Multichannel near-infrared spectroscopy brain imaging system for small animals in mobile conditions

Figures

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  Fig. 1. Custom-made CW-NIRS system and experimental setup: (a) customized CW-NIRS system consisting of an MCU, laser diode, coupler, APD, and optical fiber connector and (b) schematic diagram of the experiment. CW-NIRS, continuous-wave near-infrared spectroscopy; MCU, microcontroller unit; APD, avalanche photodiodes; and PC, personal computer.

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  Fig. 2. Customized 3D head cap printing technique: (a) a cast of the skull was formed using alginate and plaster; (b) the mold was converted to a 3D mesh; (c) the 3D-printed head cap with customized channel layout was placed on the mouse skull (Video 1, MP4, 8.4 MB [URL: https://doi.org/10.1117/1.NPh.8.2.025013.1]; Video 2, MP4, 5.7 MB [URL: https://doi.org/10.1117/1.NPh.8.2.025013.2]); and (d) a ferrule-sleeve system was used for repeated experiments.

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  Fig. 3. Customized head cap and estimated channel position on a model brain and experimental protocol: (a) estimated probe position overlayed onto a 2D model of the mouse’s brain; (b) estimated channel position according to the source-detector layout; (c) regions of the mouse cortex; and (d) experimental protocol.

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  Fig. 4. Time course of changes in HbO and HbR concentration during the visual stimulation task in each channel. The horizontal axis represents time course. The vertical axis represents changes in HbO and HbR concentration. The solid line (HbO: red; HbR: blue) shows hemodynamic responses. The black solid line shows the stimulation start time. Yellow box indicates the stimulation period. Differences in HbO response between mice in a freely moving state or under anesthesia during visual stimulation: (a) freely moving group and (b) anesthesia group. HbO, oxyhemoglobin; HbR, deoxyhemoglobin; and CH, channel.

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  Fig. 5. Differences in HbO response between mice in a freely moving state or under anesthesia during visual stimulation: (a) 2D HbO image of freely moving mice during visual stimulation; (b) 2D HbO image of anesthetized mice during visual stimulation; and (c) statistical results of mice in a freely moving state or under anesthesia during visual stimulation. HbO, oxyhemoglobin and CH, channel.