Monoamines like serotonin, dopamine, and adrenaline/noradrenaline (epinephrine/norepinephrine) act as neuromodulators in the nervous system. They play a role in complex behaviors, cognitive functions such as learning and memory formation, and fundamental homeostatic processes such as sleep and feeding.
However, the evolutionary origin of the genes required for monoaminergic modulation is uncertain.
Researchers from the University of Leicester and its colleagues have found that the genes necessary for memory, learning, aggression, and other complex behaviors first appeared roughly 650 million years ago.
Dr. Roberto Feuda, from the Neurogenetic group in the Department of Genetics and Genome Biology, said, “We’ve known for a long time that monoamines like serotonin, dopamine, and adrenaline act as neuromodulators in the nervous system, playing a role in complex behavior and functions like learning and memory, as well as processes such as sleep and feeding.”
“However, less certain was the origin of the genes required for the production, detection, and degradation of these monoamines. Using the computational methods, we reconstructed the evolutionary history of these genes and show that most of the genes involved in monoamine production, modulation, and reception originated in the bilaterian stem group.”
“This finding has profound implications on the evolutionary origin of complex behaviors such as those modulated by monoamines we observe in humans and other animals.”
Scientists noted, “This new way to modulate neuronal circuits might have played a role in the Cambrian Explosion – known as the Big Bang – which gave rise to the largest diversification of life for most major animal groups alive today by providing flexibility of the neural circuits to facilitate the interaction with the environment.”
“This discovery will open new important research avenues to clarify the origin of complex behaviors and if the same neurons modulate reward, addiction, aggression, feeding, and sleep.”