Cerebral Hemispheres 2

NEUROSCIENTIFICALLY CHALLENGED

NEUROSCIENCE MADE SIMPLER

Sweet Dreams, C. Elegans

February 6, 2008


Sleep is sometimes a vexing subject for scientists. We spend about 1/3 of our lives doing it. Yet, despite all the progress that has been made in discovering the reasons behind myriad other human behaviors, there is still no consensus on why we sleep. Some believe it has a recuperative effect on the body, allowing energy stores to be replenished. While a good night’s sleep may certainly allow us to feel more rested, this theory doesn’t explain the necessity of sleep, as the same result presumably could be obtained by lying still for eight hours. Others suggest sleep is an evolved, adaptive behavior that protected our ancestors from too much activity during the night—a dangerous time due to their inability to spot nocturnal predators. This also is an unsatisfying concept for several reasons, one being that some animals have evolved methods to enable sleep even though the act itself puts them in danger (e.g. bottlenose dolphin). Another hypothesis is that sleep is a necessary part of memory consolidation and mental functioning. While there is a great deal of debate over the particulars of this theory, it has more evidential support than the other two hypotheses.

Researchers at University of Pennsylvania School of Medicine are hoping to learn more about the purpose of sleep by studying Caenorhabditis elegans, a roundworm used as a model organism for many of the same reasons I outlined in my post about drosophila research. The group is the first to show that nematodes do experience sleep. They discovered a period in the worm’s development, which they termed lethargus, that is similar to sleep in other animals. The fact that sleep can be found in organisms so evolutionarily distant from us is further support for the idea that sleep is necessary, and not just an evolved, adaptive behavior.

But the changes that occur in the worm during lethargus may also give some clues as to the purpose of sleep. While C. elegans is in this phase of quiescence, numerous synaptic modifications take place within its nervous system. Thus, the researchers at Penn postulate that lethargus is a period in roundworm development that is necessary for nervous system growth. As synaptic changes occur during sleep in mammals as well, this lends support to the idea that sleep is necessary for proper brain functioning and development.

The group also identified a gene in C. elegans that regulates sleep. It has a human homologue that, although previously known, has not been studied in relation to sleep. The researchers hope these findings in the roundworm will eventually provide insight into the human sleep process and bring us closer to solving the mystery of why we spend so much of our lives in a seemingly nonproductive state.

YOUR BRAIN, EXPLAINED

Sleep. Memory. Pleasure. Fear. Language. We experience these things every day, but how do our brains create them? Your Brain, Explained is a personal tour around your gray matter. Building on neuroscientist Marc Dingman’s popular YouTube series, 2-Minute Neuroscience, this is a friendly, engaging introduction to the human brain and its quirks using real-life examples and Dingman’s own, hand-drawn illustrations.

  • An informative, accessible and engaging book for anyone who has even the slightest interest in how the brain works, but doesn’t know where to begin. - Dean Burnett, PhD, author, Happy Brain and Idiot Brain

  • Reading like a collection of detective stories, Your Brain, Explained combines classic cases in the history of neurology with findings stemming from the latest techniques used to probe the brain’s secrets. - Stanley Finger, PhD, Professor Emeritus of Psychological & Brain Sciences, Washington University (St. Louis), author, Origins of Neuroscience

  • Dingman weaves classic studies with modern research into easily digestible sections, to provide an excellent primer on the rapidly advancing field of neuroscience. - Moheb Costandi, author, Neuroplasticity and 50 Human Brain Ideas You Really Need to Know

  • ...a highly readable and accessible introduction to the operation of the brain and current issues in neuroscience... a wonderful introduction to the field. - Frank Amthor, PhD, Professor of Psychology, The University of Alabama at Birmingham, author, Neuroscience for Dummies