St. Louis ? Making a New Year’s resolution may be putting your dukes up against evolution and your brain’s own programming.

But don’t despair. Change is difficult, but not impossible. The key may lie in persistence and choosing the right motivation, scientists say.

“We have this view of ourselves as being the agents of our own behavior,” said Todd Braver, a cognitive neuroscientist at Washington University.

But Braver and other scientists who study thought patterns are learning that we are actually at the mercy of our brain cells. In his laboratory, Braver places volunteers in a brain-scanning functional magnetic resonance imaging machine (fMRI) and gives them a simple task; press a button with the left hand every time an X appears on the screen. After some time, he tells them to switch to pressing the button with their right hands when an X appears.

The button-pressing task is a model for more complex tasks, such as remembering to stop for groceries instead of driving straight home, Braver said.

When volunteers are concentrating on the new button-pressing task — and probably when people remind themselves to pick up groceries or dry cleaning — a part of the brain located just behind the temples and forehead becomes active, Braver found. That part of the brain, called the lateral prefrontal cortex, is involved in keeping goals, resolutions and other things in mind.

But simply having the goal in mind may not be enough to overcome years of bad habits if a person isn’t motivated. Proper motivation is key to changing behavior. Braver found that some volunteers responded to rewards, while other responded more strongly to punishments.

Edwin Fisher, a professor of psychology, medicine and pediatrics at Washington University, offers these tips for making your resolution last past Jan. 3.

• Prepare. Impulsive resolutions usually fail, so plan for success, Fisher suggests. Choose something that is important to you and plan how you will execute the change in concrete terms. Include plans for picking up after a lapse.
• Recruit help. A strong support network of family and friends can be critical for sticking to a goal. Choose someone who will help you talk through your progress and identify ways to improve. The person should provide the kind of encouragement that works for you.
• Reward yourself. Steps in the right direction deserve a reward. Rewards keep feel-good brain chemicals flowing and reinforce positive behavior.
• Rebound from relapses. Perhaps the most important ingredient for success is persistence. Realize that times will be tough sometimes and you may fall back into the old ways, Fisher said. That’s OK as long as you get back on track.
• Try again. If your resolution goes bust, don’t despair. You needn’t wait a year to try again. Set a date and start planning.