Dataset Information

The ventromedial hypothalamus mediates predator fear memory.

ABSTRACT: The amygdala has been shown to be essential for the processing of acute and learned fear across animal species. However, the downstream neural circuits that mediate these fear responses differ according to the nature of the threat, with separate pathways having been identified for predator, conspecific and physically harmful threats. In particular, the dorsomedial part of the ventromedial hypothalamus (VHMdm) is critical for the expression of defensive responses to predators. Here, we tested the hypothesis that this circuit also participates in predator fear memory by transient pharmacogenetic inhibition of the VMHdm and its downstream effector, the dorsal periaqueductal grey, during predator fear learning in the mouse. Our data demonstrate that neural activity in the VMHdm is required for both the acquisition and recall of predator fear memory, whereas that of its downstream effector, the dorsal periaqueductal grey, is required only for the acute expression of fear. These findings are consistent with a role for the medial hypothalamus in encoding an internal emotional state of fear.

SUBMITTER: Silva BA

PROVIDER: S-EPMC4899089 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Publications

The ventromedial hypothalamus mediates predator fear memory.

Silva Bianca A BA Mattucci Camilla C Krzywkowski Piotr P Cuozzo Rachel R Carbonari Laura L Gross Cornelius T CT

The European journal of neuroscience 20160429 11

The amygdala has been shown to be essential for the processing of acute and learned fear across animal species. However, the downstream neural circuits that mediate these fear responses differ according to the nature of the threat, with separate pathways having been identified for predator, conspecific and physically harmful threats. In particular, the dorsomedial part of the ventromedial hypothalamus (VHMdm) is critical for the expression of defensive responses to predators. Here, we tested the ...[more]

PMID: 26991018

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Project description:The ventromedial hypothalamus is a central node of the mammalian predator defense network. Stimulation of this structure in rodents and primates elicits abrupt defensive responses, including flight, freezing, sympathetic activation, and panic, while inhibition reduces defensive responses to predators. The major efferent target of the ventromedial hypothalamus is the dorsal periaqueductal gray (dPAG), and stimulation of this structure also elicits flight, freezing, and sympathetic activation. However, reversible inhibition experiments suggest that the ventromedial hypothalamus and periaqueductal gray play distinct roles in the control of defensive behavior, with the former proposed to encode an internal state necessary for the motivation of defensive responses, while the latter serves as a motor pattern initiator. Here, we used electrophysiological recordings of single units in behaving male mice exposed to a rat to investigate the encoding of predator fear in the dorsomedial division of the ventromedial hypothalamus (VMHdm) and the dPAG. Distinct correlates of threat intensity and motor responses were found in both structures, suggesting a distributed encoding of sensory and motor features in the medial hypothalamic-brainstem instinctive network.SIGNIFICANCE STATEMENT Although behavioral responses to predatory threat are essential for survival, the underlying neuronal circuits remain undefined. Using single unit in vivo electrophysiological recordings in mice, we have identified neuronal populations in the medial hypothalamus and brainstem that encode defensive responses to a rat predator. We found that both structures encode both sensory as well as motor aspects of the behavior although with different kinetics. Our findings provide a framework for understanding how innate sensory cues are processed to elicit adaptive behavioral responses to threat and will help to identify targets for the pharmacological modulation of related pathologic behaviors.

Dataset Information

The ventromedial hypothalamus mediates predator fear memory.

Publications

The ventromedial hypothalamus mediates predator fear memory.

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