To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images...To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images of five healthy volunteers are collected. The diffusion sensitive gradient magnetic fields are applied along 25 directions and the diffusion weighting value is 1 000 s/mm^2. Many positive-indefinite diffusion tensors can be found in the white matter area, such as the genu and the splenium of corpus callosum. Due to the positive-indefinite matrix, the mean diffusivity （MD） and the fractional anisotropy （FA） are under-estimated and over-estimated by using the conventional algorithm. Thus, the conventional algorithm is modified by using the absolute values of all eigenvalues. Results show that both the robustness and the reliability for deriving these parameters are improved by the modified algorithm.展开更多
目的:总结近10年静息态脑功能磁共振成像(resting-state functional magnetic resonance imaging,rs-fMRI)研究针刺治疗慢性疼痛脑中枢重建机制的概况。方法:以“慢性疼痛”“针刺”“rs-fMRI”为检索词,在中国知网、万方、PubMed等数...目的:总结近10年静息态脑功能磁共振成像(resting-state functional magnetic resonance imaging,rs-fMRI)研究针刺治疗慢性疼痛脑中枢重建机制的概况。方法:以“慢性疼痛”“针刺”“rs-fMRI”为检索词,在中国知网、万方、PubMed等数据库检索近10年来国内外利用rs-fMRI研究针刺治疗慢性疼痛机制文献,分析其脑中枢重建机制。结果:针刺镇痛正激活脑区包括前额叶、岛叶、扣带回、丘脑、脑干、小脑、基底核等,负激活脑区包括双侧楔前叶、双侧海马、双侧额中回等。针刺还能通过调节默认模式网络、疼痛矩阵、执行网络脑区和边缘系统等区域间的连接来缓解慢性疼痛。不过这些脑区、脑网络的激活或抑制会因个体差异、疼痛类型和针刺激参数等因素而有所不同。结论:针刺镇痛作用的实现主要是通过调节与感觉、情感、认知相关联的脑区、脑网络。基于此针刺镇痛内在机制仍需进一步研究。展开更多
Progress in surface modification of magnetic nanoparticles（MNPs） is summarized with regard to organic molecules,macromolecules and inorganic materials. Many researchers are now devoted to synthesizing new types of m...Progress in surface modification of magnetic nanoparticles（MNPs） is summarized with regard to organic molecules,macromolecules and inorganic materials. Many researchers are now devoted to synthesizing new types of multi-functional MNPs, which show great application potential in both diagnosis and treatment of disease. By employing an ever-greater variety of surface modification techniques, MNPs can satisfy more and more of the demands of medical practice in areas like magnetic resonance imaging（MRI）, fluorescent marking, cell targeting, and drug delivery.展开更多
The basal ganglia have been implicated in a modulation role in idiopathic generalized epilepsy （IGE） by an invasive electrophysioigic means. This paper investigates the basal ganglia functional connectivity by using...The basal ganglia have been implicated in a modulation role in idiopathic generalized epilepsy （IGE） by an invasive electrophysioigic means. This paper investigates the basal ganglia functional connectivity by using the region-wise functional connection analysis in resting-state functional magnetic resonance imaging （fMRI） in IGE. The increased functional connectivity within basal ganglia, and between the basal ganglia and the thalamus, and decreased functional connectivity between basal ganglia and motor cortex are found in IGE compared with the controls. These findings not only implicate dysfunctional integration in the motor loop in IGE and the enhanced interaction in the modulated loop, but also suggest that the basal ganglia modulate the generalized epileptic discharges with the influence over thalamus in the corticothalamus network.展开更多
The original temporal clustering analysis (OTCA) is an effective technique for obtaining brain activation maps when the timing and location of the activation are completely unknown, but its deficiency of sensitivity i...The original temporal clustering analysis (OTCA) is an effective technique for obtaining brain activation maps when the timing and location of the activation are completely unknown, but its deficiency of sensitivity is exposed in processing brain activation signal which is relatively weak. The time slice analysis method based on OTCA is proposed considering the weakness of the functional magnetic resonance imaging (fMRI) signal of the rat model. By dividing the stimulation period into several time slices and analyzing each slice to detect the activated pixels respectively after the background removal, the sensitivity is significantly improved. The inhibitory response in the hypothalamus after glucose loading is detected successfully with this method in the experiment on rat. Combined with the OTCA method, the time slice analysis method based on OTCA is effective on detecting when, where and which type of response will happen after stimulation, even if the fMRI signal is weak.展开更多
To investigate changes of functional activation areas of the cerebral cortex and the connectivity of motor cortex networks （MCNs） in stroke patients during the recovery, five patients with the infarct in their left ...To investigate changes of functional activation areas of the cerebral cortex and the connectivity of motor cortex networks （MCNs） in stroke patients during the recovery, five patients with the infarct in their left hemispheres are recruited. Functional magnetic resonance imaging （fMRI） is performed in the second, fourth, eighth, and sixteenth weeks after the stroke. Images are analyzed using the professional software SPM5 to obtain the bilateral activation of the motor cortex in left and right handgrip tests. MCN data are extracted from the active areas, and the structural and functional characteristic parameters are computed to indicate the connectivity of the network. Results show that the ipsilesional hemisphere recruits more areas with less active extent during the handgrip test, compared with the contralesional hemisphere. MCN shows a higher overall degree of statistical independence and more statistical dependence among motor areas with the gradual recovery. It can help physicians understand the recovery mechanism.展开更多
基金Supported by the Research Project of Dongguan Higher Education (200910815252)the Beijing Natural Science Foundation(7102102)the Scientific Research Key Program of Beijing Municipal Commission of Ed-ucation(KZ200810025011)~~
文摘To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters, a modified algorithm is proposed for calculating these parameters. Magnetic resonance （MR） diffusion tensor images of five healthy volunteers are collected. The diffusion sensitive gradient magnetic fields are applied along 25 directions and the diffusion weighting value is 1 000 s/mm^2. Many positive-indefinite diffusion tensors can be found in the white matter area, such as the genu and the splenium of corpus callosum. Due to the positive-indefinite matrix, the mean diffusivity （MD） and the fractional anisotropy （FA） are under-estimated and over-estimated by using the conventional algorithm. Thus, the conventional algorithm is modified by using the absolute values of all eigenvalues. Results show that both the robustness and the reliability for deriving these parameters are improved by the modified algorithm.
