Figure 7. Differences in correlated activity in anterior cingulate cortex (ACC) in response to startling events, conditioned on locus coeruleus (LC) spiking.

(A) Beep-related difference in ACC r_sc for trials in which LC had a transient response relative to trials in which LC had no transient response, plotted as a function of the bin size used to count spikes in ACC. Circles and vertical lines are median and bootstrapped 95% confidence estimates across the given set of ACC pairs. (B) Data from ‘fake-beep trials’ (trials with no beep but sorted according to whether or not there was a transient increase in LC spiking comparable in magnitude to the beep-evoked response), plotted as in (A). In both panels, asterisks indicate Mann–Whitney U-test for H₀: median difference in ACC r_sc (after relative to before the beep or ‘fake-beep’) between the two groups (LC-evoked and no-evoked) is different for the given time bin, p < 0.05 for both monkeys’ data pooled together; filled circles indicate sign-rank test for H₀: ACC r_sc differences (after relative to before the beep) within each group is different from zero, p < 0.05 for both monkeys’ data pooled together.

Figure 7—figure supplement 1. Consistency of locus coeruleus (LC) responses to startling sounds.

Histograms showing the proportion of LC neurons from monkeys Sp (A) and Ci (B) that exhibited a characteristic transient response followed by suppression for the given proportion of beep trials. Arrows indicate median values.

Figure 7—figure supplement 2. Differences in anterior cingulate cortex (ACC) Fano factor in response to startling events, conditioned on locus coeruleus (LC) spiking.

(A) Beep-related difference in ACC Fano factor for trials in which LC had an evoked response relative to trials in which LC had no evoked response, plotted as a function of the bin size used to count spikes in ACC. Circles and vertical lines are median and bootstrapped 95% confidence estimates across the given set of ACC neurons. (B) Data from ‘fake-beep trials’ (trials with no beep but sorted according to whether or not there was a transient increase in LC spiking comparable in magnitude to the beep-evoked response), plotted as in (A). In both panels, Mann–Whitney U-test for H₀: median difference in ACC Fano factor (after relative to before the beep or ‘fake-beep’) between the two groups (LC-evoked and not evoked) is different for the given time bin size, p < 0.05 for both monkeys’ data pooled together (*none found); filled circles indicate sign-rank test for H₀: ACC Fano factor differences (after relative to before the beep) within each group is different from zero, p < 0.05 for both monkeys’ data pooled together.