镜像视觉反馈训练影响脊髓损伤患者脑重塑的机制:功能MRI研究进展北大核心CSCD

镜像视觉反馈(MVF)训练对脊髓损伤(SCI)等运功功能障碍患者的康复具有积极作用。近年将功能MRI(fMRI)用于分析MVF对脑功能的影响及其可能机制,为揭示MVF康复机制开辟了新思路。本文对MVF用于运动功能康复及SCI后脑可塑性变化的可能机制的fMRI研究进展进行综述。     

功能磁共振成像在多发性硬化中的应用进展

多发性硬化(MS)的一个重要的临床表现是认知障碍.有越来越多的证据显示,认知障碍的程度不仅与组织损坏程度有关,还同MS患者组织受损、组织修复及大脑皮层重组等因素间复杂的制约平衡关系密切相关.神经可塑性能够在大脑中散乱分布多个病灶的情况下使得大脑维持正常运行,而功能磁共振成像(fMRI)及静息态fMRI能够为我们提供有关...     

脊髓的可塑性

脊髓损伤后,脊髓的可塑性由损伤和特殊形式的训练启动,表现为自发性可塑性(损伤诱导的可塑性)和训练任务依赖性可塑性两种类型。自发性可塑性主要表现为轴突芽生、潜伏通路重启、突触效率改变等形式;训练任务依赖性可塑性表现为中枢模式发生器重新激活、脊髓神经元回路重组。对脊髓可塑性的深入探索、最大限度地增强脊髓的可塑性,将有助于优化现有治疗方案或研究新的治疗策略,进一步促进脊髓损伤患者的康复。     

脊髓损伤后大脑皮质的变化

脊髓损伤对大脑皮质产生的影响包括神经元形态和基因的表达、大脑皮质自身的功能和结构重组、局部血流、神经营养因子及其受体的表达等.这些变化可能对脊髓损伤患者的康复治疗和功能恢复有一定的影响.因此,了解脊髓损伤后大脑皮质的变化对进一步探讨脊髓损伤的机制,寻找新的脊髓损伤治疗途径有非常重要的意义.     

重复经颅磁刺激对脊髓运动功能恢复的影响及其机制的实验研究

目的观察重复经颅磁刺激（rTMS）对大鼠脊髓损伤后运动功能恢复的影响,并对其作用机制进行初步探索。方法利用重物撞击法制作成年大鼠T10脊髓损伤模型,实验组给予经皮0.5Hz大脑皮质区磁刺激,每天500个脉冲,共4周。通过运动行为学BBB评分,组织学及免疫组化荧光法观察生长相关蛋白43（GAP43）和5-羟色胺（5-HT）在脊髓损伤区的变化情况。结果实验组BBB评分明显高于模型组（P〈0.01）;组织学表现符合慢性不完全性脊髓损伤病理变化;实验组GAP43及5-HT水平明显高于模型组（P〈0.01）;且损伤头端增加明显著高于尾端（P〈0.01）。结论rTMS有促进脊髓损伤大鼠运动功能恢复的作用,机制可能与促进轴突生长锥可塑性及残存下行5-HT能纤维神经递质分泌增加有关。     

慢性疼痛的脑机制及静息态功能性磁共振研究

疼痛具有多维属性,包括感觉识别、情绪动机和认知评价等3个方面,对于人类的生存具有重要意义.然而,持久的疼痛可能影响身体多器官系统的功能,导致严重的健康问题.研究表明:慢性疼痛患者普遍存在大脑皮层灰质减少,这反映出疼痛造成了大脑的结构性损伤.近年来功能性磁共振成像(functianal magnetic resonance imaging,fMRI)凭借其无创伤性及可准确定位脑功能区等特点,已成为脑功能成像研究的常用工具.静息态fMRI研究的是大脑在静息状态时的自发活动,通过对fMRI信号的分析,得到慢性疼痛患者静息状态时脑中性质和连接的异常改变.本文综述慢性疼痛患者的脑机制及静息态fMRI应用于慢性疼痛患者的研究现状与进展.     

