Lock-in functional near-infrared spectroscopy for measurement of the haemodynamic brain response.

ABSTRACT: Here we show a method of the lock-in amplifying near-infrared signals originating within a human brain. It implies using two 90-degree rotated source-detector pairs fixed on a head surface. Both pairs have a joint sensitivity region located towards the brain. A direct application of the lock-in technique on both signals results in amplifying common frequency components, e.g. related to brain cortex stimulation and attenuating the rest, including all components not related to the stimulation: e.g. pulse, instrumental and biological noise or movement artefacts. This is a self-driven method as no prior assumptions are needed and the noise model is provided by the interfering signals themselves. We show the theory (classical modified Beer-Lambert law and diffuse optical tomography approaches),

SUBMITTER: Wojtkiewicz S 

PROVIDER: S-EPMC9045899 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature