Related semi-off topic Issue from NYT...
Scientists Study Brain, Memory
Filed at 1:40 a.m. EDT By The Associated Press
WASHINGTON (AP) -- Scientists have literally peered inside the human brain at the split second it creates a memory to discover which parts of your brain determine what you remember and what you forget.
In a unique pair of studies at Harvard and Stanford universities, researchers used sophisticated imaging techniques to measure people's neural activity -- and accurately predicted in advance whether they would make a memory.
The findings ''mark a significant step forward,'' said memory expert Michael D. Rugg of the University of St. Andrews in Scotland, who critiqued the studies, which were published today in the journal Science.
Yes, the discovery means advertisers might one day figure out how to make commercials stick better inside the consumer brain. And yes, they show your first-grade teacher was right: Thinking about an experience does make it more likely you'll remember.
More important, because one of these memory-making regions is ravaged in Alzheimer's disease, the scientists now are studying whether their findings also could help detect the devastating brain disease in its earliest stages.
''We're really excited about the prospect of this being used for Alzheimer's disease,'' said Stanford neuroscientist James Brewer, who led the memory study and was preparing to scan the brain of an Alzheimer's patient Thursday. ''If we were able to detect Alzheimer's really early, the prospect for treatment is much, much better.''
Scientists have long suspected that how well people remember depends on differences in the way their experiences are ''encoded'' into the brain at the instant they occur. Studies of people with brain damage have suggested various brain regions were involved, but it wasn't clear if damage to those regions meant people couldn't make new memories, retrieve old ones or store memories over time.
New, high-powered ''magnetic resonance imaging,'' or MRI, machines work fast enough that scientists can measure split-second neural activity as a person's brain processes an experience.
At Harvard, neuroscientist Anthony Wagner put healthy volunteers into these ''functional MRI'' machines and rapidly flashed one word every two seconds onto a screen inside. At first, the volunteers merely noted whether words were in upper- or lower-case letters. With additional words, they were told to decide if each was concrete, like ''chair'' or ''book,'' or abstract, like ''love'' or ''democracy.''
That's because psychologists already knew that analyzing the meaning of a word helps people remember it.
In the Stanford study, Brewer showed volunteers color photographs of indoor and outdoor scenes rather than words.
Neither set of volunteers had been told this was a memory test. But after the MRI scans, they were asked which words or pictures they remembered well, remembered vaguely or didn't remember. The scientists compared those memories to the brain scans.
The longer that two brain regions -- the prefrontal lobes and the parahippocampal cortex -- both lit up on the MRI scans, the better people remembered the items. Words or pictures that caused weak activity in the two regions were forgotten.
What makes your brain more likely to react to one item over another? ''That's the million-dollar question,'' Wagner said.
The studies provided some hints. Wagner's volunteers showed more neural activity and better memory during the ''concrete-abstract'' word test than for other words. That provides biological evidence that more complex cognition increases the chances of memory.
And personal experiences probably play a role. Perhaps Brewer flashes a photo of Zion National Park: Someone who just visited there may react more than someone who says, ''Oh, a desert scene.''
Most people think of memory problems as ''failing to retrieve an event,'' Brewer explained. Instead, ''there are very important things that go on'' in that split second when your brain processes an experience that determine if you'll ever remember it. |
