Researchers find critical brain cells in mice responsible for stress-related behaviour

Researchers found that inescapable stressors impact behavior and the brain differently than stressors that can be controlled, contributing to more generalized and enduring anxiety-like behavior.

More than 70% of adults will experience at least one traumatic experience, such as a life-threatening illness or accident, violent assault or natural disaster, in their lifetimes and nearly a third will experience four or more, according to global data.

New CU Boulder research published this week in the journal Molecular Psychiatry sheds new light on why some people find it difficult to recover from trauma.(Shutterstock)

While some people who have suffered trauma fully recover, others struggle to find lasting relief. New CU Boulder research published this week in the journal Molecular Psychiatry sheds new light on why that may be.

Researchers found that inescapable stressors impact behavior and the brain differently than stressors that can be controlled, contributing to more generalized and enduring anxiety-like behavior. The study, conducted in mice, also implicates a specific type of brain cell, glutamate cells in the "ventral tegmental area (VTA)," as a key player underlying the impact of stressors.

"Understanding how stressful experiences shape our brain is critical in order for us to develop new treatments and therapies that can counteract these changes," said co-senior author Michael Baratta, an assistant professor of behavioral neuroscience at CU Boulder. "This study reveals that a little-known population of cells in the brain's reward center is critical in generating the negative consequences of exposure to stress."

Traumatic experiences, the authors note, can lead to a broad range of negative consequences. Some people experience "associative" responses, meaning that thoughts, feelings or external reminders like people, places or things related to the original trauma can prompt anxiety and fear. For instance, a war veteran might flinch at the sound of a car backfiring or fireworks crackling.

Others experience "non-associative" responses, a general aversion to stimuli -- including those unrelated to the initial trauma. These kinds of responses can permeate many aspects of life and be harder to treat.

Scientists theorize that associative and non-associative responses to stress may be driven by distinct circuits in the brain. But gold-standard treatments like exposure therapy and cognitive behavioral therapy tend to only address associative responses.

To better address trauma-related disorders like post-traumatic stress disorder or PTSD, which impacts 8% of U.S. adults, many believe both circuits must be targeted, said Baratta.