(Press-News.org) The ability to learn associations between events is critical for survival, but it has not been clear how different pieces of information stored in memory may be linked together by populations of neurons. In a study published April 2nd in Cell Reports, synchronous activation of distinct neuronal ensembles caused mice to artificially associate the memory of a foot shock with the unrelated memory of exploring a safe environment, triggering an increase in fear-related behavior when the mice were re-exposed to the non-threatening environment. The findings suggest that co-activated cell ensembles become wired together to link two distinct memories that were previously stored independently in the brain.
"Memory is the basis of all higher brain functions, including consciousness, and it also plays an important role in psychiatric diseases such as post-traumatic stress disorder," says senior study author Kaoru Inokuchi of the University of Toyama. "By showing how the brain associates different types of information to generate a qualitatively new memory that leads to enduring changes in behavior, our findings could have important implications for the treatment of these debilitating conditions."
Recent studies have shown that subpopulations of neurons activated during learning are reactivated during subsequent memory retrieval, and reactivation of a cell ensemble triggers the retrieval of the corresponding memory. Moreover, artificial reactivation of a specific neuronal ensemble corresponding to a pre-stored memory can modify the acquisition of a new memory, thereby generating false or synthetic memories. However, these studies employed a combination of sensory input and artificial stimulation of cell ensembles. Until now, researchers had not linked two distinct memories using completely artificial means.
With that goal in mind, Inokuchi and Noriaki Ohkawa of the University of Toyama used a fear-learning paradigm in mice followed by a technique called optogenetics, which involves genetically modifying specific populations of neurons to express light-sensitive proteins that control neuronal excitability, and then delivering blue light through an optic fiber to activate those cells. In the behavioral paradigm, one group of mice spent six minutes in a cylindrical enclosure while another group explored a cube-shaped enclosure, and 30 minutes later, both groups of mice were placed in the cube-shaped enclosure, where a foot shock was immediately delivered. Two days later, mice that were re-exposed to the cube-shaped enclosure spent more time frozen in fear than mice that were placed back in the cylindrical enclosure.
The researchers then used optogenetics to reactivate the unrelated memories of the safe cylinder-shaped environment and the foot shock. Stimulation of neuronal populations in memory-related brain regions called the hippocampus and amygdala, which were activated during the learning phase, caused mice to spend more time frozen in fear when they were later placed back in the cylindrical enclosure, as compared with stimulation of neurons in either the hippocampus or amygdala, or no stimulation at all.
The findings show that synchronous activation of distinct cell ensembles can generate artificial links between unrelated pieces of information stored in memory, resulting in long-lasting changes in behavior. "By modifying this technique, we will next attempt to artificially dissociate memories that are physiologically connected," Inokuchi says. "This may contribute to the development of new treatments for psychiatric disorders such as post-traumatic stress disorder, whose main symptoms arise from unnecessary associations between unrelated memories."
INFORMATION:
Cell Reports, Ohkawa et al.: "Artificial Association of Pre-Stored Information to Generate a Qualitatively New Memory"
Cell Reports, published by Cell Press, is a weekly open-access journal that publishes high-quality papers across the entire life sciences spectrum. The journal features reports, articles, and resources that provide new biological insights, are thought-provoking, and/or are examples of cutting-edge research. For more information, please visit http://www.cell.com/cell-reports. To receive media alerts for Cell Reports or other Cell Press journals, contact press@cell.com.
(Boston)--Using patient-derived stem cells known as induced pluripotent stem cells (iPSC) to study the genetic lung/liver disease called alpha-1 antitrypsin (AAT) deficiency, researchers have for the first time created a disease signature that may help explain how abnormal protein leads to liver disease.
The study, which appears in Stem Cell Reports, also found that liver cells derived from AAT deficient iPSCs are more sensitive to drugs that cause liver toxicity than liver cells derived from normal iPSCs. This finding may ultimately lead to new treatments for the condition.
IPSC's ...
Capitalizing on a rare opportunity to thoroughly analyze a tumor from a lung cancer patient who had developed resistance to targeted drug treatment, UC San Francisco scientists identified a biological escape hatch that explains the resistance, and developed a strategy in mice for shutting it down.
