Repeat After Me
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What happens to memories after they are processed for long-term storage is unclear, says Mair, although he adds they are probably stored diffusely throughout the brain. How they are retrieved is also an ongoing memory riddle, one of increasing importance to members of an aging boomer population who fear losing, if not their minds, at least their memories.

Popular media, and even some scientific journals, are full of studies on how to have a better memory. One French study, reported in the journal Neurology, found that women, especially older women, who drank at least three cups of coffee a day performed better on memory tests. Mair points out that coffee and other stimulants may help memory just because they make people more alert; just as your mind usually works better if you challenge it and if you get enough sleep.

But the most tried-and-true way to remember things is the same way you get to Carnegie Hall—practice. "It's not jazzy," says Pillemer, "but it works. We remember things we repeat—things we go over in our minds, and out loud."

Despite the emphasis in magazines on improving memory, a lot more is known about memory consolidation than about memory retrieval. "We still don't know what memory is," Mair says of the elusive unit of memory called a trace, or engram. It's probably not a protein, since memories can last 80 years or more and proteins have short lives. The current assumption is, he says, that when memories are preserved across time there is a molecular change that affects synaptic strength. Synapses are the connections that pass signals between nerve cells. Since the human brain has 100 billion nerve cells, or neurons, each with thousands of connections to other neurons (by one estimate, it has 16 quadrillion neuron connections, with new ones developing all the time), unraveling its molecular pathway will be a monumental challenge.

But perhaps not too monumental. A recent issue of Scientific American included a story on research that has tracked the activity of more than 200 individual neurons in a specific part of the hippocampus known to play a role in forming memories of events and places in both people and mice. Lab mice were exposed to a series of alarming but not painful experiences—a puff of air on their backs, for example. An examination of their neuron firings identified cliques of neurons that fired in response to different aspects of the event, including things as specific as whether the mouse was in a black or blue box. The researchers were able to tell from the neuron firings which experience the mouse had. Someday this research might provide the basis for reading human minds—understanding, perhaps, the thoughts of someone who can no longer communicate because of disease or accident. For now, the research offers tantalizing insights into how memories may be organized and stored.

However, even if the code for memory organization is deciphered—the Holy Grail of cognitive psychologists 30 years ago—scientists still face a mountain of questions about memory, ranging from its molecular structure to how it is stored; from its role in personality and creativity to its function in civilization. The one thing that appears to be certain is that the answers to these questions will require the work of both neuroscientists and cognitive scientists working with real people and real memories.

Pillemer knows he will never grow bored with this particular line of psychology. "Many of these questions," he says, "are so basic to understanding how human nature works." ~

C.W. Wolff is a freelance writer who lives in Kittery, Maine.

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