脊髓损伤导致认知障碍及其相关机制的研究进展

脊髓损伤的研究主要集中在运动功能和感觉功能的缺失及自主神经相关的并发症等方面,而对脊髓损伤后造成的大脑认知障碍的研究较少。影响脊髓损伤后认知障碍的因素主要有情绪、创伤性脑损伤、饮酒史、药物滥用史和文化水平等,可能机制主要有创伤性脑损伤、大脑结构改变、脑内损伤和功能的改变以及不恰当的治疗等。     

脊髓损伤后脑源性神经营养因子神经生物学效应的研究进展

脊髓损伤可导致不同程度的躯体及自主神经功能障碍,严重影响患者的生活质量。本文介绍脑源性神经营养因子(BDNF)对脊髓损伤后的功能恢复促进作用及神经生物学效应,包括神经保护、神经可塑性、神经炎症过程调节等;以及BDNF在脊髓损伤后的不良影响,如导致神经病理性疼痛和痉挛状态等。     

脑外伤患者督脉穴位电刺激fMRI脑成像的初步观察

目的观察脑外伤患者督脉穴位电刺激的fMRI脑成像变化。方法对1例脑外伤患者进行命门穴和腰阳关穴经皮神经电刺激,对穴位刺激时的脑功能变化进行fMRI观察。结果与静息状态比较,电刺激时出现多个脑区激活。结论电刺激督脉可能会影响脑损伤后的神经可塑性过程。     

电针刺激合谷穴在颈脊髓内效应的功能磁共振成像的初步研究

目的:观察比较穴位刺激与非穴位刺激的正常颈脊髓对针灸信号效应特征,初步探索脊髓针灸效应的作用机制,为探索针灸治疗脊髓损伤的作用机理提供一定的实验依据和方法.方法:16名健康志愿者按要求随机分成2组(每组8名)分别进行电刺右手合谷穴位和伪穴位,采用“静息-任务刺激-静息”的时段设计模式,共4次刺激,5次静息,各长35 s.获得的fMRI信号用AFNI软件进行后处理,得到激活信号与解剖信号的叠加图、激活信号值曲线.结果:神经功能激活区域大部分位于高位与低位颈脊髓平面,主要集中于C5～T1和C2～C3;5位志愿者在C2、C3、C5与C6平面脊髓前角出现神经功能激活;同时在C2、C5及C6平面对侧脊髓后角出现神经功能激活.电刺伪穴位组的脊髓fMRI激活结果:神经功能激活区域主要集中于C5～T1,高位颈脊髓未发现神经功能激活区;激活部位主要位于同侧脊髓后角.结论:利用单次激发快速自旋回波序列脊髓功能核磁共振技术能检测电刺合谷穴及其伪穴位时正常脊髓功能变化的信号,穴位刺激能引起更广泛的脊髓激活区域,高位脊髓激活区可能是针灸经络的特定激活区域;使用1.5T医用核磁共振机和常规颈线圈对脊髓损伤患者的脊髓功能核磁共振成像能检测到受损脊髓对电刺合谷穴时的神经信号,有助于评估脊髓功能状况.     

3D mapping of somatotopic reorganization with small animal functional MRI

There are few in vivo noninvasive methods to study neuroplasticity in animal brains. Functional MRI (fMRI) has been developed for animal brain mapping, but few fMRI studies have analyzed functional alteration due to plasticity in animal models. One major limitation is that fMRI maps are characterized by statistical parametric mapping making the apparent boundary dependent on the statistical threshold used. Here, we developed a method to characterize the location of center-of-mass in fMRI maps that is shown not to be sensitive to statistical threshold. Utilizing centers-of-mass as anchor points to fit the spatial distribution of the BOLD response enabled quantitative group analysis of altered boundaries of functional somatosensory maps. This approach was used to study cortical reorganization in the rat primary somatosensory cortex (S1) after sensory deprivation to the barrel cortex by follicle ablation (F.A.). FMRI demonstrated an enlarged nose S1 representation in the 3D somatotopic functional maps. This result clearly demonstrates that fMRI enables the spatial mapping of functional changes that can characterize multiple regions of S1 cortex and still be sensitive to changes due to plasticity.     

