Imaging the human motor system's beta-band synchronization during isometric contraction

Rhythmic synchronization likely subserves interactions among neuronal groups. One of the best studied rhythmic synchronization phenomena in the human nervous system is the beta-band (15-30 Hz) synchronization in the motor system. In this study, we imaged structures across the human brain that are synchronized to the motor system's beta rhythm. We recorded whole-head magnetoencephalograms (MEG) and electromyograms (EMG) of left/right extensor carpi radialis muscle during left/right wrist extension. We analyzed coherence, on the one hand between the EMG and neuronal sources in the brain, and on the other hand between different brain sources, using a spatial filtering approach. Cortico-muscular coherence analysis revealed a spatial maximum of coherence to the muscle in motor cortex contralateral to the muscle in accordance with earlier findings. Moreover, by applying a two-dipole source model, we unveiled significantly coherent clusters of voxels in the ipsilateral cerebellar hemisphere and ipsilateral cerebral motor regions. The spatial pattern of coherence to the right and left arm EMG was roughly mirror reversed across the midline, in agreement with known physiology. Subsequently, we analyzed the brain-wide pattern of beta-band coherence to the motor cortex contralateral to the contracting muscle. This analysis did not reveal any convincing pattern. Because the prior cortico-muscular analysis had demonstrated the expected pattern in our data, this negative finding demonstrates a current limitation of the applied method for cortico-cortical coherence analysis. We conclude that during an isometric muscle contraction, several distributed brain regions form a brain-wide beta-band network for motor control.     

Effects of unilateral brain damage on contralateral and ipsilateral upper extremity function in hemiplegia

This article describes the long-term effects of unilateral penetrating hemispheric lesions on contralateral and ipsilateral upper extremity motor performance and functional outcome. Activities-of-daily-living skill and gross motor performance contralateral to the lesions were compared among 32 left-sided and 19 right-sided hemiplegic subjects using analysis of variance and chi-square techniques. Ipsilateral to the damaged hemisphere, fine motor tasks of simple visual motor reaction time, grip and pinch strength, finger tapping, and Purdue Pegboard performance were tested. Analysis of covariance compared each ipsilateral task to performance in the corresponding hand of 70 matched controls. Results indicate similar long-term functional ADL outcome in right and left hemisphere-damaged subjects, despite more severe contralateral functional motor deficits following lesions of the left hemisphere. Right hemisphere lesions led to ipsilateral decrements in reaction time, and lesions of either hemisphere diminished grip or pinch strength, finger tapping, and pegboard performance ipsilaterally. These results demonstrate that unilateral brain damage involving the motor areas of either hemisphere has detrimental effects on ipsilateral upper extremity motor function. Findings are discussed and related to the concept that the left hemisphere is specialized or has greater neuronal representation for bilateral motor processes. Physical therapists involved in the treatment of patients with hemiplegia should be aware that motor functions of the ipsilateral, nonparetic upper extremity may also be affected adversely by unilateral brain lesions.     

Lesion location alters brain activation in chronically impaired stroke survivors

Recovery of motor function after stroke is associated with reorganization in central motor networks. Functional imaging has demonstrated recovery-dependent alterations in brain activation patterns when compared to healthy controls. These alterations are variable across stroke subjects. Factors identified as contributing to this variability are the degree of functional impairment, the time interval since stroke, and rehabilitative therapies. Here, the hypothesis is tested that lesion location influences the activation patterns. Using functional magnetic resonance imaging, the objective was to characterize similarities or differences in movement-related activation patterns in patients chronically disabled by cortical plus subcortical or subcortical lesions only. Brain activation was mapped during paretic and non-paretic movement in 11 patients with subcortical stroke, in nine patients with stroke involving sensorimotor cortex, and in eight healthy volunteers. Patient groups had similar average motor deficit as measured by a battery of scores and strength measures. Substantial differences between patients groups were found in activation patterns associated with paretic limb movement: whereas contralateral motor cortex, ipsilateral cerebellum (relative to moving limb), bilateral mesial (cingulate, SMA), and perisylvian regions were active in subcortical stroke, cortical patients recruited only ipsilateral postcentral mesial hemisphere regions, and areas at the rim of the stroke cavity. For both groups, activation in ipsilateral postcentral cortex correlated with motor function; in subcortical stroke, the same was found for mesial and perisylvian regions. Overall, brain activation in cortical stroke was less, while in subcortical patients, more than in healthy controls. For non-paretic movement, activation patterns were similar to control in cortical patients. In subcortical patients, however, activation patterns differed: the activation of non-paretic movement was similar to that of paretic movement (corrected for side). The data demonstrate more differences than similarities in the central control of paretic and non-paretic limb movement in patients chronically disabled by subcortical versus cortical stroke. Whereas standard motor circuitry is utilized in subcortical stroke, alternative networks are recruited after cortical stroke. This finding proposes lesion-specific mechanisms of reorganization. Optimal activation of these distinct networks may require different rehabilitative strategies.     

