Learning about learning
 
Yearning for learning
New neurons
Brains 'n sweat
Sprouting brain cells
Stem cells
.

Need new neurons?
If stress could reduce neural formation, what could accelerate it? Some evidence emerged in the 1980s when Mark Rosenzweig of the University of California at Berkeley showed that a rat's environment affected its brain weight and the number of connections between its neurons, an indication of the ability to learn. Surprisingly, even adult rats benefited from an "enriched environment" (see "Maze training alters..." in the bibliography).

The idea that a stimulating environment might help an adult learn would not shock the average educator, but the Rosenzweig finding raised an interesting question for brain researchers: Were new brain cells being formed (contradicting the prevailing dogma) or were existing cells simply gaining weight?

Fred Gage of the Salk Institute decided to plumb that question. His team grew genetically identical rats and divided the litters. Some rats were raised in standard lab cages, others in the rodent equivalent of Club Med, in a large cage with toys, exercise wheels, tunnels to explore, and plenty of playmates, including a raft of topless rodent sunbathers. beach rat

In just 45 days, the number of cells in the hippocampus -- a brain structure associated with memory -- grew 15 percent in the Club Med crew. The increase was even evident in senior rat citizens, which were nearing the end of their two-year life span. Furthermore, the pampered animals were better at learning a maze, widely considered a Rodent Aptitude Test.

In contrast to studies performed in the 1980s, Gage's group used several new techniques for identifying new neurons:

*The confocal laser microscope lights samples with two lasers mounted at right angles. Since only the spot where the lasers intersect has enough light to make an image, the microscope, unlike conventional electron microscopes, does not damage delicate biological tissues. For the first time, Gage says, the 'scope allows scientists to "prove that a particular cell is a neuron."
*Improved antibodies -- chemicals that can lock onto specific molecules -- can identify exactly which cells have divided.
*A new mathematical sampling method allows researchers to actually count neurons, so, as Gage puts it, "You were not just weighing the brain."

If we want new neurons, is Club Med the only answer?


back more
The Why Files
.
There are 1 2 3 4 5 pages in this feature.
Bibliography | Credits | Feedback | Search

©1999, University of Wisconsin, Board of Regents.