A study published yesterday reports that the role of sleep in memory consolidation has been confirmed.
The study involved mice that ran a maze and then slept. Electrodes monitored their brain activity. While awake the brains of the mice “mapped” the pattern of the maze. Results show that their brains “replayed” this pattern during slow-wave sleep.
"Ours is the first study to demonstrate this link between memory replay and memory consolidation,” study co-author Susumu Tonegawa said in an MIT statement. “The sleeping brain must replay experiences like video clips before they are transformed from short-term into long-term memories."
The study identified a specific circuit in the brain that is involved in this process - the “trisynaptic pathway.” It is located in the “hippocampus.” This is a complex brain structure that is shaped like a seahorse.
In some of the mice the trisynaptic pathway was blocked. This impaired the replay process during sleep. Only mice with a functioning trisynaptic pathway were able to form long-term memories of the maze.
"We demonstrated that this pathway is crucial for the transformation of a recent memory, formed within a day, to a remote memory that still exists at least six weeks later," Tonegawa said.
Read more about sleep and memory on the Sleep Education Blog. Learn more about the stages of sleep on SleepEducation.com.
Showing posts with label memories. Show all posts
Showing posts with label memories. Show all posts
Friday, June 26, 2009
Saturday, May 23, 2009
Sleep & Memory: “That Face Looks Familiar”
Studies show that there is a strong link between sleep and memory. A new study even examines how sleep affects memory for face identity. Does sleep help you recognize a familiar face?
The study involved 112 volunteers; their average age was 25 years. Each participant was shown 60 computer-generated faces in random order.
The heads were bald, and the faces had no unique features such as a mole or a scar. Each face was shown on a computer screen for two seconds at a time. The entire set of faces was shown five times.
Recognition was tested after varying periods of time. Some people were tested after getting sleep; others were tested before getting any sleep. Sixty faces were shown; 30 faces had been seen earlier, and 30 were new faces that had never been seen before.
The results do not show that sleep enhances memory strength. But they do suggest that time spent awake during the retention period impairs memory for face identity.
Wakefulness of 12 hours or more had a detrimental impact on recognition memory strength; it made participants less likely to feel familiar with a test face.
The authors suggest that ongoing sensory stimulation when awake may interfere with visual memory. Sleep may not actively enhance visual memory; but it may temporarily prevent memory loss by “sheltering” visual memory from interference.
Read the full text of the study online.
The study involved 112 volunteers; their average age was 25 years. Each participant was shown 60 computer-generated faces in random order.
The heads were bald, and the faces had no unique features such as a mole or a scar. Each face was shown on a computer screen for two seconds at a time. The entire set of faces was shown five times.
Recognition was tested after varying periods of time. Some people were tested after getting sleep; others were tested before getting any sleep. Sixty faces were shown; 30 faces had been seen earlier, and 30 were new faces that had never been seen before.
The results do not show that sleep enhances memory strength. But they do suggest that time spent awake during the retention period impairs memory for face identity.
Wakefulness of 12 hours or more had a detrimental impact on recognition memory strength; it made participants less likely to feel familiar with a test face.
The authors suggest that ongoing sensory stimulation when awake may interfere with visual memory. Sleep may not actively enhance visual memory; but it may temporarily prevent memory loss by “sheltering” visual memory from interference.
Read the full text of the study online.
Saturday, April 11, 2009
Sleep and Memory: Survival of the Fittest?
An article in the April issue of The Scientist takes an in-depth look at a new theory about sleep and memory.
The theory proposes that sleep’s core function is to prune the synapses formed when you are awake. Only the strongest neuronal connections “survive.”
Thus the most important connections remain; unimportant connections are eliminated. This pruning process boosts learning and memory.
The article addresses a number of questions about the theory.
Will it replace the theory that the purpose of sleep is to replay memories and “consolidate” them? What role does slow-wave sleep play in this process? What about rapid eye movement (REM) sleep? And where do memory patterns fit in – are specific memories reactivated and reorganized during sleep?
Also, how does the theory align with another study published in February? That study suggests that sleep strengthens connections instead of weakening them.
Read the article to find out more.
The theory proposes that sleep’s core function is to prune the synapses formed when you are awake. Only the strongest neuronal connections “survive.”
Thus the most important connections remain; unimportant connections are eliminated. This pruning process boosts learning and memory.
The article addresses a number of questions about the theory.
Will it replace the theory that the purpose of sleep is to replay memories and “consolidate” them? What role does slow-wave sleep play in this process? What about rapid eye movement (REM) sleep? And where do memory patterns fit in – are specific memories reactivated and reorganized during sleep?
Also, how does the theory align with another study published in February? That study suggests that sleep strengthens connections instead of weakening them.
Read the article to find out more.
Friday, April 3, 2009
Sleep & Memory: Lessons from Fruit Flies
Two new studies in the journal Science use fruit flies to examine the link between sleep and memory.
One study shows that the connections between nerve cells in the brain increase during the day. Then these “synapses” decline during sleep. This reduction of synapses is prevented by sleep deprivation.
This suggests that sleep may “prune” less important connections. This may create space for the brain to store more important memories.
Author Paul Shaw said in a statement that these results have practical implications.
