<p>From the same Wikipedia page you reference:</p>
<blockquote>
<p>The technique takes advantage of the optical window in which (a) skin, tissue, and bone are mostly transparent to NIR light (700–900 nm spectral interval) and (b) hemoglobin (Hb) and deoxygenated-hemoglobin (deoxy-Hb) are strong absorbers of light</p>
</blockquote>
<p>The page also has detailed information about the history of the technique and its advantages and disadvantages, mentions studies comparing to other modalities like <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021967/" rel="nofollow noreferrer">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021967/</a> - these would be good places to start for validation.</p>
<p>However, I'd also caution you that even fMRI which is extremely popular has questionable relationships with neuronal activity, and the BOLD signal in some circumstances may not show what is assumed or validated in other contexts; the same applies with fNIRS, see e.g. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4791590/" rel="nofollow noreferrer">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4791590/</a>. If you were going to use this technique I'd recommend validation for your specific use case.</p>

CC BY-SA 4.0
2023-11-17T16:00:41.687Z
2023-11-17T16:20:50.680Z
2023-11-17T16:20:50.680Z
Bryan Krause
<p>I came across a reference to Functional near-infrared spectroscopy (fNIRS) in a news article. <a href="https://www.cbc.ca/news/health/smartphone-brain-nov14-1.7029406" rel="nofollow noreferrer">https://www.cbc.ca/news/health/smartphone-brain-nov14-1.7029406</a></p>
<p>According to Wikipedia,</p>
<blockquote>
<p>fNIRS is an optical brain monitoring technique which uses
near-infrared spectroscopy for the purpose of functional
neuroimaging.[1] Using fNIRS, brain activity is inferred by using
near-infrared light to estimate cortical hemodynamic activity which
occurs in response to neural activity.</p>
</blockquote>
<p>I understand this to mean hemoglobin saturation (as measured at the surface of the scalp) is used to infer metabolic activity of the underlying cerebral cortex.</p>
<p>Given that light is highly diffused by soft tissue, and bone is virtually impenetrable to light, I can’t imagine how fNIRS measurements can penetrate highly vascular scalp and skull tissue to give useful resolution of brain tissue.</p>
<p>The only plausible research I could find with a Google-search showed its utility for lateralizing language dominance.</p>
<p>Is  fNIRS supported by evidence? Is there any good research on its clinical utility? Is this phrenology all over again?</p>

<pseudoscience>
Is functional Near Infrared spectroscopy supported by quality evidence?
Woody
# Is functional Near Infrared spectroscopy supported by quality evidence?

(Asked by: username_0 on 2023-11-16)

I came across a reference to Functional near-infrared spectroscopy (fNIRS) in a news article. <https://www.cbc.ca/news/health/smartphone-brain-nov14-1.7029406>

According to Wikipedia,

> fNIRS is an optical brain monitoring technique which uses
> near-infrared spectroscopy for the purpose of functional
> neuroimaging.[1] Using fNIRS, brain activity is inferred by using
> near-infrared light to estimate cortical hemodynamic activity which
> occurs in response to neural activity.

I understand this to mean hemoglobin saturation (as measured at the surface of the scalp) is used to infer metabolic activity of the underlying cerebral cortex.

Given that light is highly diffused by soft tissue, and bone is virtually impenetrable to light, I can’t imagine how fNIRS measurements can penetrate highly vascular scalp and skull tissue to give useful resolution of brain tissue.

The only plausible research I could find with a Google-search showed its utility for lateralizing language dominance.

Is fNIRS supported by evidence? Is there any good research on its clinical utility? Is this phrenology all over again?

**Tags:** pseudoscience


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## 1 answers

### Answer by username_1 on 2023-11-17. Score: 1

From the same Wikipedia page you reference:

> The technique takes advantage of the optical window in which (a) skin, tissue, and bone are mostly transparent to NIR light (700–900 nm spectral interval) and (b) hemoglobin (Hb) and deoxygenated-hemoglobin (deoxy-Hb) are strong absorbers of light

The page also has detailed information about the history of the technique and its advantages and disadvantages, mentions studies comparing to other modalities like <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021967/> - these would be good places to start for validation.

However, I'd also caution you that even fMRI which is extremely popular has questionable relationships with neuronal activity, and the BOLD signal in some circumstances may not show what is assumed or validated in other contexts; the same applies with fNIRS, see e.g. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4791590/>. If you were going to use this technique I'd recommend validation for your specific use case.


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