Where The Stress Lies


It’s a normal human experience to feel “stressed out.”. Sometimes, it allows us to do incredible things, just like how stress can spur you to run the final mile of a marathon or earn that promotion at work. However, if you don’t manage your stress and let it persist for a long time, it could potentially harm your job, family, and health. According to a source, more than 50% of Americans claim that stress is a factor in their arguments with friends and family, and more than 70% claim that stress causes physical and psychological symptoms.

Although stress has been extensively investigated, what brain processes underlie this personal experience is still unknown. We now understand that excessive subjective stress has detrimental short- and long-term repercussions on both physical and mental health and acute negative effects on cognition. The purpose of emotion regulation and mindfulness-based stress reduction is to increase awareness of feelings. However, expressing stress-related emotions can also be adaptive. Therefore, it is important to comprehend how sensations of stress develop and the brain networks that underlie this fundamental aspect of human experience.

A study from Yale University used functional magnetic resonance imaging (fMRI) to examine if changes in hippocampal connectivity as a result of a brief, sustained stressor may predict the experience of stress. Their goal was to identify the unknown mechanism where our stress lies.

The Neural Home of Stress Feelings

Although research on physiological stress responses in several species has clarified neurobiological mechanisms, such as activation of the hypothalamic-pituitary-adrenal axis resulting in glucocorticoid release, subjective sensations of stress frequently deviate from glucocorticoid responses. We cannot thus assume that the same mechanisms driving physiological stress also govern the experience of stress. According to accumulating research, the hippocampus, which is known to suppress the hypothalamus and decrease glucocorticoid release, may also be involved in the sensation of stress.

Across all animals, the hippocampus is vulnerable to stressor exposure. The hippocampus is essential for anxiety behavior in mice, but it is connected with stress in daily life, emotion dysregulation, cardiovascular stress reactivity, and susceptibility to perceived stress in humans. By enabling memory retrieval, which can either increase or decrease acute stress responses, the hippocampus system may cognitively contribute to the subjective sensation of stress.

However, the effects of functional hippocampal connection on subjective stress are yet unclear. The study’s participants, published in the journal Nature Communications, were asked to rate how stressed they felt when shown images of a growling dog, severed heads, or filthy toilets. To measure this, the researchers used functional magnetic resonance imaging (fMRI) on the participants.

The study shows that when seeing these images, neuronal connections from the hippocampus reached not only regions of the brain linked to physiological stress reactions but also the dorsal lateral frontal cortex, a region of the brain engaged in higher cognitive tasks and emotion control. The Yale researchers discovered that individuals reported feeling less worried by the distressing images when brain connections between the hippocampus and frontal cortex were stronger.

On the other hand, when the neural network between the hippocampus and hypothalamus was more active, individuals said they felt more stressed.

The authors point out that there is evidence from past studies suggesting that people with mental health conditions like anxiety may find it challenging to receive soothing feedback from the frontal cortex during stressful situations.

The study showed that hippocampal connection under stress predicts stress-related feelings. With the aid of sCPM, functional connectivity networks that predict behavior relevant to clinical settings can be found. The discovered networks shed light on the neurobiological mechanisms underlying this crucial subjective stress response component, with potential consequences for mental health and psychopathology.

Furthermore, the researchers asserted that their findings might make it possible to customize the therapeutic intervention to various objectives, such as enhancing the connections between the hippocampus and the frontal cortex or reducing transmission to the body’s stress centers.

Journal Reference

Goldfarb, E. V., Rosenberg, M. D., Seo, D., Constable, R. T., & Sinha, R. (2020). Hippocampal seed connectome-based modeling predicts the feeling of stress. Nature Communications, 11(1). https://doi.org/10.1038/s41467-020-16492-2 

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