Reproducibility of graph metrics of human brain functional networks

Graph theory provides many metrics of complex network organization that can be applied to analysis of brain networks derived from neuroimaging data. Here we investigated the test–retest reliability of graph metrics of functional networks derived from magnetoencephalography (MEG) data recorded in two sessions from 16 healthy volunteers who were studied at rest and during performance of the n-back working memory task in each session. For each subject's data at each session, we used a wavelet filter to estimate the mutual information (MI) between each pair of MEG sensors in each of the classical frequency intervals from γ to low δ in the overall range 1–60 Hz. Undirected binary graphs were generated by thresholding the MI matrix and 8 global network metrics were estimated: the clustering coefficient, path length, small-worldness, efficiency, cost-efficiency, assortativity, hierarchy, and synchronizability. Reliability of each graph metric was assessed using the intraclass correlation (ICC). Good reliability was demonstrated for most metrics applied to the n-back data (mean ICC = 0.62). Reliability was greater for metrics in lower frequency networks. Higher frequency γ- and β-band networks were less reliable at a global level but demonstrated high reliability of nodal metrics in frontal and parietal regions. Performance of the n-back task was associated with greater reliability than measurements on resting state data. Task practice was also associated with greater reliability. Collectively these results suggest that graph metrics are sufficiently reliable to be considered for future longitudinal studies of functional brain network changes.     

Characterization of task-free and task-performance brain states via functional connectome patterns

Both resting state fMRI (R-fMRI) and task-based fMRI (T-fMRI) have been widely used to study the functional activities of the human brain during task-free and task-performance periods, respectively. However, due to the difficulty in strictly controlling the participating subject’s mental status and their cognitive behaviors during R-fMRI/T-fMRI scans, it has been challenging to ascertain whether or not an R-fMRI/T-fMRI scan truly reflects the participant’s functional brain states during task-free/task-performance periods. This paper presents a novel computational approach to characterizing and differentiating the brain’s functional status into task-free or task-performance states, by which the functional brain activities can be effectively understood and differentiated. Briefly, the brain’s functional state is represented by a whole-brain quasi-stable connectome pattern (WQCP) of R-fMRI or T-fMRI data based on 358 consistent cortical landmarks across individuals, and then an effective sparse representation method was applied to learn the atomic connectome patterns (ACPs) of both task-free and task-performance states. Experimental results demonstrated that the learned ACPs for R-fMRI and T-fMRI datasets are substantially different, as expected. A certain portion of ACPs from R-fMRI and T-fMRI data were overlapped, suggesting some subjects with overlapping ACPs were not in the expected task-free/task-performance brain states. Besides, potential outliers in the T-fMRI dataset were further investigated via functional activation detections in different groups, and our results revealed unexpected task-performances of some subjects. This work offers novel insights into the functional architectures of the brain.     

抑郁症功能磁共振成像脑网络研究进展

近年来,功能磁共振成像技术的发展使得研究者可以无创地研究活体脑组织结构和功能特点,结合多种脑成像技术研究大尺度的脑结构和功能网络,为研究某些疾病的发生和发展机制提供了可靠的方法。目前抑郁症患者的磁共振脑网络研究还处在初步探索阶段,脑网络的拓扑属性在某种程度上对抑郁症患者的早期诊断和鉴别诊断起到一定的辅助作用,同时也可以作为一个衡量抑郁症严重程度的生理指标。脑结构和功能的异常模式也可作为敏感特征用于诊断相关脑疾病,因此本文将从抑郁症层面综述几个主要的磁共振脑网络的结构和功能方面的研究成果。     

