DEVELOPMENT OF LOW FREQUENCY MEG HARDWARE AND SOFTWARE

拟议研究的总体目标是开发硬件， 软件和技术，以大大扩大效用， 脑磁图（MEG），既作为临床诊断工具， 神经科学基础研究的一种模式。 MEG已被用于 迄今为止广泛用于神经发生器的本地化， 病理状况（例如局灶性癫痫）以及正常来源 (e.g.听觉、视觉或体感诱发反应）。 等 本地化总是涉及重大的简化， 将源近似为单个电流偶极子，将头近似为均匀的 球体。 该提案的一个目的是开发新的数据分析 技术和软件，以利用MEG的独特能力， 从生理磁场中获得更重要的信息 起源 其中将有方法来区分和定位弱 发电机几乎与更强的发电机同时点火， 监测MEG信号中细微光谱变化的方法， 警觉性或觉醒的变化或自发皮层的其他变化 活动 MEG的第二个功能是完全非侵入性测量 非常慢的（DC）变化，已知其出现在各种 病理条件。 这种变化不能很容易地用 表面脑电图（EEG），因为阻抗变化， 不可避免地发生在电极-皮肤界面处。 不幸的是，梅格 测量还受到环境磁噪声（甚至 在精心屏蔽的房间）和磁场产生的区域 患者的身体的噪声（“患者噪声”）。 这样的噪音 在定位研究中，低频 噪声被滤除并且在其中实现了额外的噪声降低 通过对大量重复信号进行信号平均。 这是 然而，对于自发低频的观察， 活动 到目前为止，噪声消除技术提供的 神经磁力计制造商已经证明不足以处理这种情况， 问题，在某些情况下，它们本身会将工件引入数据。 我们实验室的初步测量结果表明， 解决这些噪音问题的各种方法。 第二个目的是 建议开发可靠的DC-MEG测量技术， 将MEG的能力扩展到测量 生物磁场 为了这两个目标，我们的技术将在 模型、动物模型和人类患者和对照。

The overall objective of the proposed research is to develop hardware, software, and techniques to substantially expand the utility of Magnetoencephalography (MEG), both as a clinical diagnostic tool and as a modality for basic studies in the neurosciences. MEG has been utilized extensively to date for the localization of neural generators in pathological conditions (e.g. focal epilepsy), as well as normal sources (e.g. auditory, visual, or somatosensory evoked responses). Such localizations always involve significant simplifications such as approximating sources as single current dipoles and heads as homogeneous spheres. One aim of this proposal is to develop new data analysis techniques and software to exploit the unique ability of MEG to extract more significant kinds of information from magnetic fields of physiologic origin. Among these will be methods to distinguish and localize weak generators which fire almost simultaneously with stronger ones, and methods to monitor subtle spectral changes in MEG signals accompanying changes in alertness or arousal or other changes in spontaneous cortical activity. A second capability of MEG is the completely non-invasive measurement of very slow (DC) shifts which are known to arise in a variety of pathological conditions. Such shifts cannot readily be studied using surface electroencephalography (EEG) because of impedance changes which inevitably occur at the electrode-skin interface. Unfortunately, MEG measurements are also contaminated by environmental magnetic noise (even in elaborately shielded rooms) and magnetic fields arising from regions of the patient's body not under study ("patient noise"). Such noise has been of little consequence in localization studies in which low frequency noise is filtered out and in which additional noise reduction is achieved by signal averaging over a large number of repetitive signals. This is not the case however, for the observation of spontaneous low frequency activity. To date, noise cancellation techniques provided by neuromagnetometer manufacturers have proven inadequate to deal with such problems, in some cases themselves introducing artifacts into the data. Preliminary measurements in our laboratory point the way towards a variety of solutions to these noise problems. The second aim of this proposal is to develop technology for reliable DC-MEG measurements, and to extend the capability of MEG to the measurement of absolute values of the biomagnetic field. For both aims, our techniques will be tested in phantoms, animal models and human patients and controls, as appropriate.