Task-dependent modulations of cortical oscillatory activity in human subjects during a bimanual precision grip task

Oscillations are a widespread feature of normal brain activity and have been reported at a variety of different frequencies in different neuronal systems. The demonstration that oscillatory activity is present in motor command signals has prompted renewed interest in the possible functions of synchronous oscillatory activity within the primate sensorimotor system. In the current study, we investigated task-dependent modulations in coupling between sensorimotor cortical oscillators during a bimanual precision grip task. The task required a hold-ramp-hold pattern of grip force to be exerted on a compliant object with the dominant right hand, while maintaining a steady grip with the nondominant hand. We found significant task-related modulation of 15- to 30-Hz coherence between magnetoencephalographic (MEG) activity recorded from the left sensorimotor cortex and electromyographic (EMG) activity in hand muscles on the right side. This coherence was maximal during steady hold, but disappeared during the ramp movements. Interestingly coherence between the right sensorimotor MEG and left-hand EMG showed a similar, although less deeply modulated, task-related pattern, even though this hand was maintaining a simple steady grip. No significant ipsilateral MEG-EMG coherence was observed in the 15- to 30-Hz passband for either hand. These results suggest that the cortical oscillators in the two sensorimotor cortices are independent to some degree but that they may share a common mechanism that attenuates the cortical power in both hemispheres in the 15- to 30-Hz range during movements of one hand. The results are consistent with the hypothesis that oscillatory activity in the motor system is important in resetting the descending motor commands needed for changes in motor state, such as those that occur in the transition from movement to steady grip.     

Changes in proprioceptive systems activity during recovery from post-stroke hemiparesis.

OBJECTIVE: To investigate the activity of proprioceptive systems during early recovery of motor function after ischaemic stroke in a prospective, longitudinal, functional imaging study. METHODS: Ten patients with unilateral infarction of the posterior internal capsule were investigated using oxygen-15-water positron emission tomography during passive extension of the index finger. Patients were assessed initially after stroke (mean 4.7 days) and again after rehabilitation. Changes in brain activation patterns were analysed. RESULTS: All patients showed significant improvement in motor function of the paretic limb. During passive finger movement of the non-paretic index finger, significant increases in cerebral blood flow were observed in the somatosensory areas I and II (SI and SII) of the non-infarcted hemisphere. Additionally, significant activation of ipsilateral SII in the infarcted hemisphere was observed. After rehabilitation, ipsilateral SII activation vanished and the normal activation pattern was restored. During passive movement of the paretic index finger only SI and SII of the infarcted hemisphere were activated. During rehabilitation, additional recruitment of SII in the non-infarcted hemisphere occurred. CONCLUSION: Recovery from internal capsule infarction is accompanied by substantial changes in activity of proprioceptive systems of the paretic and non-paretic limb. These changes may reflect an inter-hemispheric shift of attention to proprioceptive stimuli associated with recovery.     

