December is a time of memories. Scents of cinnamon and fresh evergreen evoke holidays past. Dangling mistletoe conjures up long-ago kisses. With each refrain of Christmas carols, words and music not heard for a year come tumbling back.
All animals, from the lowly sea snail to humans, have some form of memory. But people possess the remarkable ability to make a nearly infinite number of memory associations. It's why the loss of memory--due to aging, illnesses such as Alzheimer's disease or accidents--is so profoundly unsettling. And it's why, as the Decade of the Brain draws to a close, neuroscientists are pressing to better understand this still-mysterious process.
"Every thought we have, every word we speak, every action we engage in--indeed, our very sense of self and our sense of connectedness to others--we owe to our memory, to the ability of our brains to record and store our experiences," say neuroscientists Larry R. Squire and Eric Kandel in their book "Memory: From Mind to Molecules." "Memory is the glue that binds our mental life, the scaffolding that holds our personal history and that makes it possible to grow and change throughout life."
Parsing Memory's Locator Points
Using a variety of sophisticated new imaging devices, researchers are beginning to understand some of neuroscience's most central questions: How are memories organized in the brain? Is there a particular brain center for seemingly mindless daily habits, from climbing out of bed to brushing your teeth? How does the brain recall vivid details from a movie, a book or a painting? Where does the memory for recognizing a face exist?
"It's a very difficult thing to find the anatomic parts of memory in the brain," said Daniel Alkon, director of the Laboratory of Adaptive Systems at the National Institute of Neurological Disorders and Stroke. "We see a picture of our father's face and hear his name and recall our relationship with him. But to find where that is stored [in the brain] is an incredibly difficult task."
Until recently, memory research was largely confined to animals and to individuals in whom memory had begun to unravel. People suffering from amnesia, the aftermath of a stroke and various forms of dementia gave scientists rare glimpses into the mysteries of memory.
One of the most fascinating cases was a 9-year-old boy who cracked his head on the sidewalk after being knocked down by a bicycle. His misfortune turned into a lengthy, classic study that provided the first riveting proof that memory is not one single brain process.
