Will we ever be able to demonstrate the exchange of psychic energy between two people? Considerable progress has been made in understanding this mysterious brain, but is there any hope of being able to read someone’s mind one day? In other words, where is the research on telepathy?
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Communicating by thought is common among Professor Xavier’s X-Men. This psychic ability has always fascinated science fiction writers, but did you know that scientists have also taken an interest in the question? Hans Berger, a German psychiatrist of the early twentiethand century, was convinced that the telepathy was possible and wanted to discover its biological basis. In his quest, he developed a technique for recording the electrical signals of the entire brain human : electroencephalography. On the other hand, he never succeeded in demonstrating the existence of a energy psychic that would be exchanged between two humans…
What about today ? Since its invention, theEEG opened new Windows on the mysterious workings of the brain. But does this technique allow us to read minds? The answer is…not really; in any case, not like in science fiction movies! Neuroscientists are interested in cognition, that is, mental processes such as thoughts, reasoning, memory or the way we perceive the world. Recording cerebral activity makes it possible to understand certain mechanisms of cognition, but in a very framed and limited way.
To understand, we have to go back to what is measured by EEG: electrodes, placed on the head, capture the electric field created by hundreds of thousands of neurons at a time. The EEG signal thus recorded often shows fluctuations in activity. In 1924, Hans Berger was the first to observe that EEG activity could vary cyclically, increasing and then decreasing every 100 milliseconds. He called this phenomenon alpha oscillations. He notices that these oscillations are larger when the participants close their eyes, which suggests a link between these brain oscillations and human behavior (closing the eyes) and therefore potential mental processes (the processing of visual information for example) .
However, in the 1940s, alpha oscillations were seen more as markers of the brain when it is at rest, leading some researchers to believe that they do not really impact the birth of thoughts. The question of the scientists of the time thus becomes the following: do brain oscillations play a direct role in cognition?
Alpha waves: the key to reading minds?
As science progresses, 50 years of accumulating experimental evidence support the hypothesis that cerebral oscillations organize neuronal activity and determine some of our cognitive processes. Alpha oscillations are no longer considered a rhythm of the brain at rest but as a neuronal excitability marker : at constant frequency, the more the oscillations present a significant electrical activity, the less likely the neurons are to react.
This means that, when the EEG signal oscillates strongly every 100 ms, the neurons communicate more with each other and therefore transmit less information. This neurophysiological mechanism has consequences for the mind: alpha oscillations have an impact on many cognitive abilities such as the perception of auditory signals Where visuals or attention.
Imagine yourself peering into the center of your screen. From flashes very low intensity lights appear from time to time on the right side of the screen: you therefore focus your attention there to detect them. In this case, there is a decrease in alpha oscillations in the visual cortex which processes information from the right side of the visual field (figure below).
The neurons are therefore ready to react to what is happening there. On the contrary, the cortex which processes information from the left visual field is inhibited by an increase in alpha oscillations. You will not be disturbed by what is happening on the left side of the screen. This double phenomenon makes it easier to detect brief flashes. There is therefore a link between the signal measured by EEG, and the oscillations that can be detected there, and our thoughts and sensory perceptions.
As we have just seen, neuroscientists are able to extract from an EEG recording information about the attentional state of a person and whatshe perceives. However, this information is not visible to the naked eye, and the EEG signal must go through several stages of analysis to be interpretable. It is first necessary to clean the signal by removing in particular the electrical noise created by the movements of the person, the beating of the heart, and the surrounding machinery. Different signal processing techniques are then applied to isolate the alpha oscillations from the rest of the signal, for example.
What are we really measuring with an EEG?
More importantly, one cannot extract the contents of thought of a person thanks to a single sample of EEG recordings: it takes several repetitions. The content of an EEG signal is very rich and potentially reflects everything that is going on in a person’s head at the time of its recording: his involvement in an attentional task for example, but also thoughts parasites on his meal evening, on the feeling of the EEG cap on his head, or on the boredom that is beginning to dawn…
The trick used by neuroscientists is to repeat many times (usually hundreds!) the task to be performed: for an hour, the participant in a research experiment must, for example, detect weak flashes of light presented on a screen. The scientist will then average the signal obtained for all these repetitions in the hope of identifying the common process that should be the one at work in the task. We are therefore still far from reading thoughts from a single EEG recording of a few minutes…
Each experiment conducted in cognitive neuroscience is very framed and aims to answer a specific question. The information that we get from it will necessarily be very specific. In the previous example, we can only predict thanks to the EEG signal if the person will perceive a flash or not. But we will not deduce anything about his evening meal or any other thoughts that have crossed him… Often, only a small part of the cerebral signal that we record explains the behavior that we are studying.
The results of a single study are also not easily transferable to daily life: we rarely spend hours detecting flashes on screens, but we will have to pay attention to the fire turning red, while keeping an eye on the rearview mirror and pedestrians on the sidewalk. Multiple processes will therefore interact and participate in the wealth of brain activity that neuroscientists are trying to decode. The EEG is a powerful tool to achieve these ends, but it will not retire the Cerebro machine anytime soon.
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