Is it true that people only use 10% of their brain?

No, the claim that humans only use 10% of their brains is a myth that has been thoroughly debunked by modern neuroscience. Here’s why:

Evidence Against the Myth

1. ·Whole-Brain Activity: Neuroimaging tools like fMRI, PET, and EEG show that even simple tasks engage most brain regions simultaneously. The brain is never idle; it remains active even during sleep.[1][2][4][5][7]
2. ·Energy Consumption: The brain consumes approximately 20% of the body’s energy despite comprising only ~2% of body mass. This high energy demand would be unnecessary if 90% of the brain were unused.[1][2][4][5]
3. ·Brain Damage: Damage to any small area of the brain often results in significant functional deficits, indicating that every region contributes to cognition or behavior.[6][7]
4. ·Neuronal Activity: Most neurons fire frequently, with some firing hundreds of times per second. Only a tiny fraction are truly silent, showing that the brain continuously processes information.[5][9][13]

Origins of the Myth

The myth likely originated from a misinterpretation of a 1908 statement by psychologist William James, who wrote that humans use only a small part of their potential mental and physical resources. It was later popularized by self-help literature and movies like Lucy and Limitless.[1][3][5][7]

Bottom Line

All major brain regions are active during waking life, sleep, and even at rest. Damage to any part of the brain can impair function, disproving the idea of a large unused reserve. Humans use essentially all of their brain—not just 10%—evidence shows.