Hemodynamic signals in fNIRS

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Physics

Background:

• Near-infrared spectroscopy (NIRS) monitors tissue oxygenation and is used in functional NIRS (fNIRS) for neuroimaging.
• fNIRS detects cerebral activation by measuring hemoglobin (Hb) changes.
• The precise correlation between NIRS signals and neural activity is not fully understood due to extracerebral signal contamination.

Purpose of the Study:

• To review the basic theory of NIRS and its application in fNIRS.
• To explore correlations between NIRS signals and fMRI/neural activities.
• To discuss methods for distinguishing cerebral from extracerebral NIRS signals.

Main Methods:

• Review of existing literature on NIRS and fNIRS.
• Analysis of signal contamination from extracerebral tissues.
• Discussion of approaches to isolate cerebral signals.

Main Results:

• NIRS signals are influenced by extracerebral tissue, complicating the interpretation of cerebral activity.
• Various methods are being investigated to separate cerebral and extracerebral signals.
• Selective measurement of cerebral Hb is crucial for fNIRS advancement.

Conclusions:

• Distinguishing between cerebral and extracerebral signals is essential for the accurate application of fNIRS.
• Further research into signal processing and measurement techniques will enhance fNIRS capabilities.
• Selective cerebral Hb measurements promise to evolve fNIRS as a neuroimaging tool.