Neurobiology: Mind Reader

The great irony of human intelligence is that the only species on Earth capable of reason, complex-problem solving, long-term planning and consciousness understands so little about the organ that makes it all possible--the brain. Scientists' knowledge of how and why the brain works is patchy at best compared with their awareness of other vital body parts--heart, lungs, kidneys, skin.

Until Patricia Goldman-Rakic started delving into it, the most important part of the brain, the frontal lobe, was a veritable blank sheet. A gray, wrinkled chunk of tissue tucked behind the forehead and taking up about a third of the total brain mass, it is to the rest of the central nervous system what a CEO is to a modern corporation. It takes sensory data fed to it by the rest of the organization (smells, sounds, tastes, etc.) and decides what it all means and what should be done about it. It's largely responsible for our thinking, planning, intellect and will.

Goldman-Rakic, a professor of neuroscience, neurology and psychiatry at Yale, has spent the past 30 years immersed in the frontal lobe. In the early 1970s, working at the National Institute of Mental Health as one of the few women in the field, she became the first scientist to draw a comprehensive biological map of neuroscience's terra incognita, showing that its tangled web of neurons is actually a series of columns of highly specialized nerve cells.

But Goldman-Rakic is probably best known for her research on working memory, which evolved out of these more fundamental discoveries. Working memory functions in the brain like a yellow sticky Post-it note. It's the place we put things to recall over the short term. We use working memory when we look up a telephone number and remember it only long enough to dial. We use it on a more basic level to remember the thread of an argument while we are trying to make a point. A brain without working memory is like a computer without its RAM; its computational abilities are crippled, as they often are in people with diseases that affect the frontal lobe, such as cerebral palsy, dementia, Alzheimer's, Parkinson's and schizophrenia.

But it's mostly the brains of monkeys, not humans, that Goldman-Rakic studies. This presents certain advantages (monkey brains are extremely similar to ours, and more invasive studies are allowed) and certain challenges. How, for example, do you explore the memories of creatures that cannot speak?

Peanut and raisin rewards have become the coins of Goldman-Rakic's realm. In a series of elegant experiments that combine memory tests with electrical recordings from brain tissue, she has learned, for example, that each part of the brain has its own short-term "scratch pad" in the frontal lobe. Within each of these areas, individual neurons are responsible for holding and processing highly specific pieces of information, like the memory of a particular face or voice.