Modern science has a thorough understanding of the human body’s physiological reaction to stress. Something happens that puts us on edge and our bodies start producing certain steroid hormones, such as cortisone, in response.
What isn’t nearly as studied or understood, though, is where the actual subjective feeling of stress comes from. You know what it’s like; uneasiness, the sensation of being overwhelmed, constant worry, etc. It doesn’t take an MD to guess that stress originates in the brain, but the finer neuronal machinations behind stressful feelings have remained very much a mystery – until now.
Researchers from Yale University believe they’ve located the “neuronal home” of stressful feelings in the brain. They’re optimistic that this discovery can lead to more stress treatment options for people in need of help with intense anxiety, stress, and fear.
A group of participants was shown a series of particularly upsetting or stressful images (a really dirty bathroom, a snarling dog, and mutilated faces). A series of fMRI brain scans while all that was happening revealed a network of neural connections spreading all over their brains originating from the hippocampus.
Additionally, the study subjects were asked to describe how stressed the images were making them feel. This was an important aspect of the study; there have been plenty of research projects focusing on stress and subsequent physiological reactions, but most were conducted with animals.
“We can’t ask rats how they are feeling,” notes lead study author Elizabeth Goldfarb, an associate research scientist at the Yale Stress Center.
Now, it’s been established for quite some time that the hypothalamus is responsible for the body’s aforementioned physiological response to stress (production of steroid hormones), but the observed neural connections stemming from the hippocampus among participants weren’t traveling to only the hypothalamus. These connections also went to the dorsal lateral frontal cortex, a brain region responsible for the regulation of emotions and higher cognitive functioning.
Here’s where things get even more interesting. Participants reported feeling less stressed when neural connections between the hippocampus and frontal cortex were at their strongest, and most stressed when neural connections between the hippocampus and hypothalamus were more active.
So, what does all this indicate? Stress originates in the hippocampus, where it is then spread throughout the brain. People who have a harder time dealing with and containing their stress appear to have stronger neural connections between their hippocampus and hypothalamus, while those who are better able to cope with their stress may have a stronger neural network between the hippocampus and frontal cortex.
Backing up these findings is prior research that had found people suffering from severe bouts of anxiety tend to have a hard time receiving calming neurons from the frontal cortex during stressful moments.
“These findings may help us tailor a 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,” comments senior author Rajita Sinha, the Foundations Fund Professor of Psychiatry, in a university release.
Professor Sinha also mentioned that many patients were able to calm down a bit after looking at the images for some time. In these cases, brain scans revealed that neural connections to the frontal cortex had slowly become stronger as the individuals looked at the upsetting pictures. It’s only speculation, but the study’s authors theorize that a strong link to the frontal cortex allows one to more easily access comforting memories and images to combat external stressors (the upsetting 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 concludes.
The full study can be found here, published in Nature Communications.