Summary: Researchers have identified a brain circuit that drives physical response to emotional stress. The circuit begins in the dorsal peduncular cortex and dorsal tenia tecta, before sending signals to the hypothalamus. The findings could help with the development of treatments for panic disorders and PTSD.
Source: Nagoya University
Researchers at Nagoya University have discovered a neural circuit that drives physical responses to emotional stress. The circuit begins in deep brain areas, called the dorsal peduncular cortex and the dorsal tenia tecta (DP/DTT), that send stress signals to the hypothalamus, a small region in the brain that controls the body’s vital functions. The findings were recently published in the journal Science.
Emotional stress activates the sympathetic nervous system, which leads to physical responses, such as a rise in blood pressure and body temperature, and a faster heart rate. Such responses are thought to be coping mechanisms in humans and many other mammals to boost physical performance in fight-or-flight situations. But nowadays, when most people rarely encounter such situations, these responses could perhaps have an adverse effect on their health. Excessive stress may cause symptoms such as psychogenic fever, a condition of abnormally high body temperature.
To develop strategies for treating stress-induced symptoms, the neural mechanism underlying physical responses to stress had first to be understood. To this end, a research team led by Professor Kazuhiro Nakamura and Designated Assistant Professor Naoya Kataoka, of the Nagoya University Graduate School of Medicine, conducted a study in which tracers were injected into the brains of a group of rats and the rats were subjected to a stressful event (rat bullying by a dominant rat).
The tracers showed that specifically the DP/DTT brain areas were highly active when exposed to stress. To further examine the role these brain areas have in stress response, the researchers impaired the areas’ connections to the hypothalamus and again exposed the rats to the same stress. Now the rats did not exhibit any stress-induced physical response, neither a rise in blood pressure nor body temperature, nor a faster heart rate.
This study demonstrates that the DP/DTT areas together are responsible for sending stress signals to the hypothalamus, and thus that blocking the DP/DTT-to-hypothalamus circuit can result in a reduction of stress symptoms in rats.
Professor Nakamura sums up the research result like this: “The DP/DTT are parts of the brain that are involved in processing emotion and stress. The DP/DTT-to-hypothalamus pathway we discovered, therefore, represents a brain mechanism for a ‘mind-body connection,’ which can be a potential target for treating stress-related disorders such as panic disorder, post-traumatic stress disorder (PTSD), and psychogenic fever.”
About this neuroscience research article
Source: Nagoya University Media Contacts: Kazuhiro Nakamura – Nagoya University Image Source: The image is credited to Kazuhiro Nakamura.
A central master driver of psychosocial stress responses in the rat
The mechanism by which psychological stress elicits various physiological responses is unknown. We discovered a central master neural pathway in rats that drives autonomic and behavioral stress responses by connecting the corticolimbic stress circuits to the hypothalamus. Psychosocial stress signals from emotion-related forebrain regions activated a VGLUT1-positive glutamatergic pathway from the dorsal peduncular cortex and dorsal tenia tecta (DP/DTT), an unexplored prefrontal cortical area, to the dorsomedial hypothalamus (DMH), a hypothalamic autonomic center. Genetic ablation and optogenetics revealed that the DP/DTT→DMH pathway drives thermogenic, hyperthermic, and cardiovascular sympathetic responses to psychosocial stress without contributing to basal homeostasis. This pathway also mediates avoidance behavior from psychosocial stressors. Given the variety of stress responses driven by the DP/DTT→DMH pathway, the DP/DTT can be a potential target for treating psychosomatic disorders.