Abstract 19: Cortical reorganization of hand motor function to primary sensory cortex in hemiparetic patients with a primary motor cortex infarct.

Objective: To demonstrate cortical reorganization in hemiparetic patients with a primary motor cortex (M1) infarct using functional magnetic resonance imaging (fMRI). Design: The hand motor function of 2 hemiparetic stroke patients and 20 control subjects was evaluated by fMRI. Setting: Academic medical center. Participants: 2 hemiparetic patients and 20 control subjects with no history of neurologic disease. Interventions: fMRI was performed using the blood oxygen level-dependent technique at 1.5T. For the motor task paradigm, hand grasp-release movements were performed at a frequency of 1Hz for stimulation, guided with a metronome, over a repeated cycle of 15 seconds of control and 15 seconds of stimulus. Each task paradigm of alternating control-stimulus (30s) was repeated 3 times. Main Outcome Measures: fMRI data were analyzed using SPM-99 software running under the Matlab environment. The images were then smoothed with an 8mm isotropic gaussian kernel. Statistical parametric maps were obtained and voxels were considered significant at P<.001, uncorrected, with the additional requirement of a cluster size of 5 voxels. Results: The contralateral primary sensorimotor cortex was activated by the hand movements of control subjects and of the unaffected side of the 2 patients. Only the contralateral (infarct side) primary sensory cortex (S1) was activated by the affected hand movements of the 2 patients, a result that was not observed in control subjects or the unaffected hand of stroke patients. Conclusions: We believe that the hand motor function of the infarcted M1 of these patients was reorganized into S1. It seems that cortical reorganization took place in patients with an M1 infarct.     

Functional MRI evidence for motor cortex reorganization adjacent to a lesion in a primary motor cortex

OBJECTIVE: The object of this study was to verify motor cortex reorganization in patients with primary motor cortex injury using functional magnetic resonance imaging. DESIGN: Ten control subjects and two patients with primary motor cortex injury, caused by a traumatic brain injury in patient 1 and meningioma in patient 2, were evaluated. Functional magnetic resonance imaging was performed using the blood oxygenation level-dependent technique at 1.5 T with hand movements. RESULTS: The contralateral primary sensorimotor cortex was activated by unaffected hand movements. However, only the contralateral primary sensory cortex in patient 1 and the premotor area in patient 2 were activated by affected hand movements, which were totally absent in control subjects. CONCLUSION: We believe that the hand motor function of injured primary motor cortex was shifted into the primary sensory cortex in patient 1 and premotor area in patient 2. In conclusion, this finding may reflect a functional reorganization of the motor area in patients with a primary motor cortex injury.     

卒中早期手指被动运动的脑功能磁共振成像研究

目的应用扩散张量成像及BOLD-fMRI技术观察卒中早期手指被动运动时大脑半球相关区域血氧水平的变化情况.方法采用1.5 T MR成像系统对6名早期卒中患者进行BOLD-fMRI及扩散张量成像,采用手指被动屈伸运动作为fMRI的刺激任务.结果在锥体束中断时,卒中早期健手运动时激活双侧SMC区,患手运动可激活对侧半球后顶叶皮层及同侧SMC区;锥体束较完整时健手运动时激活对侧SMC区,患手运动激活双侧SMC区、双侧后顶叶皮层.结论卒中早期可能发生运动功能通路的重构,但锥体束不同损伤情况下运动功能恢复可能存在不同的机制.DTI与fMRI联合应用将是监测和研究脑卒中后恢复的有用工具.     

脑肿瘤致偏瘫患者患侧运动区定位的fMRI研究

目的采用功能磁共振成像技术对脑肿瘤致偏瘫患者患侧运动皮层进行定位研究。方法选择7例运动皮层区域肿瘤致偏瘫患者,采用组块设计的方法,分别行健侧手、患侧手、双手同时的三种静止与对指任务,在GESigna1.5T磁共振成像仪下行数据采集,SPM99进行数据后处理,结果采用单样本分析,另选9例临床症状轻或无的该区域肿瘤患者作为对照。结果对照组中每位病例不同任务下对比显示激活的PM区后方紧邻M1区。偏瘫患者组中仅有3例能完成含有患侧手的动作任务(42.9%),这3例患侧SMA、PM、M1区有激活。7例患者均完成了健侧手的动作任务,且有6例患侧辅助运动区、运动前区有激活(85.7%)。结论偏瘫患者健侧手复杂对指时能激活患侧的辅助运动区和运动前区的位置,并可以PM区推断主运动区的位置,这在患侧手不能完成动作任务而患侧脑区不能定位时起到了较好的弥补作用。     

