Topographic structure and function of locus coeruleus noradrenaline neurons.

Noradrenaline (also known as norepinephrine) is released throughout most of the central nervous system by neurons in the locus coeruleus1-4. Here we identified a relationship between the morphologies, gene expression and activity of noradrenergic neurons in locus coeruleus in mice. Axonal projections of individual neurons were extensive but largely confined to subsets of brain regions. Axonal projections and graded gene expression correlated with locations of cell bodies in locus coeruleus. In a behavioural task requiring continuous learning from actions, dorsal locus coeruleus neurons projecting to isocortex were activated when mice switched choices and by reward-prediction-error signals that drive learning. Background activity of neurons in ventral locus coeruleus was higher when mice ignored stimuli indicating potential reward availability. These observations reveal a topographically organized structure and function of a neurotransmitter system and show that it contains learning signals for flexible behaviour.