Do you remember who won the world series in 1968, but forget where you left your keys? Are you great at remembering all the details of a story, but lousy when it comes to remembering people's names?
What our brains choose to remember, and exactly how they do it, has been the subject of scientific inquiry for quite some time. Only recently, however, have researchers been able to observe some of the changes taking place in the brain as memories form.
The technology that allows scientists to do this is a scanning machine called an M. R. I., or magnetic resonance imaging machine. This is able to make a real-time, three- dimensional map of certain characteristics of blood flow inside someone's brain.
In two recent studies, scientists showed volunteers a series of words or images while their brains were being monitored. The volunteers were not told it was a memory experiment, so they made no special effort to memorize the words or scenes. After the experiment, scientists quizzed the volunteers on which words or pictures they remembered.
Scientists already knew that there are two areas of the brain that deal with memory. These studies showed that if these areas showed a lot of activity on the scan while the volunteer was first seeing a specific word or picture, they would remember that one in later questioning. If there was little activity in these areas, they would not remember it.
While this doesn't explain why your brain remembers one thing but not another, it does pinpoint where to look to find the answers.