fNIRS measures brain blood flow via paired scalp light sources and detectors

Evidence

In the fNIRS imaging system optodes are placed at various locations on the scalp. Each fNIRS channel consists of a paired source and detector. The source emits a light beam, directed perpendicular to the scalp surface, and the detector detects the light emerging from the brain. The detected light beam has scattered in a banana-shaped pathway through the brain reaching a depth of approximately half the distance between the source and detector. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4274

Categorization

• DEFINE: Concise mechanics of how fNIRS channels and the banana-shaped scattering pathway operate.
• XREF: The near-infrared blood-oxygen contrast mechanism parallels the reader’s earlier physiological reading on how perceptual systems signal.