If, as is said, a physicist is an atom’s way of knowing about atoms, then a neuroscientist such as Tank is a brain cell’s way of knowing about brain cells. Each of us has about 100 billion of those, each of which communicates with an average of 10,000 other nerve cells. The goal of neuroscientists is to discover how these neural conversations give rise to a thought, a memory or a decision. And to understand how the brain functions, from which we may understand disorders such as autism, schizophrenia and epilepsy.
Biological causes have been determined for only about 3 percent of the disorders listed in the Diagnostic and Statistical Manual of Mental Disorders. With “mapping,” scientists may at last establish connections between neurotransmitters and particular mental disorders. This might influence how pharmaceutical companies direct their research. And treatments of post-traumatic stress disorders might benefit from learning how the mind erases disturbing memories.
Understanding the brain is, Tank says, different from the Human Genome Project. The latter simply sequenced, and made straightforward extrapolations, concerning a well-defined group of 3.1 billion “letters” that comprise the “alphabet” that determines the growth of a human being from a single cell to a complex human being. We are learning what each letter does, if not yet how. In the case of the brain, “mapping” is not just trying to ascertain what particular parts of the brain do in response to external events, but how the brain parts engage in “conversation” with each other and how they can change over time.
Much brain activity — much thinking — is not, Tank notes, the result of external stimuli. So, is the brain conversing with — acting upon — itself? This internal conversation is at the core of who — and what — we are.
New technologies enable scientists to watch the brain in action, monitoring neural activity as it thinks. Even a decades-old technology, functional magnetic resonance imaging (fMRI) reveals, Tank says, “what parts of the brain are active in particular computations and behaviors.”