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Neurophotonics • Open Access

Impact of heat on metabolic and hemodynamic changes in transcranial infrared laser stimulation measured by broadband near-infrared spectroscopy
Author(s): Xinlong Wang; Divya D. Reddy; Sahil S. Nalawade; Suvra Pal; Francisco Gonzalez-Lima; Hanli Liu

Paper Abstract

Transcranial infrared laser stimulation (TILS) has shown effectiveness in improving human cognition and was investigated using broadband near-infrared spectroscopy (bb-NIRS) in our previous study, but the effect of laser heating on the actual bb-NIRS measurements was not investigated. To address this potential confounding factor, 11 human participants were studied. First, we measured time-dependent temperature increases on forehead skin using clinical-grade thermometers following the TILS experimental protocol used in our previous study. Second, a subject-averaged, time-dependent temperature alteration curve was obtained, based on which a heat generator was controlled to induce the same temperature increase at the same forehead location that TILS was delivered on each participant. Third, the same bb-NIRS system was employed to monitor hemodynamic and metabolic changes of forehead tissue near the thermal stimulation site before, during, and after the heat stimulation. The results showed that cytochrome-c-oxidase of forehead tissue was not significantly modified by this heat stimulation. Significant differences in oxyhemoglobin, total hemoglobin, and differential hemoglobin concentrations were observed during the heat stimulation period versus the laser stimulation. The study demonstrated a transient hemodynamic effect of heat-based stimulation distinct to that of TILS. We concluded that the observed effects of TILS on cerebral hemodynamics and metabolism are not induced by heating the skin.

Paper Details

Date Published: 19 September 2017
PDF: 8 pages
Neurophoton. 5(1) 011004 doi: 10.1117/1.NPh.5.1.011004
Published in: Neurophotonics Volume 5, Issue 1
Show Author Affiliations
Xinlong Wang, The Univ. of Texas at Arlington (United States)
Divya D. Reddy, The Univ. of Texas at Arlington (United States)
Sahil S. Nalawade, The Univ. of Texas at Arlington (United States)
Suvra Pal, The Univ. of Texas at Arlington (United States)
Francisco Gonzalez-Lima, The Univ. of Texas at Austin (United States)
Hanli Liu, The Univ. of Texas at Arlington (United States)

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