6 experiments you should do with NIRS (vs fMRI)

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[last update: 2019-02-20]

Let’s be frank. Compared to fMRI, NIRS has a number of intrinsic weaknesses. The signal to noise ratio is lower, the spatial resolution is (10x) lower, it can’t measure the deep brain, and it only covers a portion of the brain surface. As a result, fMRI, when possible, is still the preferred method to elucidate brain mechanisms. So if we do use NIRS, we’d better do experiments fMRI can’t, or at least very difficult to, do.

Below are 6 experiments NIRS can do, but fMRI can’t (or difficult to do):

  1. Study of the mechanism of BOLD signal
    1. Study of the relationship between oxygenated and deoxygenated hemoglobin concentration
      For a given voxel, fMRI only gives you a single number at a time. The number (BOLD signal) depends on many factors. On the other hand, NIRS can give you two numbers, the concentrations of both oxygenated and deoxygenated hemoglobin. So if you ever want to study the relationship between them, we should use NIRS. For an example, please check out https://www.ncbi.nlm.nih.gov/pubmed/19945536
    2. Study of the fine temporal change of BOLD signal
      In most fMRI settings the temporal resolution of BOLD signal is low (about 2 seconds, or 0.5Hz). That means we only get a number every two seconds. If we want to know the rise and fall of the BOLD signal in much higher temporal resolution, e.g. 10Hz, then NIRS would be a good choice.
  2. Study in naturalistic settings
    If you ever participate in a fMRI study, you will feel the room far from friendly. The scanner is loud, and it looks scary. During the entire experiment, you are lonely inside the confined space. You can’t move, can’t talk (for most experiments), and feel guilty when you swallow saliva as the experimenter probably told you in advance that any motion might distort the signal. What you often see is much simple visuals (such as blocks and circles) on a computer screen. Do we live such a life in reality? On the contrary, NIRS is small, even portable, and can be used in a naturalistic environment.

    1. Sports and exercise
      As long as the optodes are attached to the head nicely to ensure proper signal collection, the participants can move freely. NIRS has been used in a number of sports or exercises studies such as running, squatting, biking, ping-pong, piano playing, and stretching etc. Be sure to check out the videos in https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434677/

      Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5430058/
    2. Face to face communication
      You might see other people’s face on a screen in fMRI, but with NIRS, you can see a real face. We humans are fundamentally social, and to study social behavior in a naturalistic environment is important. NIRS allows you to study face-to-face gaming (video or board), talking, brain storming, cooperation or competition, etc. For example, in one of our studies (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3254802/) participants played a video game together. my colleague Ning Liu et al has an experiment when two people play Jenga games (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4782164/).
    3. Study in a moving environment
      Many NIRS devices are small enough so you can carry it in a car or even a backpack. That means you can study the driver’s brain when he is actually driving! An example would be https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5671603/
  3. Hyperscanning
    fMRI can be used in hyperscanning studies, and in fact the first hyperscanning is done with fMRI by my former advisor Dr Montague (https://www.ncbi.nlm.nih.gov/pubmed/12202103). However, seeing it with first hand, I know hyperscanning with fMRI is technically challenging. You need two fMRI scanners, each costs a few million dollars; and you also need to synchronize them. On the other hand, many NIRS devices are able to do hyperscanning natually. For example, when we used ETG 4000, we simply use one patch on one participant and the other on another participant. It does not add complexity on the hardware part.
    To date there are a number of hyperscanning studies with NIRS. For a list, please refer to https://www.ncbi.nlm.nih.gov/pubmed/?term=(fnirs+OR+nirs)+hyperscanning. If you are patient enough to scroll to the last page, you will find our paper!
  4. Real time (feedback), brain computer interface
    Let’s say you want your participants to move a bar in a computer game mentally (brain computer interface), or you provide a real time neural feedback to your participants to improve cognitive function, in both cases you need the brain signal in real time.  fMRI can do this too, but first you will need to get the data in real time, and second, due to poorer time resolution (2s), there will be some lag. Many NIRS devices allows you to get the measured signal out without delay, and of course the temporal resolution of NIRS is typically much higher (e.g. 10Hz). An recent example can be found at https://www.ncbi.nlm.nih.gov/pubmed/30634177
    Some may argue that higher temporal resolution is not that useful because the BOLD signal is already slow (usually 4-6s from onset to peak). However, with finer temporal resolution, we can use algorithms (e.g. machine learning) to detect signal with much smaller delay. For example, in one of our studies the delay can be reduced by 50% (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2978722/)
  5. Field studies, large scale studies
    You can’t carry an fMRI scanner around for sure, but with NIRS’ portability, you can collect neural data in the field. My colleague Dr Baker took a NIRS device to the rural places in Costa Rica, and scanned the local farmers. Check out his paper.