Investigation of fMRI neurofeedback of differential primary motor cortex activity using kinesthetic motor imagery

Functional MRI neurofeedback (fMRI NF) is an emerging technique that trains subjects to regulate their brain activity while they manipulate sensory stimulus representations of fMRI signals in "real-time". Here we report an fMRI NF study of brain activity associated with kinesthetic motor imagery (kMI), analyzed using partial least squares (PLS), a multivariate analysis technique. Thirteen healthy young adult subjects performed kMI involving each hand separately, with NF training targeting regions of interest (ROIs) in the left and right primary motor cortex (M1). Throughout, subjects attempted to maximize a laterality index (LI) of brain activity-the difference in activity between the contralateral ROI (relative to the hand involved in kMI) and the ipsilateral M1 ROI-while receiving real-time updates on a visual display. Six of 13 subjects were successful in increasing the LI value, whereas the other 7 were not successful and performed similarly to 5 control subjects who received sham NF training. Ability to suppress activity in the ipsilateral M1 ROI was the primary driver of successful NF performance. Multiple PLS analyses depicted activated networks of brain regions involved with imagery, self-awareness, and feedback processing, and additionally showed that activation of the task positive network was correlated with task performance. These results indicate that fMRI NF of kMI is capable of modulating brain activity in primary motor regions in a subset of the population. In the future, such methods may be useful in the development of NF training methods for enhancing motor rehabilitation following stroke.     

利用fMRI和双手交替运动模式研究脑肿瘤所致的运动功能重组

目的应用fMRI研究双手交替运动模式下中央沟附近脑肿瘤患者运动功能重组的方式及特征.方法6名正常受试者和14名脑肿瘤患者采用双手交替对指运动模式行fMRI扫描,比较正常受试者与脑肿瘤患者脑激活的异同.结果正常人单手对指运动主要激活运动手对侧的大脑半球和同侧小脑半球.脑肿瘤患者非受累手运动所致的激活与正常受试者基本相同;而当受累手运动时,则出现运动功能的重组,包括肿瘤对侧正常半球内M1区的代偿性激活、肿瘤侧半球MI活动的减弱、双侧SMA等次级运动中枢激活区的增大以及双侧小脑半球的激活.结论采取双手交替运动模式,fMRI不仅显示了受累侧运动区的变形与移位,而且揭示了一种新的功能重组模式,即运动功能重组可能涉及分布于全脑的整个神经网络.     

脑缺血性卒中患者运动功能康复的功能性磁共振成像研究

目的利用功能性磁共振成像（fMRI）技术研究急性期缺血性脑卒中患者（以下简称急性期患者）运动相关皮质的激活情况，并探讨脑卒中后脑功能重组特点及其与肢体运动功能恢复的关系。方法采用GEI．5T双梯度16通道磁共振成像系统，对9例急性期患者和9例健康志愿者行Bold—fMRI检查。fMRI检查以被动对指运动（以下简称运动）为刺激任务，所有数据采用SPM2软件包进行离线后处理。比较健康志愿者与急性期患者fMRI结果的异同点，计算脑激活区体积和单侧化指数（LI），考察急性期患者患手运动LI值与患手运动功能的关系。结果健康志愿者单手运动激活对侧感觉运动皮质（SMC）、双侧辅助运动区（SMA）。急性期患者患手运动时同侧半球脑激话增多，健手运动的fMRI结果与健康志愿者基本一致。LI值也进一步确定，急性期患者患手运动时同侧半球脑激活增多。统计学分析表明，急性期患者患手运动的LI值与患手运动功能呈正相关。结论fMRI检查能客观地反映急性期患者运动相关皮质改变，提示存在脑功能代偿与重组。急性期患者患手运动LI值与患手运动功能呈正相关，提示fMRI是研究缺血性脑卒中后肢体运动功能康复与脑功能重组之间关系的一种有效工具。     

