The locus coeruleus-norepinephrine system and sensory signal processing: A historical review and current perspectives

Many studies in intact animals have shown that locally applied or synaptically released norepinephrine (NE) can enhance individual neuron and neural network responses to sensory inputs. However, a major unanswered question is how and when noradrenergically-mediated changes in sensory signal processing can influence downstream decision making, motor responding, and ultimately behavioral outcomes. Recent work using a variety of approaches in different sensory networks has started to consider this question. Evidence collected to date as reported in this Special Edition of Brain Research suggests that output from the brainstem locus coeruleus (LC)-NE system can modify task-related sensory signal processing and by so doing influence goal-directed behavioral responding. This report reviews the work leading to this most recent line of inquiry and at the same time identifies areas for future investigation.