American scientists have found that functional relationships between the hippocampus and other brain areas can predict subjective stress levels when exposed to an external stimulus. For this, they showed 60 volunteers neutral and emotionally repulsive image and watched their reaction. It turned out that less emotional response to a stimulus requires communication between the hippocampus and prefrontal cortex, which is responsible for emotional regulation and a more emotional response can be predicted for communication between the hippocampus and the hypothalamus, which is responsible for the physiological manifestation of stress. The role of the hippocampus in the regulation of subjective stress, apparently, a key, write the scientists in Nature Communications.
Subjective stress and the stress response of the organism to an external stimulus-a stressor is called one word, and even ascribe to them the same value. And indeed, psychological stress, and physiological (that is, adaptive reaction of the organism) are quite similar: both stress objectively (that is, release of steroid hormones) appear due to the activity of the pathconnecting the hypothalamus, pituitary and adrenal glands.
The subjective stress do not always correlate with the release of hormones, classically involved in the regulation of the stress response: often this stress is a kind of subjective “tension”, something close to emotions and affect. It is therefore considered that the formation and manifestation of subjective stress the important role played by some additional structure of the brain. Most often, this being considered the hippocampus, which, on the one hand, can regulate the hypothalamus (and then the release of hormones), and with another — is responsible for working memory (and could, therefore, help to either memorize the stressor and strengthen the response or quickly get rid of it).
To clarify the role of the hippocampus in the formation of subjective experience of stress is decided by scientists under the leadership of Elizabeth Goldfarb (Goldfarb Elizabeth) from the Medical school of Yale University. They conducted an fMRI experiment involving 60 volunteers: each of them showed either causing stress images (emotionally negative, such as crime, vicious dogs and decaying food) or neutral (for example, reading in the Park, man.) After each image, participants were asked to subjectively evaluate the stress they felt, as well as their own emotional excitability on two nine-point scales. Simultaneously, the researchers monitored the functional relationships between the area of interest — the hippocampus — and other active parts of the brain involved in processing stressors. Also participants were asked to fill out a questionnaire to determine the level of chronic stress.
Used in the experiment, the stressor was effective: participants reported increased subjective stress and emotional excitability (p < 0.001) after viewing pictures of stressors compared to neutral pictures. In this evaluation the participants did not influence the level of chronic stress.
The researchers then tracked how the hippocampus is functionally linked with other sites during exposure to stressful and neutral stimuli. In particular, they also decided to see if the activity of the hippocampus during exposure to the stressor predict the subsequent response to it, the subjective rating that the participants gave during the experiment.
Scientists were able to identify two functional systems, predicting the response to the stressor. The first, positive, was responsible for increased response to stress, and included a joint activity of the hippocampus, hypothalamus and parahippocampal gyrus and inferior temporal gyrus, involved in processing visual information. In contrast, a negative system, which predicted a more peaceful response to the stressor included a joint activity of the hippocampus and dorsolateral parts of the prefrontal cortex, which is responsible for emotional regulation, as well as the cerebellum and the postcentral gyrus.
The authors thus were able to show that functional relationships between the hippocampus and other brain areas can predict how people will react to the impact of the stressor. Interestingly, in fact, and in another case there was activity in the hippocampus, which suggests that its role in the regulation of subjective stress, apparently, a key.
Constant feeling of stress (even subjective) can develop into chronic stress: this condition, in turn, negatively affects the health, and not always in an obvious way. For example, recently, scientists foundthat chronic stress can alter microRNA sperm of mice and men, which their offspring then there are changes in the nervous system and stress response.