Summary: Researchers have found that sleep deprivation can mask rather than erase memories in mice and that these memories can be restored with existing drugs. Research shows that roflumilast, an asthma drug, can restore social memories, while vardenafil, an erectile dysfunction drug, can restore spatial memories.
These findings suggest new treatments for sleep-deprived memory loss. The research holds promise for developing human therapies to recover lost memories.
Key facts:
- Sleep deprivation obscures rather than erases social and spatial memories in mice.
- Roflumilast and vardenafil have been used to successfully restore these hidden memories.
- The research shows potential for developing treatments for human memory loss.
Source: FENS
A study in mice presented today (Friday) at the Federation of European Neuroscience Societies (FENS) Forum 2024 shows that the loss of social memories caused by sleep deprivation can be reversed using existing drugs.
Lack of sleep is known to affect memory in rats and humans, but studies show that these memories do not disappear, they are ‘hidden’ in the brain and difficult to retrieve.
The new study shows that these otherwise hidden social memories can be restored in mice with a drug used to treat asthma and chronic obstructive pulmonary disease. A team of researchers has shown that another drug currently used to treat erectile dysfunction can restore spatial memories.
Researchers say spatial memories in these mice are similar to remembering where people put their keys, but social memories can be compared to remembering a new person you meet.
The study was presented by Dr. Robert Hackes at the University of Groningen in the Netherlands. “Ever since I started as a PhD student several years ago, I was amazed to see how sleep deprivation can have a profound effect on memory and the brain as a whole.
“The first work published years ago helped us identify some of the molecular mechanisms that underlie dementia.
“By manipulating these pathways specifically in the hippocampus, we were able to counteract the negative effects of sleep deprivation on memory processes. In our new study, we investigated whether we can reverse the loss of memory after the initial learning event and a period of sleep deprivation.”
New research presented at the FENS Forum and funded by the Air Force Office of Scientific Research (AFOSR) was conducted by Dr. Hicks’ PhD students, Aditya Sarma and Camilla Parasiani, who will present their work in a poster presentation.
To study social memory in the lab, the researchers gave rats the chance to choose between meeting a rat they had never met before or a sibling from their own home.
Under normal conditions, the rats preferred to interact with the new rat over their already familiar littermates. When the same choice is made the next day, both rats are now considered familiar and interact with both their littermates and the rats they met the day before at the same rate.
However, if the mice were sleep-deprived after the first encounter, the next day they still preferred to meet the new mouse as if they had never encountered it before. These findings suggest that they cannot easily recall their previous findings.
The team was able to permanently restore these hidden social memories, first using a technique called optogenetic engram technology. Together, this technique allows them to identify neurons in the brain that form a memory (known as a memory engram) and change those neurons with light.
Researchers can use light to reactivate this special group of neurons, which is responsible for remembering a certain experience (in this case, social memory).
They were also able to restore the mice’s social memory with roflumilast, a type of anti-inflammatory drug approved by the US Food and Drug Administration to treat chronic obstructive pulmonary disease.
Dr. Hewes says the discovery is particularly exciting because it provides a platform for studying sleep deprivation and memory in humans, and he is now starting a human study in collaboration with another research group.
Similarly, researchers have investigated the loss of spatial memory caused by sleep deprivation by studying the ability of rats to learn and remember the location of individual objects.
A brief sleep deprivation after training meant that the rats could not remember the original location of the object and did not notice when an object moved to a new location during testing.
As with social memories, access to these spatial memories can be restored by treating rats with vardenafil, a drug currently used to treat erectile dysfunction. This is the second drug approved by the US Food and Drug Administration that researchers have successfully used to reverse dementia in mice.
Dr. Hewes said: “We were able to show that lack of sleep leads to a loss of memory in certain spatial and social recognition memories. This amnesia can be reversed days after the first learning experience and sleep deprivation using drugs previously approved for human consumption.
“Now we want to focus on understanding what the underlying processes are for these accessible and inaccessible memories. In the long term, we hope that these basic studies will pave the way for human studies aimed at reversing forgetting by restoring other inaccessible information in the brain.”
Professor Richard Roche is Chair of the FENS Forum Communications Committee and Deputy Head of the Department of Psychology at the University of Maynooth, Maynooth County Kildare, Ireland and was not involved in the research.
He said: “This study shows that it is possible to recover social and spatial memories that seem to have been lost due to sleep deprivation. Although these studies were conducted in mice, they suggest that it is possible to restore lost social and spatial memories in humans using some drug treatments previously approved for use in humans.
“There are many situations where people don’t get enough sleep, so this area of research has clear potential. However, moving this research from mice to humans will take time and a lot of work.”
So sleep, memory and neuropharmacology research news
Author: Kerry Noble
Source: FENS
Contact: Kerry Noble – FENS
Image: Image credited to Neuroscience News.
Preliminary study: The findings were presented at the FENS Forum 2024.