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Cover Story

September 3, 2007
Volume 85, Number 36
Web Exclusive

The Well-Endowed Mind

Brainy mice and mice with mental deficits reveal reasons for the differences between good and poor memory

Sophie L. Rovner

What distinguishes a person with a good memory from one with a poor memory?

The ravages of Alzheimer's or other neurodegenerative diseases can explain some memory deficits. Amnesia caused by emotional trauma or physical damage to the brain can also impair memory.

UT Southwestern Medical Center
BRAIN TRUST University of Texas Southwestern Medical???s Powell (from left), Bibb, and Donald Cooper showed that deleting the enzyme Cdk5 made mice smarter.

But if disease or damage isn't a factor, "there are probably going to be many subtle differences" between people with good and bad memory, says Craig M. Powell, a neurologist at the University of Texas Southwestern Medical Center.

Dozens of neurochemical signaling pathways and numerous molecules and genes are linked with memory, says Alcino J. Silva, a neurobiologist at the University of California, Los Angeles. "There are at least 150 genes that have been implicated in memory," he adds. "Changes in any one of these genes could easily account for why some individuals learn better than others."

Different genetic alleles that produce slightly different versions of brain-derived neurotrophic factors result in measurable differences in memory performance among humans, notes