Post Reply 
[News] Scientists: Sleep Weakens, Not Strengthens, Brain Synaptic Connections
Author Message
ApneaNews Offline
Apnea News Correspondent
Advisory Members

Posts: 170
Joined: Feb 2012

Machine: IBM Selectric II
Mask Type: Full face mask
Mask Make & Model: 3M N95 (it gets dusty in the newsroom)
Humidifier: Sears Kenmore (circa 1979)
CPAP Pressure: 3200 psi
CPAP Software: Other Software

Other Comments: I report, therefore I am.

Sex: Undisclosed
Location: In the newsroom (where else?)

Post: #1
Scientists: Sleep Weakens, Not Strengthens, Brain Synaptic Connections
Sleep Weakens, Not Strengthens, Brain Synaptic Connections, Two Scientists Argue

Two sleep scientists from the University of Wisconsin School of Medicine and Public Health say their synaptic homeostasis hypothesis (SHY) of sleep challenges the theory that sleep strengthens brain connections.

The SHY hypothesis, which takes into account years of evidence from human and animal studies, says sleep is important because it weakens the connections among brain cells to save energy, avoid cellular stress, and maintain the ability of neurons to respond selectively to stimuli.

“Sleep is the price the brain must pay for learning and memory,” says Dr Giulio Tononi, of the UW Center for Sleep and Consciousness, in a release. “During wake, learning strengthens the synaptic connections throughout the brain, increasing the need for energy and saturating the brain with new information. Sleep allows the brain to reset, helping integrate newly learned material with consolidated memories, so the brain can begin anew the next day.”

Tononi and co-author Dr Chiara Cirelli, both professors of psychiatry, explain their hypothesis in a review article in the journal Neuron. Their laboratory studies sleep and consciousness in animals ranging from fruit flies to humans; SHY takes into account evidence from molecular, electrophysiological, and behavioral studies, as well as from computer simulations. ”Synaptic homeostasis” refers to the brain’s ability to maintain a balance in the strength of connections within its nerve cells.

Why would the brain need to reset? Suppose someone spent their waking hours learning a new skill, such as riding a bike. The circuits involved in learning would be greatly strengthened, but the next day the brain will need to pay attention to learning a new task. Thus, those bike-riding circuits would need to be damped down so they don’t interfere with the new day’s learning.

“Sleep helps the brain renormalize synaptic strength based on a comprehensive sampling of its overall knowledge of the environment,” Tononi says, “rather than being biased by the particular inputs of a particular waking day.”

The reason we don’t also forget how to ride a bike after a night’s sleep is because those active circuits are damped down less than those that weren’t actively involved in learning. Indeed, there is evidence that sleep enhances important features of memory, including acquisition, consolidation, gist extraction, integration, and “smart forgetting,” which allows the brain to rid itself of the inevitable accumulation of unimportant details.

However, one common belief is that sleep helps memory by further strengthening the neural circuits during learning while awake. But Tononi and Cirelli believe that consolidation and integration of memories, as well as the restoration of the ability to learn, all come from the ability of sleep to decrease synaptic strength and enhance signal-to-noise ratios.

While the review finds testable evidence for the SHY hypothesis, it also points to open issues. One question is whether the brain could achieve synaptic homeostasis during wake, by having only some circuits engaged, and the rest off-line and thus resetting themselves.

Other areas for future research include the specific function of REM sleep (when most dreaming occurs) and the possibly crucial role of sleep during development, a time of intense learning and massive remodeling of the brain.

Fair Use from:

The above post may contain copyrighted material the use of which has not always been specifically authorized by the copyright owner. The material available is intended to advance the understanding of Sleep Apnea treatment and to advance the educational level of Sleep Apnea patients with regard to their health. Sometimes included is the full text of articles and documents rather than a simple link because outside links frequently "go bad" or change over time. This constitutes a "fair use" of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material in this post is distributed without fee or payment of any kind for research and educational purposes. If you wish to use copyrighted material from this post for purposes of your own that go beyond "fair use", you must obtain permission from the copyright owner.
02-19-2014 07:13 PM
Find all posts by this user Post Reply Quote this message in a reply

Donate to Apnea Board
JJJ Offline

Advisory Members

Posts: 751
Joined: Apr 2012

Machine: ResMed S9 Autoset
Mask Type: Nasal mask
Mask Make & Model: Most recent: Wisp, Pilairo, Mirage Vista
Humidifier: ResMed S9 Autoset
CPAP Pressure: 17-20
CPAP Software: SleepyHead

Other Comments:

Sex: Male
Location: USA 97217

Post: #2
RE: Scientists: Sleep Weakens, Not Strengthens, Brain Synaptic Connections
I am currently studying ancient Greek, a subject that requires massive amounts of mindless memorization. The most painless way for me to memorize a list of vocabulary words or a new inflection paradigm is to review everything just before going to bed. When I get up in the morning I find that it is mostly memorized, and effortlessly. Furthermore, if there is going to be a quiz in class the next morning, the best way to improve my grade is to get a good night's sleep.

I don't know what these people think their study proves, but the brain definitely does better in many ways when it gets good sleep.
02-19-2014 10:51 PM
Find all posts by this user Post Reply Quote this message in a reply
Post Reply 

Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  [News] "Sleep apnea takes a toll on brain function" [Science Daily, new study results] WakeUpTime 2 772 02-12-2016 10:17 PM
Last Post: Sleepster
Question Hyper active brain and sleep Barbz 12 1,967 06-20-2015 10:33 PM
Last Post: PaulaO2
  Mask/hose/machine connections Cygnus 8 1,589 06-10-2015 06:57 PM
Last Post: Cygnus
  Brain Fog jeffbrdr 9 3,130 02-19-2015 01:00 PM
Last Post: jeffbrdr
Question is my machine brain damaged? frogprinsce 9 1,818 02-27-2014 08:59 AM
Last Post: JWR
  [News] Scientists Identify Sleep Switch ApneaNews 0 737 02-26-2014 10:19 AM
Last Post: ApneaNews
  [News] Study: Women with sleep apnea have higher degree of brain damage than men SuperSleeper 1 1,408 12-03-2012 11:07 PM
Last Post: zonk

Forum Jump:

Who's Online (Complete List)