How Memories Trigger Behavior 

This piece, by Onno Berkan, was published on 10/22/24. The original text, by Jung et al., was published by Nature Neuroscience on 09/24/24.

A recent Hopkins study investigates how mice use spatial memory to guide escape behavior when faced with threats. The researchers examined neural activity in the hippocampus, which is important for spatial memory, as mice learned to navigate to a shelter location.

The experiments were conducted in a circular arena with visual cues on the walls and a small shelter placed at the edge. Mice were given time to explore and become familiar with the environment. Then, threatening stimuli like loud noises or bright lights were presented to trigger escape behavior.

Using advanced imaging techniques, the researchers were able to record activity from large numbers of individual neurons in the hippocampus as the mice tried to escape. They found that a specific group of hippocampal neurons became active when the mouse was in or near the shelter location– this "shelter-associated ensemble" of neurons appeared to encode a memory of the shelter's location.

Importantly, when the researchers used optogenetics to artificially activate these shelter-associated neurons, it caused the mice to move toward the shelter location, even in the absence of any threat. Conversely, inhibiting these neurons during threat presentation disrupted the mice's ability to efficiently escape to the shelter.

These results suggest that the shelter-associated neural ensemble plays a key role in guiding spatial navigation during escape behavior. The findings demonstrate how spatial memory circuits can trigger goal-directed actions.

The findings provide new insights into how the brain uses memories to guide behavior in threatening situations. It highlights the hippocampus as a key node linking cognitive maps with action selection: understanding these neural mechanisms could have implications for treating disorders involving impaired spatial navigation or maladaptive fear responses.

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