Impaired Tactile Acuity in Old Age Is Accompanied by Enlarged Hand Representations in Somatosensory Cortex
Impaired Tactile Acuity in Old Age Is Accompanied by Enlarged Hand Representations in Somatosensory Cortex
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DOI：
10.1093/cercor/bhn190
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发表时间：
2009-07-01
期刊：
影响因子：
3.7
通讯作者：
Tegenthoff, Martin
中科院分区：
文献类型：
--
作者：
Kalisch, Tobias;Ragert, Patrick;Tegenthoff, Martin
人类手在初级体感皮层（SI）中的表征经历了连续的适应性可塑性过程，这些过程源于学习、改变使用或损伤。由此产生的重组影响皮层地图的大小、范围和位置，这与触觉行为的变化相似，表明地图变化与感知之间的密切关系。本研究探讨健康老化对手皮层表征和触觉表现的影响。结合电源定位，我们发现在60-85岁的老年人中，食指和小指偶极子之间的距离增加，表明SI内的表征扩大了约40%。同一研究对象的触觉空间2点辨别阈值随年龄的增长而明显下降。这些结果表明，健康衰老强烈影响SI内手部表征的小样结构。在学习过程中，通常在年轻人和成人受试者中观察到的地图扩展与表现的提高有关。虽然学习相关图谱的变化被认为是突触连接特异性增强的结果，但我们认为年龄相关图谱的变化与随着年龄增长而发生的皮质内抑制的减少有关。
The representations of the human hand in primary somatosensory cortex (SI) undergo continuous adaptational plastic processes, which arise from learning, altered use, or injury. The resulting reorganization affects size, extent, and position of the cortical maps, which parallels alterations of tactile behavior indicating a close relationship between map changes and perception. Here we investigate the influence of healthy aging on the cortical hand representation and on age-related changes of tactile performance. Using somatosensory evoked potential mapping in combination with electric source localization, we found that in elderly subjects aged 60-85 years the distance between the dipoles of the index and the little fingers increased indicating an expansion of the representations within SI by approximately 40%. Assessment of tactile spatial 2-point discrimination thresholds in the same subjects showed a strong decline with age. These results indicate that healthy aging strongly affects the homuncular structures of the hand representations within SI. Map expansion typically observed in young and adult subjects during learning is associated with a gain in performance. Whereas learning-related map changes are assumed to result from specific strengthening of synaptic connections, we suggest that the age-related map changes are related to the reduction of intracortical inhibition developing with age.