Graduate Course of Health and Social Work, Kanagawa University of Human Services, Yokosuka City, Kanagawa, Japan.
Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata City, Niigata, Japan; Department of Physical Therapy, Niigata University of Health and Welfare, Niigata City, Niigata, Japan.
Neuroimage. 2024 Oct 1;299:120834. doi: 10.1016/j.neuroimage.2024.120834. Epub 2024 Sep 3.
Grating orientation discrimination (GOD) is commonly used to assess somatosensory spatial processing. It allows discrimination between parallel and orthogonal orientations of tactile stimuli applied to the fingertip. Despite its widespread application, the underlying mechanisms of GOD, particularly the role of cortico-cortical interactions and local brain activity in this process, remain elusive. Therefore, we aimed to investigate how a specific cortico-cortical network and inhibitory circuits within the primary somatosensory cortex (S1) and secondary somatosensory cortex (S2) contribute to GOD.
In total, 51 healthy young adults were included in our study. We recorded resting-state magnetoencephalography (MEG) and somatosensory-evoked magnetic field (SEF) in participants with open eyes. We converted the data into a source space based on individual structural magnetic resonance imaging. Next, we estimated S1- and S2-seed resting-state functional connectivity (rs-FC) at the alpha and beta bands through resting-state MEG using the amplitude envelope correlation method across the entire brain (i.e., S1/S2-seeds × 15,000 vertices × two frequencies). We assessed the inhibitory response in the S1 and S2 from SEFs using a paired-pulse paradigm. We automatically measured the GOD task in parallel and orthogonal orientations to the index finger, applying various groove widths with a custom-made device.
We observed a specific association between the GOD threshold (all P < 0.048) and the alpha rs-FC in the S1-superior parietal lobule and S1-adjacent to the parieto-occipital sulcus (i.e., lower rs-FC values corresponded to higher performance). In contrast, no association was observed between the local responses and the threshold.
The results of this study underpin the significance of specific cortico-cortical networks in recognizing variations in tactile stimuli.
栅格方位辨别（GOD）常用于评估躯体感觉空间加工。它可以辨别施加于指尖的触觉刺激的平行和正交方位。尽管它的应用广泛，但 GOD 的潜在机制，特别是皮质-皮质相互作用和初级躯体感觉皮层（S1）和次级躯体感觉皮层（S2）内局部脑活动在这个过程中的作用，仍然难以捉摸。因此，我们旨在研究特定的皮质-皮质网络以及初级躯体感觉皮层（S1）和次级躯体感觉皮层（S2）内的抑制性回路如何有助于 GOD。
共有 51 名健康年轻成年人参与了我们的研究。我们在参与者睁眼时记录静息态脑磁图（MEG）和体感诱发电磁场（SEF）。我们将数据基于个体结构磁共振成像转换到源空间。接下来，我们使用振幅包络相关方法通过静息态 MEG 估计在 alpha 和 beta 频段的 S1 和 S2 静息态功能连接（rs-FC），跨越整个大脑（即，S1/S2 种子×15,000 个顶点×两个频率）。我们使用配对脉冲范式评估 SEF 中 S1 和 S2 的抑制反应。我们使用定制设备以平行和垂直于食指的方向自动测量 GOD 任务，应用各种狭缝宽度。
我们观察到 GOD 阈值（均 P < 0.048）与 S1-上顶叶和 S1-毗邻顶枕沟的 alpha rs-FC 之间存在特定关联（即，较低的 rs-FC 值对应于较高的性能）。相比之下，局部反应与阈值之间没有关联。
本研究结果支持了特定皮质-皮质网络在识别触觉刺激变化方面的重要性。