Dynamic causal modeling of cortical activity from the acute to the chronic stage after stroke

Functional neuroimaging studies frequently demonstrated that stroke patients show bilateral activity in motor and premotor areas during movements of the paretic hand in contrast to a more lateralized activation observed in healthy subjects. Moreover, a few studies modeling functional or effective connectivity reported performance-related changes in the motor network after stroke. Here, we investigated the temporal evolution of intra- and interhemispheric (dys-) connectivity during motor recovery from the acute to the early chronic phase post-stroke. Twelve patients performed hand movements in an fMRI task in the acute (≤72 hours) and subacute stage (2 weeks) post-stroke. A subgroup of 10 patients participated in a third assessment in the early chronic stage (3-6 months). Twelve healthy subjects served as reference for brain connectivity. Changes in effective connectivity within a bilateral network comprising M1, premotor cortex (PMC), and supplementary motor area (SMA) were estimated by dynamic causal modeling. Motor performance was assessed by the Action Research Arm Test and maximum grip force. Results showed reduced positive coupling of ipsilesional SMA and PMC with ipsilesional M1 in the acute stage. Coupling parameters among these areas increased with recovery and predicted a better outcome. Likewise, negative influences from ipsilesional areas to contralesional M1 were attenuated in the acute stage. In the subacute stage, contralesional M1 exerted a positive influence on ipsilesional M1. Negative influences from ipsilesional areas on contralesional M1 subsequently normalized, but patients with poorer outcome in the chronic stage now showed enhanced negative coupling from contralesional upon ipsilesional M1. These findings show that the reinstatement of effective connectivity in the ipsilesional hemisphere is an important feature of motor recovery after stroke. The shift of an early, supportive role of contralesional M1 into enhanced inhibitory coupling might indicate maladaptive processes which could be a target of non-invasive brain stimulation techniques.     

Brain activity is similar during precision and power gripping with light force: an fMRI study

Handgrips can be broadly classified into precision and power grips. To compare central neuronal control of these tasks, functional magnetic resonance imaging was used in 14 healthy right-handed volunteers, who repetitively squeezed non-flexible force transducers with a precision grip and a power grip of the dominant hand. The relative grip force levels and movement rates (0.45 Hertz) of both tasks were comparable. Peak isometric grip forces ranged between 1% and 10% of the maximum voluntary force. Reflecting the additional recruitment of extrinsic hand muscles and the higher absolute force, activation of the contralateral primary sensorimotor cortex (M1/S1) and ipsilateral cerebellum was significantly stronger during power than during precision grip. No brain areas exhibited stronger activity during the precision grip than during the power grip. The left M1/S1 and right cerebellum showed a positive linear relationship with the grip force, while the right angular gyrus and left superior frontal gyrus showed a gradual increase in activity when less force was applied. However, these force-dependent modulations of brain activity were similar for the precision and power grip tasks. No brain region was specifically activated during one task but not during the other. Activity during precision gripping did not exceed the activity associated with power gripping possibly because the precision grip task was not challenging enough to call on dexterous fine motor control.     

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.     

Transcallosal inhibition in chronic subcortical stroke

Movements of the paretic hand in patients with chronic subcortical stroke are associated with high interhemispheric inhibition (IHI) targeting the motor cortex in the lesioned hemisphere relative to healthy controls. The purpose of this investigation was to determine whether this abnormality also involves IHI operating during movements of the non-paretic hand. Here, we studied IHI in the process of generation of voluntary index finger movements by the paretic and non-paretic hands in a simple reaction time paradigm in a group of patients with chronic subcortical stroke. With movements of the non-paretic index finger, IHI targeting the contralateral primary motor cortex ((c)M1) decreased progressively to turn into facilitation at around movement onset, similar to healthy controls. In contrast, movements of the paretic index finger resulted in significantly deeper inhibition at all premovement timings relative to the non-paretic hand. In conclusion, these results document a deeper premovement IHI with paretic than non-paretic hand movements of patients with chronic subcortical stroke, a possible mechanism underlying deficits in motor control.     

