The role of contralesional dorsal premotor cortex after stroke as studied with concurrent TMS-fMRI.
The role of contralesional dorsal premotor cortex after stroke as studied with concurrent TMS-fMRI.
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DOI：
10.1523/jneurosci.5642-09.2010
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发表时间：
2010-09-08
期刊：
影响因子：
--
通讯作者：
Ward NS
中科院分区：
文献类型：
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作者：
Bestmann S;Swayne O;Blankenburg F;Ruff CC;Teo J;Weiskopf N;Driver J;Rothwell JC;Ward NS
对侧背侧运动前皮层（cPMd）可能支持脑卒中后的剩余运动功能。我们进行了两个互补的实验来探索cPMd如何在一组慢性中风患者中发挥这一作用。首先，我们采用对线圈经颅磁刺激（TMS）来确定cPMd对静息时同侧初级运动皮层（iM1）的生理影响。我们发现，这种影响在临床障碍较大的患者中变得更少抑制/更容易。其次，我们在这些患者的功能磁共振成像（fMRI）中应用经颅磁刺激对cPMd的TMS，以检查cPMd TMS对两个半球幸存的皮质运动区整个网络的因果影响，以及这些影响是否在受影响的手部运动中发生变化。我们证实，在更多受损的患者中，cPMd中与握力相关的激活更大。此外，在更多的受损患者中，同侧感觉运动皮层活动的峰值向后移动。重要的新发现是，同时进行的TMS- fmri结果与临床损伤和神经生理损伤的水平相关（即，用配对线圈TMS评估静止时cPMd-iM1的抑制程度较低/促进程度较高）。具体而言，更大的临床和神经生理损伤与cPMd TMS对握握过程中同侧感觉运动皮层后部BOLD信号的促进作用更强相关，这与更多受损患者的后向感觉运动活动相对应。对侧经前不悦经颅磁刺激未发现影响两个半球其他脑区活动。这种对同侧感觉运动区域的状态依赖性影响可能提供了cPMd支持中风后功能恢复的机制。
Contralesional dorsal premotor cortex (cPMd) may support residual motor function following stroke. We performed two complementary experiments to explore how cPMd might perform this role in a group of chronic human stroke patients. First, we used paired-coil transcranial magnetic stimulation (TMS) to establish the physiological influence of cPMd on ipsilesional primary motor cortex (iM1) at rest. We found that this influence became less inhibitory/more facilitatory in patients with greater clinical impairment. Second, we applied TMS over cPMd during functional magnetic resonance imaging (fMRI) in these patients to examine the causal influence of cPMd TMS on the whole network of surviving cortical motor areas in either hemisphere, and whether these influences changed during affected hand movement. We confirmed that hand grip-related activation in cPMd was greater in more impaired patients. Furthermore, the peak ipsilesional sensorimotor cortex activity shifted posteriorly in more impaired patients. Critical new findings were that concurrent TMS-fMRI results correlated with the level of both clinical impairment and neurophysiological impairment (i.e., less inhibitory/more facilitatory cPMd-iM1 measure at rest as assessed with paired-coil TMS). Specifically, greater clinical and neurophysiological impairment was associated with a stronger facilitatory influence of cPMd TMS on BOLD signal in posterior parts of ipsilesional sensorimotor cortex during hand grip, corresponding to the posteriorly shifted sensorimotor activity seen in more impaired patients. Contralesional PMd TMS was not found to influence activity in other brain regions in either hemisphere. This state-dependent influence on ipsilesional sensorimotor regions may provide a mechanism by which cPMd supports recovered function after stroke.