History
In the late 19th century Spain's Santiago Ramón y Cajal speculated that learning might strengthen connections between neurons, but until the mid-20th century the dominant view was that the adult brain is fixed. In his 1949 book The Organization of Behavior, Canada's Donald Hebb proposed that neurons active together strengthen their links, now summed up as "cells that fire together wire together." In 1973 Timothy Bliss and Terje Lømo found long-term potentiation (LTP) in the rabbit hippocampus, where repeated stimulation leaves signals lastingly stronger. David Hubel and Torsten Wiesel showed that covering one eye of a kitten remaps the visual cortex, winning a 1981 Nobel Prize.
The adult brain changes too
From the 1990s research showed adult brains keep changing. In 1998 Peter Eriksson's team reported new neurons forming in the adult hippocampus, and in 2000 Eleanor Maguire's MRI study found London cab drivers, who memorize a maze of streets, had larger posterior hippocampi than controls. Learning an instrument or juggling thickens the relevant cortex, and unused connections weaken. Dopamine reward signals and sleep help consolidate changes, while narrow drills such as working-memory training often improve mainly the task itself.
Rehab, learning and hype
Constraint-induced movement therapy after a stroke forces use of the weakened arm so surrounding brain areas take over lost functions, a direct use of plasticity. Ongoing exercise, learning and social life build "cognitive reserve" linked to lower dementia risk, and Carol Dweck's growth mindset teaching leans on the message that effort changes the brain. Yet in 2016 the US Federal Trade Commission fined Lumosity $2 million for claiming its games could stave off dementia. Plasticity is real, but claims that an app boosts general intelligence are weak.
FAQ
- Does neuroplasticity continue in old age?
- Yes, more slowly than in childhood but throughout life. Learning new skills, exercising regularly and sleeping well are the best-supported ways to support it.
- Do brain-training apps work?
- Your scores in the games improve, but evidence that everyday memory or general intelligence improves is weak. Real-world new challenges do more.
Sources reviewed: 2026-10-26
References
- Hebb, D. O. (1949). The Organization of Behavior: A Neuropsychological Theory. New York: Wiley.
- Maguire, E. A., et al. (2000). Navigation-related structural change in the hippocampi of taxi drivers. PNAS, 97(8), 4398–4403.
- Eriksson, P. S., et al. (1998). Neurogenesis in the adult human hippocampus. Nature Medicine, 4(11), 1313–1317.