VIRTUAL ELECTRODE ESTIMATION FROM MAGNETOENCEPHALOGRAPHIC RECORDINGS

根据脑磁记录进行虚拟电极估计

基本信息

批准号：
8171809
负责人：
DONALD KRIEGER
金额：
$ 0.11万
依托单位：
CARNEGIE-MELLON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-08-01 至 2013-07-31
项目状态：
已结题

项目摘要

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The promise of magnetoencephalography (MEG) is to be the next great imaging modality. It provides sub-centimeter spatial resolution, millisecond time resolution, and direct access to functional processing by the brain. These are clear indicators for the potentiality of its uses for diagnosis of pathology, monitoring of treatment, identification of recovery milestones, and substantively advancing our direct access to and understanding of brain processes which underlie sensation, cognition, memory, attention, affect, movement, and pathologies which affect any one or more of these. But the devices are cumbersome, the analysis complex, the possibilities for application endless. The raw measurements provide voluminous data sets. Each of the typically hundreds of channels are, in general, a "superposition" of overlapping signals from numerous sources within (and outside) the brain, each of which is may or may not be of potential significance in understanding the problem under study. The overall goal of the project is to implement and demonstrate methods which provide the full range of information accessible via MEG and to then use that information to identify biomarkers which distinguish normal brain function and that for patients with mild Traumatic Brain Injury (mTBI). For every individual studied, the methods will reliably separate the signals from multiple sources within the brain, provide interpretable tracings from each of the chosen "virtual electrode" source locations, and will identify which sources are differentially activated under different conditions encountered during the recording session. Analysis of the resulting waveforms, parameters, and summary statistics obtained for each individual will provide "biomarkers" which reliably distinguish normal and pathological brain function. : In general, the signal observed at each MEG sensor is the superposition of magnetic field signals from many sources within the brain. Virtual Electrode Estimation simplifies this by casting the 306 MEG sensor signals into some 100 virtual electrode signals. Each of these is the estimate of the electric current at a specific location within the brain. This casts the raw MEG measures into a form which is "as if" 100+ wire recording electrodes had been placed directly in the brain. This both markedly "simplifies" the signals and allows interpretation of the variables which are retained by the stepwise classification analysis directly as locations within the brain. Virtual Electrode Estimation is carried out for all locations and for 30 msec at a time all at once. The noise rejection and signal identification properties of the method are very powerful and precise. The Virtual Electrode tracings are single trial evoked responses. 4. Identification of biomarkers which differentiate normal vs pathologic brain function. Rationale: Our working hypothesis is that changes due to mTBI in cognition, memory, and attention all arise from moderate slowing of white matter transmission speed. This slight slowing produces reduced synchronization in the arrival times for volleys of actions potentials, resulting in decreased activation in the receiving dendritic domain and consequent reduced likelihood of information transmission and subsequent information propagation. The decreased activation produced by information bearing action potential volleys gives rise to reduced ability to evoke memories. The decreased likelihood of information propogation gives rise to both cognitive and attentional deficits. In the short to medium term, to compensate for this, the tonic level of activation of the cortex is globally increased, increasing the likelihood that a moderately desynchronized volley of action potentials will produce sufficient activation in the receiving cell populations to induce action potential volleys and resultant persistence and propagation of information. Specific Aim 4: For each of the normal subjects and concussion patients, produce standardized reports containing the virtual electrode waveforms, classification accuracies, collapsed waveforms showing differential activation tracings, etc. Note that each concussion patient will have 2 studies, one acute and one 2-3 months post-injury. Provide reports from half of the normal subjects and half of the patients to each of the members of the clinician panel along with the diagnoses so that each clinician can independently identify those measures which they think will "stand up" as biomarkers of pathology. Then bring the panel together to discuss and refine those variables on which they agree. Finally, present each clinician, now blinded to the diagnoses, with reports from the other half of the subjects and patients and have them score and classify them. Hypothesis 4A: In the acute concussion, averaged evoked responses will show peaks with reduced amplitude and temporal prolongation. Hypothesis 4B: In the acute concussion, classification results will be less sensitive to the latency both following the stimulus and preceding the response. Hypothesis 4C: In the acute concussion, the collapsed differential activation tracings will show prolonged peaks. Hypothesis 4D: In the acute concussion, locations which are differentially activated will be distributed most widely in the brain.

