The brains of healthy people distinguish hallucinations from reality due to a special area in the prefrontal cortex that logically tests the perceived picture. This is stated in an article published in the Journal of Neuroscience.
“In principle, we were able to discover something similar to visual metacognition that helps to distinguish reality from fiction. Have we found a place where human consciousness is hiding? It includes and is generated by so many different processes that we cannot yet talk about it, said Dobrimir Ranev from the University of Georgia (USA).
In a world of crooked mirrors
For a long time, scientists believed that schizophrenia and many other mental disorders arise mainly for genetic reasons, due to the presence of a special combination of small mutations that cause serious disruptions in the functioning of nerve cells and lead to a deformation of the perception of reality.
On the other hand, recent observations of the mental health of large groups of people and experiments with schizophrenics have shown that often a person begins to see hallucinations and hear voices not only due to mutations, but also due to disturbances in the functioning of neuronal chains connecting different parts of the brain. and participating in the processing of information from the senses.
Ranev and his colleagues discovered one of the possible building blocks of consciousness by studying how these areas work and how they help distinguish reality from the fantasies of our nervous system.
One of these areas, as the authors of the article found out, is located between the upper and right parts of the prefrontal cortex (DLPFC) and its lower half (aPFC). Both regions of the cortex, according to scientists, are responsible for processing the image perceived by the eyes, but it was not yet clear what exactly they do.
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Neurophysiologists managed to find the answer to this question by observing the behavior of two dozen volunteers whose prefrontal cortex was irradiated with special magnetic pulses that either suppressed or stimulated the DLPFC and aPFC, as well as the connections between them.
Edge of reality
At the moment when this happened, the participants in the experiments looked at the monitor, where a set of thin black and white stripes was displayed, slightly turned to the left or right. The volunteers had to understand which way the lines were looking and press the corresponding button on the remote control, while the scientists monitored whether the brain irradiation changed the quality of the responses.
There were indeed changes in the work of the brain: when Ranev and his colleagues turned on the DLPFC, the accuracy of the volunteers' responses dropped, as did their confidence in their innocence. This, according to the researchers, indicates that this part of the cortex is involved in the primary processing of data and its stimulation generated a lot of "noise" in the perceived picture.
The suppression of aPFC's work led to more interesting consequences - the wards of neurophysiologists began to make more mistakes and more often see mirages instead of real lines, but at the same time their confidence in their actions and answers did not fall and they did not believe that they were seeing something that did not exist.
It turns out that this part of the cortex plays the role of a neurocensor - it analyzes the data coming from a neighbor, comparing them with what is already in the person's memory, and checking the level of attentiveness and arousal. This part of the cortex, as scientists explain, helps to look at the brain from the outside and check the correctness of its work using logic and alternative data sources.
Accordingly, stimulating this region of the brain can help many schizophrenics and other people with problems with perception of reality to return from the world of illusions and inaudible voices to normal life. Further study of it, as scientists themselves hope, will help to understand where human consciousness is hidden and how it works.