040318 Common Nutrient Boosts Memory, Learning

Until now, however, no one has been able to pinpoint the exact cellular mechanisms that are responsible for these changes.

Now researchers at Duke University, publishing in the April issue of the Journal of Neurophysiology, have found that neurons in the hippocampal region of rats' brains are larger and have more dendrites, which are tentacles on the ends of neurons that act much like antennae. Having more dendrites enabled them to send and receive information faster. The hippocampus is an area of the brain that is key to learning and memory.

"What makes this study very exciting from a scientific standpoint -- and, from a social standpoint, very interesting -- is that the cells look different and behave differently," says Scott Swartzwelder, a professor of psychiatry at Duke Medical Center and senior research scientist at Durham VA Medical Center in North Carolina. He is the study's senior author.

The findings raise the possibility that adding extra choline to the diets of pregnant women may have a lifelong effect on babies' learning and memory.

Swartzwelder and his colleagues fed extra choline to pregnant rats during a critical period of their pregnancy.

They then took out the hippocampus and sliced it up so as to maintain intact most of its internal circuitry. Then they fused a tiny glass pipette filled with an electrolytic solution to the membrane of the cell. In essence, the pipette -- a small device that allows the transfer of a small amount of liquid from one container to another -- provided a window onto the internal workings of the cell, not unlike the view through the glass side of an aquarium.

When compared to cells from rats who had not received extra choline, these cells were "more excitable, and a cell that is more excitable is more likely to communicate with the next cell in the network," Swartzwelder explains. "The more that happens, the more likely you are to produce synaptic plasticity, which is an underpinning of memory."

In the next phase of the experiment, the researchers injected dye into the cell so they could see how big it was and how many dendrites it had. Dendrites are the protruding tentacles that are in charge of receiving and sending signals. "We found that the cell body areas were larger but, more importantly, there were more dendrites on these cells," Swartzwelder says.

This essentially means two things: that the cell is capable of receiving and of sending more information. "It really is a cell that is hypertuned to communicate," Swartzwelder says. "It's built to receive signals more effectively and it functions to produce signals."

But how relevant is a rat study to human beings? In this case, more relevant than you would think.

"The hippocampus is much more similar in rats and humans than it is different," Swartzwelder explains. "That's in part because it's a very, very old structure from an evolutionary standpoint, and it is very, very similar both functionally and structurally in humans and other mammals. While I wouldn't argue that it is a perfect correspondence, it certainly is a good one."

Nevertheless, the subject does need to be studied in humans as well. "The critical next step is human trials," Swartzwelder confirms. "A human study is doing exactly that -- supplementing through normal dietary constituents in pregnant women, then following their kids after they are born."

Since choline is an everyday nutrient and not a dangerous or unknown medicine, a real-world effect may be closer that you'd think. "We're talking about something that people eat anyway," Swartzwelder says. "It's an essential nutrient, part of everybody's diet. The question is how much."

One interesting twist on the matter is that over the last 15 or so years, many people have decreased their intake of meat, eggs and liver, all of which contain choline, because they've been worried about cholesterol.

"Now this study and others are suggesting there might be really good reasons to like eggs," Swartzwelder says.

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