脑卒中患者不同强度随意运动时的sEMG反应特点

目的：观察不同强度静态及动态运动负荷对脑卒中患者四肢肌肉sEMG信号变化的影响,研究脑卒中患者四肢肌肉活动的表面肌电信号特征与其神经运动控制的关系。方法：24例脑卒中患者参加本项研究,采用患、健侧自身对照实验方法设计,采用上肢屈肘和下肢伸膝静态运动,以及肘关节和膝关节动态屈伸运动负荷试验,采集主动肌和拮抗肌的表面肌电信号,分析信号振幅和拮抗比值等sEMG信号活动特征。结果：最大用力收缩时,上、下肢患侧主动肌AEMG小于健侧,而拮抗比大于健侧;小强度静态运动负荷过程中,患侧上肢主动肌的AEMG略高于患侧,拮抗比明显大于健侧。患侧下肢股外侧肌（VL）、股直肌（RF）和股内侧肌（VM）的平均AEMG、?T标准化值大于健侧,拮抗比小于健侧;小强度动态运动负荷过程中,上肢患侧主动肌AEMG明显高于健侧。下肢患侧VL、RF和VM的AEMG均值具有增大趋势,但无明显差异。而患侧拮抗比明显小于健侧。结论：脑卒中患者由于高位神经元和运动控制功能受损,导致其患侧在最大随意收缩时运动单位募集能力下降,而在轻负荷运动时运动单位募集过度。     

Imaging correlates of motor recovery from cerebral infarction and their physiological significance in well-recovered patients

We studied motor representation in well-recovered stroke patients. Eighteen right-handed stroke patients and eleven age-matched control subjects underwent functional Magnetic Resonance Imaging (fMRI) while performing unimanual index finger (abduction-adduction) and wrist movements (flexion-extension) using their recovered and non-affected hand. A subset of these patients underwent Transcranial Magnetic Stimulation (TMS) to elicit motor evoked potentials (MEP) in the first dorsal interosseous muscle of both hands. Imaging results suggest that good recovery utilizes both ipsi- and contralesional resources, although results differ for wrist and index finger movements. Wrist movements of the recovered arm resulted in significantly greater activation of the contralateral (lesional) and ipsilateral (contralesional) primary sensorimotor cortex (SM1), while comparing patients to control subjects performing the same task. In contrast, recovered index finger movements recruited a larger motor network, including the contralateral SM1, Supplementary Motor Area (SMA) and cerebellum when patients were compared to control subjects. TMS of the lesional hemisphere but not of the contralesional hemisphere induced MEPs in the recovered hand. TMS parameters also revealed greater transcallosal inhibition, from the contralesional to the lesional hemisphere than in the reverse direction. Disinhibition of the contralesional hemisphere observed in a subgroup of our patients suggests persistent alterations in intracortical and transcallosal (interhemispheric) interactions, despite complete functional recovery.     

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.     

Neuronal network coherent with hand kinematics during fast repetitive hand movements

We quantified the coupling between magnetoencephalographic (MEG) cortical signals and the kinematics of fast repetitive voluntary hand movements monitored by a 3-axis accelerometer. Ten healthy right-handed adults performed self-paced flexion-extension movements of right-hand fingers at ~ 3 Hz with either touching the thumb during flexions (TOUCH) or not (noTOUCH). At the sensor level, we found in all subjects and conditions significant coherence at the movement frequency (F0) and its first harmonic (F1). Coherence values were significantly higher in TOUCH compared to noTOUCH. At the group level, dynamic imaging of coherent sources localized the main source of coherent activity at the left primary motor (M1) hand area, except at F0 TOUCH were the main source was localized at the left primary sensory (S1) hand area. Other coherent brain areas were also identified at right S1-M1 cortices (F0), left dorsolateral prefrontal cortex (F1), left posterior parietal cortex (F0 TOUCH and F1 noTOUCH) and left medial S1-M1 areas (TOUCH). This study highlights the prominent role of rhythmic neuronal activity phase-locked to movements for the encoding and the integration of key sensori-motor features of limb kinematics. This study also suggests that somatosensory afferences play a key role to sustain a high synchronization level between the neuronal activity in coherent brain areas and hand acceleration. Some coherent brain regions differed between F0 and F1 in both conditions, suggesting that distinct cortical areas are involved in different features of hand kinematics.     

