论文标题

在局灶性和快速的E/MEG传感大脑活动中的随机多分辨率扫描,深度可变

Randomized Multiresolution Scanning in Focal and Fast E/MEG Sensing of Brain Activity with a Variable Depth

论文作者

Rezaei, Atena, Koulouri, Alexandra, Pursiainen, Sampsa

论文摘要

我们专注于神经活动的电磁脑摄影成像,尤其是通过分层贝叶斯模型(HBM)找到了对主要电流分布的强大估计值。我们的目的是开发一种相当快的后验(MAP)估计技术,该技术将适用于浅表和深区域,而没有特定的活动数量或位置的特定知识。为了启用任何深度的源可区分性,我们引入了一种随机的多分辨率扫描(RAMUS)方法,其中在重建过程中大脑活动的MAP估计值变化。 Ramus旨在为整个大脑提供强大而准确的成像结果,同时保持适当水平的计算成本。为了实现大脑深部的最佳性能,将反伽马(IG)分布作为主要的高位。在这项概念验证的研究中,我们通过数值模拟的数据模拟刺激后的14-20 ms,诱发了对电腕刺激的潜在和现场反应,从而考虑了同时检测丘脑和体感活性。球形和现实模型均用于分析源重建差异。在数值检查的情况下,观察到Ramus可以增强深层组成部分的可见性,并在没有明显的计算成本的情况下使离散化和优化的随机效应边缘化。在大脑的浅表和深部位都获得了一级电流密度的强大而准确的MAP估计。

We focus on electromagnetoencephalography imaging of the neural activity and, in particular, finding a robust estimate for the primary current distribution via the hierarchical Bayesian model (HBM). Our aim is to develop a reasonably fast maximum a posteriori (MAP) estimation technique which would be applicable for both superficial and deep areas without specific a priori knowledge of the number or location of the activity. To enable source distinguishability for any depth, we introduce a randomized multiresolution scanning (RAMUS) approach in which the MAP estimate of the brain activity is varied during the reconstruction process. RAMUS aims to provide a robust and accurate imaging outcome for the whole brain, while maintaining the computational cost on an appropriate level. The inverse gamma (IG) distribution is applied as the primary hyperprior in order to achieve an optimal performance for the deep part of the brain. In this proof-of-the-concept study, we consider the detection of simultaneous thalamic and somatosensory activity via numerically simulated data modeling the 14-20 ms post-stimulus somatosensory evoked potential and field response to electrical wrist stimulation. Both a spherical and realistic model are utilized to analyze the source reconstruction discrepancies. In the numerically examined case, RAMUS was observed to enhance the visibility of deep components and also marginalizing the random effects of the discretization and optimization without a remarkable computation cost. A robust and accurate MAP estimate for the primary current density was obtained in both superficial and deep parts of the brain.

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