Serious thinking poisons your mind

A new study finds that mentally hard work is stressful because it leads to a buildup of toxic byproducts in the brain.

Chess players have to deal with it and you probably have to deal with it after a long day at work: mental exhaustion. You’d rather fall on the couch and not think about anything. It now appears that this phenomenon can also be explained physiologically. Scientists from the Brain Institute in Paris and the Sorbonne universities led by Matthias Besiglione, Discover Thinking long and hard will poison your mind a little.

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sorting letters

For a long time, neuroscientists have believed that mental fatigue is an illusion that your brain creates simply because it wants to do more enjoyable things. But the current researchers wanted to know if there was a physiological cause. They suspected that fatigue comes from processing toxic byproducts of brain activity.

The hypothesis was tested in 40 volunteers. These people were divided into two groups. One group had to do hard mental work for more than 6 hours. This work consists of sorting characters on the screen into vowels / consonants or uppercase / lowercase letters, depending on the color. The other group had to do the same but were given more time and the color change was slower.

accumulation of toxins

During the ‘working day’ the participants underwent brain scanning technology at regular intervals Magnetic resonance spectroscopy (MRS) is called. Using MRS, certain substances can be mapped into the brain. For example, Bisiglione and colleagues saw that the concentration of the chemical glutamate in the brain rose faster in serious thinkers than in less difficult thinkers.

glutamate It is a neurotransmitter necessary for proper communication between brain cells. But too much of it acts as a poison, slowing down your brain. So it needs to be cleaned quickly before it builds up.

glutamate cleanse

The research team now thinks mental fatigue is a kind of signal from your brain: “I’m going to cut it, because I have to get rid of toxic glutamate first.” Serious thinkers were clearly more fatigued at the end of the “workday” than the higher levels of fatigue they reported. The researchers also noticed more signs of fatigue in this group, such as decreased pupil dilation.

After the work day, participants were also allowed to choose from various rewards. This showed that serious thinkers chose a quick and easy reward (such as transferring money to them) rather than a prize that had to wait longer and caused more uncertainty (such as a lottery).

According to Bisiglioni and his team, this indicates that serious thinking has not only a physiological cause (the recycling of a potentially toxic substance) but also influences decision-making. The latter makes perfect sense; You have to sit for a while to get rid of the glutamate buildup.

Refreshing experience

“It is refreshing to see these researchers attempt to determine their association with measurable data from the brain: brain activation with fMRI and the amount of glutamate with MRS, “explains cognitive neuroscientist Fren Smulders (Maastricht University). Moreover, their theoretical model seems to be put together quite well. The results of pupil measurements also support their arguments well.”

He says there is a “but”. “As the authors of the publication themselves point out, it is difficult to draw strong conclusions about causation. So: is glutamate build-up the real cause of fatigue, or is it a consequence of it? Is it perhaps an attempt by the brain to compensate for fatigue? That would be an entirely different explanation, with the same data “.

feet up

Therefore, more research is needed to find conclusive evidence that too much of the neurotransmitter makes you fatigued. Bisiglione hopes that in the future it will indeed be possible to stimulate the production of glutamate and other neurotransmitters. “The next step is really to directly manipulate glutamine,” Smulders says.

The knowledge can then also provide new insights into treating the burnout that hard workers sometimes experience. But for now, the old recipe after a heavy mental task is this: Lift those legs and rest.

Sources: current biologyAnd the Click on the cell through EurekAlert!