多聚(ADP-核糖)聚合酶不同时空的表达特征对缺血性脑损伤细胞修复的影响

目的:研究局灶性脑缺血再灌注后多聚(ADP-核糖)聚合酶(PARP)表达的时空变化及其作用。方法:采用改良线栓法建立大鼠大脑中动脉缺血再灌注模型(MCAO-R,)运用免疫组织化学方法检测PARPM116000),PARP(r(Mr24000)和caspasse-3表达的时空变化,苏木精-伊红染色观察组织病理变化。结果:脑缺血2h再灌注12h,PARP(M116000)及caspase-3表达增r多,且随再灌时间的延长而表达逐渐增多(P<0.05),并向四周动态扩展。缺血3h组PARP(M116000)蛋白阳性表达也增强,但表达程度与r缺血2h组相比略有下降,在再灌注3d时表达最少。缺血6h组PARP(M116000)蛋白表达减少,且不随再灌注时间的延长而有明显变化。r而PARP(M24000)蛋白在缺血2h再灌注12h阳性表达增加,但不r随缺血时间及再灌注时间的延长而明显变化,呈平稳的低水平表达,与caspase-3的变化趋势也无相关性。结论:在脑缺血再灌注损伤中PARP活化的主要损伤作用是坏死而非凋亡。     

CT直接定位脑立体定向手术治疗顽固性癌痛

目的应用立体定向技术与CT相结合,通过CT扫描图像上直接定位对丘脑中央中核损毁的方法,对顽固性癌痛进行治疗,并探讨顽固性癌痛的发生机制.方法对颅内阴性靶点进行三维成像,立体定位,应用射频电凝对其靶点进行损毁.结果35例晚期不同癌痛病人,术后效果获得控制33例,缓解2例.结论CT扫描直接定位行靶点损毁术,操作简单,创伤小,图像较清晰,易于推断靶点位置.     

Characteristic and functional specificity of anti-human BAT (brain associated thymocyte antigen) serum

A rabbit antiserum to human fetal brain after multiple absorption reacted with 100% of thymocytes, 55% of peripheral blood lymphocytes and 90% of enriched T lymphocytes, but not significantly with B lymphocytes. Spontaneous SRBC rosette formation was inhibited by anti-BAT pretreatment, but EAC-rosette formation remained unaffected. The antiserum was itself highly stimulatory. However, cells treated with the antiserum and complement exhibited marked inhibition of responsiveness to Con A, little effect with PHA and no alteration with PWM. The MLC reaction was inhibited only when the responder cells were treated with the antiserum and complement. Treatment of sensitized lymphocytes with the antiserum and complement caused a dose-dependent suppression of blastogenic response to both PPD and n-DNA. No effect, however, was noted in MIF producing cells. Con A induced suppressor function of lymphocytes was abolished by treatment with the antiserum and complement. These results indicate that the anti-BAT serum obtained by us can be utilized for the isolation of T lymphocyte subsets.     

Appraisal of Cu(ii) adsorption by graphene oxide and its modelling via artificial neural network

Graphene oxide (GO), as an emerging material, exhibits extraordinary performance in terms of water treatment. Adsorption is a process that is influenced by multiple factors and is difficult to simulate by traditional statistical models. Artificial neural networks (ANNs) can establish highly accurate nonlinear functional relationships between multiple variables; hence, we constructed a three-layered ANN model to predict the removal performance of Cu(ii) metal ions by the prepared GO. In the present research work, GO was prepared and characterized by FT-IR spectroscopy, SEM, and XRD analysis techniques. In ANN modeling, the Levenberg–Marquardt learning algorithm (LMA) was applied by comparing 13 different back-propagation (BP) learning algorithms. The network structure and parameters were optimized according to various error indicators between the predicted and experimental data. The hidden layer neurons were set to be 12, and optimal network learning rate was 0.08. Contour and 3-D diagrams were used to illustrate the interactions of different influencing factors on the adsorption efficiency. Based on the results of batch adsorption experiments combined with the optimization of influencing factors by ANN, the optimum pH, initial Cu(ii) ion concentration and temperature were anticipated to be 5.5, 15 mg L⁻¹ and 318 K, respectively. Moreover, the adsorption experiments reached equilibrium at about 120 min. Combined with sensitivity analysis, the degree of influence of each factor could be ranked as: pH > initial concentration > temperature > contact time.

Graphene oxide (GO), as an emerging material, exhibits extraordinary performance in terms of water treatment.     

