“Blindsight” – the key to the work of consciousness?

In life, each of us has had to rely on intuition more than once. From time to time we make mistakes, but we continue to believe, and we explain our mistakes by bad luck, the evil eye, or the intervention of higher powers. Where do these premonitions come from? Who owns that inner voice that sends us signals? From a scientific point of view, all this is generated by our brain. But we cannot track many processes in the brain consciously. And yet they influence our decisions. This becomes especially noticeable when the work of the areas responsible for conscious activity suddenly fails. This is evidenced by the curious story of a TN patient.

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• Do you hear the signals of the unconscious?

In 2003, TN had a series of strokes in a row that disabled his primary visual cortex. This area is responsible for processing signals from the organs of vision and converting them into a whole meaningful image. The destruction of the visual cortex is tantamount to loss of vision – after all, in fact, we see not with our eyes, but with our brain. Standard tests showed that although the pupils of the TN reacted to light, and the retina was not damaged, it did not even recognize moving large objects directly in front of it. But his behavior was different from the behavior of people with eye damage. His eyes seemed to work independently of his brain, from time to time giving him only vague hints of them instead of images.

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• “Consciousness makes us believe that we are unique”

Neuroscientists have become interested in the TN case. They conducted an experiment: they invited him to walk along the corridor without a white cane and any insurance. Various obstacles were placed along his path to see if he would deliberately walk in such a way as not to stumble upon them. Their assumptions were confirmed: TN not only carefully avoided all obstacles, but at some point even moved to the opposite wall in order to go around the wastebasket. When asked why he chose this particular route, the patient replied that he did not choose it on purpose – he simply “went as he goes.”

TN showed all the signs of “blindsight”, or “false blindness”. This syndrome was first described by psychologist Lawrence Weiskrantz back in the 1970s. Together with his student, now famous psychologist Nicholas Humphrey, he studied monkeys that had damage to the primary visual cortex. Despite the fact that at first the monkeys looked blind, scientists managed to restore their ability to navigate in space for several years. As in the case of TN, the monkeys acted rather instinctively, obeying a kind of random insight. For example, when one of them was shown a favorite treat, the monkey did not react in any way. But as soon as he was placed next to her, she immediately stretched out her hand to him.

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• How does science explain consciousness?

People and animals with signs of blindsight clearly used some other way of processing information from their eyes. What we perceive simply as the ability to see is actually a complex system of encoding and recognizing visual stimuli. Its first step is in the retina, which converts light quanta into nerve impulses. They, in turn, enter the diencephalon – the thalamus. “Reports” of other sense organs are also collected there. The information is then passed on to the primary visual cortex for analysis, which picks out objects and familiar images. The analysis ends in the secondary cortex and association areas of the brain, which form a reaction to what is seen.

But at one stage there is a “leakage” of information. There is another intermediary between the retina and the visual cortex – the superior colliculus. This site is associated with reflex actions: in amphibians, reptiles, birds and fish, it plays a crucial role, allowing you to instantly respond to danger or the appearance of prey. The superior colliculus transmits information directly to the secondary visual cortex and association centers. As shown by recent research conducted by teams of neuroscientists at Maastricht and Nijmegen Universities (Netherlands), blind people use this bypass to evaluate the information that comes to it. But he can no longer “explain” to his consciousness how she got to him.¹.

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Subsequently, Nicholas Humphrey discovered that monkeys restored vision much more fully than humans. The alternative visual pathway obeyed them better than us. Humphrey suggested that this is due to the fact that they do not have the same developed idea of ​​uXNUMXbuXNUMXbtheir own self as we do. Therefore, they are not surprised that sometimes they can see and not see at the same time. “Unlike animals, we need to understand where information comes from,” explains Humphrey. – We are sure that our consciousness has a monopoly on all the information that comes to us from the outside world. That’s why we feel so uncomfortable if it suddenly comes out of nowhere.”

This discrepancy, and the anxiety associated with it, may also explain why blind patients tend to retroactively find “acceptable” explanations for their answers, which for some unknown reason turn out to be correct. The fact that our brain is able to process information (and, accordingly, draw conclusions) unconsciously has been known before. But now it is becoming more and more obvious how exactly this happens. If we try to present consciousness in the form of a metaphor, then it resembles a state that seeks to give its citizens a clear and positive agenda. To do this, it collects statistics and regularly reports in the news: everything is fine, milk yields are increasing, enemies are hindering us, but we can handle it. But citizens have their own sources of information, to which they also listen. And at the moment of weakness or confusion of the center, it is they who can tell people what to do.

¹ Frontiers of Human Neuroscience, online publication January 5, 2016.