FactSentinel

The claim that humans only use 10% of their brain is a persistent myth with no scientific basis. Modern neuroimaging techniques, including functional MRI and PET scans, consistently demonstrate that virtually all parts of the brain show activity over the course of a day. Even during simple tasks, multiple brain regions activate simultaneously, and no large areas remain perpetually dormant. Brain scans of people at rest still show significant neural activity throughout the entire organ. Additionally, evolutionary biology argues against this myth—the brain consumes approximately 20% of the body's energy despite representing only 2% of body weight, making it highly unlikely that nature would maintain such a large, energy-intensive organ if 90% served no purpose.

The misconception likely originated from early neurological research that was misinterpreted or oversimplified. Some researchers in the early 1900s noted that only about 10% of brain cells are neurons, while the rest are glial cells, which were initially thought to serve only supportive functions. However, scientists now understand that glial cells play crucial roles in brain function, including supporting neuron health, modulating neural signals, and maintaining the blood-brain barrier.

Brain damage studies further disprove this myth. Injury to even small brain areas—far less than 90%—can result in profound impairments to speech, movement, memory, or personality, demonstrating that all brain regions serve important functions.