Prenatal diagnosis of congenital heart disease using four-dimensional spatio-temporal image correlation (STIC) telemedicine via an Internet link: a pilot study.

OBJECTIVE: To assess whether the spatio-temporal image correlation (STIC) acquisition technique can be taught to a general obstetrician by e-mail; whether STIC volume datasets can be transmitted over the Internet; and whether STIC volume datasets analyzed offline at a remote setting can be used to confirm or exclude major cardiac defects (TELE-STIC). METHODS: This was a prospective study involving 50 pregnant women with gestational ages ranging between 20 and 36 weeks. These patients were selected by two general obstetricians (operators) working in geographically remote areas of Chile. Although both obstetricians were users of equipment capable of four-dimensional (4D) ultrasound with STIC, they lacked skill in the performance of fetal cardiac examination. A dedicated web disk was created to upload the acquired volume datasets using an Internet broadband connection. Offline analysis was performed by a single investigator experienced in fetal echocardiography (the administrator). RESULTS: A telemedicine link via the Internet was possible in all cases. Seventy-seven volume datasets were sent to the web server. A complete cardiac examination according to set criteria was achieved by the administrator in 86% of the cases scanned by one operator and 95% of the cases scanned by the other operator. Three patients had cardiac defects confirmed postnatally, two fetuses had extracardiac anomalies and one fetus had a suspected cardiac defect unconfirmed by second-opinion TELE-STIC. There were two isolated major congenital heart defects. Both patients were given advice by e-mail and teleconference using a web camera about the likely outcome and benefits of scheduling in utero transport to a tertiary care center. CONCLUSIONS: STIC volumes can be obtained by operators inexperienced in fetal echocardiography, transmitted via the Internet, and their analysis enables recognition of most of the structures and views necessary to assess fetal cardiac anatomy. The preliminary use of TELE-STIC allowed us to demonstrate that some intracardiac anomalies can be ruled out and others confirmed, allowing perinatal management to be tailored accordingly.     

Chronic stress is linked to 5-HT(1A) receptor changes and functional disintegration of the limbic networks

There are increasing reports about stress related cognitive and psychic declines in subjects who have no psychiatric premorbidity, depression, or major life trauma. Yet, little is known about the underlying neurobiology. Based on the typical symptomatology, fMRI data suggesting that stress activates the limbic circuits, and animal data showing a major involvement of the 5-HT(1A) receptor in stress regulation, we hypothesized that enduring daily stress causes widespread limbic dysfunctions, and specific changes of the 5-HT(1A) receptor. To test these hypotheses combined PET studies were carried out in 16 chronically stressed, and 16 non-stressed subjects. Limbic function was tested by measuring cerebral blood flow during rest, and when using an odor activation paradigm. 5-HT(1A) receptor binding potential (BP) was assessed with [(11)C]WAY100635. All subjects went through a battery of neuropsychological tests. Stressed subjects showed a functional disconnection between the amygdala and ACC/medial prefrontal cortex (mPFC), and an impaired odor activation of the ACC. They also displayed a reduced 5-HT(1A) receptor BP in the anterior cingulate (ACC), the insular-cortex, and the hippocampus. Their performance in attention-, odor discrimination-, and semantic memory tasks was impaired, and correlated with the BP-values in the respective region. The degree of reported stress was inversely correlated with activation of ACC, and the 5-HT(1A) receptor BP in the amygdala and hippocampus. Enduring every day psychosocial stress seems to be associated with a limbic reduction of 5-HT(1A) receptor binding and functional disintegration of ACC/mPFC. These changes support the notion of an impaired top-down regulation of stress stimuli, and identify potential targets for early treatment.     

