NIMH MEG Core Facility

MEG核心员工与NIMH、NINDS和NIDCD的一大批PI互动工作，进行研究设计、任务开发、采集协议、信号处理和数据分析。通过将主数据档案移至Helix维护的NIMH数据存储，改进了数据安全、传输和存储程序。与科学和统计计算核心合作，以便能够将CTF MEG文件传输到非洲非政府组织，并开发了群体统计分析工具，以前已扩展到包括额外的维度格式，以促进主题群体之间基于时间的联系。这一范围已经扩大，可以跨受试者和群体进行时间维度比较。现在可以使用基于解剖图谱的对象对齐来分析比较。 信号分析在与事件有关的SAM(合成孔径磁学)和275通道ICA(独立分量分析)方面继续发展。时频分析方法的发展包括斯托克韦尔变换和小波变换以及多锥度技术。分析包扩展到包括符号熵测量和转移熵互信息技术，以探索大脑网络，一些用户群体正在使用。使用SAM波束形成器方法分析Tacs(经颅交流电刺激)和tdcs(经颅直流电刺激)期间和之后的脑磁图信号的能力使我们能够探索对大脑节律和记忆的影响。 将替换外部电子设备的升级包的早期测试版本已在所有渠道进行了测试并正常运行。全面安装计划于2016年秋季完成。先前安装和测试的新的眼动监测系统继续促进认知激活范例。电力系统检修后，系统可靠性有了很大提高。 康威尔和他的同事的早期工作表明，使用脑磁图波束形成技术，脑磁图可以可靠地区分杏仁核和海马区的信号。持续的研究表明，在接受氯胺酮治疗时，患有严重抑郁症和其他脑部变化的患者的海马体功能会受到损害。进一步的研究表明，海马区的快速伽马活动与空间学习相关。这些研究对可能阐明氯胺酮输注的抗抑郁作用的机制特别有意义。先前的研究结果表明，在工作记忆任务中，前扣带回活动的增加和功能连接的增加都可以预测氯胺酮的抗抑郁反应。Zarate和他的同事利用脑磁图表明，突触增强对于治疗难治性重度抑郁症的抗抑郁作用至关重要。在此之前，Nugent等人。显示了脑磁图休息数据的组间差异，这些数据突出了严重抑郁障碍的功能障碍。现在已经扩展到探索氯胺酮给药后的网络变化。研究继续探索任务组和患者组之间的高伽马频段活动。与特定钠通道基因的相互作用发现，认知差异可能与伽马波段活动有关。 研究大脑如何将自己组织成功能网络，是理解正常人类认知以及精神疾病中大脑何时变得混乱的关键。此前，巴西特和他的同事利用脑磁图的空间和时间能力发现，功能性网络的特征是小世界属性，表明既有本地连接，也有远程连接。我们还发现了患者群体中休息网络模式的差异，现在已经使用图论方法来检查功能网络。功能连通性度量在视听任务中进行了研究，表明跨大脑区域的交流有几种形式，没有一种衡量标准足以捕捉信息流的丰富性。 一项将脑磁图动力学与新的扩散张量成像(DTI)测量方法相关联以确定跨大脑区域潜伏期的项目提案受到了欢迎，MEG小组将开始与Peter Basser的DTI小组合作。

The MEG Core staff works interactively with a large group of PI's in NIMH, NINDS and NIDCD for study design, task development, acquisition protocols, signal processing and data analysis. Procedures for data security, transfer and storage have been improved by moving the main data archive to the Helix maintained NIMH data store. Work with the Scientific and Statistical Computing Core to enable transfer of CTF MEG files to AFNI and developed tools for group statistical analysis was previously extended to include an extra-dimensional format to facilitate time-based connectivity across subject groups. This has been expanded to allow time-dimension comparison across subjects and groups. The comparisons can now be analyzed using anatomic atlas based alignment across subject. Signal analysis development has continued on event-related SAM (synthetic aperture magnetometry) and 275-channel ICA (independent component analysis). Development of time-frequency analysis methods has included Stockwell and wavelet transforms as well as multi-taper techniques. The analysis packages extended to include symbolic entropy measures and transfer entropy mutual information techniques to explore brain networks are in use by a number of user groups. The ability to use SAM beamformer methods to analyze MEG signals during and after tACS (transcranial alternating current stimulation) as well as tDCS (transcranial direct current stimulation) has allowed exploration of effects on brain rhythms and memory. An early test version of the upgraded package that will replace the external electronics has been tested and performed properly across all channels. Full installation is planned for fall 2016. The new eye-movement monitoring system previously installed and tested continues to contribute to cognitive activation paradigms. System reliability has been substantially improved after power system repairs. Early work by Cornwell and colleagues demonstrated that MEG can reliably discriminate amygdala and hippocampal signals using MEG beamforming techniques. Continuing studies have shown that hippocampal function is impaired in patients with major depression as well as other brain changes when treated with ketamine. Further studies have shown that fast gamma activity in the hippocampus correlates with spatial learning. These studies are of particular interest to possibly elucidate the mechanism of the anti-depressant action of ketamine infusion. Previous results have shown that both increased anterior cingulate activity and functional connectivity during a working memory task can predict the antidepressant response of ketamine. Zarate and colleagues have utilized MEG to show that synaptic potentiation is critical for the antidepressant action in treatment resistant major depression. Previously Nugent et al. have shown group differences in MEG resting data that highlight dysfunction in major depressive disorder. This has now been extended to explore the network changes with ketamine administration. Studies continue to explore high gamma band activity across task and patient groups. Interaction with specific sodium channel genes finds that the cognitive differences may be related to gamma band activity. Studying how the brain organizes itself into functional networks is key to understanding normal human cognition as well as when it becomes disordered in mental illness. Previously, Bassett and co-workers using the spatial and temporal ability of MEG found that functional networks were characterized by small-world properties indicating a mix of both local connections and long range connections. We have also found differences in resting network patterns in patient groups, and have now used graph theoretical methods to examine functional networks. Functional connectivity metrics have been studied in an audio-visual task demonstrating that the communication across brain regions takes on several forms and that no one measure will suffice to capture the richness of information flow. A project proposal to relate MEG dynamics to new Diffusion Tensor Imaging (DTI) measures for determining latency across brain regions was favorably received and the MEG groups will begin collaboration with Peter Basser's DTI group.