文摘目的:总结近10年静息态脑功能磁共振成像(resting-state functional magnetic resonance imaging,rs-fMRI)研究针刺治疗慢性疼痛脑中枢重建机制的概况。方法:以“慢性疼痛”“针刺”“rs-fMRI”为检索词,在中国知网、万方、PubMed等数据库检索近10年来国内外利用rs-fMRI研究针刺治疗慢性疼痛机制文献,分析其脑中枢重建机制。结果:针刺镇痛正激活脑区包括前额叶、岛叶、扣带回、丘脑、脑干、小脑、基底核等,负激活脑区包括双侧楔前叶、双侧海马、双侧额中回等。针刺还能通过调节默认模式网络、疼痛矩阵、执行网络脑区和边缘系统等区域间的连接来缓解慢性疼痛。不过这些脑区、脑网络的激活或抑制会因个体差异、疼痛类型和针刺激参数等因素而有所不同。结论:针刺镇痛作用的实现主要是通过调节与感觉、情感、认知相关联的脑区、脑网络。基于此针刺镇痛内在机制仍需进一步研究。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51125001 and 51172005)the Natural Science Foundation of Beijing,China(Grant No.2122022)+1 种基金the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.81421004)the Doctoral Program of the Education Ministry of China(Grant No.20120001110078)
文摘Progress in surface modification of magnetic nanoparticles（MNPs） is summarized with regard to organic molecules,macromolecules and inorganic materials. Many researchers are now devoted to synthesizing new types of multi-functional MNPs, which show great application potential in both diagnosis and treatment of disease. By employing an ever-greater variety of surface modification techniques, MNPs can satisfy more and more of the demands of medical practice in areas like magnetic resonance imaging（MRI）, fluorescent marking, cell targeting, and drug delivery.
基金supported by the National Natural Science Foundation of China under Grant No. 81071222
文摘The basal ganglia have been implicated in a modulation role in idiopathic generalized epilepsy （IGE） by an invasive electrophysioigic means. This paper investigates the basal ganglia functional connectivity by using the region-wise functional connection analysis in resting-state functional magnetic resonance imaging （fMRI） in IGE. The increased functional connectivity within basal ganglia, and between the basal ganglia and the thalamus, and decreased functional connectivity between basal ganglia and motor cortex are found in IGE compared with the controls. These findings not only implicate dysfunctional integration in the motor loop in IGE and the enhanced interaction in the modulated loop, but also suggest that the basal ganglia modulate the generalized epileptic discharges with the influence over thalamus in the corticothalamus network.
基金the National Natural Science Foundation of China (30370432)
文摘The original temporal clustering analysis (OTCA) is an effective technique for obtaining brain activation maps when the timing and location of the activation are completely unknown, but its deficiency of sensitivity is exposed in processing brain activation signal which is relatively weak. The time slice analysis method based on OTCA is proposed considering the weakness of the functional magnetic resonance imaging (fMRI) signal of the rat model. By dividing the stimulation period into several time slices and analyzing each slice to detect the activated pixels respectively after the background removal, the sensitivity is significantly improved. The inhibitory response in the hypothalamus after glucose loading is detected successfully with this method in the experiment on rat. Combined with the OTCA method, the time slice analysis method based on OTCA is effective on detecting when, where and which type of response will happen after stimulation, even if the fMRI signal is weak.
基金Supported by the National Natural Science Foundation of China (30670543)~~
文摘To investigate changes of functional activation areas of the cerebral cortex and the connectivity of motor cortex networks （MCNs） in stroke patients during the recovery, five patients with the infarct in their left hemispheres are recruited. Functional magnetic resonance imaging （fMRI） is performed in the second, fourth, eighth, and sixteenth weeks after the stroke. Images are analyzed using the professional software SPM5 to obtain the bilateral activation of the motor cortex in left and right handgrip tests. MCN data are extracted from the active areas, and the structural and functional characteristic parameters are computed to indicate the connectivity of the network. Results show that the ipsilesional hemisphere recruits more areas with less active extent during the handgrip test, compared with the contralesional hemisphere. MCN shows a higher overall degree of statistical independence and more statistical dependence among motor areas with the gradual recovery. It can help physicians understand the recovery mechanism.
