基于全局信号获得的特定于主题的 BOLD fMRI 呼吸和心脏反应功能。
Subject specific BOLD fMRI respiratory and cardiac response functions obtained from global signal.
机构信息
Laureate Institute for Brain Research, 6655 South Yale Avenue, Tulsa, OK 74136, USA.
出版信息
Neuroimage. 2013 May 15;72:252-64. doi: 10.1016/j.neuroimage.2013.01.050. Epub 2013 Jan 31.
Subtle changes in either breathing pattern or cardiac pulse rate alter blood oxygen level dependent functional magnetic resonance imaging signal (BOLD fMRI). This is problematic because such fluctuations could possibly not be related to underlying neuronal activations of interest but instead the source of physiological noise. Several methods have been proposed to eliminate physiological noise in BOLD fMRI data. One such method is to derive a template based on average multi-subject data for respiratory response function (RRF) and cardiac response function (CRF) by simultaneously utilizing an external recording of cardiac and respiratory waveforms with the fMRI. Standard templates can then be used to model, map, and remove respiration and cardiac fluctuations from fMRI data. Utilizing these does not, however, account for intra-subject variations in physiological response. Thus, performing a more individualized approach for single subject physiological noise correction becomes more desirable, especially for clinical purposes. Here we propose a novel approach that employs subject-specific RRF and CRF response functions obtained from the whole brain or brain tissue-specific global signals (GS). Averaging multiple voxels in global signal computation ensures physiological noise dominance over thermal and system noise in even high-spatial-resolution fMRI data, making the GS suitable for deriving robust estimations of both RRF and CRF for individual subjects. Using these individualized response functions instead of standard templates based on multi-subject averages judiciously removes physiological noise from the data, assuming that there is minimal neuronal contribution in the derived individualized filters. Subject-specific physiological response functions obtained from the GS better maps individuals' physiological characteristics.
呼吸模式或心搏率的细微变化会改变血氧水平依赖功能磁共振成像信号(BOLD fMRI)。这是有问题的,因为这种波动可能与感兴趣的潜在神经元激活无关,而是生理噪声的来源。已经提出了几种方法来消除 BOLD fMRI 数据中的生理噪声。一种方法是通过同时利用 fMRI 与心脏和呼吸波的外部记录,从多个人体数据中得出基于模板的呼吸响应函数(RRF)和心脏响应函数(CRF)。然后可以使用标准模板来对 fMRI 数据进行建模、映射和消除呼吸和心脏波动。然而,利用这些方法并不能解释生理响应的个体差异。因此,对于临床目的,对于单个对象的生理噪声校正,执行更个体化的方法变得更加可取。在这里,我们提出了一种新的方法,该方法使用从整个大脑或脑组织特定的全局信号(GS)获得的特定于对象的 RRF 和 CRF 响应函数。在全局信号计算中对多个体素进行平均,可以确保生理噪声在即使是高空间分辨率的 fMRI 数据中也占主导地位,超过热噪声和系统噪声,从而使 GS 适合为个体对象导出稳健的 RRF 和 CRF 估计值。明智地使用这些基于个体的响应函数代替基于多个人体平均值的标准模板,可以从数据中消除生理噪声,假设在得出的个体滤波器中神经元的贡献最小。从 GS 获得的特定于对象的生理响应函数更好地映射个体的生理特征。