Development of wearable optical topography system for mapping the prefrontal cortex activation

Abstract

Optical topography (OT) based on near infrared spectroscopy is effective for measuring changes in the concentrations of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) in the brain. It can be used to investigate brain functions of subjects of all ages because it is noninvasive and less constraining for subjects. Conventional OT systems use optical fibers to irradiate the scalp and detect light transmitted through the tissue in the human head, but optical fibers limit the subject's head position, so some small systems have been developed without using optical fibers. These systems, however, have a small number of measurement channels. We developed a prototype of a small, light, and wearable OT system that covers the entire forehead. We measured changes in the concentrations of oxy-Hb and deoxy-Hb in the prefrontal cortex while a subject performed a word fluency task. The results show typical changes in oxy-Hb and deoxy-Hb during the task and suggest that the prototype of our system can be used to investigate functions in the prefrontal cortex.

Night duty and decreased brain activity of medical residents: a wearable optical topography study

“…The details of the WOT-100 (Hitachi High-Technologies Corporation Co. Ltd., Tokyo, Japan) have been described in a previous study [19,20]. The probe unit has a 2 × 8 alternating arrangement of irradiation and detection positions covering the entire forehead, with 22 measurement points (Figure 3 (A)).…”

Using Fiberless, Wearable fNIRS to Monitor Brain Activity in Real-world Cognitive Tasks

“…The first fiberless systems were equipped only with a small number of channels (e.g., single channel 15 and 2 channels 16 ) limiting the investigation to small areas. More recently, multichannel wireless and wearable fNIRS devices have been developed 6,7,[17][18][19][20] giving the possibility to monitor larger portions of the head on freely moving participants.…”

“…Given the need to bring functional imaging instruments outside the lab and given recent technological improvements, portable and wearable electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) systems have been developed [6][7][8][9][10][11] . One of the major advantages of fNIRS over EEG is its higher spatial resolution.…”

“…The absence of optical fibers reduces the weight and the bulk of the probe, being more comfortable and robust against motion artifacts. The optodes are arranged in an alternating geometry ( Figure 1A) with an inter-optode separation of 3 cm, creating 16 source-detector combinations (e.g., 16 measurement channels) 6 . In order to shield the headset from the surrounding light, a shading cap is provided ( Figure 1D).…”

A wireless handheld probe with spectrally constrained evolution strategies for diffuse optical imaging of tissue

“…A flexible printed circuit board holds the illumination, detection, and wireless transmission electronics. Similarly, a larger, but still portable wearable brainimaging system developed by Atsumori et al 10 uses eight CW sources and eight detectors with two wavelengths for imaging the frontal cortex. Along with a portable pack that attaches to the subject's waist, the wireless system allows for the subject to move around during imaging.…”