A DAQ-device-based continuous wave near-infrared spectroscopy system for measuring human functional brain activity

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Instrumentation

Background:

• Functional near-infrared spectroscopy (fNIRS) is a growing neuroimaging technique measuring hemodynamic responses to infer neural activity.
• Existing fNIRS systems can be expensive, limiting accessibility for research and clinical applications.
• Developing cost-effective and easily implemented fNIRS systems is crucial for broader adoption.

Purpose of the Study:

• To propose and validate an easily implemented, DAQ-device-based functional near-infrared spectroscopy (fNIRS) system.
• To describe the essential instrumentation components for constructing a custom fNIRS system.
• To demonstrate the system's efficacy through simultaneous measurements and neural activation detection.

Main Methods:

• A custom fNIRS system was built using basic instrumentation components.
• Digital in-phase and quadrature demodulation in LabVIEW software was employed to differentiate light sources.
• The custom system's performance was validated against a commercial ETG-4000 instrument during Valsalva maneuver and mental arithmetic tasks.

Main Results:

• High correlation (r=0.92 for lower, r=0.84 for higher wavelengths) was observed between custom and commercial fNIRS systems.
• Significant cerebral activation in the prefrontal cortex was detected in participants during a mental arithmetic task.
• The system successfully identified changes in oxyhemoglobin and deoxyhemoglobin levels indicative of neural activity.

Conclusions:

• The developed DAQ-device-based fNIRS system offers a viable and cost-effective alternative to commercial systems.
• The custom fNIRS system demonstrates reliable performance for measuring hemodynamic responses and detecting brain activation.
• This approach facilitates wider accessibility to fNIRS technology for neuroscience research and clinical applications.