Do we really use only 10 percent of our brains?

No. The claim that people use only 10 percent of their brains has been scientifically disproven. Imaging techniques such as functional MRI show that almost all areas of the brain are active even during simple activities or sleep. Erin Hecht, an evolutionary neuroscientist at Harvard, told Live Science that we are always using all of our brain. The idea has persisted for over a century despite advances in neuroscience. [1] [2] [3]

Barry Beyerstein, a neuroscientist at Simon Fraser University, points first to evolution. Brain tissue is expensive to grow and run, so it is implausible that natural selection would allow 90 percent of it to sit idle. Clinical neurology agrees: losing far less than 90 percent of the brain has catastrophic effects, and damage to almost any area leaves some functional deficit. [4]

Direct probing has found no dormant zones either. Electrical stimulation during neurosurgery has not uncovered areas that produce no sensation, emotion or movement. Scanning methods such as EEG, magnetoencephalography, PET and functional MRI have tied many functions to specific regions without revealing quiet areas. A BMJ review adds that single-neuron studies and metabolic studies show no gaps or inactive areas. One scientist quoted by Live Science also noted that the claim is vague, since it is unclear whether 10 percent would refer to volume, energy use, electrical activity or blood oxygenation. [4] [3] [2]

The exact origin is uncertain, despite considerable research. The most common attribution is to the psychologist William James. In a 1906 speech he said people make use of only a small part of their physical and mental resources, but the 10 percent figure has not been found in his writings. Beyerstein likewise found that James spoke of undeveloped potential, never of a specific amount of gray matter. In 1936 the writer Lowell Thomas, in the preface to Dale Carnegie's How to Win Friends and Influence People, attributed the claim to James, and self-help writers then let potential become brain. Whether James himself originated the statement remains uncertain. [5] [4] [2]

Other possible sources have been suggested. Early researchers used the term silent cortex for regions without a clear sensory or motor role, which could be misread as unused cortex. Researchers' candid admissions that they did not know what most of the brain did may have had a similar effect. Nature Neuroscience also mentions a possible early misreading of interneurons as undeveloped neurons held in reserve. The BMJ review says the myth was circulating by 1907, spread by self-improvement advocates. [5] [4] [3]

The claim is sometimes attributed to Albert Einstein. The Albert Einstein archives found no record of such a statement, and the BMJ review says none has ever been recorded. The myth's appeal is plain: the idea of a vast untapped reservoir suits those selling self-improvement. [4] [3] [5]

The University of Basel notes that the brain does have a kind of reserve capacity, though not in unused areas. It lies in neuroplasticity, the ability to adapt its microscopic structure and networks in response to experience, which is developed through continuous learning of complex skills. [1]