Combined functional MRI and tractography to demonstrate the connectivity of the human primary motor cortex in vivo

In this study, we combined advanced MR techniques to explore primary motor cortex (M1) connectivity in the human brain. We matched functional and anatomical information using motor functional MRI (fMRI) and white matter tractography inferred from diffusion tensor imaging (DTI). We performed coregistered DTI and motor task fMRI in 8 right-handed healthy subjects and in 1 right-handed patient presenting with a left precentral tumour. We used the fast-marching tractography (FMT) algorithm to define 3D connectivity maps within the whole brain, from seed points selected in the white matter adjacent to the location of the maximum of fMRI activation. Connectivity maps were then anatomically normalised and analysed using statistical parametric mapping software (SPM99) allowing group comparisons (left versus right hemisphere in control subjects and patient versus control subjects). The results demonstrated, in all control subjects, strong connections from M1 to the pyramidal tracts, premotor areas, parietal cortices, thalamus, and cerebellum. M1 connectivity was asymmetric, being more extensive in the dominant hemisphere. The patient had differences in M1 connectivity from the control group. Thus, fMRI-correlated DTI-FMT is a promising tool to study the structural basis of functional networks in the human brain in vivo.     

MEG imaging of sensorimotor areas using inter-trial coherence in vibrotactile steady-state responses

We utilized a novel analysis technique to identify brain areas that activate synchronously during the steady-state interval of responses to vibrotactile stimulation of the right index finger. The inter-trial coherence at the stimulation rate (23 Hz) was determined for whole-brain neural activity estimates based on a linearly-constrained minimum variance beamformer applied to the MEG data. Neural activity coherent with the stimulus occurred in the contralateral primary somatosensory cortex in all subjects, and matched well with equivalent dipole modeling of the same data. Subsets of subjects exhibited additional loci of strongly coherent activity in the contralateral primary motor cortex, posterior parietal cortex, and supplementary motor area, as well as in deeper brain structures above the brainstem. An activation delay of 7 ms from deep structures to cortical areas was estimated based on the mean phase at each coherent neural source within a single subject. This new approach - volumetric mapping of the statistical parameter of inter-trial coherence in steady-state oscillations - broadens the range of MEG beamformer applications specifically for identifying brain areas that are synchronized to repetitive stimuli.     

Neural correlates of age-related changes in cortical neurophysiology

Functional imaging studies of cortical motor systems in humans have demonstrated age-related reorganisation often attributed to anatomical and physiological changes. In this study we investigated whether aspects of brain activity during a motor task were influenced not only by age, but also by neurophysiological parameters of the motor cortex contralateral to the moving hand. Twenty seven right-handed volunteers underwent functional magnetic resonance imaging whilst performing repetitive isometric right hand grips in which the target force was parametrically varied between 15 and 55% of each subject's own maximum grip force. For each subject we characterised two orthogonal parameters, B(G) (average task-related activity for all hand grips) and B(F) (the degree to which task-related activity co-varied with peak grip force). We used transcranial magnetic stimulation (TMS) to assess task-related changes in interhemispheric inhibition from left to right motor cortex (IHIc) and to perform measures relating to left motor cortex excitability during activation of the right hand. Firstly, we found that B(G) in right (ipsilateral) motor cortex was greater with increasing values of age(2) and IHIc. Secondly, B(F) in left ventral premotor cortex was greater in older subjects and in those in whom contralateral M1 was less responsive to TMS stimulation. In both cases, neurophysiological parameters accounted for variability in brain responses over and above that explained by ageing. These results indicate that neurophysiological markers may be better indicators of biological ageing than chronological age and point towards the mechanisms by which reconfiguration of distributed brain networks occurs in the face of degenerative changes.     

Activation likelihood estimation meta-analysis of motor-related neural activity after stroke

Over the past two decades, several functional neuroimaging experiments demonstrated changes in neural activity in stroke patients with motor deficits. Conclusions from single experiments are usually constrained by small sample sizes and high variability across studies. Here, we used coordinate-based activation likelihood estimation meta-analyses to provide a quantitative synthesis of the current literature on motor-related neural activity after stroke. Of over 1000 PubMed search results through January 2011, 36 studies reported standardized whole-brain group coordinates. Meta-analyses were performed on 54 experimental contrasts for movements of the paretic upper limb (472 patients, 452 activation foci) and on 20 experiments comparing activation between patients and healthy controls (177 patients, 113 activation foci). We computed voxelwise correlations between activation likelihood and motor impairment, time post-stroke, and task difficulty across samples. Patients showed higher activation likelihood in contralesional primary motor cortex (M1), bilateral ventral premotor cortex and supplementary motor area (SMA) relative to healthy subjects. Activity in contralesional areas was more likely found for active than for passive tasks. Better motor performance was associated with greater activation likelihood in ipsilesional M1, pre-SMA, contralesional premotor cortex and cerebellum. Over time post-stroke, activation likelihood in bilateral premotor areas and medial M1 hand knob decreased. This meta-analysis shows that increased activation in contralesional M1 and bilateral premotor areas is a highly consistent finding after stroke despite high inter-study variance resulting from different fMRI tasks and motor impairment levels. However, a good functional outcome relies on the recruitment of the original functional network rather than on contralesional activity.     

