Wiesman Alex I, Heinrichs-Graham Elizabeth, Coolidge Nathan M, Gehringer James E, Kurz Max J, Wilson Tony W
Department of Neurological Sciences.
Center for Magnetoencephalography.
J Physiol. 2017 Feb 15;595(4):1365-1375. doi: 10.1113/JP273192. Epub 2016 Dec 12.
Sensory gating is important for preventing excessive environmental stimulation from overloading neural resources. Gating in the human somatosensory cortices is a critically understudied topic, particularly in the lower extremities. We utilize the unique capabilities of magnetoencephalographic neuroimaging to quantify the normative neural population responses and dynamic functional connectivity of somatosensory gating in the lower extremities of healthy human participants. We show that somatosensory processing is subserved by a robust gating effect in the oscillatory domain, as well as a dynamic effect on interhemispheric functional connectivity between primary sensory cortices. These results provide novel insight into the dynamic neural mechanisms that underlie the processing of somatosensory information in the human brain, and will be vital in better understanding the neural responses that are aberrant in gait-related neurological disorders (e.g. cerebral palsy).
Sensory gating (SG) is a phenomenon in which neuronal responses to subsequent similar stimuli are weaker, and is considered to be an important mechanism for preventing excessive environmental stimulation from overloading shared neural resources. Although gating has been demonstrated in multiple sensory systems, the neural dynamics and developmental trajectory underlying SG remain poorly understood. In the present study, we adopt a data-driven approach to map the spectrotemporal amplitude and functional connectivity (FC) dynamics that support gating in the somatosensory system (somato-SG) in healthy children and adolescents using magnetoencephalography (MEG). These data underwent time-frequency decomposition and the significant signal changes were imaged using a beamformer. Voxel time series were then extracted from the peak voxels and these signals were examined in the time and time-frequency domains, and then subjected to dynamic FC analysis. The results obtained indicate a significant decrease in the amplitude of the neural response following the second stimulation relative to the first in the primary somatosensory cortex (SI). A significant decrease in response latency was also found between stimulations, and each stimulation induced a sharp decrease in FC between somatosensory cortical areas. Furthermore, there were no significant correlations between somato-SG metrics and age. We conclude that somato-SG can be observed in SI in both the time and oscillatory domains, with rich dynamics and alterations in inter-hemispheric FC, and that this phenomenon has already matured by early childhood. A better understanding of these dynamics may provide insight to the numerous psychiatric and neurologic conditions that have been associated with aberrant SG across multiple modalities.
感觉门控对于防止过多的环境刺激使神经资源过载很重要。人类躯体感觉皮层中的门控是一个研究严重不足的主题，尤其是在下肢方面。我们利用脑磁图神经成像的独特能力来量化健康人类参与者下肢体感门控的标准神经群体反应和动态功能连接。我们表明，体感处理在振荡域中由强大的门控效应以及对初级感觉皮层之间半球间功能连接的动态效应所支持。这些结果为人类大脑中体感信息处理背后的动态神经机制提供了新的见解，对于更好地理解与步态相关的神经系统疾病（如脑瘫）中异常的神经反应至关重要。
感觉门控（SG）是一种神经元对后续相似刺激的反应较弱的现象，被认为是防止过多环境刺激使共享神经资源过载的重要机制。尽管门控已在多个感觉系统中得到证实，但SG背后的神经动力学和发育轨迹仍知之甚少。在本研究中，我们采用数据驱动的方法，使用脑磁图（MEG）来绘制支持健康儿童和青少年体感系统（体感SG）门控的频谱时间幅度和功能连接（FC）动态。这些数据经过时频分解，显著的信号变化使用波束形成器成像。然后从峰值体素中提取体素时间序列，并在时间和时频域中检查这些信号，然后进行动态FC分析。获得的结果表明，相对于第一次刺激，初级躯体感觉皮层（SI）中第二次刺激后神经反应的幅度显著降低。刺激之间还发现反应潜伏期显著缩短，并且每次刺激都会导致体感皮层区域之间的FC急剧下降。此外，体感SG指标与年龄之间没有显著相关性。我们得出结论，在SI的时间和振荡域中都可以观察到体感SG，具有丰富的动态变化和半球间FC的改变，并且这种现象在幼儿期就已经成熟。更好地理解这些动态变化可能有助于深入了解与跨多种模式的异常SG相关的众多精神和神经疾病。