Cortical activity in multiple motor areas during sequential finger movements: an application of independent component analysis

Multiple cortical regions such as the supplementary motor area (SMA), premotor cortex (PM), and primary motor cortex (M1) are involved in the sequential execution of hand movements, but it is unclear how these areas collaborate in the preparation and execution of ipsilateral and contralateral hand movements. In this study, we used right-handed subjects to examine the spatial distribution and temporal profiles of motor-related activity during visually cued sequential finger movements by applying independent component analysis (ICA) to event-related functional magnetic resonance imaging (fMRI) signals. The particular merit of the ICA method is that it allows brain activity in individual subjects to be elucidated without making a priori assumptions about the anatomical areas that are activated or the temporal profile of activity. By applying ICA, we found that (1) the SMA contributed to both the preparation and execution of movements of the right and left hand; (2) the left M1 and dorsal premotor cortex (PMd) contributed to both the preparation and execution of movements of the right and left hand, whereas the right M1 and PMd contributed mainly to the execution of movements of the left hand; (3) pre-SMA areas were activated in some subjects in concert with the posterior parietal and prefrontal cortex; and (4) fMRI signals over superficial cortical draining veins could be distinguished from cortical activation. We suggest that ICA is useful for categorizing distributed task-related activities in individual subjects into several spatially independent activities that represent functional units in motor control.     

Structural damage to the corticospinal tract correlates with bilateral sensorimotor cortex reorganization in stroke patients

Damage to the corticospinal tract (CST) in stroke patients has been associated with functional reorganization in the ipsilesional and contralesional sensorimotor cortices. However, it is unknown whether a quantitative relationship exists between the extent of structural damage to the CST and functional reorganization in stroke patients. The purpose of the current study was to examine the relationship between structural CST damage and motor task-related cortical activity in chronic hemiparetic stroke patients. In 10 chronic hemiparetic stroke patients with heterogeneous lesions, CST damage was quantified using conventional structural magnetic resonance imaging and tractography based on diffusion tensor imaging. Cortical activity was measured using functional magnetic resonance imaging during repetitive flexion/extension movements of the digits. We found that the two measures of CST damage were strongly correlated. Moreover, greater CST damage was significantly and linearly correlated with increased activation during affected hand movement in the hand area of the contralesional primary sensorimotor cortex (M1/S1) and in the ipsilesional M1/S1 ventral to the hand area. To our knowledge, this is the first demonstration of a quantitative relationship between the extent of structural damage to the CST and functional reorganization in stroke patients. This relationship was observed in stroke patients with heterogeneous lesions, suggesting that CST damage is a factor relevant to the variation in functional reorganization in the clinical population.     

功能性核磁共振成像在计算机辅助的上肢功能训练治疗脑梗死上肢偏瘫中的应用研究

目的:探讨计算机辅助训练上肢对脑可塑性的可能作用。方法:脑卒中上肢偏瘫患者10例,均进行计算机辅助训练,治疗前后采用偏瘫上肢功能测试-香港版(FTHUE-HK),Fulg-Meyer上肢评定(FMA)及改良Barthel指数量表(MBI)评定上肢运动功能,及患者屈伸腕关节时进行功能核磁共振扫描(fMRI)。结果:治疗6周后,10例患侧的上肢功能评定FTHUE-HK、FMA及MBI评分均较治疗前后患侧上肢功能评定变化明显提高(P0.05)。fMRI扫描示:患者健侧手运动脑功能激活区主要位于对侧初级运动皮质区(SMC)及同侧小脑,患者健手在康复训练后脑激活区增多,包括对侧SMC区及同侧小脑、部分边缘系统;患者治疗前患侧手运动激活区分布广泛,而对侧SMC激活减少,同侧SMC激活增多,另主要还见辅助运动区激活增多;治疗后可见双侧SMC及辅助运动区激活,对侧SMC激活较治疗前增多,另主要还见对侧顶上小叶激活增多。结论:计算机训练可以有效改善脑卒中患者上肢运动功能,诱发大脑皮质功能重塑是其机制的重要组成部分。     

