Neuroscientists at the University of Pittsburgh have identified the neural networks that connect the cerebral cortex to the adrenal medulla, which is responsible for the body’s rapid response in stressful situations. These findings, reported in the online Early Edition of the journal Proceedings of the National Academy of Sciences (PNAS), provide evidence for the neural basis of a mind-body connection.
We all accept that stress is terrible for us, and that when our mental health suffers, the rest of our health follows suit. And yet the branch of medicine that’s devoted to this integral relationship—psychosomatic medicine—is often written off as pseudoscience.
This study is the first to map the elusive networks that connect an internal organ all the way to the brain. The researchers say the adrenal gland (specifically, the region therein known as the adrenal medulla, which is central to the fight-or-flight reaction), is the first of many internal organs that they plan to trace, a prospect that offers hope for broadening our understanding of how the brain influences the rest of the body.
This study may help explain why meditation and certain exercises such as yoga and Pilates can be so helpful in modulating the body’s responses to physical, mental and emotional stress.
The research team found brain regions, hard-wired directly to the adrenal medulla, involved in core-muscle movement—a finding that offers a possible explanation for why activities that focus on engaging these muscles, like yoga and Pilates, are said to be such stress relievers.
“This observation,” said Dr. Strick, “raises the possibility that activity in these cortical areas when you re-imagine an error, or beat yourself up over a mistake, or think about a traumatic event, results in descending signals that influence the adrenal medulla in just the same way as the actual event.”
The research team also found circuits to brain regions involved in certain mood disorders. This new stress-and-depression connectome also includes a brain region that lights up in mindful meditation, adding to a list of findings that show the ancient practice actually does influence the brain. “Those things have worked for people for thousands of years,” Levinthal says. “I think we just need to be open to the fact that, if done the right way, mind-body interventions could be just as valuable as everything else we do.”
“One way of summarizing our results is to say that we may have uncovered the connection between stress and depression,” says Dr. Strick.
Overall, these results indicate that circuits exist to link movement, cognition and affect to the function of the adrenal medulla and the control of stress. This circuitry may mediate the effects of internal states like chronic stress and depression on organ function and, thus, provide a concrete neural substrate for some psychosomatic illness.