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We fixed the brains of awake mice and imaged them in a calcium fluorescence imaging system (see Supplement Fig. 1) as previously described^{71 (link)}. We used a frame rate of 30 Hz and a resolution of 512 × 512 with 4 × 4 binning. Illumination was provided by a high-power mercury lamp (UHGLGPS, Olympus; 130 W) through a liquid light guide (ULLG150/300, Olympus). The excitation beam, ~488 nm for GCaMP fluorescence, was created by an excitation filter (FF01-480/40-25, Semrock) and reflected onto the cortical surface with a dichroic mirror (FF495-Di0325 × 36, Semrock). Video was captured using an sCMOS camera (16 bits, 65 × 6.5 μm, Flash4.0V2C11440-22CU, Hamamatsu, Japan), with a dichroic mirror filtering out GCaMP6f excitation light. The objective lens was defocused down by ~400 μm to minimize vascular artifacts. Fluorescence imaging was performed in a darkened, soundproof chamber after 15 min of acclimation. We monitored the mice via a body camera throughout the imaging process. The fluorescent signals showed obvious changes, as demonstrated in Supplementary Fig. 1. Under anesthesia, electroencephalogram (EEG) data were monitored using two stainless steel screws implanted into the prefrontal cortex.

WFI was performed on day 1or 2 of the training step 3 (beginner) and on day 21 or 22 (expert) using a CMOS camera (FLASH4; C-13 440-20CU; Hamamatsu) system, adapted from a previous study (Kim et al., 2016 (link)). The cortical surface was imaged through a 2×/0.08 NA objective (PlanApo N; Olympus). For measurement of GCaMP6 emission, a 470 nm LED (Optogenetics-LED-Blue; Prizmatrix) was connected to the dichroic cube holder using a 1000-μm-diameter 0.50-NA fiber (M59L01; Thorlabs). The light was filtered with a 470 nm bandpass filter (FB470-10; Thorlabs) that was fiber-coupled into the dichroic mirror (FF495-Di03-25 × 36; Semrock). Fluorescence emitted from the cortical surface was passed through a 530 nm bandpass fluorescence emission filter (FF01-520/35-25; Semrock). Images were acquired using HCImage Live (Hamamatsu) at 20 Hz (50 ms/frame) and 192 × 192 pixels. Imaging was started by using the transistor-transistor logic (TTL) signal generated from the Arduino to synchronize the imaging and behavior data.