Transcranial red and near infrared light transmission in a cadaveric model

PLoS One. 2012;7(10):e47460. doi: 10.1371/journal.pone.0047460. Epub 2012 Oct 15.


Background and objective: Low level light therapy has garnered significant interest within the past decade. The exact molecular mechanisms of how red and near infrared light result in physiologic modulation are not fully understood. Heme moieties and copper within cells are red and near infrared light photoreceptors that induce the mitochondrial respiratory chain component cytochrome C oxidase, resulting in a cascade linked to cytoprotection and cellular metabolism. The copper centers in cytochrome C oxidase have a broad absorption range that peaks around 830 nm. Several in vitro and in vivo animal and human models exist that have demonstrated the benefits of red light and near infrared light for various conditions. Clinical applications for low level light therapy are varied. One study in particular demonstrated improved durable functional outcomes status post-stroke in patients treated with near infrared low level light therapy compared to sham treatment [1]. Despite previous data suggesting the beneficial effect in treating multiple conditions, including stroke, with low level light therapy, limited data exists that measures transmission in a human model.

Study design/materials and methods: To investigate this idea, we measured the transmission of near infrared light energy, using red light for purposes of comparison, through intact cadaver soft tissue, skull bones, and brain using a commercially available LED device at 830 nm and 633 nm.

Results: Our results demonstrate that near infrared measurably penetrates soft tissue, bone and brain parenchyma in the formalin preserved cadaveric model, in comparison to negligible red light transmission in the same conditions.

Conclusion: These findings indicate that near infrared light can penetrate formalin fixed soft tissue, bone and brain and implicate that benefits observed in clinical studies are potentially related to direct action of near infrared light on neural tissue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain / radiation effects
  • Cadaver
  • Copper / chemistry
  • Electron Transport Complex IV / chemistry*
  • Electron Transport Complex IV / isolation & purification
  • Heme / chemistry
  • Humans
  • Infrared Rays*
  • Male
  • Phototherapy*
  • Skull / chemistry
  • Skull / radiation effects


  • Heme
  • Copper
  • Electron Transport Complex IV

Grants and funding

There was no funding provided for this study. Photomedex provided the low level light therapy device. They had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. A travel grant was provided to present results at 2010 American Society for Laser Medicine and Surgery conference in Phoenix, Arizona.