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浅谈近红外脑成像(fNIRS)任务态实验设计(一)

March 10th, 2018

本文作者是斯坦福大学刘宁

对于一个近红外初学者,特别是没有任何脑成像背景的初学者,他们往往没有想到脑成像的实验设计和别的学科的实验设计,诸如行为科学或者生物实验等有很大不同。通过一些文献阅读或者相关培训,初学者可能注意到脑成像的任务态实验设计往往有很多重复的环节。那么,为什么脑成像的实验需要这样的设计?究其根本原因,其实是因为现有的无侵入式脑成像技术,无论是核磁共振脑功能成像(fMRI) 还是近红外脑功能成像(fNIRS), 其直接测量到的信号变化与噪音相比都太小(~1%量级)。换言之,巨大的生理噪音掩盖了信号的变化。因此,为了能测量到与大脑活动相关的信号,具体到近红外成像中就是测量到氧合血红蛋白和脱氧血红蛋白的浓度变化,就需要巧妙的设计实验和分析数据。

对于任务态实验,有两种基本的实验设计:一种是采用组块设计(block design),另一种是采用事件设计(event design)。然而,无论哪种,它们的共同点是:实验中多次重复同一个任务/操作,数据处理时通过建立模型,用统计的办法找出具有统计意义的相关活跃脑区。

任务态的实验设计中常常被初学者忽略的另一个重要环节就是对照条件(control condition)的设计。刺激任务除了设计能激活相关脑区的任务以外,一般还应该设计一个好的对照条件,进而可以通过两种条件下脑信号的对比,找出真正与任务相关的脑区。

Author: Xu Cui Categories: brain, nirs Tags:
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Xu Cui is a human brain research scientist in Stanford University. He lives in the Bay Area in the United States. He is also the founder of Stork (smart publication alert app), PaperBox and BizGenius.

 

He was born in He'nan province, China. He received education in Beijing University(BS), University of Tennessee (Knoxville) (MS), Baylor College of Medicine (PhD) and Stanford University (PostDoc). Read more ...
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