Fact check: How much of our brain do we actually use?
Text: Georg KellerDo we really use only 10 percent of our brain? Neuroscience shows that we use all of it. Its capacity to learn and adapt—known as neuroplasticity—is where its true potential lies, and physical activity can help.
The claim that people use only 10 percent of their brain has been scientifically disproven. Indeed, imaging techniques such as functional magnetic resonance imaging (fMRI) show that almost all areas of the brain are active even during simple activities or sleep. The myth emerged in the late 19th and early 20th century, with the psychologist William James writing in around 1908 that people use just a fraction of their mental and physical resources. Although he never specified a percentage, the 10-percent claim was later attributed to him.
Brain activity: Why coordination matters
In disorders of brain function, such as schizophrenia, the problem can stem from an excess of uncoordinated activity. One example is the “default mode network” — a network that is active especially while we are at rest and that, in healthy individuals, is downregulated during focused activities. In people with schizophrenia, the network often remains active, leading to an overlap between internal thought processes and external information processing. Likewise, acoustic hallucinations can be attributed to uncontrolled activity in the auditory cortex, which the brain wrongly interprets as external stimuli. Rather than a lack of activity, the problem here is a lack of coordination.
Neuroplasticity: How the brain learns and adapts
Nevertheless, our brain maintains some reserve capacity, although this doesn’t lie in unused areas of the brain but rather in neuroplasticity — that is, in the brain’s ability to adapt its microscopic structure and its networks in response to experiences. This potential is not unleashed by activating unused areas but rather through the continuous learning of complex skills.
How exercise supports learning and memory
One of the most effective ways of promoting this process is sport. Physical activity stimulates the production of key growth factors, and studies show that regular endurance training stimulates the formation of new nerve cells and increases the volume of specific areas of the brain. Even short, intensive periods of exertion immediately after learning help to consolidate what people have learned, allowing new cognitive or motor skills to be established faster and more robustly.
Georg Keller is a neurobiologist and research group leader at the Friedrich Miescher Institute for Biomedical Research. He researches how brain networks are affected by psychiatric treatments.
More articles in this issue of UNI NOVA (November 2026).