Figure 9. Temporal relationships between locus coeruleus (LC) firing and anterior cingulate cortex (ACC) correlated activity.
No-beep trials: (A) LC firing rate aligned to the start of stable fixation. Solid and dotted lines are mean and bootstrapped 95% confidence estimates across the set of LC neurons. (B) Mean and 95% confidence estimates of ACC rsc computed across trials in time bins aligned to the start of stable fixation, separated into trials on which the simultaneously measured LC neuron did not (LC = 0) or did (LC > 0) fire an action potential. Beep trials (C–F). Panels as in (A) and (B), except with LC firing and ACC rsc now aligned to the time of the beep and separated into trials with (C, D) or without (E, F) an LC response to the beep. Red portions of lines indicate Mann–Whitney U-test for H0: per bin value is different from pre-beep baseline, p < 0.05 for both monkeys’ data pooled together. Gray shaded areas in (C–F) indicate epochs in which statistical comparisons were made for trials with (LC-evoked) versus without (LC not evoked) an LC transient response; gold shaded areas indicate epochs in which ACC rsc slopes were compared. For trials, see text.