In REM sleep, our eyes move forward and backward, but our body is completely motionless.
We often see Homer Simpson, the main character of The Simpsons series, driving a car, worshipping in a church, and even suddenly falling asleep while working in a nuclear reactor. Although we laugh at these scenes, in fact, narcolepsy, cataplexy, and rapid eye movement (REM) sleep behavior disorder are serious sleep-related diseases.
As seen in Homer Simpson (he was diagnosed with narcolepsy), narcolepsy is characterized as sudden falling asleep at any time of the day, and even in the middle of one's speech. Cataplexy, on the other hand, is a disorder in which people suddenly lose muscle tone and novelize. Although these people are awake, their muscles act as if they are in REM sleep.
REM sleep is a process associated with dreaming. During this phase of sleep, our eyes move forward and backward, but our body is motionless. However, at this stage, neurological disorders in which the body does not remain motionless have been identified.
This condition of almost paralysis of the muscles while dreaming is called REM-atonia, and this condition is missing in people with REM sleep behavior disorder. So these people, instead of being motionless during REM sleep, their muscles move and often go so far as to stand up, jump, shout or punch.
A study published in the Journal of Neuroscience on December 28 (2020), studying mice, identified a special group of neurons in the brain that could be the likely cause of this disorder. According to the study, these cells are located in an area of the brain called the ventral medial medulla and receive input from another area called the sublaterodorsal tegmental nucleus (SLD).
The study found that neurons are connected to neurons that control volitional movements, but not to those that control muscles in the eyes or internal organs. The researchers observed that when these neurons blocked their entry in mice, the mice acted during sleep, just like in a person with REM sleep behavior disorder.
Thinking that this particular group of neurons could be neurons associated with narcolepsy and cataplexy, the researchers tested their hypothesis using a mouse model of narcolepsy, in which cataplexic attacks can be triggered by chocolate. As a result of the tests, cataplexic crises were reduced when ventral medial medulla entry was blocked with SLD.
As seen in Homer Simpson (he was diagnosed with narcolepsy), narcolepsy is characterized as sudden falling asleep at any time of the day, and even in the middle of one's speech. Cataplexy, on the other hand, is a disorder in which people suddenly lose muscle tone and novelize. Although these people are awake, their muscles act as if they are in REM sleep.
REM sleep is a process associated with dreaming. During this phase of sleep, our eyes move forward and backward, but our body is motionless. However, at this stage, neurological disorders in which the body does not remain motionless have been identified.
This condition of almost paralysis of the muscles while dreaming is called REM-atonia, and this condition is missing in people with REM sleep behavior disorder. So these people, instead of being motionless during REM sleep, their muscles move and often go so far as to stand up, jump, shout or punch.
A study published in the Journal of Neuroscience on December 28 (2020), studying mice, identified a special group of neurons in the brain that could be the likely cause of this disorder. According to the study, these cells are located in an area of the brain called the ventral medial medulla and receive input from another area called the sublaterodorsal tegmental nucleus (SLD).
The study found that neurons are connected to neurons that control volitional movements, but not to those that control muscles in the eyes or internal organs. The researchers observed that when these neurons blocked their entry in mice, the mice acted during sleep, just like in a person with REM sleep behavior disorder.
Thinking that this particular group of neurons could be neurons associated with narcolepsy and cataplexy, the researchers tested their hypothesis using a mouse model of narcolepsy, in which cataplexic attacks can be triggered by chocolate. As a result of the tests, cataplexic crises were reduced when ventral medial medulla entry was blocked with SLD.
In general, experiments showed that these specific circuits control muscle atony in both REM sleep and cataplex Nov. This suggests that glycinergic neurons identified in the ventral medial medulla may be a good target for drug treatments that can be developed for people with narcolepsy, cataplexy, or REM sleep behavior disorder. For the next step, the researchers plan to study how emotions known to trigger cataplexy can affect these neurons.