使用功能性磁共振观察不同运动任务在颈部脊髓引发的去激活效应

Task Induced Deactivation Observed in Human Cervical Spinal Cord with Bold fMRI

目的采用功能性磁共振成像技术,观察右侧手指执行不同运动任务时颈段脊髓内的去激活效应。方法实验方案采用组块设计,共9例健康受试者接受颈段脊髓功能性磁共振成像。以SPM5软件包分析数据,采用贝叶斯推断方法,效应水平阈值1.0,概率阈值0.95,识别相对于基线水平,每种运动任务执行期间出现的去激活效应信号,观察不同运动任务引发去激活效应的空间分布及信号强度。结果所有受试者脊髓中均可观察到去激活性体素分布。右手运动时脊髓左侧和右侧均可出现去激活性体素。执行非次序对指和用力非次序对指任务时,部分脊髓节段的右侧未出现去激活性体素,部分脊髓节段左侧也未出现去激活性体素。此外,执行用力次序对指任务时有少数脊髓节段左侧未出现去激活性体素。结论右侧手指运动时,脊髓内神经组织的去激活效应是广泛存在的,提示脊髓水平运动控制机制的复杂性。

Objective To investigate task induced deactivation in human spinal cord. Methods Nine male healthy volunteers received functional MRI examination with a 1.5 T GE scanner. Different types of motor tasks were employed, including right index finger tapping, right band grasping, finger - tapping in sequential/interleaved order with or witbout effort. T2 ＊ weigbted functional images from C5 to T1 vertebral body was acquired in the axial plane with the duration of 6 min for a single session. Functional MRI data was analyzed with SPM5 software package under MATLAB 7.5. After motion correction, task induced deactivation of each motor task was modeled using a boxcar input vector convolved with the canonical hemodynamic response function provided in SPMS. Bayesian inference （effect size threshold 1.0, probability threshold 0.95） was applied to calculate task induced deactivation signal changes. Posterior Probability Maps were overlaid into the mean of BOLD images written by SPM software after motion correction. Percent of signal changes of voxels shown task induced deactivation were acquired from fitted response curves after adjusted with confounds. Results Task induced deactivation was observed in the spinal cord from all subjects. Voxels shown deactivation were distributed in both right and left sides of the cervical spinal cord during performing different motor tasks. Several spinal segments of subjects did not contain deactivated voxels in their right parts during finger - tapping in interleaved order with and without effort. Similarly, several other spinal segments did not contain deactivated voxels in their left parts during finger - tapping in interleaved order with and without effort. Besides, several spinal segments of subjects did not contain deactivated voxels in their left parts during finger - tapping in sequential order with effort. Conclusion During motor task performance by the right hand, task induced deactivation distributes in both sides and most segments of the spinal cord observed in this study. Our results suggest that motor control mechanisms are complicated in spinal level.