Scientists have traced the neural pathway of fainting spells
Last reviewed: 07.06.2024
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The brain and the heart are connected by a kind of neural connection that takes part in shutting down consciousness.
Fainting is a fairly common condition that every second person in the world has experienced at least once. It is a short loss of consciousness, after which a person can wake up on his own. It is believed that the immediate cause of such a phenomenon is a sudden deficit in cerebral circulation. This may be due to cardiovascular disorders, including arrhythmia or hypotension. However, there are also other causes - for example, a person may faint from hunger, from fear or anxiety, from the sight of blood, and so on. These conditions are caused by a similar mechanism of development: there is a malfunction in the heart, blood pressure decreases sharply, breathing "freezes".
Researchers representing the University of California San Diego and the Scripps Institute set out to determine if there is any neural connection between a person's overall health and their cardiac function.
Specialists studied the work of the vagus nerve, which has a large number of branches that lead to various systems and organs, as well as to the heart. Its neurons form ganglion bundles, one of which contains a cell group that produces the protein NPY2R. Scientists figured out the path of the NPY2R-producing cell bundles: they went to the heart ventricles and one of the brainstem, which controls the constancy of the chemical composition of the blood and the absence of toxins in it. Also this department interacts with the cardiovascular system, affects metabolic processes and eating behavior of a person.
The study was conducted on rodents, artificially stimulating their NPY2R-neurons. As a result, at the moment of stimulation the animals lost consciousness: their blood pressure dropped, breathing became rare, heart rate slowed down, that is, the symptoms of fainting did not differ from those in humans. When the transportation of signals along this neural pathway was artificially interrupted, the rodents stopped losing consciousness, or their fainting was incomplete and smoothed.
During the experiment, the scientists recorded the activity of different nerve cells, which in general decreased significantly. But in one of the zones neurons continued to function: this happened in the hypothalamus cells.
Since the study was conducted on rodents, it is difficult to say how this pathway of fainting can be related to the psycho-emotional stresses typical of humans. Perhaps what is involved here is some kind of stress impulses acting on the cranial nerves. To provide answers to these questions, it is important that the work of scientists continues. This will make it possible to understand the work of consciousness as a whole, to trace its interaction with other physiological reactions in the body.
The material can be found at of the journal Nature