“The brain’s energy budget is fixed – this is why ‘perceptual blindness’ causes accidents’


A research group led by Prof. Nili Lavie of University College London has directly discovered the pathway in the brain that causes temporary perceptual blindness, during which important warning signals do not reach the brain even though the senses perceive them. In a conversation with the Yadan website, Prof. Lavie explains that this feature has implications for what the human factor is called in work and home road accidents, medical errors and more.

The eye and optic nerves in the cerebral cortex. Illustration: shutterstock

“The computational ability of the brain is constant, so if it is cluttered, attentional blindness is created where the eye sees but the brain does not process.” This emerges from a study published this week (August 3, 2020) in the Journal of Neuroscience. The study was led by Prof. Nili Lavie, an expert in neuroscience from University College London.

Limitations on perceptual ability cause various symptoms of perceptual blindness. In the study we propose a neurophysiological calculation, which attributes these perceptual abilities directly to the limitations of brain cell metabolism. We assumed that the total brain energy supply remained constant, “Regulating cellular metabolism levels according to task requirements. Increased perceptual load on the task (imposing greater demand on neural calculations) should therefore increase metabolism in the area where processing takes place, and reduce metabolism involved in processing in other areas of the brain. Processing is done unintentionally.” The researchers write in the article.

To test this, the researchers monitored levels of a substance involved in the metabolic process of neurons in the cerebral cortex – the area where visual processing takes place in participants of both sexes. The substance, cytochrome C oxidase (OxCCO) is an intracellular marker. Non-invasive – Broadband spectroscope in the near infrared. Participants performed a continuous continuous visual search task under high perceptual load (complex search for a combination of features) or low load (search for items whose features stand out). Irrelevant searches were shown to a random half of users. ”

It turns out that OxCCO levels in the visual cortex areas responded to stimuli when the task required a high load, compared to cases of low perceptual load, whereas OxCCO levels in the areas performing unattended processing were significantly reduced. “These findings suggest an attention-compensation mechanism that regulates metabolic levels according to processing requirements. Furthermore, they provide new evidence for the widespread assumption that overall brain metabolism levels remain constant regardless of load levels.”

In an interview with the Yadan website, Prof. Lavie explains: “We wanted to discover the source of the cognitive limitation and the feeling that our brain has a limited capacity for processing information.”

“Many studies to date have shown that our brain has limited capacity, and this is noticeable in cases of high load so we experience blindness or unintentional perceptual deafness. Our goal this time was to directly find the causes of these effects. To do this we used a method that isolates one of the enzymes. The main in the mitochondria of neurons participated in the chain of metabolism of oxygen in the cell.Our hypothesis was that the source of the limited capacity of processing capacity is the metabolic energy limit that the brain receives.Although the brain receives a large amount of about 20% of total body energy Ability to increase energy consumption when required for complex mental tasks. ”

“It follows that energy is a limited resource that the brain must do a trade-off of attention. If a task requires a higher computational ability, there is not enough capacity left for other tasks.
If something happens that is supposed to alert us and we do not notice it is not because we do not see it. The eye sees, but the brain cannot process this visual information because there is no energy left for the neurons to respond to the new information that is out of focus. ”

The first association I thought of in this context is forgetting children in general and in general the human factor in accidents. Is that what I mean?

The human factor in road accidents. Illustration: shutterstock
The human factor in road accidents. Illustration: shutterstock

Prof Lavie: “It explains why people do not see a car or motorcycle approaching them or a pedestrian about to cross the road, when their attention is turned to something else. It is real blindness. It is not enough to have eye stimulation – that is, our eye looks in the direction. To see the brain The image needs to be processed in the visual cortex but in order for the neurons there to respond they need to get energy, which was taken for another task.We showed this unplanned blindness in previous studies using fMRI.In the experiment this time we did not test the effect on memory, But one should not just rely on memory. To forget a child, one should also not hear them in the background. “Do not concentrate on them. It is also a statistical fact that the human factor is the biggest cause of road accidents rather than mechanical errors. The accidents are due to the driver’s lack of attention.”

How do you solve it?
“You should take care of driving priorities, and not try to look at the Wise screen, for example, if you are not sure exactly where to turn at a complex intersection. It is better to get to the wrong place (and fix it later) than not to get there at all.”
“And not just while driving. There have been cases where in complex surgery, surgeons who were busy with a particular task do not hear the warning signs, as in one case where rest was resolved because they did not realize she had a lack of oxygen in the brain, even though the alerts were conspicuous.”

If the human factor is the most dangerous perhaps it is better to switch to autonomous cars?

“Since 2010 I work with Toyota, as part of a company that develops artificial intelligence for cars. For the past five years I have been a member of Jaguar-Land Rover’s smart and connected technology group. We have made a lot of progress, but artificial intelligence still has a limit. There are many cases where artificial intelligence will not know how to drive. Because it did not encounter a similar situation while studying the machine, there were also accidents such as the famous Tesla accident in which the driver watched a Harry Potter movie, and did not pay attention to the warning signs that were activated when the car tried to transfer control to it. Unlimited graphics processors (GPUs) because of the weight, “explains Prof. Lavie.
(In a boxed article, this is why autonomous cars are able to get along mainly on interurban roads, or on specially designed urban roads that have been trained in mechanical learning and despite developments in the field of car computing, this barrier still prevents grade 5 autonomous cars, including vehicle and infrastructure communication And the other cars on the road – that is, autonomous cars in any situation.

We all need to be careful and avoid critical actions that require concentration when we are not focused, now we at least know why.

To the scientific paper

More on the subject on the Yadan website:


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