Context-Dependent Relationships between Locus Coeruleus Activation and Coordinated Neural Activity Patterns in the Anterior Cingulate Cortex

Abstract

Ascending neuromodulatory projections from the locus coeruleus (LC) affect cortical neural networks via the release of norepinephrine (NE). However, the exact nature of these modulatory effects on neural activity patterns in vivo is not well understood. Here we show that in awake monkeys, LC activation is associated with changes in coordinated activity patterns in the anterior cingulate cortex (ACC). These effects, which are largely independent of changes in firing rates of individual ACC neurons, depend on the type of LC activation: ACC pairwise correlations are reduced when tonic (baseline) LC activity increases but are enhanced when external events drive phasic LC responses. Both effects also covary with pupil changes that reflect LC activation and arousal. These results suggest that modulations of information processing that reflect changes in coordinated activity patterns in cortical networks can, at least in part, result from ongoing, context-dependent, arousal-related changes in activation of the LC-NE system.