Human beings are creatures of habit. We find an easier way to drive to work, so we always drive that way, even to point where we wind up at work without realizing how we got there.

We eat the same food, talk to the same people, watch the same TV shows. Over and over and over again.

In the long run, there are high costs to being in a rut, both psychological and physiological, experts say. At the neurological level, it could even mean you are losing brainpower, says Lawrence C. Katz, a professor of neurobiology at Duke University Medical School in North Carolina and co-author of the book "Keep Your Brain Alive" (Workman Publishing).

As people age, the number of dendrites — branch — like connections that link nerve cells and convey information — tend to thin out, he says. The dendrites are where synapses, or chemical links, are made that allow us to process information, memorize it and do critical thinking. It's part of why people who don't have any diseases have "senior moments" where they forget why they just ran down to the basement.

It takes work, and variety, to keep the synaptic connections in the brain alive and growing, Katz says.

Katz's book coined the term "neurobics" to describe the kind of mental exercises that preserve our brain health. "Neurobics really emphasize variety more than complexity of activity, though that's not to say that complexity's not important. What we're really trying to emphasize is doing routine things in a nonroutine way, so even a simple task done in a nonroutine way can activate underused brain pathways.

"By providing a new pattern of activity, we think that those brain cells that normally wouldn't get activated during that task will be stimulated." That in turn causes them to produce larger quantities of brain-enhancing chemicals, known as neurotrophins and other molecules.

"Active brain cells produce more brain chemicals which help keep brain cells alive," Katz says.

Research has shown that an extremely stimulating environment could repair some of the damage rats had received from prenatal exposure to alcohol.

Some specific activities include learning a new language, writing a short story or learning a new musical instrument, especially if none of those activities is something you do all the time. But most people don't have the time or opportunity to do that intense an activity, so Katz emphasizes everyday activities to change your routine.

"Try brushing your teeth with the opposite hand. Or take a new route to work," he says. "Any exercise that gives your brain a break from the routine is establishing vital new pathways and circuits among brain cells. The idea is to weave a more dense network of connections so if a few fray as you get older, you'll have others to fall back on."

He eschews tricks like memorizing poems or random lists to impress people with at dinner parties. "We are really emphasizing just overall kind of brain health and agility, being able to think creatively, feeling confident that you can undertake mental challenges, rather than being able to astound your friends with your prodigious memorization powers."

Dr. Amir Soas, of the Case Western Reserve University Medical School in Cleveland, says the more complex the task, the more synaptic activity is taking place. He believes that more cerebral activities like creating something, playing chess, learning a new language or doing a crossword puzzle, are more valuable.

"You're reading, you're thinking, you're writing, so there's more motor and sensory areas of the brain that are working simultaneously, so you have a greater number of synapses working simultaneously. And of course, like anything else, the more you use it, the better it becomes."