fNIRS only images near-surface cortex because depth is spatially limited

Evidence

However, there are also limitations of fNIRS. The spatial resolution is limited by the density of the optodes used, and is not generally as good as that found with fMRI or PET. The depth of imaging is limited, so that it is only suitable for imaging areas of the cortex near the surface [although other designs of fNIRS systems that use lasers instead of diodes and use pulsatile stimuli can derive 3-dimensional images of the brain, at least in infants (Cooper et al. 2014 )]. However, fNIRS has been successfully used in a range of studies to determine effects on language processing in hearing populations of adults and children (Quaresima et al. 2012 ), therefore it shows promise for assessing language processing in deaf populations and those with cochlear implants. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4285

Categorization

• QUESTION: Worth chasing: can laser-based pulsed fNIRS actually yield useful 3-D brain images beyond infants, and how shallow is ‘near surface’ in practice?