Segmentation of cellular patterns in confocal images of melanocytic lesions in vivo via a multiscale encoder-decoder network (MED-Net)

In-vivo optical microscopy is advancing into routine clinical practice for non-invasively guiding diagnosis and treatment of cancer and other diseases, and thus beginning to reduce the need for traditional biopsy. However, reading and analysis of the optical microscopic images are generally still qualitative, relying mainly on visual examination. Here we present an automated semantic segmentation method called “Multiscale Encoder-Decoder Network (MED-Net)” that provides pixel-wise labeling into classes of patterns in a quantitative manner. The novelty in our approach is the modeling of textural patterns at multiple scales (magnifications, resolutions). This mimics the traditional procedure for examining pathology images, which routinely starts with low magnification (low resolution, large field of view) followed by closer inspection of suspicious areas with higher magnification (higher resolution, smaller fields of view). We trained and tested our model on non-overlapping partitions of 117 reflectance confocal microscopy (RCM) mosaics of melanocytic lesions, an extensive dataset for this application, collected at four clinics in the US, and two in Italy. With patient-wise cross-validation, we achieved pixel-wise mean sensitivity and specificity of 74% and 92%, respectively, with 0.74 Dice coefficient over six classes. In the scenario, we partitioned the data clinic-wise and tested the generalizability of the model over multiple clinics. In this setting, we achieved pixel-wise mean sensitivity and specificity of 77% and 94%, respectively, with 0.77 Dice coefficient. We compared MED-Net against the state-of-the-art semantic segmentation models and achieved better quantitative segmentation performance. Our results also suggest that, due to its nested multiscale architecture, the MED-Net model annotated RCM mosaics more coherently, avoiding unrealistic-fragmented annotations.     

Physiological self-regulation of regional brain activity using real-time functional magnetic resonance imaging (fMRI): methodology and exemplary data

A brain-computer interface (BCI) based on real-time functional magnetic resonance imaging (fMRI) is presented which allows human subjects to observe and control changes of their own blood oxygen level-dependent (BOLD) response. This BCI performs data preprocessing (including linear trend removal, 3D motion correction) and statistical analysis on-line. Local BOLD signals are continuously fed back to the subject in the magnetic resonance scanner with a delay of less than 2 s from image acquisition. The mean signal of a region of interest is plotted as a time-series superimposed on color-coded stripes which indicate the task, i.e., to increase or decrease the BOLD signal. We exemplify the presented BCI with one volunteer intending to control the signal of the rostral-ventral and dorsal part of the anterior cingulate cortex (ACC). The subject achieved significant changes of local BOLD responses as revealed by region of interest analysis and statistical parametric maps. The percent signal change increased across fMRI-feedback sessions suggesting a learning effect with training. This methodology of fMRI-feedback can assess voluntary control of circumscribed brain areas. As a further extension, behavioral effects of local self-regulation become accessible as a new field of research.     

Measuring functional change in children with acquired brain injury (ABI): comparison of generic and ABI-specific scales using the Pediatric Evaluation of Disability Inventory (PEDI)

BACKGROUND AND PURPOSE: The Pediatric Evaluation of Disability Inventory (PEDI) subscales are hierarchic in nature, with item placements within each subscale reflecting the general order of skill attainment in children without disabilities. The purpose of this study was to determine whether a hierarchical subscale developed in this study for children with acquired brain injuries (ABIs) corresponds to the generic PEDI subscales, and, if not, whether condition-specific (ABI-specific) PEDI subscales are more sensitive for measuring change. SUBJECTS: Eighty-seven children and adolescents (mean age=9.2 years, SD=5.2, range=1-20) with ABI during inpatient rehabilitation admissions were included. METHODS: Data were collected by retrospective chart review. Rasch one-parameter analyses were conducted to construct the ABI-specific PEDI scale focusing on the Mobility and Self-care domains (content areas) only. Each domain consists of a Functional Skills subscale and a Caregiver Assistance subscale. Thus, in all, 4 scales were constructed within the ABI-specific PEDI scale. Differences in item hierarchies and sensitivity between generic and ABI-specific PEDI subscales for each domain were then examined. RESULTS: Both generic and ABI-specific PEDI scales were sensitive for measuring functional changes during inpatient rehabilitation hospitalization. Even though the generic and ABI-specific item hierarchies differed substantially, only one of the 4 ABI-specific PEDI subscales (Caregiver Assistance Self-care subscale) was more sensitive for measuring change than the generic PEDI scale. DISCUSSION AND CONCLUSION: The ABI-specific scales added relatively little improvement in sensitivity compared with the generic PEDI scales of the Mobility and Self-care domains. Thus, for group analyses, the authors recommend use of the generic PEDI subscales for children with ABI. Future work with ABI-specific subscales may improve the physical therapist's ability to describe an individual's pattern of functional recovery.     

