Morgan Victoria L, Chang Catie, Englot Dario J, Rogers Baxter P
Institute of Imaging Science, Vanderbilt University Medical Center, USA.
Institute of Imaging Science, Vanderbilt University Medical Center, USA; Department of Electrical Engineering and Computer Science, Vanderbilt University, USA.
Neuroimage Clin. 2020;26:102254. doi: 10.1016/j.nicl.2020.102254. Epub 2020 Mar 25.
Mesial temporal lobe epilepsy (TLE) is characterized by transient abnormal electrical activity originating in the hippocampus. The objective of this study was to characterize dynamic spatio-temporal fluctuations in hippocampal network connectivity in mTLE using functional connectivity (FC) mapping in 41 unilateral mTLE patients (28 right, 13 left) and 56 healthy control participants using 3T MRI. Dynamic FC was computed across the scan using sliding 60-s windows. This was compared to static FC computed using the whole 10-min functional MRI scan, and to the variance in the hippocampal functional MRI signal. Four states of healthy hippocampal dynamic FC were identified and compared to TLE patients. TLE patients fluctuated between these four states, but the hippocampus ipsilateral to the seizure focus spent more time in a state distinguished by lower prefrontal and parietal FC than the dominant healthy state. Increased time spent in this state was associated with increased impairment in static FC and increased variance in the hippocampal functional MRI signal. Overall, this work provides evidence that increases in variance in signal fluctuations occurring at the seizure focus in the hippocampus in patients with mTLE may contribute to disruptions in healthy FC network dynamics within an fMRI scan that contribute to decreases in static hippocampal FC. These alterations result in decreased hippocampal connectivity to bilateral prefrontal and parietal regions in TLE which may be related to behavior and cognitive impairments in these patients. Therefore, characterization of an individual patient's hippocampal dynamics at different time scales may provide more specific spatio-temporal profiles of network impairment that may be related to hippocampal dysfunction in TLE.
内侧颞叶癫痫（TLE）的特征是起源于海马体的短暂异常电活动。本研究的目的是使用功能连接（FC）映射，对41例单侧内侧颞叶癫痫患者（28例右侧，13例左侧）和56名健康对照参与者的海马网络连接中的动态时空波动进行特征描述，采用3T磁共振成像。在扫描过程中使用滑动60秒窗口计算动态FC。将其与使用整个10分钟功能磁共振成像扫描计算的静态FC以及海马功能磁共振成像信号的方差进行比较。识别出健康海马动态FC的四种状态并与内侧颞叶癫痫患者进行比较。内侧颞叶癫痫患者在这四种状态之间波动，但癫痫灶同侧的海马体在一种以较低的前额叶和顶叶FC为特征的状态下停留的时间比主要的健康状态更长。在这种状态下停留时间的增加与静态FC的损害增加以及海马功能磁共振成像信号的方差增加有关。总体而言，这项工作提供了证据，表明内侧颞叶癫痫患者海马体癫痫灶处信号波动方差的增加可能导致功能磁共振成像扫描中健康FC网络动态的破坏，进而导致静态海马FC的降低。这些改变导致内侧颞叶癫痫患者海马与双侧前额叶和顶叶区域的连接减少，这可能与这些患者的行为和认知障碍有关。因此，在不同时间尺度上对个体患者海马动态进行特征描述，可能会提供更具体的网络损伤时空特征，这可能与内侧颞叶癫痫中的海马功能障碍有关。
