A new study at Yale University has identified specific brain mechanisms behind our feelings of stress.
The new findings, published in the journal Nature Communications, may help people dealing with the debilitating sense of fear and anxiety that stress can evoke.
For the study, the research team scanned participants’ brains while exposing them to highly stressful and troubling images, such as a growling dog, mutilated faces or filthy toilets. The results reveal a network of neural connections emanating throughout the brain from the hippocampus, an area of the brain that helps regulate motivation, emotion and memory.
The brain networks that support the physiological response to stress have been well studied in animals. Research has shown that the activation of brain areas such as the hypothalamus triggers the production of steroid hormones called glucocorticoids in the face of stress and threats. But the source of the subjective experience of stress experienced by people during the COVID-19 pandemic, for example, has been more difficult to figure out.
“We can’t ask rats how they are feeling,” said Dr. Elizabeth Goldfarb, associate research scientist at the Yale Stress Center and lead author of the study.
Goldfarb and her co-authors, including senior author Dr. Rajita Sinha, the Foundations Fund Professor of Psychiatry, conducted a series of functional magnetic resonance imaging (fMRI) scans of participants who were asked to rate their stress levels when presented with troubling images.
The results show that neural connections emanating from the hippocampus when the participants were viewing these images reached not only areas of the brain associated with physiological stress responses, but also the dorsal lateral frontal cortex, an area of the brain involved in higher cognitive functions and the regulation of emotions.
The research team also discovered that when the neural connections between the hippocampus and frontal cortex were stronger, the participants reported feeling less stressed by the troubling images.
On the other hand, the subjects reported feeling more stressed when the neural network between the hippocampus and hypothalamus was more active.
The authors note there is also evidence from other studies that those struggling with mental health disorders such as anxiety may have a difficult time receiving calming feedback from the frontal cortex in times of stress.
“These findings may help us tailor therapeutic intervention to multiple targets, such as increasing the strength of the connections from the hippocampus to the frontal cortex or decreasing the signaling to the physiological stress centers,” said Sinha, who is also a professor in Yale’s Child Study Center and neuroscience department.
All of the study participants were healthy, she said, and in some cases their responses during the experiment seemed to be adaptive; in other words, the network connections with the frontal cortex became stronger as the subjects were exposed to the stressful images. Sinha and Goldfarb speculated that these individuals might be accessing memories that help moderate their response to stressful images.
“Similar to recent findings that remembering positive experiences can lower the body’s stress response, our work suggests that memory-related brain networks can be harnessed to create a more resilient emotional response to stress,” Goldfarb said.
Source: Yale University