Fear memories serve a purpose: A mouse in the wild learns to fear the sound of footsteps, which helps it avoid predators. But in certain situations, t

Stress warps fear memories in multiple ways

submited by
Style Pass
2024-11-16 20:00:02

Fear memories serve a purpose: A mouse in the wild learns to fear the sound of footsteps, which helps it avoid predators. But in certain situations, those fear memories can also tinge neutral memories with fear, resulting in maladaptive behavior. A mouse or person, for instance, may learn to fear stimuli that should presumably be safe.

This shift can occur when an existing fear memory broadens—either by recruiting inappropriate neurons into the cell ensemble that contains it or by linking up to a previously neutral memory, according to two new studies in mice, one published today and another last week.

Memories are embodied in the brain through sparse ensembles of neurons, called engrams, that activate when an animal forms a new memory or recalls it later. These ensembles were thought to be “stable and permanent,” says Denise Cai, associate professor of neuroscience at the Icahn School of Medicine at Mount Sinai, who led one of the studies.

But the new findings reveal how, during times of fear and stress, memories can become malleable, either as they are brought back online or as the neurons that encode them expand.

Leave a Comment