Fig. 1.

OISI instrumentation, processing scheme, and data quantification. (a) A typical OISI setup where a computer syncs the exposure time of the camera and switching of the LEDs. DM, dichroic mirror; CL, condenser lens; P, polarizer; LED, light-emitting diode; Cam, camera. (b) OISI processing pipeline from raw data with representative images of whisker stimulation on awake mice (adapted from Ref. 12). (Top) Using the original OISI approach, relative reflectance changes in % of 530 ($\sim \mathrm{HbT}$) and 630 nm ($\sim \mathrm{HbR}$) light during whisker stimulation are visualized (adapted from Ref. 12). (Bottom) Using spectroscopic OISI, relative changes in $C_{\mathrm{HbR}}$, $C_{\mathrm{HbO}2}$, $C_{\mathrm{HbT}}$, and calcium indicator GCaMP fluorescence during whisker stimulation are visualized (adapted from Ref. 12).