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How the science of memory might help us all remember things better

Wouldn't it be great to have a better memory? This week, a new study in the journal Science showed that people who received a certain type of electromagnetic stimulation to their brains ended up better able to remember things — and the effects lasted for at least a day after treatment.

This is hardly the first experiment about boosting memory. Scientists haven't yet discovered a magic pill that will help you remember things more easily. But there's a lot of research into how memory works and how it could work better. Here's an overview:

How memory works

Neuron

A neuron imaged under a microscope. (BSIP/UIG/Getty Images)

There are all different kinds of memory. These types matter because they seem to function differently. So boosting one type of memory won't necessarily help another kind.

For instance, there's semantic memory, which involves all kinds of concepts and facts. There's episodic memory, which lets us remember our personal past. Spatial memory allows us to navigate our environments and remember, say, how to drive home. And then there's verbal memory, which is for words.

These various types of memory add another layer of complexity to all the work that researchers do. Techniques that improve verbal memory, for example, won't necessarily improve episodic memory.

On top of that, there's also a difference between short-term memory — what's been in your head within the past few seconds — and long-term memory.

How memory physically works is something that neuroscientists are still figuring out. But researchers do know that it has to do with neurons strengthening their connections to one another — as well as making new connections altogether. The details, however, are still being explored. That means that when a study finds that a certain technique can boost memory, it's often the case that no one really knows why.

Using electromagnetic stimulation to boost memory

Brain electric

This is not how transcranial magnetic stimulation works. (Mauricio Lima/AFP/Getty Images)

There are a couple different possible approaches for boosting the brain. Drugs and nutrients are obvious ones — but not those aren't the only options. The brain is also an electrical organ that uses currents to help send messages. And researchers have recently been exploring techniques to alter these electrical signals.

One benefit of this latter approach is that electrical interventions — such as transcranial magnetic stimulation (TMS) — can be narrowly targeted to a particular brain region, whereas drugs often affect the entire brain.

"We think this is a pretty important advantage of TMS in that drugs are pretty nonspecific," says the Science study's first author, Jane Wang. "The TMS device, we can aim it at specific parts of the brain to get at specific circuits."

Early studies into this technique were performed on people who already had electrodes implanted inside their brains to treat epilepsy. Those studies showed that stimulating certain brain regions could lead to some positive effects on memory.

In the Science study released this week, researchers went even further, using a technique that doesn't require any brain surgery and therefore could be applicable to a much wider swath of the human population. These scientists placed electromagnets outside of their participants' heads to produce a focused electrical current in a brain region that's connected to the hippocampus — a key area for memory function.

Participants were stimulated for several days in a row and did better on a memory test afterwards (and better than those who had been treated with a placebo). What's more, the memory boost lasted about 24 hours after the last stimulation, not just during the treatment. Brain-imaging results suggest that this is because of stronger connections between memory-related brain regions.

Still, neuroscientists don't know how long the effects of this sort of stimulation will last.

Note: do not try this at home. No one has determined the long-term consequences of such kinds of stimulation.

Other activities that could boost memory

Running exercise

(Shutterstock)

Of course, even if you don't have access to magnetic stimulation, there are plenty of easy things people can do that might boost memory. Some of the best research on the subject points to two activities in particular: sleep and exercise.

Many studies have shown that sleep seems to be especially important for solidifying memories — and for reinforcing important details while discarding irrelevant ones. Indeed, this may be one reason why older adults often have memory problems: they experience changes in their sleep patterns.

A few lab studies have suggested that being exposed to scent or sound cues while learning and then again while sleeping might have a memory-boosting effect. It's hard to know how to use that fact in everyday life, but it's an intriguing place for further study.

A whole host of other studies have explored the link between exercise and memory. Scientists have found that exercise generally seems to help boost memory, but the details are still being worked out. A few recent studies have shown that exercising while studying leads to better recall days later, but not immediately after. Another showed that exercising vigorously right after learning leads to immediately better memory.

Gretchen Reynolds at the New York Times has been following these studies closely, and I'd recommend looking up her stuff if you want to dive in more deeply.

Several other studies have shown that exercise can help older adults with age-related memory problems. "Time and again they have shown cognitive improvement," says Molly Wagster, chief of the Behavioral and Systems Neuroscience Branch at the National Institute on Aging. The results seem to point to aerobic fitness as a key component.

One recent study showed that older women with mild cognitive impairment who were told to do walking or weight training for six months ended up improving on memory tests.

Lab rats also have better memories if allowed to exercise regularly, and researchers are looking into what exactly is going on there that's boosting the brain. One factor might be the protein BDNF, which helps brain cells survive and grow. Exercise makes both rats and people produce more BDNF protein.

Some drugs might boost memory, too

Coffee cup

Yes, caffeine is a drug. (Shutterstock)

An intriguing study came out recently that showed that caffeine might have effects not just on attention but on memory. The experiment demonstrated that consuming the caffeine equivalent of about two cups of coffee after learning something improved recall the next day.

A lot more research will need to be done here to determine that this was truly a real effect and, if so, how to use it to one's benefit. But it's certainly intriguing.

Researchers are also finding new molecules that seem to affect the memory of lab animals. The list includes BDNF, IGF-II, and the posited possible key to all long-term memory, PKMzeta.

The latter molecule is thought to naturally strengthen connections between brain cells, which is part of how memories form. Indeed, a drug that inhibits PKMzeta has been shown to wipe out all kinds of memories in rats. And then giving these animals a dose of PKMzeta has been shown to revive faded memories.

However, that doesn't mean that any human should go around messing with this just yet. (For one, having too many memories could also be problematic and cloud up your thinking.) And PKMzeta's exact role in memory is still contentious.

A lot of this animal research is still at the basic level of trying to figure out how memories work, physically, rather than hunting for a specific therapy. And very few drugs that work in lab animals then go on to be effective and safe drugs in people.

It's especially difficult to determine mental side effects in a rat if it can't talk to you and doesn't have the smarts of a human. A rat test won't necessarily tell you if a drug is going to make someone forget her childhood memories, the names of her loved ones, or make her more sluggish at complex math. There are inherent risks when messing with memory.

Further reading: For advice specifically related to studying, Joseph Stromberg put together a list of tips from memory researchers.