Depending on what technology reigned supreme at the time, the human brain has been compared to a telegraph, a TV and a computer.
But it's also a three-pound, flesh-and-blood human organ, and with 100 billion neurons, a very demanding one at that. Even though it comprises only 2 percent of the body's weight, it consumes 20 percent of its oxygen and a majority of its blood sugar.
It makes sense that a biochemical factory that complicated will work best with proper care and feeding, even in young and healthy college students.
The brain starts out with some built-in advantages. Not only is it encased in a sturdy skull, but a set of cells known as the blood-brain barrier keeps many bacteria and other harmful substances out of the cerebrospinal fluid that bathes the brain and spinal cord.
The brain also gets first dibs on a lot of vitamins and nutrients, says Simon Evans, a University of Michigan neuroscientist who wrote the book "BrainFit for Life: A User's Guide to Life-Long Brain Health and Fitness."
Even so, college students still need to pay attention to their diets, exercise and sleep patterns, all of which play key roles in basic brain health, Dr. Evans says.
In fact, taking care of your brain when you are in your late teens and early 20s will pay lifelong benefits, he and other experts say.
The human brain continues to form new internal connections throughout youth, adolescence and early adulthood, they say. While the peak demand for brain-boosting nutrition is from 4 to 8 years of age, the process continues into the college years, says Robert Clark, a brain researcher and chief of pediatric critical care medicine at Children's Hospital of Pittsburgh of UPMC.
"There is an idea out there that if you produce a lot of new neurons when you're young, that once they are there, they are there for good," adds Henriette Van Praag, a brain researcher with the National Institute on Aging.
Sleep is one commodity that college students often shortchange, and that not only can affect their thinking ability, but their memories, their growth and even their weight, Dr. Evans says.
Research has shown that sleep is when the day's memories are consolidated in the brain. It is also when the body secretes most of its growth hormone, which is why children who don't get enough sleep tend to be shorter than average, he says. Sleep is also a time when the body uses energy from fat cells, which is one reason why too little sleep is linked with obesity, Dr. Evans says.
Exercise doesn't just build muscles, burn fat and expand heart and lung capacity. It also makes the brain smarter.
That's one result of studies done by Dr. Van Praag and others on mice that use treadmills and perform learning tasks.
After training mice to press their noses against icons on a computer screen to get a sugar pellet, her team split them into two groups -- one that was sedentary and the other that had plenty of treadmill workouts.
The mice that exercised were not only better at pressing the right icons and learning to negotiate a maze, but were quicker to adapt when researchers changed the icon that yielded the reward, she says.
When the scientists examined the mice brains later, they found that the ones that exercised had grown new neurons in a key part of the hippocampus, a brain area involved in memory and learning, and that the number of fresh neurons correlated nicely with how well the mice performed on the tests.
While she is cautious about extrapolating her results to humans, Dr. Van Praag says that the exercise-induced brain growth in mice seems to be connected to substances that flow into the brain in the bloodstream, particularly one called insulin-like growth factor.
On the nutritional front, college students' bodies are pretty good at supplying energy to the brain. "Anybody who can take an Extra Value Meal at McDonald's and convert it into something useful has a pretty sophisticated digestive system," says Dr. Clark.
That doesn't mean a balanced diet is unimportant, though, the experts say.
Like the rest of the body, the brain benefits when a person's diet has a proper ratio of Omega-3 and Omega-6 fatty acids. Americans tend to consume too much Omega-6, which is prevalent in vegetable oils and can constrict blood vessels and cause inflammation, Dr. Evans says, while Omega-3, found most famously in fish oil, is anti-inflammatory.
Dr. Clark has found in his own research that when the brain is starved of nutrients, it begins to eat itself to survive, a process known as autophagy.
The same thing happens during starvation in the rest of the body, he says, but the effects are not as dire. " If you're sick and don't eat, you will lose muscle mass," he says, "but after a couple of weeks you'll be back to your old self. But if that happens to the brain it can be kind of catastrophic," and can kill off neurons.
That kind of brain stress doesn't happen easily with college students, he notes, but it is possible, especially with students who drink too much.
"It used to be thought that alcohol kills brain cells because of its chemical makeup," Dr. Clark says, "but it's possible it has more to do with swapping alcohol for other nutrition."
"To maximize your academic potential," he adds, "you want to have a balanced diet. In general, it's pretty hard to be malnourished in America, but if you add another stress -- you're anorexic or most of your calories are coming through alcohol or you get sick -- that's when the brain is most vulnerable to nutritional shortcomings."
Exercise, diet and sleep are not just about preserving neurons -- they also boost the health of the rest of the brain, the cells known as white matter.
They get that name from the fatty myelin sheaths that protect neurons connecting one brain region to another. Just like the insulation on an electrical cable, myelin can speed up brain transmissions a hundredfold, says R. Douglas Fields, a senior investigator at the National Institutes of Health and author of a new book, "The Other Brain: From Dementia to Schizophrenia, How New Discoveries About the Brain Are Revolutionizing Medicine and Science."
White matter in the brain doesn't just help link together brain regions, he says. Emerging research shows it also helps the brain fight off infections, regulates the chemicals that the neurons use to function and can even stimulate the growth of new neurons and blood vessels in the brain.
One study showing the importance of white matter was the analysis of autopsy slices from Albert Einstein's brain, he says. Much to the scientists' surprise, the famous physicist did not have any more gray matter neurons than other people, but his brain did have a much denser network of white matter.
There is one other thing to remember, says Michigan's Dr. Evans. Whether it's gray matter or white matter, all those cells are active all the time.
"The brain is an electrochemical organ," he says, "and it's always on. Even when you're sleeping it's recharging hormones that were depleted during the day. The brain is at constant, almost full tilt."
Mark Roth: firstname.lastname@example.org or 412-263-1130.