Fig. 1

Representative time-frequency spectrogram of raw trace waveform (top, Ampl. In mV) and LFP power (bottom) of freely-moving (left column) and anesthetized animals (right column) during euthanasia in the (A) right ACC, (B) right Po, (C) left TG, and (D) right V1M, respectively. The y-axis represents the frequency power intensity (bottom, red for higher power, maximum at 56dB), and the x-axis represents time (s). The blue arrow is the start of CO₂ at 300s (5 min), and the red arrow indicates a rebound activity around 7–8 min. An expansion of different time segments (5s) for ACC freely-moving traces are shown above to represent the following status: alive (160–165 s), early euthanasia after CO₂ (360–365 s), rebound (440–445 s), and dead (1500–1505 s).