A tiny part of the brain plays a key role in what we successfully remember during stressful or emotional situations, according to a new USC study.

Researchers at the USC Leonard Davis School of Gerontology found that the locus coeruleus, a small region in the brainstem, is helping to select and form what are known as “adaptive memories,” which are important for survival.

“This area in the brainstem is helping us catalog the memories of experiences that are exciting or traumatic,” said senior author Mara Mather, a professor at the USC Leonard Davis School of Gerontology. “During these experiences, it is sorting which information is important to remember to help us avoid similar negative situations in the future.”

The locus coeruleus is highly connected to the rest of the brain. This small nucleus releases norepinephrine, a neurotransmitter and hormone responsible for regulating heart rate, attention, memory, and cognition.

The memories that get preserved during arousing or frightening events may seem random. For instance, a witness to a robbery may recall what they were wearing that day but forget the perpetrator’s face.

“A surge in locus coeruleus activity during highly emotional or arousing events, such as a car crash or a scene of violence, helps to transform those experiences into vivid and lasting memories,” said David Clewett, the study’s lead author and a New York University postdoctoral fellow who completed a PhD in neuroscience at USC in 2016.

The study was published Feb. 7 in the Journal of Neuroscience.