Neural regeneration therapy after spinal cord injury induces unique brain functional reorganizations in rhesus monkeys

PurposeSpinal cord injury (SCI) destroys the sensorimotor pathway and induces brain plasticity. However, the effect of treatment-induced spinal cord tissue regeneration on brain functional reorganization remains unclear. This study was designed to investigate the large-scale functional interactions in the brains of adult female Rhesus monkeys with injured and regenerated thoracic spinal cord.Materials and methodsResting-state functional magnetic resonance imaging (fMRI) combined with Granger Causality analysis (GCA) and motor behaviour analysis were used to assess the causal interaction between sensorimotor cortices, and calculate the relationship between causal interaction and hindlimb stepping in nine Rhesus monkeys undergoing lesion-induced spontaneous recovery (injured, n = 4) and neurotrophin-3/chitosan transplantation-induced regeneration (NT3-chitosan, n = 5) after SCI.ResultsThe results showed that the injured and NT3-chitosan-treated animals had distinct spatiotemporal features of brain functional reorganization. The spontaneous recovery followed the model of “early intra-hemispheric reorganization dominant, late inter-hemispheric reorganization dominant”, whereas regenerative therapy animals showed the opposite trend. Although the variation degree of information flow intensity was consistent, the tendency and the relationship between local neuronal activity properties and coupling strength were different between the two groups. In addition, the injured and NT3-chitosan-treated animals had similar motor adjustments but various relationship modes between motor performance and information flow intensity.ConclusionsOur findings show that brain functional reorganization induced by regeneration therapy differed from spontaneous recovery after SCI. The influence of unique changes in brain plasticity on the therapeutic effects of future regeneration therapy strategies should be considered.

Key messages

• Neural regeneration elicited a unique spatiotemporal mode of brain functional reorganization in the spinal cord injured monkeys, and that regeneration does not simply reverse the process of brain plasticity induced by spinal cord injury (SCI).
• Independent “properties of local activity – intensity of information flow” relationships between the injured and treated animals indicating that spontaneous recovery and regenerative therapy exerted different effects on the reorganization of the motor network after SCI.
• A specific information flow from the left thalamus to the right insular can serve as an indicator to reflect a heterogeneous “information flow – motor performance” relationship between injured and treated animals at similar motor adjustments.

     

功能磁共振成像在脑损伤康复期演变中的应用

脑损伤患者在康复过程中会伴有不同程度的脑组织重塑和功能重组.功能磁共振成像(fMRI)能够获得脑组织的解剖学、生理学及病理学信息,并且在一定程度上反映各功能区间的相互联系.因此.fMRI技术能够反映脑损伤康复过程中脑组织发生的结构和功能变化,为临床开展有针对性的治疗提供有价值的信息.     

Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI)

Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed 2 weeks following transection of the four major nerves of the brachial plexus. Direct stimulation of the intact radial nerve reveals a functional magnetic resonance imaging (fMRI) activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. Results of this fMRI experiment were used to determine seed voxel regions for fcMRI analysis. Intrahemispheric connectivities in the sensorimotor forelimb representations in both hemispheres are largely unaffected by deafferentation, whereas substantial disruption of interhemispheric sensorimotor cortical connectivity occurs. In addition, significant intra- and interhemispheric changes in connectivities of thalamic nuclei were found. These are the central findings of the study. They could not have been obtained from fMRI studies alone—both fMRI and fcMRI are needed. The combination provides a general marker for brain plasticity. The rat visual system was studied in the same animals as a control. No neuroplastic changes in connectivities were found in the primary visual cortex upon forelimb deafferentation. Differences were noted in regions responsible for processing multisensory visual-motor information. This incidental discovery is considered to be significant. It may provide insight into phantom limb epiphenomena.     

