Aging-related decline in somatosensory inhibition of the human cerebral cortex
Aging-related decline in somatosensory inhibition of the human cerebral cortex
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DOI：
10.1007/s00221-013-3420-9
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发表时间：
2013-04-01
影响因子：
2
通讯作者：
Lin, Yung-Yang
中科院分区：
文献类型：
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作者：
Cheng, Chia-Hsiung;Lin, Yung-Yang
对重复刺激的初级躯体感觉（SI）皮层抑制倾向于随年龄增长而下降。然而，年龄对次级躯体感觉皮层（SII）抑制机制的影响仍然是难以捉摸的。我们的目的是研究人类躯体感觉系统中皮层抑制的年龄相关变化。记录了21名青年和20名老年男性对正中神经双脉冲电刺激的神经磁反应。SI和SII活动的配对脉冲抑制（PPS）通过对刺激2的响应与对刺激1的响应的比率来估计。基于等效电流偶极子模型，老年受试者对侧（SIIc）和同侧（SIIi）次级躯体感觉皮层的PPS比率高于年轻受试者（SIIc p < 0.001，SIIi p = 0.034）。在个体基础上，20名老年参与者中有16名（80%）的SIIc的PPS比率高于SI;相比之下，年轻参与者中SIIc和SI皮质的PPS比率相似（p = 0.031）。总之，老年人的PPS比率较大，表明躯体感觉皮层抑制的年龄相关性下降。此外，与SI相比，SII皮层的电生理反应在皮层对重复刺激的抑制方面特别容易受到老化的影响。
Primary somatosensory (SI) cortical inhibition to repetitive stimuli tends to decline with increasing age. However, aging effects on the inhibition mechanism of secondary somatosensory cortex (SII) remain elusive. We aimed to study the aging-related changes of cortical inhibition in the human somatosensory system. Neuromagnetic responses to paired-pulse electrical stimulation to the median nerve were recorded in 21 young and 20 elderly male adults. Paired-pulse suppression (PPS) of SI and SII activities was estimated by the ratio of the response to Stimulus 2 to the response to Stimulus 1. Based on equivalent current dipole modeling, PPS ratios of the contralateral (SIIc) and ipsilateral (SIIi) secondary somatosensory cortices were higher in elderly than in young subjects (p < 0.001 in SIIc and p = 0.034 in SIIi). At an individual basis, a higher PPS ratio in SIIc than in SI was found in 16 (80 %) out of the 20 elderly participants; in contrast, the PPS ratios of SIIc and SI cortices were similar in young participants (p = 0.031). In conclusion, a larger PPS ratio in elderly suggests an aging-related decline in somatosensory cortical inhibition. Furthermore, compared to SI, the electrophysiological responses of SII cortex are especially vulnerable to aging in terms of cortical inhibition to repetitive stimulation.