Illusory movements of the paralyzed limb restore motor cortex activity

In humans, limb amputation or brachial plexus avulsion (BPA) often results in phantom pain sensation. Actively observing movements made by a substitute of the injured limb can reduce phantom pain, Proc. R. Soc. London B Biol. Sci. 263, 377-386). The neural basis of phantom limb sensation and its amelioration remains unclear. Here, we studied the effects of visuomotor training on motor cortex (M1) activity in three patients with BPA. Functional magnetic resonance imaging scans were obtained before and after an 8-week training program during which patients learned to match voluntary "movements" of the phantom limb with prerecorded movements of a virtual hand. Before training, phantom limb movements activated the contralateral premotor cortex. After training, two subjects showed increased activity in the contralateral primary motor area. This change was paralleled by a significant reduction in phantom pain. The third subject showed no increase in motor cortex activity and no improvement in phantom pain. We suggest that successful visuomotor training restores a coherent body image in the M1 region and, as a result, directly affects the experience of phantom pain sensation. Artificial visual feedback on the movements of the phantom limb may thus "fool" the brain and reestablish the original hand/arm cortical representation.     

Self-modulation of primary motor cortex activity with motor and motor imagery tasks using real-time fMRI-based neurofeedback

Advances in fMRI data acquisition and processing have made it possible to analyze brain activity as rapidly as the images are acquired allowing this information to be fed back to subjects in the scanner. The ability of subjects to learn to volitionally control localized brain activity within motor cortex using such real-time fMRI-based neurofeedback (NF) is actively being investigated as it may have clinical implications for motor rehabilitation after central nervous system injury and brain-computer interfaces. We investigated the ability of fifteen healthy volunteers to use NF to modulate brain activity within the primary motor cortex (M1) during a finger tapping and tapping imagery task. The M1 hand area ROI (ROI_m) was functionally localized during finger tapping and a visual representation of BOLD signal changes within the ROI_m fed back to the subject in the scanner. Surface EMG was used to assess motor output during tapping and ensure no motor activity was present during motor imagery task. Subjects quickly learned to modulate brain activity within their ROI_m during the finger-tapping task, which could be dissociated from the magnitude of the tapping, but did not show a significant increase within the ROI_m during the hand motor imagery task at the group level despite strongly activating a network consistent with the performance of motor imagery. The inability of subjects to modulate M1 proper with motor imagery may reflect an inherent difficulty in activating synapses in this area, with or without NF, since such activation may lead to M1 neuronal output and obligatory muscle activity. Future real-time fMRI-based NF investigations involving motor cortex may benefit from focusing attention on cortical regions other than M1 for feedback training or alternative feedback strategies such as measures of functional connectivity within the motor system.     

计算机辅助上肢训练对脑卒中患者与正常人脑可塑性影响的功能磁共振成像对比研究

摘要 目的：探讨计算机辅助训练上肢对脑卒中患者与正常人脑可塑性的可能作用。 方法：对5名正常志愿者（对照组）及5例脑卒中上肢偏瘫患者（实验组）进行6周的计算机辅助训练,每周训练5次,在训练前、训练后分别在受试者屈伸左右腕关节时进行功能磁共振成像（fMRI）扫描,并对实验组进行Fulg-Meyer上肢功能评定（FMA）,改良Barthel指数（MBI）量表评定。 结果：实验组与对照组相比,治疗前,运动左侧腕关节时,激活脑区主要在左额中央前回（同侧的感觉运动皮质区）;治疗后,运动左侧腕关节时,实验组与对照组相比,激活脑区在同侧感觉运动皮质区,但激活强度及体素均较治疗前有明显的降低。治疗前,运动右腕关节时,两者的激活脑区的部位相似,均在对侧的SMC区及同侧的小脑,但激活强度和体素较对照组小;治疗后,运动右腕关节时,两组之间无显著差异。 结论：计算机辅助训练可诱导出大脑皮质功能区的重组与代偿,使其趋向正常化。     

Ipsilateral motor pathway confirmed by combined brain mapping of a patient with hemiparetic stroke: a case report

