Et eksempel som citeres vidt og bredt er eksemplet med taxachaufførerne i London. Gamle taxachauffører har et markant forstørret hjernemodul end gennemsnithjernen i det område i højre hjernehalvdel som vi bruger til stedgenkendelse og geografisk orientering.
The term brain fitness reflects a hypothesis that cognitive abilities can be maintained or improved by exercising the brain, in analogy to the way physical fitness is improved by exercising the body. Although there is strong evidence that aspects of brain structure remain plastic throughout life, and that high levels of mental activity are associated with reduced risks of age-related dementia, scientific support for the concept of "brain fitness" is limited. The term is virtually never used in the scientific literature, but is commonly used in the context of self-help books and commercial products. It first came into play in the 1980s, and appeared in the titles of self-help books in 1989 and 1990.
Når det med 'hjerne-fittness' interesserede mig, så var det fordi jeg må være stødt på begrebet - eller stødt på den bagvedliggende tænkning, teoretiseren og forskning i avisartikler allerede et stykke tid før jeg begyndt på bloggen her - marts 2010.
Og også før jeg begyndte at genoptage min ungdoms interesse for at male og tegne - men nu med et ret ensporet fokus på akvarelmaleriets udfordringer og 'mysterier'.
Jeg er mig nogenlunde bevidst at jeg i efteråret 2009 var begyndt at tænke på at holde op med at undervise på universitetet (seriøs forskning opgave jeg allerede da jeg forlod journalistikuddannelsen på SDU i 2004). Og jeg var også begyndt at tænke på at holde op med at påtage mig større eller mindre konsulentopgaver, privat kursusundervisning, m.v.
Og jeg syntes at alt pegede i retning af - at hvis jeg holdt op med at foretage mig alt det der i mange år havde holdt mig mentalt i live, så ville min hjerne sløve hen og skrumpe ind - eller bare stivne når jeg havde hevet hele cirkusset ned med deadline omkring min 70-års fødselsdag (som var sidste år).
Brain fitness is the capacity of a person to meet the various cognitive demands of life. It is evident in an ability to assimilate information, comprehend relationships, and develop reasonable conclusions and plans. Brain fitness can be developed by formal education, being actively mentally engaged in life, continuing to learn, and exercises designed to challenge cognitive skills. Healthy lifestyle habits including mental stimulation, physical exercise, good nutrition, stress management, and sleep can improve brain fitness. On the other hand, chronic stress, anxiety, depression, aging, decreasing estrogen, excess oxytocin, and prolonged cortisol can decrease brain fitness as well as general health.[16 Brain fitness can be measured physically at the cellular level by neurogenesis, the creation of new neurons, and increased functional connections of synapses and dendrites between neurons. It can also be evaluated by behavioral performance as seen in cognitive reserve, improved memory, attention, concentration, executive functions, decision-making, mental flexibility, and other core capabilities.
Like physical fitness, brain fitness can be improved by various challenging activities such as practicing sports, playing chess or bridge, dancing regularly, practicing yoga and tai chi and also by engaging in more structured computer based workouts. Some research shows that brain stimulation can help prevent age-related cognitive decline, reverse behavioral assessment declines indementia and Alzheimer’s and can also improve normally functioning minds. In experiments, comparing some computer based brain boosting exercises to other computer based activities, brain exercises were found to improve attention and memory in people over age 60. Other studies have evaluated other brain boosting exercises and not found improvements. A study of 67 schoolchildren aged 10 compared 7 week Nintendo brain training to engaging in pen and paper puzzles. The study found that the brain training group suffered a 17 percent decrease in memory tests after the seven-week course, while the pen and paper group saw an increase of 33 percent. Some experts are skeptical with regard to the real value of particular commercial brain boosting products. For example, a panel of experts gathered by Which? Magazine have concluded that ‘Dr Kawashima’s Brain Training’ for the Nintendo DS will not enhance brainpower at all. However, other researchers underline the growing amount of studies indicating that some commercial brain training products have shown measurable results in improving various cognitive skills.
Not all brain activity exercises the brain in the same way.
Activities that require you to use all your senses, break your routines and engage in novel experiences which can create BDNFs(neurotrophins) as explained in the book Keep Your Brain Alive, Workman Publishing.
Activities that involve planning ahead, like chess, stimulate the Frontal lobe area of the brain. Activities like ballroom dance and basketball, train short range spatial skills, used when one walks through a short limited space, like the interior of a house.
Activities that combine intellectual and physical demands improve spatial and reasoning skills  Activities like learning a new language or painting require the coordinating of multiple regions of the brain.
Physical exercise promotes BDNF. Reading books, and writing Cognitive training games, such as Lumosity 
"The SharpBrains Guide to Brain Fitness: How to Optimize Brain Health and Performance at Any Age" - by Dr. Sandra Bond Chapman, Alvaro Fernandez, Dr. Elkhonon Goldberg and Dr. Pascale Michelon (4 Apr 2013)
Den bog har jeg nu bestilt. Så får vi se hvor meget hold seriøse forskere mener der er i begrebet.