Magnetoencephalographic analysis of cortical oscillatory activity in patients with brain tumors: Synthetic aperture magnetometry (SAM) functional imaging of delta band activity

Abnormal focal slow wave activity on electroencephalography and magnetoencephalography (MEG) is often seen in patients with various brain pathologies and MEG is capable of localizing cortical oscillatory activity with enhanced accuracy. In addition, MEG with synthetic aperture magnetometry (SAM) can depict changes in cortical oscillatory activity tomographically. Using SAM, we recorded cortical rhythms in patients with a brain tumor and evaluated the tomographic appearance of focal slow wave activity in relation to clinical signs and symptoms. Spontaneous MEG recordings were obtained in 15 patients with brain tumors. Statistically-determined power distributions in the delta-, theta-, and alpha-frequency bands were displayed tomographically and overlaid on individual magnetic resonance images. The location, strength and volume of enhanced activity were analyzed. Delta and theta band activities were significantly more intense in the cortex adjacent to tumors and in the surrounding edematous cortical areas than in other portions of the cortex. In 13 of the 15 patients, spatial distribution of enhanced focal delta activity coincided with the area responsible for the presenting signs and symptoms. Volumetric analysis revealed that emergence of tumor-related focal delta band activity in the cortex adjacent to a tumor, or with peritumoral edema, was greater for intra-axial tumors involving subcortical fibers than for extra-axial tumors. Patients with an increased volume of enhanced delta activity exhibited poor recovery of function in the early postoperative period. It is concluded that SAM imaging of focal delta activity can reveal functional alterations in cortical activity in patients with brain tumors and is useful for assessing cortical states associated with the existing pathology.     

经颅磁刺激对脑缺血大鼠功能恢复和健侧突触结构的影响

目的观察经颅磁刺激（TMS）对大鼠大脑中动脉栓塞后神经功能恢复和健侧突触结构参数变化的影响，探讨其代偿机理。方法24只雄性SD大鼠应用线栓法建立大鼠大脑中动脉栓塞（MCAO）模型，随机分为TMS组和对照组，前者给予TMS治疗28d，后者常规饲养，观察大鼠神经功能恢复情况和健侧大脑感觉运动皮质区突触超微结构参数的变化。结果TMS组大鼠治疗后神经功能恢复优于对照组（P〈0．05），电镜下观察到TMS组大鼠脑感觉运动皮质区突触界面曲率、突触后致密物质（PSD）厚度增加，突触间隙变窄，与对照组比较，差异有统计学意义（P〈0．05）。结论TMS可促进脑缺血大鼠神经功能的改善，其机制可能与健侧突触超微结构参数的改变有关。     

A pilot study of functional magnetic resonance imaging of the brain during manual and electroacupuncture stimulation of acupuncture point (LI-4 Hegu) in normal subjects reveals differential brain activation between methods