    In addition, since you may carry NIRS devices around, you can scan a lot of participants, e.g. a few hundred or even thousand. Imagine you are to study the brain and cognitive development of children in rural areas in China in a large scale (say 10,000 participants), then NIRS will become your top choice.
  6. Study on special participants
    Due to safety reason, the following people should not do fMRI experiments (source):

    1. with shrapnel or other metal or electronic implants in their bodies (such as pacemakers, aneurysm clips, surgical devices, metallic tattoos on the head, etc.)
    2. pregnant
    3. with a history of head trauma or fainting
    4. currently using sleeping aids, painkillers (including aspirin), or other agents known to affect brain function (for instance, antihistamines, decongestants, etc.)
    5. with major medical, neurological, or psychological disorders (including depression, generalized anxiety, panic attacks, AD(H)D, strokes, tumors, heart conditions, claustrophobia, etc.)

    In addition to this list, fMRI is also not friendly to infants (but still can be done in fMRI). In contrast, NIRS does not have issues with the participants in the list. Imagine you can do an experiment on claustrophobia with NIRS, but probably not with fMRI.

So, what is the ideal experiment with NIRS? Based on the above list, if one is to use hyperscanning to study the face-to-face communication when two claustrophobia participants are running together along a mountain trail, I would say it’s pretty hard for fMRI to catch on.

第十九期 fNIRS Journal Club 通知 2021/05/29,9:30am

美国普渡大学童云杰助理教授,将为大家讲解他们组最近被接受的一篇使用近红外相位信息研究脑血流变化的文章。热烈欢迎大家参与讨论。 时间: 北京时间2021年5月29日上午9:30地点: https://zoom.com房间号: 846 8391 7517密码: 805190 童云杰教授简介:普渡大学 生物医学工程助理教授、博士生导师。主攻方向是多模态脑成像, 包括核磁,fNIRS, EEG。关注脑功能及生理信号的提取与研究。发表论文九十余篇,引用上千次(H-index = 20)。 童教授要讲解的文章如下: Liang Z, Tian H, Yang HC, Arimitsu T, Takahashi...
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第十八期 fNIRS Journal Club 视频

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会议日期:2021年5月22日-24日会议地点:天津师范大学 一、 会议简介       近红外光谱脑功能成像(fNIRS)具有设备购买与使用成本低、可在自然环境条件下使用、具有较高的时间分辨率和空间定位能力等特点,受到了脑科学研究的高度重视。“近红外光谱脑功能成像学术会议”是由北京师范大学认知神经科学与学习国家重点实验室朱朝喆教授发起并组织的全国性学术会议。已连续成功举办六届,共吸引全国近百家高校、科研院所及医院的六百余名学者参加。该会议已成为国内规模和影响力最大的fNIRS脑成像学术活动。       本届会议由北京师范大学与天津师范大学联合主办。会议将延用往届会议将学术报告与研究方法工作坊相结合的模式。学术报告模块(5月22日周六)将邀请心理学与认知神经科学领域、基础与临床医学领域以及工程技术领域知名学者汇报其fNIRS最新研究成果;工作坊模块(5月23-24日)由fNIRS领域一线研究者系统讲授fNIRS成像原理、fNIRS实验设计、fNIRS数据分析与统计、fNIRS论文写作以及fNIRS前沿技术等。除理论讲授外,还设置了fNIRS空间定位与数据分析操作(NIRS-KIT软件)环节,此外还安排充足的研讨答疑时间以便与会人员交流互动。       具体日程与详细内容等最新消息请关注后续通知,可通过天津师范大学心理部网站http://psych.tjnu.edu.cn/或北京师范大学国家重点实验室网站http://brain.bnu.edu.cn/,或者扫描下方二维码关注微信公众号-“fNIRS脑成像实验室”查阅更新信息,期盼在天津师范大学与您相聚! 二、会议组织机构 主办单位:教育部人文社会科学重点研究基地天津师范大学心理与行为研究院、天津师范大学心理学部、北京师范大学认知神经科学与学习国家重点实验室会议主席:白学军、朱朝喆组织委员会:赵春健、杨邵峰、侯鑫、曹正操 三、说明1.        学术报告模块注册费:人民币500元/人;工作坊模块注册费:人民币2500元/人。发票为电子发票,内容均为:“会议费”。两个模块各自独立收费,参会者可根据自己需要进行选择。2.        注册费包括各自模块的资料费、午餐费;其他费用自理。3.        会议报告人免除会议模块注册费,其他费用请自理。4.       ...
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One Reply to “6 experiments you should do with NIRS (vs fMRI)”

  1. Hi Dr. Cui,

    This was very helpful. I am sure someone will ask the same question in my defense (soon to come)! Thank you!

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