Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA; Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA.
Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Biomedical Engineering, Boston University, Boston, MA, USA.
Prog Neurobiol. 2021 Dec;207:102174. doi: 10.1016/j.pneurobio.2021.102174. Epub 2021 Sep 12.
Fast fMRI enables the detection of neural dynamics over timescales of hundreds of milliseconds, suggesting it may provide a new avenue for studying subsecond neural processes in the human brain. The magnitudes of these fast fMRI dynamics are far greater than predicted by canonical models of the hemodynamic response. Several studies have established nonlinear properties of the hemodynamic response that have significant implications for fast fMRI. We first review nonlinear properties of the hemodynamic response function that may underlie fast fMRI signals. We then illustrate the breakdown of canonical hemodynamic response models in the context of fast neural dynamics. We will then argue that the canonical hemodynamic response function is not likely to reflect the BOLD response to neuronal activity driven by sparse or naturalistic stimuli or perhaps to spontaneous neuronal fluctuations in the resting state. These properties suggest that fast fMRI is capable of tracking surprisingly fast neuronal dynamics, and we discuss the neuroscientific questions that could be addressed using this approach.
快速功能磁共振成像能够检测数百毫秒时间尺度内的神经动力学，这表明它可能为研究人类大脑中亚秒级神经过程提供了新途径。这些快速 fMRI 动力学的幅度远远大于血液动力学响应的典型模型所预测的幅度。几项研究已经确定了血液动力学响应的非线性特性，这些特性对快速 fMRI 有重要意义。我们首先回顾了可能是快速 fMRI 信号基础的血液动力学响应函数的非线性特性。然后，我们在快速神经动力学的背景下说明了典型血液动力学响应模型的崩溃。然后我们认为，典型的血液动力学响应函数不太可能反映稀疏或自然刺激驱动的神经元活动或静息状态下自发神经元波动的 BOLD 响应。这些特性表明，快速 fMRI 能够跟踪令人惊讶的快速神经元动力学，我们讨论了可以通过这种方法解决的神经科学问题。