OBJECTIVES: To characterize the brain activation patterns evoked by manual and electroacupuncture on normal human subjects. DESIGN: We used functional magnetic resonance imaging (fMRI) to investigate the brain regions involved in electroacupuncture and manual acupuncture needle stimulation. A block design was adopted for the study. Each functional run consists of 5 minutes, starting with 1-minute baseline and two 1-minute stimulation, the interval between the two stimuli was 1 minute. Four functional runs were performed on each subject, two runs for electroacupuncture and two runs for manual acupuncture. The order of the two modalities was randomized among subjects. During the experiment, acupuncture needle manipulation was performed at Large Intestine 4 (LI4, Hegu) on the left hand. For each subject, before scanning started, the needle was inserted perpendicular to the skin surface to a depth of approximately 1.0 cm. Electroacupuncture stimulation was delivered using a continuous rectangular wave form (pulse width 30 ms) at a frequency of 3 Hz. For manual acupuncture, the needle was rotated manually clockwise and counterclockwise at a rate of about 180 times per minute (3 Hz). SUBJECTS: Eleven right-handed, normal, healthy volunteer adults, 6 male and 5 female, ages 21-64 participated in the experiment. RESULTS: Results showed that electroacupuncture mainly produced fMRI signal increases in precentral gyrus, postcentral gyrus/inferior parietal lobule, and putamen/insula; in contrast, manual needle manipulation produced prominent decreases of fMRI signals in posterior cingulate, superior temporal gyrus, putamen/insula. CONCLUSION: These results indicate that different brain networks are involved during manual and electroacupuncture stimulation. It suggests that different brain mechanisms may be recruited during manual and electroacupuncture.     

Go with the flow: use of a directed phase lag index (dPLI) to characterize patterns of phase relations in a large-scale model of brain dynamics

We introduce a directed phase lag index to investigate the spatial and temporal pattern of phase relations of oscillatory activity in a model of macroscopic structural and functional brain networks. Direction of information flow was determined with the directed phase lag index (dPLI) defined as the probability that the instantaneous phase of X was smaller than the phase of Y (modulo π). X was said to phase-lead Y if 0.5相似文献   

How reliable is the predictive value of SEP (somatosensory evoked potentials) patterns in severe brain damage with special regard to the bilateral loss of cortical responses?

Objective: In patients sustaining severe brain damage (SBD), prediction of later outcome is often very difficult, in particular under conditions of therapeutic management like relaxation and intravenous phenobarbital. Somatosensory evoked potentials (SEP) correlated best with later prognosis and expected neurological deficit. In detail, the primary bilateral loss of cortical responses (BLCR) is regarded to be a reliable marker for poor prognosis. The goal of the following prospective study was to reassess the prognostic value of early serial median nerve SEP recording in severe brain damage in comparison to other neurophysiologica, clinical, and neuroradiological parameters and, additionally, to test the hypothesis, that the BLCR-pattern is always associated with a poor prognosis and is never reversible. Design: Prospective study. Setting: Anaesthesiological hospital intensive care unit. Patients and participants: 42 comatose patients with severe brain damage (29 males/13 females), mean age 39.6 ± 19.3 years, mean initial Glasgow Coma Score (GCS) 6.6 ± 3.1, investigated by means of median somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) with serial recordings on day 1, 3 to 4, and 8 to 1, and repeated cra- nial computerized tomo- graphy. Measurements and results: We classified the outcome according to the Glasgow Outcome Scale (GOS). Our data showed a high correlation of initial SEP scores (Spearman correlation coefficient = − 0.70) with outcome for both a favorable and an unfavorable prognosis (p = 0.0001). The reliability increased with serial recordings. The SEPs showed superiority to parallel brainstem auditory evoked potentials (Spearman correlation coefficient = − 0.50, p = 0.0007), GCS, and standardized neuroradiological criteria. Primary (BLCR) occurred in 16 patients (38 %) and implied a fatal prognosis in all adult patients (n = 15, specificity = 93.3 %, sensitivity = 59.3 %). In contrast, a young child with predominant brainstem hemorrhagic contusions regained consciousness and developed mild to moderate neurological deficit (GOS 3–4) during long-term follow-up of 4 years. This clinical improvement paralleled bilateral asymmetric recovery of cortical SEP responses. Conclusions: SEP allow an early reliable assessment of both poor and good prognosis in SBD, in particular when applied serially. BLCR does not always imply a fatal diagnosis, as a circumscribed contusional lesion rarely may lead to selective reversible blockage of ascending somatosensory pathways in the brainstem. In contradiction to this lesional etiology, a hypoxia-induced BLCR pattern seems to correlate strictly with a poor prognosis, reflecting a different pathogenesis with diffuse destruction of cortex and thalamocortical pathways. Received: 16 February 1996 Accepted: 7 November 1996