该副本是利用众多研究子项目之一由NIH/NCRR资助的中心赠款提供的资源。子弹和调查员（PI）可能已经从其他NIH来源获得了主要资金，因此可以在其他清晰的条目中代表。列出的机构是对于中心，这不一定是调查员的机构。磁脑摄影（MEG）的承诺是下一个出色的成像方式。它提供了亚中心空间分辨率，毫秒时间分辨率以及大脑对功能处理的直接访问。这些是其在诊断病理学，监测治疗，恢复里程碑的识别以及对我们直接访问和对脑过程的理解中的潜力的明确指标，这些指标是影响，认知，记忆，注意力，情感，运动，运动和影响其中任何一个或多个或多个或多个或多个或多个人的病理的基础。但是这些设备很麻烦，分析复杂，应用程序无限的可能性。原始测量值提供大量的数据集。通常，通常数百个渠道都是来自（和外部）大脑内部多个来源的重叠信号的“叠加”，每个信号在理解正在研究的问题中可能具有或可能没有潜在的意义。该项目的总体目标是实施和演示可以通过MEG访问的全部信息，然后使用该信息来识别区分正常脑功能的生物标志物，并适用于轻度创伤性脑损伤（MTBI）的患者。对于每个研究的个人，这些方法将可靠地将信号与大脑中的多个来源分开，从每个选定的“虚拟电极”源位置提供可解释的跟踪，并将确定在录制会议期间遇到的不同条件下差异激活了哪些源。分析每个个体获得的波形，参数和摘要统计数据将提供“生物标志物”，从而可靠地区分正常和病理大脑功能。：通常，在每个MEG传感器上观察到的信号是来自大脑中许多来源的磁场信号的叠加。虚拟电极估计通过将306 MEG传感器信号施放到大约100个虚拟电极信号中来简化这一点。这些都是大脑内特定位置的电流的估计。这将原始MEG测量施加了一种形式，该形式像“好像” 100+电线记录电极直接放置在大脑中。这两者都显着“简化”信号，并允许解释由逐步分类分析直接作为大脑内部位置保留的变量。对所有位置进行虚拟电极估计，一次一次对30毫秒进行一次。该方法的噪声排斥和信号识别属性非常强大且精确。虚拟电极示踪是单个试验的诱发响应。 4。鉴定生物标志物，该生物标志物区分正常与病理大脑功能。理由：我们的工作假设是，由于MTBI在认知，记忆和注意力方面的变化都是由于白质传递速度中等速度而引起的。这种轻微的放缓会导致动作电位弹的到达时间的同步减少，从而导致接收树突状域的激活减少，从而降低信息传输的可能性和随后的信息传播。信息轴承动作电势量产生的降低激活导致唤起记忆的能力降低。信息传播的可能性降低会导致认知和注意力缺陷。在短期到中期，为了弥补这一点，皮质的激活水平在全球范围内增加，增加了中等显着的动作电位射电射击的可能性，将在接收细胞种群中产生足够的激活，以诱导动作电位伏特利和导致的持久性和信息信息。特定目的4：对于每个正常受试者和脑震荡患者，产生包含虚拟电极波形，分类精度，折叠波形的标准化报告，显示差异激活示踪等等。请注意，每个脑震荡患者将进行2项研究，一项急性研究，1个急性和2-3个月。提供一半正常受试者和一半患者的报告，以及临床医生小组的每个成员以及诊断，以便每个临床医生都可以独立地识别他们认为将“站立”作为病理学的生物标志物的措施。然后将小组聚集在一起，讨论和完善他们同意的变量。最后，向每个临床医生展示了现在对诊断视而不见的临床医生，并在其他一半的受试者和患者的报告中获得了报道，并将其分类并对其进行分类。假设4a：在急性脑震荡中，平均诱发反应将显示峰值幅度降低和时间延长。假设4b：在急性脑震荡中，分类结果对刺激和响应之前的潜伏期敏感。假设4C：在急性脑震荡中，倒塌的差分激活示踪物将显示长时间的峰。假设4D：在急性脑震荡中，被差异激活的位置将在大脑中分布最广泛。