This study investigated the motor control pathway using both functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) in a patient with left hemiparesis with an infarction on the posterior limb of the right internal capsule. fMRI was performed using the blood oxygen level-dependent technique at 1.5 T with a standard head coil. The motor activation task consisted of hand grasp-release movements in 1-Hz cycles. TMS was performed using a butterfly coil; the intersection of the wings (center of the coil) was applied tangentially to the scalp 1.0 cm apart. Stimulation was performed at 100% of maximal output. Motor evoked potentials (MEPs) from both abductor pollicis brevis (APB) muscles were obtained simultaneously. fMRI showed that the unaffected (left) primary sensorimotor cortex (SM1) was activated by movements of the unaffected (right) hand. Conversely, the bilateral SM1 were activated by movements of the affected (left) hand. Brain mapping using TMS showed that ipsilateral MEPs were obtained at the affected (left) APB muscle when the unaffected (left) motor cortex was stimulated. We concluded that the ipsilateral motor pathway from the unaffected motor cortex to the affected hand was present in this patient.     

运动想象训练促进脑卒中患者上肢运动功能恢复的功能磁共振研究

摘要 目的：利用功能磁共振（fMRI）研究脑卒中患者运动想象训练后上肢功能重组潜在的脑重塑机制,为临床脑卒中患者的康复治疗提供一定的理论基础。 方法：选择9例脑卒中偏瘫患者,进行运动想象训练每周5次,每次约30min,共4周,并进行常规康复训练。应用Fugl-Meyer上肢运动功能量表（FMA-UL）分别在治疗前和治疗后4周评估患者的上肢运动功能。在4周康复干预前后对患者进行患手被动握拳任务下的fMRI检查,采用组块设计,利用SPM8软件进行数据处理,采用感兴趣区（ROI）的个体化分析,统计各ROI区的脑皮质激活情况,比较干预前后对侧感觉运动区（cSMC）的激活变化,分析脑卒中患者的脑重塑模式。 结果：4周运动想象干预后脑卒中患者的FM-UL评分从（22.44±11.59）分提高到（39.78±14.03）分（P=0.011）。比较干预前后两次fMRI检查脑皮质SMC区的激活情况,发现9例脑卒中患者的功能恢复呈现出两种不同的皮质重塑模式：一种模式为募集激活,即大部分患者第二次fMRI检查,患手被动任务下cSMC的激活增加（有6例患者）;另一种模式是集中激活,即小部分患者第二次fMRI检查,患手被动任务下cSMC的激活虽然是减少的,但其偏侧指数（LI-SMC）却是显著增加的（有3例患者）。 结论：运动想象训练可改善脑卒中患者的上肢运动功能,经过4周干预后脑卒中患者存在损伤同侧SMC区的募集激活和集中激活两种脑重塑模式,随着患者上肢功能的恢复,脑重塑机制逐渐倾向于损伤侧SMC的激活。     

fMRI signal decreases in ipsilateral primary motor cortex during unilateral hand movements are related to duration and side of movement

Interactions between the primary motor cortices of each hemisphere during unilateral hand movements appear to be inhibitory, although there is evidence that the strengths of these interactions are asymmetrical. In the present study, functional magnetic resonance imaging (fMRI) was used to investigate the effects of motor task duration and hand used on unilateral movement-related BOLD signal increases and decreases in the hand region of primary motor cortex (M1) of each hemisphere in six right-handed volunteers. Significant task-related BOLD signal decreases were observed in ipsilateral M1 during single and brief bursts of unilateral movements for both hands. However, these negative-to-baseline responses were found to intensify with increasing movement duration in parallel with greater task-related increases in contralateral M1. Movement-related BOLD signal decreases in ipsilateral M1 were also stronger for the right, dominant hand than for the left hand in our right-handed subjects. These findings would be consistent with the existence of interhemispheric interactions between M1 of each hemisphere, whereby increased neuronal activation in M1 of one hemisphere induces reduced neuronal activity in M1 of the opposite hemisphere. The observation of a hemispheric asymmetry in inhibition between M1 of each hemisphere agrees well with previous neuroimaging and electrophysiological data. These findings are discussed in the context of current understanding of the physiological origins of negative-to-baseline BOLD responses.     

