1Departments of Biomedical Engineering and.
5Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.
J Neurosurg. 2022 Jul 8;138(3):810-820. doi: 10.3171/2022.5.JNS22837. Print 2023 Mar 1.
It is poorly understood why patients with mesial temporal lobe epilepsy (TLE) have cognitive deficits and brain network changes that extend beyond the temporal lobe, including altered extratemporal intrinsic connectivity networks (ICNs). However, subcortical arousal structures project broadly to the neocortex, are affected by TLE, and thus may contribute to these widespread network effects. The authors' objective was to examine functional connectivity (FC) patterns between subcortical arousal structures and neocortical ICNs, possible neurocognitive relationships, and FC changes after epilepsy surgery.
The authors obtained resting-state functional magnetic resonance imaging (fMRI) in 50 adults with TLE and 50 controls. They compared nondirected FC (correlation) and directed FC (Granger causality laterality index) within the salience network, default mode network, and central executive network, as well as between subcortical arousal structures; these 3 ICNs were also compared between patients and controls. They also used an fMRI-based vigilance index to relate alertness to arousal center FC. Finally, fMRI was repeated in 29 patients > 12 months after temporal lobe resection.
Nondirected FC within the salience (p = 0.042) and default mode (p = 0.0008) networks, but not the central executive network (p = 0.79), was decreased in patients in comparison with controls (t-tests, corrected). Nondirected FC between the salience network and subcortical arousal structures (nucleus basalis of Meynert, thalamic centromedian nucleus, and brainstem pedunculopontine nucleus) was reduced in patients in comparison with controls (p = 0.0028-0.015, t-tests, corrected), and some of these connectivity abnormalities were associated with lower processing speed index, verbal comprehension, and full-scale IQ. Interestingly, directed connectivity measures suggested a loss of top-down influence from the salience network to the arousal nuclei in patients. After resection, certain FC patterns between the arousal nuclei and salience network moved toward control values in the patients, suggesting that some postoperative recovery may be possible. Although an fMRI-based vigilance measure suggested that patients exhibited reduced alertness over time, FC abnormalities between the salience network and arousal structures were not influenced by the alertness levels during the scans.
FC abnormalities between subcortical arousal structures and ICNs, such as the salience network, may be related to certain neurocognitive deficits in TLE patients. Although TLE patients demonstrated vigilance abnormalities, baseline FC perturbations between the arousal and salience networks are unlikely to be driven solely by alertness level, and some may improve after surgery. Examination of the arousal network and ICN disturbances may improve our understanding of the downstream clinical effects of TLE.
目前尚不清楚为什么患有内侧颞叶癫痫（TLE）的患者会出现认知缺陷和超出颞叶范围的脑网络变化，包括皮质下唤醒结构广泛投射到新皮质，受 TLE 影响，因此可能导致这些广泛的网络效应。作者的目的是研究皮质下唤醒结构与新皮质内连接网络（ICN）之间的功能连接（FC）模式、可能存在的神经认知关系以及癫痫手术后的 FC 变化。
作者在 50 名 TLE 患者和 50 名对照者中获得了静息状态功能磁共振成像（fMRI）。他们比较了显着性网络、默认模式网络和中央执行网络内的无定向 FC（相关性）和定向 FC（格兰杰因果关系侧性指数），以及皮质下唤醒结构之间的 FC；还比较了这 3 个 ICN 在患者和对照组之间的差异。他们还使用基于 fMRI 的警觉指数将警觉性与唤醒中心 FC 相关联。最后，在 29 名患者行颞叶切除术后> 12 个月时重复进行 fMRI。
与对照组相比，患者的显着性（p = 0.042）和默认模式（p = 0.0008）网络内的无定向 FC（t 检验，校正）降低，但中央执行网络内的无定向 FC（p = 0.79）没有降低。与对照组相比，患者的显着性网络与皮质下唤醒结构（Meynert 基底核、丘脑中央正中核和脑桥被盖脚核）之间的无定向 FC 降低（p = 0.0028-0.015，t 检验，校正），并且这些连接异常中的一些与较低的处理速度指数、言语理解和全量表智商相关。有趣的是，定向连接测量表明，患者的显着性网络对唤醒核的自上而下影响丧失。术后，某些唤醒核与显着性网络之间的 FC 模式向患者的对照值移动，表明可能存在一些术后恢复。尽管基于 fMRI 的警觉测量提示患者随着时间的推移警觉性降低，但显着性网络和唤醒结构之间的 FC 异常不受扫描期间的警觉水平影响。
皮质下唤醒结构与 ICN 之间的 FC 异常，例如显着性网络，可能与 TLE 患者的某些神经认知缺陷有关。尽管 TLE 患者表现出警觉异常，但唤醒和显着性网络之间的基线 FC 扰动不太可能仅由警觉水平驱动，并且一些可能在手术后改善。检查唤醒网络和 ICN 紊乱可能会增进我们对 TLE 下游临床影响的理解。
