。CPT与年龄呈正相关。fMRI分析显示,老年受试者对侧SI和同侧运动皮层的激活显着增加。此外,我们证明了与年龄相关的SII,ACC,PCC和call体背侧活动的减少。我们的研究揭示了体感网络中简单触觉刺激处理过程中与年龄相关的显着差异。具体来说,我们检测到对侧SI和同侧运动皮层的激活增强,假定是由于老年受试者的体感加工 (SII,扣带回皮层) 后期的抑制不足和激活减少所致。这些结果表明,除了过度激活以补偿大脑功能受损外,衰老大脑的体感过程还涉及改良的抑制和兴奋性的复杂机制。

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