Short term Effects of Transcranial Near-infrared Photobiomodulation on Motor Performance in Healthy Human Subjects: An Experimental Study

Transcranial near-infrared photobiomodulation (NIR-PBM) is a new noninvasive procedure which transcranially applies a near-infrared wavelength to the scalp with a laser or a light-emitting diode (LED) source. Improvement in the neurological or psychological symptoms has been reported following light irradiation. However, to our knowledge, there is no study to investigate the effects of transcranial NIR-PBM on motor performance directly. Therefore, the objective of this study was to investigate the short-term effects of transcranial NIR-PBM on motor performance in healthy human subjects.

In this experimental single-blind randomized clinical trial study, 56 right-handed healthy participants, whose ages ranged from 18 to 30, were randomly assigned to (1) Real transcranial NIR-PBMC3 group (n=14), (2) Sham transcranial NIR-PBMC3 group (n=14), (3) Real transcranial NIR-PBMC4 group (n=14), and (4) Sham transcranial NIR-PBMC4 group (n=14). We applied the 808 nm laser with irradiation energy density of 60 J/cm2 and power density of 200 mw/cm2 to the C3 or C4 points of the scalp. The number of finger taps as an indicator of motor performance was assessed by the finger-tapping test (FTT) before and after irradiation of transcranial NIR-PBM on the corresponding points of the scalp for 5 minutes.

The results showed that the number of finger taps in both right and left hands following the use of transcranial NIR-PBM in the real transcranial NIR-PBMC3 group significantly increased (P < 0.05).

We concluded that using transcranial NIR-PBM with a laser source on C3 point of the motor cortex in right-handed healthy people can increase the number of finger taps in both hands as an indicator of motor performance improvement.