"You're standing at your front door, juggling five bags of groceries in your arms, when you realize you put your keys in the wrong pocket. So what do you do?" Jim Bower asks, staring levelly at me across his littered desk, nestled in one corner of his equally cluttered office. "Do you put the bags down, or do you just adjust and reach for your keys? So you think:

I've done this before, I'll adjust. But your perception that you've done this before is not true because you've never juggled these particular bags," he goes on, leaning back in his chair while two large computer monitors flicker in the background. "And your impression that it's easier to get the keys out than put down the bags is also not true: it's much more difficult to juggle all that weight. So your perceptions of that whole incident are wrong. But your brain is doing a miraculous thing because somehow you get those keys.

"The brain is an incredibly complicated machine -- perhaps hundreds of orders of magnitude more powerful than today's most powerful computers. And if we really knew all the computations we had to go through to arrive at these conclusions, we'd all stand at the door frozen. Compared to our perceptions, which are simple, what we do is really biomechanically complex. And that's what we're trying to do here: understand those biomechanics."

Figuring out how the brain works in action -- even devising methods of studying living brain tissue in a way that yields reliable data -- has daunted scientists for decades. Bower, however, likes tough problems: the harder, the better. Low key with a puckish sense of humor, the perpetually jeans clad Bower is hardly the typical high-powered lab chief. With his gray-flecked beard and wavy hair haphazardly clamped in a ponytail that trails down his back, he looks he just wandered in from the Haight Ashbury. But there's nothing fuzzy about his thinking.

For him, the quest to identify the neuronal basis of consciousness -- the big kahuna sought by eminences such as Francis Crick or his Bower's Caltech colleague, Christof Koch -- isn't particularly interesting. In his view, perceiving -- or conscious recognition -- is only an infinitesimal part of what the brain does. Far more intellectually stimulating to him is unraveling the structure of the nervous system and the processing done by the brain.

Toward that end, Bower has spent much of the past two decades grappling with some of the most difficult problems in neuroscience: deciphering the goings on in the cerebral cortices, considered the center of higher thought, and especially the cerebellum, the region associated with finely-tuned physical movement, and probably much more.

--Linda Marsa