Common Myths About How the Brain Works — and What Neuroscience Actually Says

This myth likely gained traction from misquoted psychology research and popular self-help culture. In reality, brain scans using functional MRI (fMRI) technology show activity distributed throughout the brain — not a vast silent reserve. While not every neuron fires simultaneously (which would cause a seizure), there is no dormant 90 percent waiting to be tapped. The brain consumes roughly 20 percent of the body's energy despite being only about 2 percent of its mass — an evolutionary cost that would be difficult to justify for an organ used so sparingly.

It's true that certain functions show some degree of lateralization — language processing, for example, tends to be more concentrated in the left hemisphere for most right-handed adults. But this is a far cry from the popular claim that individuals are dominated by one hemisphere in ways that define their personality or talents. A large-scale study analyzing brain scans of over 1,000 individuals found no evidence that people consistently have stronger networks on one side than the other. Creativity and logic both draw on widespread, bilateral brain networks.

Decades of research by cognitive psychologists, including landmark work on the misinformation effect, has established that human memory is not a faithful recording. When we recall an event, the brain reconstructs it using available cues, expectations, and information acquired afterward. This is why eyewitness testimony can be unreliable, and why people can develop confident memories of events that never occurred. Each act of remembering also slightly alters the memory itself — a process called reconsolidation.

The idea that every drink kills neurons is an oversimplification. What alcohol primarily affects at moderate levels are the dendrites — the branching extensions that neurons use to communicate. These can be impaired or pruned but are not outright destroyed. However, this does not make heavy or chronic alcohol use safe. Long-term excessive consumption is associated with conditions such as Wernicke-Korsakoff syndrome (related to thiamine deficiency), overall brain volume reduction, and impaired memory formation. The message is nuanced: moderate use and heavy chronic use carry very different neurological consequences.

While the most dramatic period of brain development does occur in childhood and adolescence — with the prefrontal cortex not fully maturing until the mid-twenties — this does not mean the adult brain is static. Neuroplasticity, the brain's capacity to reorganize itself by forming new connections, continues across the lifespan. Research has shown that learning new skills, physical exercise, and cognitively stimulating environments all support ongoing structural brain changes in adults. The hippocampus, a region central to memory, is one area where neurogenesis (the formation of new neurons) has been documented in adults, though the extent and significance of this remains an active area of research.