Red and Infrared Light Go Deep Into the Brain

Posted in Brain Health

Phys Med Biol. 2015 Apr 7;60(7):2921-37. doi: 10.1088/0031-9155/60/7/2921. Epub 2015 Mar 19.

Red and NIR light dosimetry in the human deep brain.

Author information

  • 1Federal Institute of Technology (EPFL), Institute of Chemical Sciences and Engineering (ISIC), 1015 Lausanne, Switzerland.

Abstract

Photobiomodulation (PBM) appears promising to treat the hallmarks of Parkinson’s Disease (PD) in cellular or animal models. We measured light propagation in different areas of PD-relevant deep brain tissue during transcranial, transsphenoidal illumination (at 671 and 808 nm) of a cadaver head and modeled optical parameters of human brain tissue using Monte-Carlo simulations. Gray matter, white matter, cerebrospinal fluid, ventricles, thalamus, pons, cerebellum and skull bone were processed into a mesh of the skull (158 × 201 × 211 voxels; voxel side length: 1 mm). Optical parameters were optimized from simulated and measured fluence rate distributions. The estimated μeff for the different tissues was in all cases larger at 671 than at 808 nm, making latter a better choice for light delivery in the deep brain. Absolute values were comparable to those found in the literature or slightly smaller. The effective attenuation in the ventricles was considerably larger than literature values. Optimization yields a new set of optical parameters better reproducing the experimental data. A combination of PBM via the sphenoid sinus and oral cavity could be beneficial. A 20-fold higher efficiency of light delivery to the deep brain was achieved with ventricular instead of transcranial illumination. Our study demonstrates that it is possible to illuminate deep brain tissues transcranially, transsphenoidally and via different application routes. This opens therapeutic options for sufferers of PD or other cerebral diseases necessitating light therapy.

PMID:
25789711
DOI:
10.1088/0031-9155/60/7/2921
[PubMed – indexed for MEDLINE]