Neurobiologist Orie Shafer at the University of Michigan is trying to understand how the brain's cells communicate in order to control sleep patterns. To help solve this mystery, Shafer is teaming up with mathematician Victoria Booth to study a tiny and very unlikely specimen: the fruit fly. "Mysteries of the Brain" is produced by NBC Learn in partnership with the National Science Foundation.
Mysteries of the Brain - Brain States and Consciousness
TOM COSTELLO, reporting:
For sixteen hours a day, we are awake and active. From getting up in the morning to when we go to bed, our brains are constantly working. But what are our brains doing for the other eight hours of our day when we are asleep?
ORIE SHAFER (University of Michigan): Quite surprisingly, there are some states of sleep when the brain actually appears to be more active, more coordinated than it does when we are awake.
COSTELLO: Dr. Orie Shafer is a neurobiologist at the University of Michigan and funded by the National Science Foundation. He is investigating the brain's activity during sleep, specifically, a part of the brain that governs every aspect of the daily lives of all animals, from insects to fish, to humans: the internal clock.
SHAFER: Every brain on the planet, and every animal has deep within it, a clock. And that clock controls the onset and the offset of sleep in a way that we're all familiar with, in that we all tend to wake up and become sleepy at the same time every day.
COSTELLO: Called the circadian clock, it controls the patterns in the brain that tells animals when to go to sleep and when to wake up.
SHAFER: In fact, if you take a human being or a mouse or a fruit fly and you removed them from the cues from the environment, daily cues of light, daily cues of temperature, they continue to show a rhythm in sleep and wakefulness.
COSTELLO: Instead of studying the human brain, Shafer's research focuses on the fruit fly, a common household insect with a tiny brain that offers a lot of clues about what makes the circadian clock tick.
SHAFER: If you think about the human brain, the estimate is that there is one times ten to the eleventh neurons in our brain. That's an impossibly large number of neurons to keep track of. So the fruit fly, its entire nervous system has one hundred thousand neurons.
COSTELLO: Though it may be significantly smaller, the fruit fly's basic brain structure and neural activity is very similar to that of many other animals, including that of humans. In mammals, the brain's primary time-keeper is located in the hypothalamus. Called the suprachiasmatic nucleus, this tiny area of the brain is responsible for setting our master clock.
SHAFER: If you don't have a suprachiasmatic nucleus in your brain, you can't keep time, you have no set rhythm in your sleep activity cycles. That is the master clock in your brain.
COSTELLO: Shafer hopes the fruit fly will help solve how the master clock communicates time throughout the vast network of neurons in the brain.
SHAFER: Where does the time go within the brain? How does that dedicated network of neurons that keeps track of internal time, talk to the parts of the brain that controls sleep?
VICTORIA BOOTH (University of Michigan): You had the model take a nap by just like doing a wake bout like up here...
COSTELLO: Helping in this effort is one of Shafer's colleagues, Dr. Victoria Booth, who is also funded by the National Science Foundation. She uses mathematical modeling and analysis as predictive tools to study the problem through a slightly different perspective.
BOOTH: What we've been motivated by is to actually build a mathematical model based on what the hypothesized network looks like, how these different areas of the brain are connected together.
COSTELLO: By building a mathematical and computational model, Booth and her students will be able to plug in different scenarios of sleep cycles to see how the brain model responds in hopes of further understanding the circadian clock and its control of other parts of the brain.
BOOTH: By building a math model, we could test some of the ideas the experimentalists have about how the system may work, and then identify which areas of the brain might be targets for future experimental investigation.
SHAFER: I'm confident, very confident that the answers we get to those fundamental questions in the fly are going to continue to inform and enrich our attempts to understand timekeeping in the human brain.
COSTELLO: Combining the fields of math and science, Booth and Shafer are unraveling one of the mysteries of the brain: how the circadian clock helps us know when it's time to sleep and when it’s time to wake up.
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