Chapter 23 Role of the locus coeruleus in emotional activation

Abstract

This chapter discusses recent studies of the noradrenergic locus coeruleus (LC) system to consider its possible roles in emotion. It describes the recent studies of the effects of manipulating LC neurons on electroencephalographic (EEG) activity and attentional behavior. Emotional responses are typically measured by EEG or autonomic arousal. Emotionally arousing stimuli produce activation of the cortical EEG, and parallel activation of autonomic measures such as blood pressure, heart rate, or galvanic skin response (as commonly used in lie detector tests). Recent results link the LC both to the EEG and autonomic responses that accompany emotionally arousing events LC neuronal projections, effects of NE on LC target cells, and discharge characteristics of LC neurons in unanesthetized, unconditioned animals are reviewed. More recent studies on the effects of stress on LC neurons, and on activity of LC neurons in behaving monkeys during a conditioned attentional task are also examined. The chapter reviews new findings on afferents to the LC that indicate the status of this key noradrenergic system in brain circuitry. Although the LC is not typically considered in the context of emotion, the analysis suggests that the LC system could play an important role in the process of emotional activation.