Your Brain Boots Up Like a Computer

By Abigail W. Leonard
Special to LiveScience
posted: 17 August 2006

As we yawn and open our eyes in the morning, the brain stem sends little puffs of nitric oxide to another part of the brain, the thalamus, which then directs it elsewhere.

Like a computer booting up its operating system before running more complicated programs, the nitric oxide triggers certain functions that set the stage for more complex brain operations, according to a new study.

In these first moments of the day, sensory information floods the system—the bright sunlight coming through the curtains, the time on the screeching alarm clock—and all of it needs to be processed and organized, so the brain can understand its surroundings and begin to perform more complex tasks.

"The thinking part of the brain is applying a sort of stencil to the information coming in and what the nitric oxide is doing is allowing more refinement of that stencil," says Dwayne Godwin, an associate professor at Wake Forest University and lead author of the study, which was funded by the National Eye Institute.

The little two-atom molecule, it seems, is partly responsible for our ability to perceive whatever it is we're sensing.

The thalamus sits atop the brain stem.

Image courtesy 3DScience.com

The finding, published last week in the journal Neuroscience, changes the way scientists understand nitric oxide's role in the brain, and it also has them rethinking the function of the thalamus, where it is released. The thalamus was thought to be a fairly primitive structure, sort of a gate that could either open and allow sensory information to stream into the cortex, the higher functioning part of the brain, or cut off the flow entirely.

Godwin says the new research shows it's more accurate to think of the thalamus not as a gate but as a club bouncer, who doesn't simply allow a huge rush of people to go in or no one at all, but picks and chooses whom to let in and out.

"Instead of vision being a process going straight from eye to cortex, it's more of a loop," Godwin explained. "This constitutes a new role for the thalamus in directing, not just modulating."

While this study is the first to identify nitric oxide's role in the thalamus, elsewhere in the body it was already known to have an important, if somewhat different function. The molecule is actually integral to controlling blood flow and is, in fact, the molecule Viagra targets in order to increase blood flow to the penis.

The teeny molecule might have other medical uses.

"This study shows a unique role for nitric oxide. It may help us to someday understand what goes wrong in diseases that affect cognitive processing, such as attention deficit disorder or schizophrenia, and it adds to our fundamental understanding of how we perceive the world around us," Godwin said.

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Zapping sleepers’ brains boosts memory
18:00 05 November 2006
NewScientist.com news service
Roxanne Khamsi

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Stimulating the brain with a gentle current during sleep can improve memory (Image: Lisa Marshall)
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Jan Born, University of Luebeck
Nature

Applying a gentle electric current to the brain during sleep can significantly boost memory, researchers report.

A small new study showed that half an hour of this brain stimulation improved students’ performance at a verbal memory task by about 8%. The approach enhances memory by creating a form of electrical current in the brain seen in deep sleep, the researchers suggest.

Jan Born at the University of Luebeck in Germany, and colleagues, recruited 13 healthy medical students for the study and gave them a list of word associations, such as “bird” and “air”, to learn late in the evening. Afterwards, researchers placed two electrodes on the forehead and one behind each ear of the volunteers and let them sleep.

The students’ various sleep stages were monitored using an electroencephalogram (EEG) machine. When the students entered a period of light sleep, Born’s team started to apply a gentle current in one-second-long pulses, every second, for about 30 minutes. The EEG readings revealed that this current had put students into a deeper state of sleep.

The next morning, the students performed about 8% better on the word memory test than when they underwent the same type of memory experiment without brain stimulation.

Nerve firing

Born believes this memory boost was due to the pattern of the applied current mimicking that seen in naturally occurring deep sleep, where memory consolidation is thought to take place.

Strong brain currents in this stage of sleep probably cause more intense nerve firing, he says, which might enhance activity in the brain’s memory centre, the hippocampus.

Some researchers are sceptical of Born's "mimicking deep sleep" theory, however. Felipe Fregni at the Harvard Center for Non-invasive Brain Stimulation in Boston, US, says that he and other scientists have shown that brain stimulation with non-sleep-type currents can produce similar memory enhancements.

Potential side effects

There is growing evidence that brain stimulation might one day help improve memory in patients with dementia or other forms of cognitive impairment, experts say.

“It could be very useful to restore function in people with brain injury,” says Daniel Herrera at Weill Medical College of Cornell University in New York, US, who has studied the effects of brain stimulation in rats.

Healthy people might eventually try using this approach to maximise their brainpower, Herrera says: “I think every single medical student in the country might want to plug into this type of device at home or in the dorm.” But he stresses that applying electrical currents to the brain might have unwanted side effects.

Born also says he would be "a little hesitant” to regularly use brain stimulation during sleep to boost memory: “In the end we don’t know if there are adverse side effects that we just don’t recognise at the moment.”

Journal reference: Nature (DOI: 10.1038/nature05278)

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