A functional magnetic resonance imaging study of patients with secondary progressive multiple sclerosis

Although several functional magnetic resonance imaging (fMRI) studies have shown adaptive cortical changes in patients with early multiple sclerosis (MS), the presence of brain plasticity and its role in limiting the functional consequences of brain tissue damage in patients with secondary progressive (SP) MS have not been fully investigated yet. In this study, we assessed the movement-associated brain pattern of cortical activations in patients with SPMS and investigated whether the extent of cortical brain activations is correlated with the extent of brain structural changes. From 13 right-handed SPMS patients and 15 sex- and age-matched healthy volunteers, we obtained: (a) brain dual-echo scans; (b) brain mean diffusivity and fractional anisotropy maps of the normal-appearing white (NAWM) and gray matter (NAGM); (c) fMRI during the performance of simple motor tasks [flexion-extension of the last four fingers of the right hand (task 1) and flexion-extension of the right foot (task 2)]. Compared to healthy volunteers, during task 1 performance, SPMS patients showed more significant activations of the ipsilateral inferior frontal gyrus, middle frontal gyrus, bilaterally, and contralateral intraparietal sulcus. During task 2 performance, SPMS patients had more significant activations of the contralateral primary sensorimotor cortex and thalamus and of the ipsilateral upper bank of sylvian fessure. For both tasks, strong correlations (r values ranging from -0.83 to 0.88) were found between relative activations of cortical areas of the motor network and the severity of structural changes of the NAWM and NAGM. This study demonstrates that cortical plasticity does occur in patients with SPMS and that it might have a role in limiting the clinical impact of MS-related damage. It also suggests that, in these patients, functional abilities are sustained by increased recruitment of highly specialized cortical areas.     

神经精神性狼疮认知功能改变机制及结构和功能MRI研究进展

25%~75%的系统性红斑狼疮患者中存在中枢神经系统受累,尤其是脑,可产生各种神经精神症状,而且有证据表明嗅觉和认知功能改变可能早于神经精神症状的发生,因此有助于对狼疮脑病的早期诊断。近年来,随着各种功能MRI技术的发展,对系统性红斑狼疮的诊断、评估以及疾病的发生发展有重要价值。作者就系统性红斑狼疮患者在嗅觉和认知方面的改变,以及结构和功能MRI在其中的应用展开综述。     

神经影像在卒中后脑可塑性机制中的应用进展

神经影像技术是进行卒中后脑可塑性机制研究的重要手段.弥散张量成像可用于描述白质纤维束结构,评估受损程度,但不能反映不同脑区之间的功能联系;任务态功能磁共振成像(fMRI)可检测特定任务引起对应的脑区激活情况,但试验设计复杂,对受试者要求高;静息态fMRI可进行复杂脑网络分析,反映不同脑区功能联系,但数据分析方法复杂;功...     

Sparse representation of whole-brain fMRI signals for identification of functional networks

There have been several recent studies that used sparse representation for fMRI signal analysis and activation detection based on the assumption that each voxel’s fMRI signal is linearly composed of sparse components. Previous studies have employed sparse coding to model functional networks in various modalities and scales. These prior contributions inspired the exploration of whether/how sparse representation can be used to identify functional networks in a voxel-wise way and on the whole brain scale. This paper presents a novel, alternative methodology of identifying multiple functional networks via sparse representation of whole-brain task-based fMRI signals. Our basic idea is that all fMRI signals within the whole brain of one subject are aggregated into a big data matrix, which is then factorized into an over-complete dictionary basis matrix and a reference weight matrix via an effective online dictionary learning algorithm. Our extensive experimental results have shown that this novel methodology can uncover multiple functional networks that can be well characterized and interpreted in spatial, temporal and frequency domains based on current brain science knowledge. Importantly, these well-characterized functional network components are quite reproducible in different brains. In general, our methods offer a novel, effective and unified solution to multiple fMRI data analysis tasks including activation detection, de-activation detection, and functional network identification.     

疼痛的脑功能MRI研究进展

功能MRI(f MRI)是一种无创性的功能成像技术,近年来被广泛应用于疼痛方面的研究,使得人们对疼痛的生理有了进一步的认识。作者通过对不同类型疼痛的分析,从痛觉中枢的定位、临床疼痛的f MRI研究及疼痛治疗等方面综述了近年关于疼痛的脑f MRI研究进展。