Source of nonlinearity of the BOLD response revealed by simultaneous fMRI and NIRS
Source of nonlinearity of the BOLD response revealed by simultaneous fMRI and NIRS
复制标题
DOI：
10.1016/j.neuroimage.2007.09.053
复制
发表时间：
2008-02-01
期刊：
影响因子：
5.7
通讯作者：
Sadato, Norihiro
中科院分区：
文献类型：
--
作者：
Toyoda, Hiroshi;Kashikura, Kenichi;Sadato, Norihiro
功能磁共振成像（fMRI）已经很好地研究了血氧水平依赖性（BOLD）对不同持续时间的刺激（特别是短持续时间的刺激）反应的非线性。假设这种非线性是由于神经适应和氧提取分数 (OEF) 响应的非线性造成的；后者尚未在人体中进行定量研究。为了评估 OEF 响应如何影响 BOLD 神经活动响应的非线性，我们使用了同步 fMRI 和近红外光谱 (NIRS)。对四种不同持续时间的视觉刺激的反应通过 BOLD 信号和 NIRS 衍生的血红蛋白浓度的变化来测量。假设未知的神经适应参数在生理上可行的范围内变化，则使用响应幅度中具有饱和非线性缩放的脉冲响应函数模型来量化血液动力学响应非线性。与神经适应程度无关，BOLD 响应始终显示出与根据 NIRS 测量估计的 OEF 响应相似的饱和非线性，其非线性大于代表脑血容量 (CBV) 的总血红蛋白浓度的响应。我们还发现 OEF 响应对 BOLD 响应的贡献比 CBV 响应的贡献大四到七倍。因此，我们得出结论，BOLD 对神经活动反应的非线性主要源于 OEF 反应的非线性。 (c) 2007 Elsevier Inc. 保留所有权利。
The nonlinearity of the blood oxygenation level-dependent (BOLD) response to stimuli of different duration, particularly those of short duration, has been well studied by functional magnetic resonance imaging (fMRI). This nonlinearity is assumed to be due to neural adaptation and the nonlinearity of the response in the oxygen extraction fraction (OEF); the latter has not been examined quantitatively in humans. To evaluate how the OEF response contributes to the nonlinearity of the BOLD response to neural activity, we used simultaneous fMRI and near-infrared spectroscopy (NIRS). The responses to visual stimuli of four different durations were measured as changes in the BOLD signal and the NIRS-derived hemoglobin concentrations. The hemodynamic response nonlinearity was quantified using an impulse response function model with saturation nonlinearity scaling in the response amplitude, assuming that the unknown neural adaptation parameters varied within a physiologically feasible range. Independent of the degree of neural adaptation, the BOLD response consistently showed saturation nonlinearity similar to that of the OEF response estimated from the NIRS measures, the nonlinearity of which was greater than that of the response in the total hemoglobin concentration representing the cerebral blood volume (CBV). We also found that the contribution of the OEF response to the BOLD response was four to seven times greater than the contribution of the CBV response. Thus, we conclude that the nonlinearity of the BOLD response to neural activity originates mainly from that of the OEF response. (c) 2007 Elsevier Inc. All rights reserved.