Fig. 1.

Arousal modulates frequency tuning of L2/3 pyramidal cells. (A) Experiment schematic. An IR camera records pupil size (Top Left) during imaging of GCaMP6s-expressing neurons (Bottom Left). (B, Top) Tones presented during imaging. (B, Middle) Pupil diameter for 1 experiment. (B, Bottom) Simultaneous recording of mouse velocity. (C) Summary of pupil diameters (n = 8 experiments) when mice were stationary (black) or walking (pink) shows that locomotion only occurred during high arousal and mice were typically stationary. (D) A representative cell showing enhancement of tone-evoked responses as arousal (pupil diameter) increases. Bold trace, average response. Colored bold traces indicate frequencies eliciting a significant response. Gray, individual trial. (E₁) Arousal increases the amplitude (filled circles) and reliability (open circles) of BF responses (n = 195 cells). (E₂) Arousal increases percentages of tones evoking significant responses (filled circles) and reduces lifetime sparseness (Sp) (1-Sp, open circles). (F) Arousal broadens frequency tuning curves. (Left) Average tuning (n = 195 cells) during low (blue), moderate (green), and high (red) arousal aligned to low arousal BF. (Right) Low and high arousal curves scaled. (Middle) Cumulative probability plots show no shift in BF (1–35% [Constricted] vs. 66–100% [Dilated] maximum diameter, n = 119,186 cells). Error bars, SEM.