Transcranial red and near infrared light transmission in a cadaveric model.
Level 5 - mechanism / opinion, no new human data
Ex vivo cadaveric bench study
PubMed 23077622 · doi:10.1371/journal.pone.0047460
What was done
Researchers measured the transmission of near-infrared light (830 nm) compared to red light (633 nm) from a commercial LED device through intact soft tissue, skull bone, and brain parenchyma in a formalin-preserved human cadaveric model.
What was found
Near-infrared light (830 nm) measurably penetrated soft tissue, skull bone, and brain parenchyma in the formalin-preserved cadaver model. In contrast, red light (633 nm) transmission was negligible under the same conditions. The abstract reports no numerical transmission percentages or physical quantities.
Why it matters
These findings provide physical evidence that near-infrared wavelengths can penetrate intact human cranial structures, supporting the plausibility of direct neural effects in transcranial photobiomodulation.
Limits
The study used a formalin-fixed cadaver model, which lacks blood flow and may have different optical and scattering properties compared to living tissue. The abstract does not state the sample size (number of cadavers) nor provide quantitative penetration measurements.
Cited by
- supports Long-wavelength light can pass through the human body and improve mitochondrial health.
- supports Infrared and red light can penetrate biological tissue, including hair and the skull, into the brain, where mitochondrial cytochrome c oxidase acts as the photoreceptor absorbing photons.