Reliability of Wearable Two Channel CW-NIRS in Measurements of Brain Function

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Imaging

Background:

• Multi-channel near-infrared spectroscopy (NIRS), or optical topography (OT), enables functional brain mapping but is time-consuming and costly, limiting its use for large-scale screening.
• A new wearable two-channel continuous wave NIRS (CW-NIRS) device offers a simpler approach, but its reliability for assessing brain function requires validation.

Purpose of the Study:

• To evaluate the reliability of a two-channel CW-NIRS device for measuring brain function compared to time-resolved NIRS (TNIRS).
• To assess the feasibility of using CW-NIRS for screening brain disorders and preventing stress-related conditions.

Main Methods:

• A two-channel CW-NIRS device measuring total hemoglobin (t-Hb) changes using a single 800 nm LED was tested.
• t-Hb changes in the bilateral prefrontal cortex (PFC) during mental arithmetic tasks were recorded using both CW-NIRS and TNIRS.
• Laterality index (LI) of t-Hb, reflecting PFC activity asymmetry and mental stress, was calculated and compared between the two NIRS methods.

Main Results:

• A significant positive correlation was found between the laterality index (LI) of t-Hb measured by CW-NIRS and TNIRS.
• The interval between measurements was 1-13 days, indicating stable results.
• The study suggests that PFC activity asymmetry is relatively stable.

Conclusions:

• The simple two-channel CW-NIRS device demonstrates reliability in measuring brain function, particularly PFC activity.
• This wearable NIRS technology may be suitable for screening brain disorders and potentially preventing stress-induced diseases.
• The findings highlight the stability of left-right PFC activity asymmetry.