Home News The mystery of hallucinations

The mystery of hallucinations

These visual or auditory mirages reflect the constant activity of our mind, which sometimes loses connection with reality.


The most silent place in the world, according to The Guinness Book of Records, is in Minnesota (USA). Designed by Orfield Laboratories, the steel and fiberglass walls of this anechoic chamber absorb 99.99% of the noise. A sensory void that can become unbearable: nobody is able to endure it for more than 45 minutes without becoming tarumba. In fact, after around twenty, most of the people who remain there begin to hear strange things.

One of the theories to explain it is that your mind misinterprets the murmur of blood that passes through your ears. As the neurologist and writer Oliver Sacks affirmed in 2014, a year before he died, the brain cannot bear to be inactive and invents parallel realities, “autonomous sensations of his harvest”. It also happens to truckers or pilots, victims of monotony.

Usually associated with mental disorders or drug use, hallucinations are, however, a fairly frequent phenomenon. “Almost everyone has ever experienced a pseudo perception: we think they have called us when we are waiting for them to do so, for example. And children see monsters or have imaginary friends, because it takes us a while to differentiate between internal and consensual reality, shared by society. There is a learning of distinction in which culture is very important, the exchange, “says Dr. Luis de Rivera, director of the Institute of Psychotherapy and Psychosomatic Research in Madrid.

The brain invents it

Situations of stress, lack of sleep, falls in blood sugar levels and, as we have already pointed out, sensory deprivation can make us hallucinate. A case in point is the Charles Bonnet syndrome, which is experienced by 10% of people with eye diseases and visual loss. Those affected see colored patterns, people or animals that do not exist. Although in this case we should talk about pseudo-hallucinations, because the patient is aware that the mirages have been manufactured by his mind.

The Charles Bonnet syndrome confirms the idea that our gray mass never fails to entangle, and that, when it receives no external stimuli, it fills the gaps on its own. An experiment conducted by researchers at the universities of Cardiff and Cambridge in 2015 showed that people with psychotic tendencies were better at giving a concrete interpretation to ambiguous images in black and white. The result suggests that their minds would be more predisposed to create images from the scarce data that comes from outside. An excess of heat that could lead to hallucinations.

Anyway, it is not too much what science knows today about the neuronal mechanisms that trigger this phenomenon. In the first place, because it is difficult to study it just when someone is living it. The experts have confirmed that the sensation of reality arises because the same neural zones are activated when we contemplate or hear something of the objective world. Already in 1998, researchers from King’s College London observed that those who claimed to see faces were fused to the fusiform gyrus, the part of the brain specialized in identifying them.

Neuronal short circuit

The problem arises when the connection between the sensory cortex and other brain areas is interrupted or deteriorated, such as the prefrontal cortex -the center of thought and decisions- or the hippocampus -the center of operations of memory-, responsible for discerning the inner reality of the outside. In this sense, the study conducted by the team of the British neuroscientist Sarah-Jayne Blakemore, who set out to find out why we cannot tickle ourselves, is enlightening. Among its conclusions, there was one that drew attention: some psychotic patients were able to provoke them, because they did not detect that it was an internal experience, self-induced.

Such derailments of the mind are common symptoms of serious psychic ailments, especially of schizophrenia, as their victims hear critical or vexatious voices for themselves. They can also suffer auditory hallucinations depressed or those affected by a bipolar disorder, consistent with their mood, recalls Rivera’s doctor.

If it is not your case, but you have suffered a hallucinatory episode, you can take it with philosophy, as did Sacks, who experienced them at the end of his life, when he began to lose his sight. “I like to see what my brain is capable of,” he joked.


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