Want to learn about the way the human brain works? Don't open up a textbook. Just lift the hood of your car.

The simple analogy for psychologists may not work completely, but it's a good start, according to Instructor of Psychiatry Dr. Jeffrey P. Sutton.

In essence, says Sutton, traditional studies of brain lesions, or distinct areas of the brain which don't function properly, are like concluding that the fact that a car that won't start has a loose spark plug means that spark plugs alone run a car.

But even a novice auto mechanic should realize that while a spark plug is necessary for a car to run, it is not sufficient: All the parts must work together, or in parallel.

And cutting-edge research in neurology may have more in common with automechanics than you might think. In the past, lesion studies led brain scientists to believe that after a dysfunction was observed in a patient along with a lesion in a certain part of the brain, that part solely controlled the function that had been damaged.

It is now understood that, like a car, the brain functions through a series of highly interconnected networks--in the brain's case, neural networks--which work in parallel. These networks connect the various parts of the brain needed to carry out any particular process.

The example of Ms. H., a 40-year-old amnesiac unable to recall incidents even moments after they happen, shows the healing power that this new understanding of the brain has given us.

Professor of Psychology Daniel L. Schacter, a cognitive scientist studying theories of perception, was able to teach Ms. H. how to access alternate memory systems to overcome her deficiency.

Schacter is currently investigating a form of memory called implicit memory, which he describes as an "unintentional, nonconscious form of retention." While Ms. H. appeared to have lost her memory completely, Schacter's work, consistent with the idea of parallel processing, shows that memory in actuality consists of several sub-components--only one of which Ms. H. had lost.

Typical conceptions of memory as intentional and conscious recollections actually describe memory known as explicit. But, says Professor of Psychology Daniel L. Schacter, implicit memory involves recollections which were formed without our awareness, and thus cannot be recalled on demand.

Typical conceptions of memory as intentional and conscious recollections actually describe memory known as explicit. For example, questions such as: "What is the square root of four?" or "When was the last time you ate spaghetti?" involve explicit memory.

But implicit memory, says Schacter, involves recollections which were formed without our awareness and thus cannot be accessed on demand.

Neurologist David Kaplan, who is currently involved in research with Schacter, explained that information becomes part of implicit memory when certain recognition systems are activated. Implicit memory differs from explicit memory in that one need not understand the information or remember learning it.

And while this idea may seem to provide a scientific basis for subliminal learning, students who look forward to acquiring knowledge while they sleep should not be hopeful. Schacter has found that subjects who were exposed to auditory information while asleep are unable to remember it upon waking.

"There may be some role in terms of education," says Schacter, "but it's not going to provide an easy way out for students."

All hope is not lost, however: Schacter found that certain patients who received surgical anesthesia did retain information when they awoke.

While Schacter's research is not a college student's panacea, colleagues say that they are excited about its significance.

"He's going to tell us much more about the way the human brain is wired," said Dr. Verne S. Caviness Jr., Kennedy professor of child neurology and mental retardation at the Medical School.

Caviness, who also directs the division of child neurology at the Massachusetts General Hospital (MGH), suggests that implicit memory may play a role in disorders currently attributed solely to explicit memory systems.

Schacter's research, Caviness says, will enable neurologists to see correlated defects and better understand the brain as a parallel processor.

For example, Caviness says he believes that examining the implicit memory of stroke victims will give scientists a more complete understanding of the disabilities they suffer.

Schacter's research should provide a greater ability to understand and diagnose neurological disorders. Because we do not knowingly retrieve implicit memories in our daily lives, we may be unaware of memory disorders in these systems.

Exploring implicit memory is not only useful in locating the source of dysfunction, but also in rehabilitation. According to Associate Professor of Neurology Sandra Weintraub, Schacter's research demonstrates that patients suffering from memory disorders possess information they are unable to access through usual routes. As seen in the example of Ms. H., implicit memory may provide such an alternate route.

"What Schacter has shown is that patients who have a disturbance of the memory system...can demonstrate an ability to remember some aspects of what was previously known," she says.

Cary R. Savage, a clinical fellow in psychology, said that while Schacter's techniques are accepted by the majority of neuroscientists, including himself, some in the field question whether implicit memory is really an unconscious process. Others, he says, believe that conscious awareness could be found in what is considered implicit memory if one could find the right way to question subjects.

But researchers are clearly intrigued. "I think you'd have a hard time finding someone who wouldn't want to collaborate with Dr. Schacter," says Savage.

An unexpected collaborator of Schacter's is Mary J. Olmsted, associate director of Gallery NAGA, a Boston art gallery. Together they serve as curators of the exhibit entitled "Fragile Power: Explorations of Memory," which features a collection of artistic works addressing memory.

And Schacter will be releasing a book that uses works of art to explain memory within the next two years.

You might even say, then, that the Salvador Dali painting hanging on Schacter's office wall serves more than an aesthetic purpose for this professor of psychology. The painting is a tribute to the "art" of memory--an art which colors all our lives.