Canadian mouse experiment reveals overlap in brain representations — ScienceDaily

Researchers from the Douglas Research Centre at McGill University and the University of Toronto in Canada found in experiments on mice that fear can blur the boundary between neural representations of safe and dangerous situations. As ScienceDaily reports, the results were published in the journal Nature Neuroscience.

The mice were taught to associate one environment with danger and another with safety. Instead of forming increasingly clearly separated neural representations of these places, their brain activity began to show similar, partially overlapping patterns.

Virtual environmental change

For the experiment, scientists combined augmented reality with real-time imaging of brain activity. They created a special arena in which the animals could virtually move between environments associated with safety or threat by changing visual and sound cues without physically moving the mice.

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Miniature microscopes simultaneously tracked hundreds of neurons in the hippocampus, a brain region important for learning and memory. This made it possible to observe how brain activity changed during transitions between experiences associated with threat and safety.

Speed over accuracy

According to the authors, the overlap of such representations could help the brain retrieve information about previous danger more quickly and trigger a defensive response more promptly. At the same time, this mechanism comes at a cost: the brain may respond to a potential threat even in a harmless situation, prioritizing speed over accuracy.

The researchers link this process to the ventral part of the hippocampus, which is involved in processing emotionally significant experiences, including fear and anxiety. They suggest that excessive sensitivity of a normal survival mechanism may partly explain strong fear responses in anxiety disorders and post-traumatic stress disorder. At the same time, the authors emphasize that the experiments were conducted on mice, so further research is needed to determine the role of this mechanism in humans.