Cheng Chia-Hsiung, Chan Pei-Ying S, Baillet Sylvain, Lin Yung-Yang
Department of Occupational Therapy and Graduate Institute of Behavioral Sciences, Chang Gung University, Taoyuan, Taiwan ; Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan.
McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, No. 3801, University Street, Montreal, QC, Canada H3A 2B4.
Neural Plast. 2015;2015:302878. doi: 10.1155/2015/302878. Epub 2015 Aug 31.
Sensory gating (SG), referring to an attenuated neural response to the second identical stimulus, is considered as preattentive processing in the central nervous system to filter redundant sensory inputs. Insufficient somatosensory SG has been found in the aged adults, particularly in the secondary somatosensory cortex (SII). However, it remains unclear which variables leading to the age-related somatosensory SG decline. There has been evidence showing a relationship between brain oscillations and cortical evoked excitability. Thus, this study used whole-head magnetoencephalography to record responses to paired-pulse electrical stimulation to the left median nerve in healthy young and elderly participants to test whether insufficient stimulus 1- (S1-) induced event-related desynchronization (ERD) contributes to a less-suppressed stimulus 2- (S2-) evoked response. Our analysis revealed that the minimum norm estimates showed age-related reduction of SG in the bilateral SII regions. Spectral power analysis showed that the elderly demonstrated significantly reduced alpha ERD in the contralateral SII (SIIc). Moreover, it was striking to note that lower S1-induced alpha ERD was associated with higher S2-evoked amplitudes in the SIIc among the aged adults. Conclusively, our findings suggest that age-related decline of somatosensory SG is partially attributed to the altered S1-induced oscillatory activity.
感觉门控（SG）是指对第二个相同刺激的神经反应减弱，被认为是中枢神经系统中的预注意处理过程，用于过滤冗余的感觉输入。在老年人中发现体感SG不足，尤其是在次级体感皮层（SII）。然而，尚不清楚哪些变量导致与年龄相关的体感SG下降。有证据表明脑振荡与皮层诱发兴奋性之间存在关联。因此，本研究使用全脑磁脑电图记录健康年轻和老年参与者对左侧正中神经的双脉冲电刺激的反应，以测试刺激1（S1）诱发的事件相关去同步化（ERD）不足是否导致刺激2（S2）诱发反应的抑制减弱。我们的分析显示，最小范数估计表明双侧SII区域中SG存在与年龄相关的降低。频谱功率分析表明，老年人对侧SII（SIIc）中的α波ERD显著降低。此外，值得注意的是，在老年人中，较低的S1诱发的α波ERD与SIIc中较高的S2诱发振幅相关。总之，我们的研究结果表明，与年龄相关的体感SG下降部分归因于S1诱发的振荡活动改变。
