Neurobiology of stress and substance use

In a small biological psychology classroom at California State University, San Bernardino, Bryan Cruz became captivated by the inner workings and structures of human and animal brains. He envisioned himself making future contributions to neuroscience by drawing inspiration from a fellow Latino and professor.

“As the first generation to go to college in my family, for me, seeing a Latino mentor, especially of the same ethnicity was really meaningful,” Cruz said. “I really felt like … ‘Oh, hey, here's this Latino mentor who's doing science, something I'm interested in. Maybe I can do this too.’”

Courtesy of Bryan Cruz

Bryan Cruz, a postdoctoral fellow working on post-traumatic stress disorder and alcohol use disorder, sits at a microscopy station to take sample images in a lab at at the Scripps Research Institute.

“Having someone who has the same ethnic background, and the same interest that I had, helped me solidify that science was the thing I wanted to do,” he said.

Cruz completed an undergraduate summer research program at City College of New York, Hunter College, with a lab that investigates how stress disrupts memory. He obtained his Ph.D. in behavioral neuroscience at the University of Texas at El Paso, where his research focused on how diabetes can promote nicotine use.

Cruz then became a postdoctoral fellow in Marisa Roberto’s lab at the Scripps Research Institute. There, he studied addiction neuroscience in the context of post-traumatic stress disorder, or PTSD, and alcohol use disorder, or AUD.

“People with PTSD are more susceptible to taking drugs of abuse … and alcohol is more commonly abused (in these people),” Cruz said. “They're trying to alleviate some kind of emotional or physical pain with the alcohol, so the framework I have is trying to understand the mechanisms that drive those behaviors.”

Cruz focuses on the neurochemistry, or chemical processes and substances, of a brain region called the central amygdala. This area modulates stress, anxiety and addiction and is impaired by PTSD and AUD.

Cruz’s National Institutes of Health grant examines the role of the neuropeptide somatostatin in the central nervous system. Previous studies explored the role of somatostatin in the peripheral nervous system and its role in regulating food intake. However, Cruz found that somatostatin regulates alcohol consumption and helps reduce PTSD-related stress and anxiety in the brain. Related work was recently published in Nature’s Journal of Molecular Psychiatry.

Currently, he is exploring the role of somatostatin in PTSD and AUD, specifically in the extended amygdala. To dissect this neuropeptide’s role further, he and his team are applying a multidisciplinary approach and using multiple methods, such as ex vivo electrophysiology, imaging analysis, chemogenetics and site-specific behavioral pharmacology. With these techniques, they aim to examine the circuit and behavioral function of PTSD/AUD by systems involving somatostatin and a related stress-inducing neuropeptide.

Cruz earned a Maximizing Opportunities for Scientific and Academic Independent Careers, or MOSAIC, award in 2024.

In early 2026, Cruz will transition to an assistant professor position at the University of Tennessee Health Science Center in Memphis, Tennessee. There, he will continue to study somatostatin and PTSD/AUD. He will have a separate program on diabetes–alcohol–pain interactions. He said he ultimately hopes to mentor aspiring scientists and give back to his community.

“Seeing a diverse pool of faculty (at Scripps) that were just like me and have a really deep interest in human behavior was key,” Cruz said. “I really want to pay it forward and push (my students) to be successful in any career they pick.”