Neuroscience: Neurotransmitters get emotional

Levels of the neurotransmitters hypocretin and melanin-concentrating hormone are differentially linked to emotional states and social interaction reports a study in Nature Communications this week. The findings represent the first direct study of neurotransmitter levels in relation to human emotions

The neurotransmitters melanin-concentrating hormone and hypocretin are implicated in sleep and maintenance of arousal states. However, their roles have remained unclear because the release of the neurotransmitters across the sleep-wake cycle and their relation to specific behaviours has not been measured in any species. Jerome Siegel and colleagues investigate the levels of these neurotransmitters in the amygdala and hypothalamus of the rat as well as the amygdala of human subjects and find that hypocretin is linked to positive emotions such as happiness, but melanin-concentrating hormone isn’t.

The authors hope that these findings will further our understanding of some psychiatric disorders.