Combining EEG and MEG to localize distributed sources of neural activity

描述（由申请人提供）：该项目的目标是探索性研究，从联合MEG/EEG测量的神经活动的分布式源的本地化，使用最近开发的方法的逆问题（局部基扩展或LBEX）。 10-100 ms时间尺度的神经动力学是与精神障碍研究相关的广泛认知功能的基础。EEG和MEG是唯一实用的非侵入性技术与此时间分辨率，但有限的空间分辨率，由于不适定的逆问题相关的传感器测量的基础来源。EEG被更广泛地使用，但也受到头部传导率分布的不确定性的影响。MEG逆问题已被证明是比较容易处理的。然而，MEG实质上更昂贵，并且期望将这两种技术联合收割机组合，使得可以使用同时的MEG测量来更好地精确定位EEG源。将这两种方法联合收割机的另一个原因是逆问题的互补性质：EEG沉默源可以是MEG活跃的，反之亦然。由于最近仪器的进步， 同时测量现在通常是可能的，但联合定位问题尚未得到充分研究。我们已经开发了一种方法MEG源定位（LBEX），它允许系统的分析分辨率限制，通过数学处理的不确定性原理的逆问题。在这个建议中，我们建议探索扩展的LBEX方法联合MEG/EEG源定位。具体目标包括：（i）在理想化的球形模型中的联合定位问题的理论分析，（ii）评价该技术在现实头部模型的数值模拟中的性能，以及（iii）联合定位技术应用于通过实验合作获得的同时MEG/EEG记录。研究计划的成功完成将建立我们的算法框架的效用，也将评估从同时MEG/EEG定位获得的增益。一旦该方法通过探索性研究得到验证，我们打算在未来将结果编码到用户友好的软件中，这将使联合EEG/MEG定位的广泛使用成为可能。

DESCRIPTION (provided by applicant): The goal of this project is exploratory research into localization of distributed sources of neural activity from joint MEG/EEG measurements, using a recently developed methodology for the inverse problem (Local Basis Expansions or LBEX). Neural dynamics in the 10-100 ms timescale underlie a broad spectrum of cognitive function relevant to the study of mental disorders. EEG and MEG are the only practical noninvasive techniques with this time resolution, but are limited in spatial resolution due to the ill posed inverse problem relating sensor measurements to underlying sources. EEG is more widely used, but also suffers from uncertainties about head conductivity profiles. The MEG inverse problem has proven to be comparatively more tractable. However, MEG is substantially more expensive, and it is desirable to combine the two techniques, so that EEG sources can be better pinpointed using simultaneous MEG measurements. Another reason to combine the two methods is the complementary nature of the inverse problems: EEG silent sources can be MEG active, and vice versa. Thanks to recent instrumental advances, simultaneous measurements are now routinely possible, but the joint localization problem has not yet been fully studied. We have developed a methodology for MEG source localization (LBEX), which permits a systematic analysis of resolution limits, through a mathematical treatment of the uncertainty principle governing the inverse problem. In this proposal, we propose to explore extensions of the LBEX method to joint MEG/EEG source localization. Specific aims include (i) a theoretical analysis of the joint localization problem in an idealized spherical model, (ii) evaluation of the performance of the technique in numerical simulations with a realistic head model, and (iii) application of the joint localization technique to simultaneous MEG/EEG recordings obtained through an experimental collaboration. Successful completion of the research program will establish the utility of our algorithmic framework, and will also evaluate the gain obtained from simultaneous MEG/EEG localization. Once the methodology is validated by the exploratory research, we intend in the future to encode the results into user friendly software which will enable widespread usage of joint EEG/MEG localization.