Functional near-infrared imager

We developed a continuous wave (cw) light imaging probe which includes 9 light sources and 4 pairs detectors (each pair has one 850 nm filtered detector and one 760 nm filtered detector). The light sources are controlled by a computer and the signals from the detectors are converted and processed in the computer. There are 16 measurement sections and total detection area is 9 cmx4 cm which can be scanned every 8 seconds. The detector-source uses 2.5 tm spacing. In this study, we present the noise, drift, detectivity and spatial resolution test results of the imager. Changes of oxygenation and blood volume in about 2 cm depth from the surface, of brain model can be detected. The temporal resolution is 8 seconds and spatial resolution is about 2 cm. The detectivity of O.D. changes can reach 0.008. With this cw imaging probe, se measured motor function in motor cortex are;?, visual function in occipital area, and cognitive activity in frontal forehead area of the human brain when the subjects are stimulated by moving fingers, viewing a flashing light and doing an analogy test, respectively. The experimental results show that the cw imaging probe can be used for functional images of brain activity based upon changes of oxygenation and blood volume due to the stimulus.