Send to

Choose Destination
J Cereb Blood Flow Metab. 2017 Dec;37(12):3789-3802. doi: 10.1177/0271678X17691783. Epub 2017 Feb 9.

Up-regulation of cerebral cytochrome-c-oxidase and hemodynamics by transcranial infrared laser stimulation: A broadband near-infrared spectroscopy study.

Author information

1 Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA.
2 Joint Graduate Program between University of Texas at Arlington and UT Southwestern Medical Center at Dallas, University of Texas at Arlington, Arlington, TX, USA.
3 Department of Psychology and Institute for Neuroscience, the University of Texas at Austin, Austin, TX, USA.


Transcranial infrared laser stimulation (TILS) is a noninvasive form of brain photobiomulation. Cytochrome-c-oxidase (CCO), the terminal enzyme in the mitochondrial electron transport chain, is hypothesized to be the primary intracellular photoacceptor. We hypothesized that TILS up-regulates cerebral CCO and causes hemodynamic changes. We delivered 1064-nm laser stimulation to the forehead of healthy participants ( n = 11), while broadband near-infrared spectroscopy was utilized to acquire light reflectance from the TILS-treated cortical region before, during, and after TILS. Placebo experiments were also performed for accurate comparison. Time course of spectroscopic readings were analyzed and fitted to the modified Beer-Lambert law. With respect to the placebo readings, we observed (1) significant increases in cerebral concentrations of oxidized CCO (Δ[CCO]; >0.08 µM; p < 0.01), oxygenated hemoglobin (Δ[HbO]; >0.8 µM; p < 0.01), and total hemoglobin (Δ[HbT]; >0.5 µM; p < 0.01) during and after TILS, and (2) linear interplays between Δ[CCO] versus Δ[HbO] and between Δ[CCO] versus Δ[HbT]. Ratios of Δ[CCO]/Δ[HbO] and Δ[CCO]/Δ[HbT] were introduced as TILS-induced metabolic-hemodynamic coupling indices to quantify the coupling strength between TILS-enhanced cerebral metabolism and blood oxygen supply. This study provides the first demonstration that TILS causes up-regulation of oxidized CCO in the human brain, and contributes important insight into the physiological mechanisms.


Cerebral hemodynamics; energy metabolism; mitochondria; near-infrared spectroscopy; neuroprotection

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center