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."