In experiments that combined the drug the patient had taken with a second compound that blocks off this newly discovered resistance pathway, the researchers were able to durably wipe out cancer cells in mice implanted with cells from the drug-resistant tumor.
"Even in cancers ...
CANCER RESEARCH UK scientists have discovered that a vital self-destruct switch in cells is hijacked - making some pancreatic and non small cell lung cancers more aggressive, according to research published in Cancer Cell today (Thursday)*.
The team, from the Cancer Research UK Centre at the UCL (University College London) Cancer Institute, found that mutations in the KRAS gene interferes with protective self-destruct switches, known as TRAIL receptors, which usually help to kill potentially cancerous cells.
The research, carried out in cancer cells and mice, shows ...
Researchers have identified a new genetic mutation at the heart of a severe and potentially deadly seizure disorder found in infants and young children. The finding, which was reported today in the journal American Journal of Human Genetics, may help scientists unravel the complex biological mechanism behind these diseases.
"These findings allow us to open up what was, up to this point, a 'black box' and more fully understand the biological pathways associated with these disorders and why some individuals do not respond to treatment," said Alex Paciorkowski, M.D., an ...
In one of the first studies to examine the potential for using municipal wastewater as a feedstock for algae-based biofuels, Rice University scientists found they could easily grow high-value strains of oil-rich algae while simultaneously removing more than 90 percent of nitrates and more than 50 percent of phosphorous from wastewater.
The findings, which are based on a five-month study at a wastewater treatment facility in Houston, are available online in the journal Algae.
"Biofuels were the hot topic in algaculture five years ago, but interest cooled as the algae ...
WASHINGTON --Two new studies, published online Tuesday in Annals of Emergency Medicine, illustrate the power of social media and the Internet to promote scholarly dialogue around the world and the importance of establishing criteria for what constitutes high-quality blogs and podcasts ("Global Emergency Medicine Journal Club: A Social Media Discussion About the ADJUST-PE Trial" and "Emergency Medicine and Critical Care Blogs and Podcasts: Establishing an International Consensus on Quality").
"Our Global Emergency Medicine Journal Club creates a virtual space to allow ...
Highly pathogenic avian influenza (HPAI) H5 viruses of Eurasian origin continue to circulate and evolve in North American wild birds.
The U.S. Geological Survey and U.S. Department of Agriculture published the genetic analysis of a mixed-origin HPAI H5N1 avian flu virus in the journal Genome Announcements today. This novel virus was discovered in a green-winged teal in Washington State that was sampled at the end of 2014. It is a mixed-origin virus containing genes from the Eurasian HPAI H5N8 and genes from North American low pathogenic avian influenza from wild birds. ...
BUFFALO, N.Y. - Shred a document, and you can piece it back together. Burn a book, and you could theoretically do the same. But send information into a black hole, and it's lost forever.
That's what some physicists have argued for years: That black holes are the ultimate vaults, entities that suck in information and then evaporate without leaving behind any clues as to what they once contained.
But new research shows that this perspective may not be correct.
"According to our work, information isn't lost once it enters a black hole," says Dejan Stojkovic, PhD, associate ...
Researchers found that consuming the fish herring and mackerel, as well as three kinds of fish oils, raised blood levels of the fatty acid 16:4(n-3), which experiments in mice suggest may induce resistance to chemotherapy used to treat cancer, according to a study published online by JAMA Oncology.
Patients with cancer often adopt lifestyle changes and those changes often include the use of supplements. But there is growing concern about the use of supplements while taking anticancer drugs and the possible effect on treatment outcomes, according to the study background.
Emile ...
COLUMBUS, Ohio - A study of 4,500 U.S. children over 20 years has identified a single test that can predict which kids will become nearsighted by the eighth grade: a measure of their current refractive error.
The refractive error, or eyeglasses prescription, results from mismatches in the size and optical power of the eye that lead to blurry vision.
The study also counters the notion that near work such as frequent reading or sitting too close to the television can bring on myopia, or nearsightedness.
"Near work has been thought to be a cause of myopia, or at least ...
