For much of the 20th century, science held that the human brain remained unchanging once it hit adulthood.

But in the early 1980s, neuroscientist Michael Merzenich, now a professor emeritus of neuroscience at the University of California San Francisco, showed through his research that the brain is plastic. In other words, the brain can alter itself depending on environmental input.

The real?life implications of this are several and varied. For instance, it means that the brain can regenerate itself after a neurological injury. Other research has found that stress?reduction practices like meditation help the brain reorganize.

Recently, Dr. Merzenich and his Brain Plasticity Inc. have begun to test whether brain training can help war veterans who have suffered traumatic brain injuries. The idea, says Dr. Merzenich, is to use software to help damaged or sluggish brains to perform better and better until they've regained most of their cognitive ability. Sort of like physical therapy for someone who is paralyzed, but this time it's for the brain.

The initial results of Dr. Merzenich's study have been encouraging. The bigger application of this idea, though, is more exciting. it means that we can train our brains to prevent the onset of neurological diseases like Alzheimer's. Below is Dr. Merzenich's list of everyday things you can do to keep your brain fit.

Exercise Your Peripheral Vision

Actively challenging your peripheral vision improves brain performance and helps you navigate the world safely.

Recent studies shows that drivers stay on the road longer and have fewer accidents after actively training their useful field of view.

Memorize A Song

Developing better habits of careful listening will help your ability to understand, think and remember.

Reconstructing the song requires close attentional focus and an active memory.

When you focus, you release brain chemicals like the neurotransmitter acetylcholine that enable plasticity and vivifies memory.

1Learn To Play A New Instrument

Playing an instrument helps you exercise many interrelated dimensions of brain function, including listening, control of refined movements and translation of written notes (sight) to music (movement and sound).

Don't Rely On Crossword Puzzles And Sudoku

Heavy crossword players show the same rate of cognitive decline as people who do few crossword puzzles.

Turn Down The Volume On Your Television

Think of this: You can't get rid of radio static by turning up the volume. Many people raise the volume because their listening has become "detuned" ?? a little fuzzy.

Matching TV volume to a conversational level can help you catch every word when talking with others.

Reacquaint Yourself With The Ball

Practice throwing and catching a ball up in the air.

People who master these kinds of sensory?guided movement activities can hone their brains' visual, tactile and hand?eye coordination responses, with widespread positive impacts for the brain.

This type of activity has been shown in MRI studies to thicken parts of the brain's cortex.

Learn To Use Your 'Other Hand'

If you're right?handed, use your left hand for daily activities (or vice?versa) like brushing your teeth and eating.

Doing such activities can drive your brain to make positive changes.

Think of millions of neurons learning new tricks as you finally establish better control of that other hand!

Choose Bumpy Surfaces

Walking on bumpy surfaces, such as cobblestones, improves the vestibular system of the inner ear, which plays a central role in balance and equilibrium.

Cobblestone walking challenges the vestibular system in ways that improve its function, which translates into better balance ?? the key to preventing serious injuries.

Make A Jigsaw Puzzle

Mentally rotating the shape of each piece in your head helps brain fitness.

Become A Child Again

Start paying attention to the physical world around you. Start noticing things and make an active effort to find new details even in a familiar situation.

When you stop learning, your brain stops growing.