Response from Michael R. Kreutz, head of the Neuroplasticity Research Group at the Leibniz Institute for Neurobiology in Magdeburg: From a scientific point of view, there is no reason to believe that we only use a fraction of our brain's resources. Such claims suggest that we could greatly improve our cognitive performance or achieve higher states of consciousness if we only used our full potential. This is usually based on ideology or, at the very least, marketing. Scientology, for example, propagates the so-called ten percent myth and claims that its teachings can activate the unused part of the brain. Popular self-help literature also repeatedly refers to percentages of brain capacity utilization. Such statements are not credible. It remains unclear what exactly is meant by the term “brain capacity.”

In order to make scientific statements about brain usage, one must refer to a specific cognitive performance, for example. One could, for example, examine how well a person's Episodic memory functions. It is responsible for personal memories and is severely affected in dementia. In order to quantify performance in percentages, one would first have to define a standard value for normal Memory performance. People with particular illnesses would then deviate significantly from this.

A healthy brain that is up to 90 percent unused, on the other hand, is a myth. After all, 25 percent of our total energy budget goes to the brain. Keeping it running is therefore expensive for the human body. Evolution would not produce a brain that is so inefficient. But it is true that when we take on mental challenges and learn something new, we train our brains. Individual cognitive limits have to do with the connections between nerve cells, known as connectivity. Over time, every person reaches a certain optimum for their brain in this regard, at which point the synapses have stabilized. Because cognitive performance has to do with how we use our brain, there is still room for improvement.

However, if a person is healthy and uses their brain normally, I doubt that they can improve their performance significantly. In my opinion, improving brain performance through medication or special training only becomes relevant when disorders or diseases such as dementia occur. This is where the so-called brain reserve comes into play: figuratively speaking, it is the capital available to the brain with which it can cover unavoidable expenses. Thanks to its plasticity, the brain can compensate for losses and damage to a certain extent by creating new synaptic connections. Brain stimulation is a promising area of dementia research. It involves using magnetic fields or implanted electrodes to activate certain areas of the brain and thus help the brain reserve get started.

Recorded by Natalie Steinmann