Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
Harvard Medical School, Boston, MA, USA.
Sci Adv. 2019 Apr 17;5(4):eaav3816. doi: 10.1126/sciadv.aav3816. eCollection 2019 Apr.
Mapping neuronal activity noninvasively is a key requirement for in vivo human neuroscience. Traditional functional magnetic resonance (MR) imaging, with a temporal response of seconds, cannot measure high-level cognitive processes evolving in tens of milliseconds. To advance neuroscience, imaging of fast neuronal processes is required. Here, we show in vivo imaging of fast neuronal processes at 100-ms time scales by quantifying brain biomechanics noninvasively with MR elastography. We show brain stiffness changes of ~10% in response to repetitive electric stimulation of a mouse hind paw over two orders of frequency from 0.1 to 10 Hz. We demonstrate in mice that regional patterns of stiffness modulation are synchronous with stimulus switching and evolve with frequency. For very fast stimuli (100 ms), mechanical changes are mainly located in the thalamus, the relay location for afferent cortical input. Our results demonstrate a new methodology for noninvasively tracking brain functional activity at high speed.
非侵入性地映射神经元活动是进行活体人类神经科学研究的关键要求。传统的功能磁共振成像（MR）具有秒级的时间响应，无法测量在数十毫秒内演化的高级认知过程。为了推进神经科学的发展，需要对快速神经元过程进行成像。在这里，我们通过使用磁共振弹性成像技术无创地定量测量脑生物力学，展示了在 100 毫秒时间尺度上快速神经元过程的活体成像。我们发现，在对小鼠后脚进行重复电刺激时，大脑的刚度变化约为 10%，刺激频率范围从 0.1 到 10 Hz，跨越了两个数量级。我们在小鼠中证明，刚度调制的区域模式与刺激切换同步，并随频率而演变。对于非常快的刺激（100 毫秒），机械变化主要位于丘脑，这是传入皮质输入的中继位置。我们的结果展示了一种用于高速非侵入性追踪大脑功能活动的新方法。
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