Fig. 7: Direction of FC changes within the inverted U-shaped pattern under LC-NE activation was dependent on the baseline arousal level.

A Schematic setup of mouse fMRI under hM3Dq-based chemogenetic excitation of LC-NE neurons for both awake and anaesthetized states. B Chemogenetic activation of LC-NE neurons promoted significant increase of arousal from middle to high level in awake mice. Upper left, averaged iEEG power spectrum in hM3Dq and Sham groups. Upper right, significant increase of mouse arousal level of hM3Dq group, compared to that of Sham group. Lower, chemogenetic activation of LC-NE neurons increased the arousal from middle to high level in awake mice. Here, iEEG recording with chemogenetics was conducted outside the magnet. Each line represented an individual mouse (N = 22 mice for hM3Dq & N = 9 mice for Sham). Error bar, the standard error of the mean (SEM). Statistical significance was determined using (two tails) paired t-test. *, p < 0.05. n.s. no significance. C, D Chemogenetic activation of LC-NE neurons decreased whole-brain FC in awake mice. Each dot represented an individual mouse (N = 11 mice for hM3Dq & N = 7 mice for Sham). Error bar, the SEM. Statistical significance was determined using (two tails) two-sample t-test. *, p < 0.05. E Schematic summary of increased arousal from middle to high level and decreased whole-brain FC after chemogenetic activation on LC-NE neurons in awake mice. F–H Similar to (B–D) but for isoflurane anaesthetized mouse (iEEG: N = 15 mice for hM3Dq & N = 10 mice for Sham, fMRI: N = 10 mice for hM3Dq & N = 7 mice for Sham). Chemogenetic activation of LC-NE neurons promoted significant increase of arousal from low to middle level and whole-brain FC in anaesthetized mice. **p < 0.01. Functional MRI data²⁰ was obtained from Zerbi. et al. I Schematic summary of increased arousal and whole-brain FC after chemogenetic activation on LC-NE neurons in anaesthetized mice. Source data are provided as a Source Data file.