运动皮质的功能分离与功能整合的功能磁共振研究进展

运动皮质由多个皮质区域相互连接而组成[1],包括:初级运动皮质(primary motor cortex,M1,Brodmann 4),位于中央前回;前运动区(premotor area,PM,Brodmann 6),位于大脑外侧面中央前回;辅助运动区(supplementary motor area,SMA,Brodmann 6),位于中央前回大脑内侧面;扣带运动区cingulated motor areas,CMA,Brodmann 24).上述与运动相关的皮质区域在运动功能的实现中扮演不同的角色,以网络连接的形式发挥作用.

Non-invasive brain stimulations mainly consist of repetitive transcranial magnetic stimulation and transcranial direct current stimulation. Repetitive transcranial magnetic stimulation exhib-its satisfactory outcomes in improving multiple sclerosis, stroke, spinal cord injury and cerebral palsy-induced spasticity. By contrast, transcranial direct current stimulation has only been studied in post-stroke spasticity. To better validate the effcacy of non-invasive brain stimulations in im-proving the spasticity post-stroke, more prospective cohort studies involving large sample sizes are needed.

Many studies have examined motor impairments using voxel-based lesion symptom mapping, but few are reported regarding the corresponding relationship between cerebral cortex injury and lower limb motor impairment analyzed using this technique. This study correlated neuro-nal injury in the cerebral cortex of 16 patients with chronic stroke based on a voxel-based lesion symptom mapping analysis. Neuronal injury in the corona radiata, caudate nucleus and putamen of patients with chronic stroke could predict walking speed. The behavioral measure scores were consistent with motor deifcits expected after damage to the cortical motor system due to stroke. These ifndings suggest that voxel-based lesion symptom mapping may provide a more accurate prognosis of motor recovery from chronic stroke according to neuronal injury in cerebral motor cortex.

经颅磁刺激及其在运动科学中的应用展望

1980年,Merton要求Morton制造一个高电压电流刺激仪,他设想通过非侵人性方式直接刺激大脑中枢运动皮层相关部位产生相应的肌肉活动,而不是通过刺激外周神经.后,他们制造出经颅电刺激仪(transcranialelectrical stimulation,TES),它可以通过刺激初级运动皮层(primary motor cortex,M1),并几乎同时产生肌肉反应,即运动诱发电位(motor evoked potential,MEP)[1].

大脑皮层运动功能区的功能性磁共振成像

Objective To observe the motor cortex activitie s on fMR imaging. Method The fMR study of motor cortex was performed in 15 normal volunteers using 1. 5T superconducting MR system, EPI pulse sequences, and BOLD fMR imaging. Six axial slices centered approxi- matdy at the precentral gyrus was obtained wit h or without both hands finger tapping motion under the operator instruction during the scanning. Pixels with significant signal differences ( P ＜0.0001) between with and without finger tapping were calculated as functional signal. Thefunctional signal was superimposed on the corresponding T1 WI and brain water images Results The motor cortex ac tivities stimulated by finger tapping show as the area of increased signalintensity. The location of actwities is correspondent very well with the location of motor cortex. Most of activities present at the lateral aspect of precentral gyrus. In our group, the motion activities of left hemisphere is larger than that of right side in 10 volunteers, almost same sixe in 3 volunteers, smaller than that of right side in 1 volunteer. The fMR scan failed in 1 volunteer. Super-imposing the functional signals on the brain uner image may help to display the location of the activities. Conlusion fMR can show the location and size of motor cortex. It is simple, fast, noninvasive, and very convenient to implements with routine MR study.