Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, NE, USA.
Center for Magnetoencephalography, University of Nebraska Medical Center (UNMC), Omaha, NE, USA.
Cereb Cortex. 2019 Feb 1;29(2):680-688. doi: 10.1093/cercor/bhx349.
Sensory gating is a neurophysiological process whereby the response to a second stimulus in a pair of identical stimuli is attenuated, and it is thought to reflect the capacity of the CNS to preserve neural resources for behaviorally relevant stimuli. Such gating is observed across multiple sensory modalities and is modulated by age, but the mechanisms involved are not understood. In this study, we examined somatosensory gating in 68 healthy adults using magnetoencephalography (MEG) and advanced oscillatory and time-domain analysis methods. MEG data underwent source reconstruction and peak voxel time series data were extracted to evaluate the dynamics of somatosensory gating, and the impact of spontaneous neural activity immediately preceding the stimulation. We found that gating declined with increasing age and that older adults had significantly reduced gating relative to younger adults, suggesting impaired local inhibitory function. Most importantly, older adults had significantly elevated spontaneous activity preceding the stimulation, and this effect fully mediated the impact of aging on sensory gating. In conclusion, gating in the somatosensory system declines with advancing age and this effect is directly tied to increased spontaneous neural activity in the primary somatosensory cortices, which is likely secondary to age-related declines in local GABA inhibitory function.
感觉门控是一种神经生理过程，即一对相同刺激中的第二个刺激的反应减弱，它被认为反映了中枢神经系统为行为相关刺激保存神经资源的能力。这种门控在多种感觉模式中都有观察到，并受到年龄的调节，但涉及的机制尚不清楚。在这项研究中，我们使用脑磁图（MEG）和先进的振荡和时域分析方法，检查了 68 名健康成年人的体感门控。MEG 数据进行了源重建，提取了峰值体素时间序列数据，以评估体感门控的动力学以及刺激前自发神经活动的影响。我们发现，随着年龄的增长，门控能力下降，与年轻人相比，老年人的门控能力明显降低，这表明局部抑制功能受损。最重要的是，老年人在刺激前有明显升高的自发活动，而这种效应完全介导了年龄对感觉门控的影响。总之，随着年龄的增长，体感系统的门控能力下降，这种效应与初级体感皮层中自发神经活动的增加直接相关，这可能是 GABA 局部抑制功能随年龄下降的结果。
