Supplementary Figure 2: Task-related changes in tonic firing rate and optogenetically identified cell characterization.

(a) Tonic firing rate (20 sec prior to first stimulus in each session) changes across pre-CS, fear conditioning (FC), early and late extinction trials for all LC neurons held across all sessions (n=37) (one-way RM ANOVA, F_{3, 111} = 0.90, P = 0.37). (b) Tonic firing rate changes for each auditory CS defined cell population during pre-CS, early and late extinction (two-way repeated RM ANOVA; interaction F_9,63 = 0.74, P = 0.67; effect of time F_{3, 63} = 0.62, P = 0.60; effect of neuron type F_{3, 21} = 0.21, P = 0.89). (c) Baseline firing rate (60 sec prior to first stimulus in each session) changes across pre-CS, fear conditioning (FC), early and late extinction trials for all LC neurons held across all sessions (n=37) (one-way RM ANOVA, F_{3, 111} = 0.90, P = 0.37). (d) Baseline firing rate changes for each auditory CS defined cell population during pre-CS, early and late extinction (two-way repeated RM ANOVA; interaction F_9,63 = 0.87, P = 0.56; effect of time F_{3, 63} = 1.06, P = 0.37; effect of neuron type F_{3, 21} = 0.44, P = 0.73). (e) Schematic showing optogenetic identification and electrophysiological recording experimental approach. (f) Example perievent time histogram of cell showing laser inhibition of an LC neuron for optogenetic identification. (g) Pie chart showing proportion of optogenetically identified LC cells recorded across all tasks (n=10) which were classified as pre-CS (gray, 20%), ‘Fear’ (red, 10%), ‘Fear & Extinction’ (purple, 10%), ‘Extinction’ (blue, 30%) or not responsive (black, 30%). Yellow inside chart shows proportion of shock responsive cells in each cell classification. (h) Population averaged auditory CS-evoked responses (y-axis) at pre-CS, early and late extinction for each cell type showing a similar trend to that seen when analyzing all LC cells recorded (see Fig. 2g for comparison). Data represent the mean ± SEM.