Reduction of excitability ("inhibition") in the ipsilateral primary motor cortex is mirrored by fMRI signal decreases

Functional magnetic resonance imaging (fMRI) was used to investigate how focal cortical inhibition affects the blood oxygen level-dependent (BOLD) signal. Phasic low force pinch grip reduces excitability of the ipsilateral primary motor cortex. This task was used to study BOLD signal changes during inhibition. Six right-handed normal volunteers participated in the study. They were asked to perform a right-handed pinch grip repetitively at 1 Hz and 5% of their individual maximal voluntary contraction (MVC). Data were acquired with a 1.5 Tesla Magnetom and continuous multislice T2*-weighted images. The contralateral primary motor cortex (M1) revealed an activation in the knob-shaped hand representation of the central sulcus area. More importantly, a decreased (often referred to as "negative") BOLD signal in the ipsilateral M1 was observed. We suggest phasic low force pinch grip as a reproducible, easy model of focal inhibition. Decreased cortical excitability presents as decreased BOLD signal using fMRI.     

Correlated change in upper limb function and motor cortex activation after verum and sham acupuncture in patients with chronic stroke

BACKGROUND: Acupuncture may improve motor function in patients with chronic hemiparetic stroke, yet the neural mechanisms underlying such an effect are unknown. As part of a sham-controlled, randomized clinical trial testing the efficacy of a 10-week acupuncture protocol in patients with chronic hemiparetic stroke, we examined the relationship between changes in function of the affected upper limb and brain activation using functional magnetic resonance imaging (fMRI). METHODS: Seven (7) chronic hemiparetic stroke patients underwent fMRI and testing of function of the affected upper limb (spasticity and range-of-motion) before and after a 10-week period of verum (N=4) or sham (N=3) acupuncture. The correlation between changes in function of the affected upper limb and brain activation after treatment was tested across patients. RESULTS: We found a significant positive correlation between changes in function of the affected upper limb (spasticity and range of motion) and activation in a region of the ipsilesional motor cortex. Patients treated with verum acupuncture showed a trend toward a greater maximum activation change in this motor cortical area as compared to those treated with sham acupuncture. CONCLUSIONS: Acupuncture may improve function of the affected upper limb in chronic hemiparetic stroke patients by increasing activity in the ipsilesional motor cortex.     

初级运动皮层躯体分布图功能磁共振成像研究

目的检验功能性磁共振绘制大脑初级运动皮层躯体分布的能力和激活区特点。方法12例健康志愿者完成手部、肘部和肩部简单上肢运动任务。功能磁共振检查采用平面回波BOLD序列,得出原始图像,利用SPM99软件进行图像后处理,记录初级运动皮层最强信号像素Talairach坐标值,然后采用方差分析方法对x、y、z轴数值进行统计分析。结果所有受检者上肢各部分运动均可以在对侧初级运动皮层产生具有统计学意义的信号变化。激活区分布遵循躯体分布模式,统计分析显示:手部、肘部和肩部激活区最强信号像素x轴数值存在显著差异,手部和肩部激活区最大信号像素z轴数值也存在显著差异。结论f MRI能够准确绘制个体初级运动皮层躯体分布图。     

Ankle dorsiflexion as an fMRI paradigm to assay motor control for walking during rehabilitation

The ability to walk independently with the velocity and endurance that permit home and community activities is a highly regarded goal for neurological rehabilitation after stroke. This pilot study explored a functional magnetic resonance imaging (fMRI) activation paradigm for its ability to reflect phases of motor learning over the course of locomotor rehabilitation-mediated functional gains. Ankle dorsiflexion is an important kinematic aspect of the swing and initial stance phase of the gait cycle. The motor control of dorsiflexion depends in part on descending input from primary motor cortex. Thus, an fMRI activation paradigm using voluntary ankle dorsiflexion has face validity for the serial study of walking-related interventions. Healthy control subjects consistently engaged contralateral primary sensorimotor cortex (S1M1), supplementary motor area (SMA), premotor (PM) and cingulate motor (CMA) cortices, and ipsilateral cerebellum. Four adults with chronic hemiparetic stroke evolved practice-induced representational plasticity associated with gains in speed, endurance, motor control, and kinematics for walking. For example, an initial increase in activation within the thoracolumbar muscle representation of S1M1 in these subjects was followed by more focused activity toward the foot representation with additional pulses of training. Contralateral CMA and the secondary sensory area also reflected change with practice and gains. We demonstrate that the supraspinal sensorimotor network for the neural control of walking can be assessed indirectly by ankle dorsiflexion. The ankle paradigm may serve as an ongoing physiological assay of the optimal type, duration, and intensity of rehabilitative gait training.