Sörös Peter, Schäfer Sarah, Witt Karsten
Neurology, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.
Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany.
Front Neurosci. 2020 Mar 24;14:226. doi: 10.3389/fnins.2020.00226. eCollection 2020.
The tongue performs movements in all directions to subserve its diverse functions in chewing, swallowing, and speech production. Using task-based functional MRI in a group of 17 healthy young participants, we studied (1) potential differences in the cerebral control of frontal (protrusion), horizontal (side to side), and vertical (elevation) tongue movements and (2) inter-individual differences in tongue motor control. To investigate differences between different tongue movements, we performed voxel-wise multiple linear regressions. To investigate inter-individual differences, we applied a novel approach, spatio-temporal filtering of independent components. For this approach, individual functional data were decomposed into spatially independent components and corresponding time courses using independent component analysis. A temporal filter (correlation with the expected brain response) was used to identify independent components time-locked to the tongue motor tasks. A spatial filter (cross-correlation with established neurofunctional systems) was used to identify brain activity not time-locked to the tasks. Our results confirm the importance of an extended bilateral cortical and subcortical network for the control of tongue movements. Frontal (protrusion) tongue movements, highly overlearned movements related to speech production, showed less activity in the frontal and parietal lobes compared to horizontal (side to side) and vertical (elevation) movements and greater activity in the left frontal and temporal lobes compared to vertical movements (cluster-forming threshold of > 3.1, cluster significance threshold of < 0.01, corrected for multiple comparisons). The investigation of inter-individual differences revealed a component representing the tongue primary sensorimotor cortex time-locked to the task in all participants. Using the spatial filter, we found the default mode network in 16 of 17 participants, the left fronto-parietal network in 16, the right fronto-parietal network in 8, and the executive control network in four participants (Pearson's > 0.4 between neurofunctional systems and individual components). These results demonstrate that spatio-temporal filtering of independent components allows to identify individual brain activity related to a specific task and also structured spatiotemporal processes representing known neurofunctional systems on an individual basis. This novel approach may be useful for the assessment of individual patients and results may be related to individual clinical, behavioral, and genetic information.
舌头能向各个方向运动，以实现其在咀嚼、吞咽和言语产生中的多种功能。我们对17名健康年轻参与者进行了基于任务的功能磁共振成像研究，以探究：(1) 大脑对舌头前伸（额向）、水平（左右）和垂直（抬高）运动控制的潜在差异；(2) 个体间舌头运动控制的差异。为研究不同舌头运动之间的差异，我们进行了体素-wise多元线性回归。为研究个体间差异，我们应用了一种新方法，即对独立成分进行时空滤波。对于该方法，使用独立成分分析将个体功能数据分解为空间上独立的成分和相应的时间序列。使用时间滤波器（与预期脑反应的相关性）来识别与舌头运动任务时间锁定的独立成分。使用空间滤波器（与已建立的神经功能系统的互相关性）来识别与任务非时间锁定的脑活动。我们的结果证实了一个扩展的双侧皮质和皮质下网络对舌头运动控制的重要性。与水平（左右）和垂直（抬高）运动相比，与言语产生高度过度学习相关的前伸（额向）舌头运动在额叶和顶叶的活动较少，与垂直运动相比，在左侧额叶和颞叶的活动较多（聚类形成阈值>3.1，聚类显著性阈值<0.01，经多重比较校正）。对个体间差异的研究揭示了一个在所有参与者中都与任务时间锁定的代表舌头初级感觉运动皮层的成分。使用空间滤波器，我们在17名参与者中的16名中发现了默认模式网络，16名中发现了左侧额顶网络，8名中发现了右侧额顶网络，4名中发现了执行控制网络（神经功能系统与个体成分之间的Pearson相关系数>0.4）。这些结果表明，对独立成分进行时空滤波能够识别与特定任务相关的个体脑活动，并且还能在个体基础上识别代表已知神经功能系统的结构化时空过程。这种新方法可能有助于评估个体患者，其结果可能与个体临床、行为和遗传信息相关。
