Study identifies how muscles are paralyzed during sleep

July 11, 2012

Two powerful brain chemical systems work together to paralyze skeletal muscles during rapid eye movement (REM) sleep, according to new research in the July 11 issue of The Journal of Neuroscience. The finding may help scientists better understand and treat sleep disorders, including narcolepsy, tooth grinding, and REM sleep behavior disorder.

During REM — the deep sleep where most recalled dreams occur — your eyes continue to move but the rest of the body's muscles are stopped, potentially to prevent injury. In a series of experiments, University of Toronto neuroscientists Patricia L. Brooks and John H. Peever, PhD, found that the neurotransmitters gamma-aminobutyric acid (GABA) and glycine caused REM sleep paralysis in rats by "switching off" the specialized cells in the brain that allow muscles to be active. This finding reversed earlier beliefs that glycine was a lone inhibitor of these motor neurons.

"The study's findings are relevant to anyone who has ever watched a sleeping pet twitch, gotten kicked by a bed partner, or has known someone with the sleep disorder narcolepsy," said Dennis J. McGinty, PhD, a behavioral neuroscientist and sleep researcher at the University of California, Los Angeles, who was not involved in the study. "By identifying the neurotransmitters and receptors involved in sleep-related paralysis, this study points us to possible molecular targets for developing treatments for sleep-related motor disorders, which can often be debilitating," he said

The researchers measured electrical activity in the facial muscles responsible for chewing of sleeping rats. Brain cells called trigeminal motor neurons communicate the brain's message to move to these muscles. Previous research suggested neurotransmitter receptors called ionotropic GABAA/glycine receptors in the motor neurons caused REM sleep paralysis. However, when the researchers blocked these receptors, REM sleep paralysis still occurred.

The researchers found that to prevent REM sleep paralysis, they had to block both the ionotropic receptors and metabotropic GABAB receptors, a different receptor system. In other words, when the motor cells were cut off from all sources of GABA and glycine, the paralysis did not occur, allowing the rats to exhibit high levels of activity when their muscles should have been inactive. The data suggest the two neurotransmitters must both be present together to maintain motor control during sleep, rather than working separately.

The finding could be especially helpful for those with REM sleep disorder, a disease that causes people to act out their dreams. This can cause serious injuries to patients and others around them. It is also often an early indicator of neurodegenerative diseases, such as Parkinson's.

"Understanding the precise mechanism behind these chemicals' role in REM sleep disorder is particularly important because about 80 percent of people who have it eventually develop a neurodegenerative disease, such as Parkinson's disease," study author Peever added. " behavior disorder could be an early marker of these diseases, and curing it may help prevent or even stop their development," he said.

Explore further: Potential cause of severe sleep disorder discovered, implications for Parkinson's disease

Related Stories

Potential cause of severe sleep disorder discovered, implications for Parkinson's disease

June 15, 2011
Researchers at the University of Toronto are the first to indentify a potential cause for a severe sleep disorder that has been closely linked to Parkinson's disease and other neurodegenerative diseases.

Smoking, head injury, pesticide use may be risk factors for rare sleep disorder

June 27, 2012
Smoking, head injury, pesticide exposure, farming and less education may be risk factors for a rare sleep disorder that causes people to kick or punch during sleep, according to a study published in the June 27, 2012, online ...

Inducing non-REM sleep in mice by novel optogenetical control technique

July 20, 2011
Recently, optogenetics, which controls the activity of neuron using the light-activated protein, has been getting a lot of attention. This light-activated protein works like a switch of neurons by sensing specific color of ...

REM sleep behavior disorder is a risk factor for Parkinson's disease

July 29, 2011
Patients suffering REM sleep behaviour disorders dream nightmares in which they are attacked and pursued, with the particularity that they express them by screaming, crying, punching and kicking while sleeping. Lancet Neurology ...

Recommended for you

Scientists discover common obesity and diabetes drug reduces rise in brain pressure

August 23, 2017
Research led by the University of Birmingham, published today in Science Translational Medicine, has discovered that a drug commonly used to treat patients with either obesity or Type II diabetes could be used as a novel ...

Use of brain-computer interface, virtual avatar could help people with gait disabilities

August 23, 2017
Researchers from the University of Houston have shown for the first time that the use of a brain-computer interface augmented with a virtual walking avatar can control gait, suggesting the protocol may help patients recover ...

Researcher working to develop new tool for non-invasive neuromodulation of human brain

August 23, 2017
A UTA researcher is developing a technology that will map and image the effects of infrared light shone on the human brain that may be able to modulate and improve brain waves and circuits at certain spots in the brain.

Physicist reports binary marker of preclinical and clinical Alzheimer's disease

August 23, 2017
A new technique shows high potential for providing a discrete, non-invasive biomarker of Alzheimer's disease (AD) at the individual level during both preclinical and clinical stages. The proposed biomarker has a large effect ...

Firing of neurons changes the cells that insulate them

August 22, 2017
Through their pattern of firing, neurons influence the behavior of the cells that upon maturation will provide insulation of neuronal axons, according to a new study publishing 22 August in the open access journal PLOS Biology ...

Activating brain region creates intense desire to use cocaine

August 22, 2017
Researchers have identified a portion of the brain that intensifies one's desire for certain rewards—in this case, mimicking addiction to cocaine.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.