“These data suggest the best thing you can do to make sure you stay sharp…is to make getting enough sleep a top priority," he said.
Another study used three-dimensional photos to look at protein levels in the brains of fruit flies. It focused on proteins that carry messages in the synapses between neurons.
These protein levels dropped by 30 percent to 40 percent during sleep. But the same proteins accumulated in the brains of fruit flies that were deprived of sleep by a “fly agitator.”
This suggests that sleep “resets” the brain. It empties the junk mail from the previous day. This prepares the brain for more learning the next day.
"Much of what we learn in a day, we don't really need to remember," author Chiara Cirelli said in a statement. "If you've used up all the space, you can't learn more before you clean out the junk that is filling up your brain."
But can we really learn about ourselves by studying fruit flies? Why are they useful study subjects? And how do we study them anyway?
A TIME article provides some useful insights. Fruit flies are simple enough to study. But with a genome that has 14,000 genes, they are more complex than you may think.
One study shows that the connections between nerve cells in the brain increase during the day. Then these “synapses” decline during sleep. This reduction of synapses is prevented by sleep deprivation.
This suggests that sleep may “prune” less important connections. This may create space for the brain to store more important memories.
Author Paul Shaw said in a statement that these results have practical implications.
“These data suggest the best thing you can do to make sure you stay sharp…is to make getting enough sleep a top priority," he said.
Another study used three-dimensional photos to look at protein levels in the brains of fruit flies. It focused on proteins that carry messages in the synapses between neurons.
These protein levels dropped by 30 percent to 40 percent during sleep. But the same proteins accumulated in the brains of fruit flies that were deprived of sleep by a “fly agitator.”
This suggests that sleep “resets” the brain. It empties the junk mail from the previous day. This prepares the brain for more learning the next day.
"Much of what we learn in a day, we don't really need to remember," author Chiara Cirelli said in a statement. "If you've used up all the space, you can't learn more before you clean out the junk that is filling up your brain."
But can we really learn about ourselves by studying fruit flies? Why are they useful study subjects? And how do we study them anyway?
A TIME article provides some useful insights. Fruit flies are simple enough to study. But with a genome that has 14,000 genes, they are more complex than you may think.
Monday, January 19, 2009
Preventing Nightmares and PTSD Flashbacks with Tetris
A new study in the online journal PLoS ONE shows that playing the computer game Tetris can reduce unwanted “flashbacks.”
This is promising for people who suffer from post-traumatic stress disorder (PTSD). Could it also help other people who suffer from nightmares?
The study involved 40 people who watched a traumatic, 12-minute film. It contained scenes of real injury and death.
After a 30-minute break, half of the group played Tetris for 10 minutes. The other half sat quietly.
Flashbacks were monitored for one week using a daily diary. Subjects then returned to the lab for an assessment.
Results show that Tetris players had significantly fewer flashbacks. They also had fewer clinical symptoms of trauma.
At the one-week follow up, both groups scored the same on a recognition memory test for the film. This indicates that voluntary recall was similar between the groups. It was the rate of involuntary memories – flashbacks – that was different.
Tetris requires you to arrange a falling puzzle of colorful block-like shapes. The authors told Reuters that the visual aspect of the game may compete with the traumatic, visual memories. It may interfere with how your mind forms and stores the memories.
One of the study’s authors noted that you have about six hours to affect memories before they are stored in the brain. Any type of intervention needs to be done in this window of time.
The AASM reports that nightmares tend to be the most disturbing aspect of PTSD. Often the dreams involve a flashback to the event that seems shockingly real.
Potential implications of the study also extend beyond PTSD. It suggests that a visual distraction like Tetris could reduce nightmares for anyone after a stressful event.
It could be especially helpful for children who are prone to having nightmares after seeing a scary movie or other distressing images.
This is promising for people who suffer from post-traumatic stress disorder (PTSD). Could it also help other people who suffer from nightmares?
The study involved 40 people who watched a traumatic, 12-minute film. It contained scenes of real injury and death.
After a 30-minute break, half of the group played Tetris for 10 minutes. The other half sat quietly.
Flashbacks were monitored for one week using a daily diary. Subjects then returned to the lab for an assessment.
Results show that Tetris players had significantly fewer flashbacks. They also had fewer clinical symptoms of trauma.
At the one-week follow up, both groups scored the same on a recognition memory test for the film. This indicates that voluntary recall was similar between the groups. It was the rate of involuntary memories – flashbacks – that was different.
Tetris requires you to arrange a falling puzzle of colorful block-like shapes. The authors told Reuters that the visual aspect of the game may compete with the traumatic, visual memories. It may interfere with how your mind forms and stores the memories.
One of the study’s authors noted that you have about six hours to affect memories before they are stored in the brain. Any type of intervention needs to be done in this window of time.
The AASM reports that nightmares tend to be the most disturbing aspect of PTSD. Often the dreams involve a flashback to the event that seems shockingly real.
Potential implications of the study also extend beyond PTSD. It suggests that a visual distraction like Tetris could reduce nightmares for anyone after a stressful event.
It could be especially helpful for children who are prone to having nightmares after seeing a scary movie or other distressing images.
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