A new brain connection discovered by researchers at the University of California, Irvine, explains how early-life stress and adversity disrupt the operation of the brain’s reward circuit, providing a new therapeutic target for treating mental illness. This circuit’s dysfunction is thought to be at the root of several significant disorders, including depression, substance abuse, and excessive risk-taking.
Brief Overview
In a recent article published online in Nature Communications, Dr. Tallie Z. Baram, lead scientist and UCI Donald Bren Professor and Renowned Professor in the Departments of Anatomy & Neurobiology, Pediatrics, Neurology, and Physiology & Biophysics, and Matt Birnie, lead author, and research fellow, describe the cellular changes in the brain’s circuitry caused by childhood adversity.
Baram mentioned, “We are aware that childhood stress affects the brain, but we didn’t know how until now,” said Baram. “Our group focused on discovering plausibly stress-sensitive brain pathways. We discovered an entirely novel pathway within the reward circuit that conveys a corticotropin-releasing hormone molecule that regulates our stress responses. We found that negative experiences cause this central nervous system pathway can become overactive.”
“In humans, such behavioral changes, known as “anhedonia,” are linked to emotional disorders. Importantly, we discovered that using modern technology to silence this pathway restores the brain’s normal reward behaviors.”
End Note
Researchers tracked back all CRH-expressing connections to the nucleus accumbens, the brain’s pleasure and motivation hub, and discovered a previously unknown projection originating from the basolateral amygdala.
Along with CRH, projection fibers expressed gamma-aminobutyric acid. They discovered that stimulating this new pathway suppresses several reward behaviors in male mice.
