Functional near-infrared spectroscopy matches fMRI at detecting task-related brain signals

Whole-head functional near-infrared spectroscopy (fNIRS) can perform comparably to functional magnetic resonance imaging (fMRI) at detecting task-related cortical haemodynamic changes across the lateral cortex, a recent study has found.

The study included 18 healthy adults (mean age 38.9±15.1 years, six men) who completed a same-day fNIRS-fMRI study, which involved a right- and left-handed finger-tapping task and a semantic-decision tones-decision (SDTD) task.

During the finger-tapping tasks, the oxyhaemoglobin (HBO) and deoxyhaemoglobin (HBR) fNIRS channels showed significant activity over the contralateral primary motor cortex, corresponding to the same clusters of task-related activity as detected by fMRI.

In particular, the fNIRS HBO channel for the right finger-tapping task correlated strongest with fMRI, with five channels overlapping the cluster. Two channels each for the HBR right and HBO left conditions overlapped with the fMRI cluster.

During the SDTD task, fNIRS HBO and HBR activity likewise overlapped with fMRI clusters for both the semantic and tones conditions. There were additional fNIRS channels with significant activity that did not overlap with fMRI clusters and vice-versa.

“In this study, full-head fNIRS was compared with same-day fMRI in 18 subjects while performing motor and language tasks. We found overlap between channel HBO and HBR fNIRS results and surface-projected fMRI results for all tasks, especially the motor task, at the group level,” the researchers said.

“These results suggest that whole-head fNIRS is comparable to fMRI in detecting task-related cortical haemodynamic changes across lateral cortex,” they added.

Nevertheless, future studies are needed to determine whether fNIRS and fMRI are indeed comparable at the source level, which would underpin the clinical utility of fNIRS.