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.     

运动想象联合常规康复促进脑卒中患者上肢运动功能恢复的fMRI研究

目的 采用基于静息态功能磁共振(fMRI)的Granger因果分析方法研究运动想象(MIT)联合常规康复促进脑卒中患者上肢功能恢复的作用机制。 方法 招募14例脑卒中后偏瘫患者纳入MIT组,对其进行4周MIT治疗,每周治疗5 d,每天治疗30 min,并同时辅以常规康复及药物治疗。于治疗前、后采用Fugl-Meyer量表上肢部分(FMA-UE)及改良Barthel指数(MBI)对患者进行评估,并进行静息态fMRI扫描。本研究同期招募28例年龄、性别与MIT组匹配的健康人纳入健康对照组,并对其进行静息态fMRI扫描。采用Granger因果分析方法探讨患者经治疗后其损伤侧初级运动皮质(M1)与全脑间有效连接的变化情况,并与健康对照组进行比较。 结果 治疗后,MIT组患者FMA-UE评分由 (18.4±12.0）分提升至(33.4±15.4)分,MBI评分由(58.6±14.7)分提升至(78.2±14.8）分,差异均具有统计学意义（P<0.05）。治疗前,MIT组患者有效连接模式明显异于健康对照组,其损伤侧M1到双侧前额叶的有效连接异常增强,从损伤对侧M1、顶下小叶和小脑到损伤侧M1的有效连接则明显减弱。治疗后,MIT组有效连接模式趋近于健康对照组,且顶上小叶、顶下小叶、丘脑和梭状回等与运动想象相关脑区和损伤侧M1的有效连接显著增强。通过相关性分析发现,治疗前,患者损伤侧M1到损伤对侧小脑的有效连接与FMA-UE评分具有正相关性(R=0.601,P=0.023),损伤对侧额中回到损伤侧M1的有效连接与FMA-UE评分具有负相关性(R=-0.638,P=0.015)。 结论 MIT联合常规康复促进脑卒中患者上肢运动功能改善可能与有效连接模式重塑有关,如治疗后脑卒中患者运动想象相关脑区和损伤对侧小脑到损伤侧M1的有效连接增强,而损伤对侧额中回到损伤侧M1的有效连接代偿效应解除。     

Weight-bearing on the lower limbs in a sitting position during bilateral movement of the upper limbs in post-stroke hemiparetic subjects.

OBJECTIVE: Verify weight-bearing on the feet in a sitting position during pointing in different directions with 1 or both upper limbs. DESIGN: Comparative study. SUBJECTS: Fifteen subjects with post-stroke hemiparesis with good to very good motor recovery and 13 healthy subjects participated in the study. METHODS: The subjects were seated on a chair with each foot resting on a force plate. They had to touch with 1 or, simultaneously with both hands, 2 target(s) located in front of them or at a 45 degrees angle on either side at a standardized distance beyond their upper limb's length. The percentage of weight loading variation under each foot was measured. RESULTS: Weight-bearing on the paretic foot is reduced during unilateral and bilateral pointing in the anterior direction and 45 degrees ipsilateral to the paretic side. However, both unilateral and bilateral pointing 45 degrees contralateral to the paretic side produced symmetrical weight-bearing on both feet, paretic and non-paretic. CONCLUSION: Since the paretic muscles of the trunk are probably used to control the leaning of the trunk towards the non-paretic side, the subjects with hemiparesis may put weight on the paretic foot to compensate for trunk weakness and maintain balance.