<br>层流 fMRI 的线性系统分析：评估亮度对比度操作的 BOLD 幅度缩放。,Scientific Reports

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层流 fMRI 的线性系统分析：评估亮度对比度操作的 BOLD 幅度缩放。
Scientific Reports ( IF 3.8 ) Pub Date : 2020-03-25 , DOI: 10.1038/s41598-020-62165-x
Jelle A van Dijk _{1,

2} , Alessio Fracasso _{2,

3,

4} , Natalia Petridou ₄ , Serge O Dumoulin _{1,

2,

5}

Affiliation

几乎所有功能磁共振成像 (fMRI) 分析的基本假设是，局部神经元活动与血氧水平依赖 (BOLD) 信号之间的关系可以按照线性系统理论进行描述。随着超高场（7T 及更高）MRI 扫描仪的出现，对人体进行亚毫米分辨率的 fMRI 已成为可能。亚毫米功能磁共振成像的一个新颖且有前途的应用是测量皮质深度的响应，即层流成像。然而，皮质脉管系统和相关的朝向软脑膜表面的定向血液汇集强烈影响皮质深度依赖性 BOLD 信号，特别是对于梯度回波 BOLD。这种定向池可能会影响整个皮质深度的 BOLD 线性。在这里，我们评估线性系统理论的幅度缩放假设是否适用于整个皮质深度。为此，我们使用具有不同亮度对比度的刺激来引发不同的 BOLD 响应幅度。我们发现皮质深度尺度上的大胆幅度具有亮度对比度，并且这种尺度在皮质深度上是相同的。尽管不同的刺激配置和采集协议可能存在非线性，但我们的结果表明，跨皮层深度的线性系统理论的幅度缩放假设适用于亚毫米层流 BOLD fMRI 中的亮度对比度操作。

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Linear systems analysis for laminar fMRI: Evaluating BOLD amplitude scaling for luminance contrast manipulations.

A fundamental assumption of nearly all functional magnetic resonance imaging (fMRI) analyses is that the relationship between local neuronal activity and the blood oxygenation level dependent (BOLD) signal can be described as following linear systems theory. With the advent of ultra-high field (7T and higher) MRI scanners, it has become possible to perform sub-millimeter resolution fMRI in humans. A novel and promising application of sub-millimeter fMRI is measuring responses across cortical depth, i.e. laminar imaging. However, the cortical vasculature and associated directional blood pooling towards the pial surface strongly influence the cortical depth-dependent BOLD signal, particularly for gradient-echo BOLD. This directional pooling may potentially affect BOLD linearity across cortical depth. Here we assess whether the amplitude scaling assumption for linear systems theory holds across cortical depth. For this, we use stimuli with different luminance contrasts to elicit different BOLD response amplitudes. We find that BOLD amplitude across cortical depth scales with luminance contrast, and that this scaling is identical across cortical depth. Although nonlinearities may be present for different stimulus configurations and acquisition protocols, our results suggest that the amplitude scaling assumption for linear systems theory across cortical depth holds for luminance contrast manipulations in sub-millimeter laminar BOLD fMRI.

更新日期：2020-03-26

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