Ann Kennedy is the winner of the 2022 Eppendorf & Science Prize for Neurobiology for research that provides new insight into aggression and how aggressive motivation is regulated by the brain. Although it can take many forms, aggression exists in many animal species. But engaging in a fight can be costly to an individual as even the winners can walk away with serious injuries. Thus, it is common – and safer – to begin a conflict with threat displays and posturing, and attack only if necessary. This type of aggressive arousal is an archetypal motivational state that exhibits persistence and graded intensity – it builds and maintains until the threat or the need to intimidate is gone. However, how this is accomplished in the brain is unknown. Previous research has shown that the ventrolateral portion of the ventromedial hypothalamus (VMHvl) is implicated in control of aggression in mice. To better understand how this works, Kennedy and her colleagues used head-mounted miniaturized microendoscopes to characterize the activity of neurons in this region as mice freely interacted. Although the researchers found that activity in these cells was only weakly correlated with when mice fight, the researchers revealed that a small population of neurons was persistently active over the duration of a social encounter with modest fluctuation in the intensity of their activity as animals interacted in different ways. When this patterning was weak, mice investigated or ignored one another, but as the pattern grew, so did aggressive posturing, including actions like dominance mounting. When it saturated, animals began to exhibit outright attacks. Kennedy suggests that this signal reflects a level of aggressive motivation and argues that the scalable and persistent activity within the VMHvl is a mechanism for setting an animal’s motivational state.
Finalists for the prize were Kevin Guttenplan for his essay, “Why do neurons die: astrocytes emerge as key mediators of neurodegeneration,” and Filipa Cardoso for her essay, “The brain fat connection: type 2 innate lymphoid cells shape metabolism through a brain-body circuit.”
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