Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Shining a light on memory


It's all about strengthened connections between neurons, NIH-funded study confirms

Using a flash of light, scientists have inactivated and then reactivated a memory in genetically engineered rats. The study, supported by the National Institutes of Health, is the first cause-and-effect evidence that strengthened connections between neurons are the stuff of memory.

Scientists have switched a fear memory on and off in genetically-engineered rats -- using a flash of light. Optogenetic technology produced this first cause-and-effect evidence that memories are formed by strengthened connections between neurons.

Credit: Roberto Malinow, M.D., Ph.D., of the University of California, San Diego

"Our results add to mounting evidence that the brain represents a memory by forming assemblies of neurons with strengthened connections, or synapses, explained Roberto Malinow, M.D., Ph.D., of the University of California, San Diego (UCSD), a grantee of the NIH's National Institute of Mental Health (NIMH). "Further, the findings suggest that weakening synapses likely disassembles neuronal assemblies to inactivate a memory."

Malinow, Roger Tsien, Ph.D., a grantee of NIH's National Institute on Neurological Disorders and Stroke (NINDS), and other UCSD colleagues, report June 1, 2014 in the journal Nature on their findings using cutting edge optical/gene-based technology.

... more about:
»Health »LTP »NIH »NIMH »UCSD »evidence »long-term »memories »neurons »synapses »targeting

"Beyond potential applications in disorders of memory deficiency, such as dementia, this improved understanding of how memory works may hold clues to taking control of runaway emotional memories in mental illnesses, such as post-traumatic stress disorder," said NIMH director Thomas R. Insel, M.D.

Neuroscientists have long suspected that strengthened connections between neurons – called long-term potentiation (LTP) – underlies memory formation, But proof had remained elusive, until now.

The Malinow team proved it by detecting LTP when forming a memory, removing the memory with a process known to reverse LTP, and then bringing the memory back via LTP – all by modifying the strength of synapses in a memory circuit.

To gain the precise control needed to show such a cause-and-effect relationship, Malinow's team turned to one of neuroscience's most powerful new tools: optogenetics. It adapts the same cellular machinery that allows primitive organisms like algae to be controlled by light from the sun to control specific brain circuit components instantly with a laser – even in a behaving animal.

In conventional rodent fear conditioning experiments, a tone is paired with a foot shock to induce a fear memory of the tone. If the memory is active, the animal freezes and shows reduced reward-seeking behaviors when it hears the tone. Instead of the tone, Malinow's team paired the shock with direct optogenetic stimulation, lighting up a specific group of neurons in a known auditory fear memory circuit.

Such precise targeting wasn't possible with earlier electrical stimulation techniques. "It's just a jungle in the brain – too many nerve cells coming through in any one place," explained Malinow.

By varying the pattern of optogenetic stimulation, the researchers were able to strengthen connections between neurons in the circuit by promoting LTP or weaken the connections by promoting a countervailing process called long-term depression (LTD). This made it possible to readily form a fear memory, remove it, and then bring it back.

Moreover, upon closer optogenetic probing in postmortem brains, the targeted circuit neurons showed telltale changes in sensitivity of brain chemical messenger systems. These changes confirmed the hypothesized role of strengthening and weakening of synaptic connections in the switching on-and-off of the memory.

"We have shown that the damaging products that build up in the brains of Alzheimer's disease patients can weaken synapses in the same way that we weakened synapses to remove a memory," said Malinow. "So this line of research could suggest ways to intervene in the process."

"In addition to eliminating any doubt about a link between LTP/LTD with memories, this work highlights the staggering potential of precision targeting and circuit manipulation for alleviating maladaptive memories," said project officer Chiiko Asanuma,Ph.D., of the NIMH Division of Neuroscience and Basic Behavioral Science.

"This work provides a nice demonstration of how the field of neuroscience is being transformed by the types of technologies that are at the heart of President Obama's BRAIN Initiative," said Edmund Talley, Ph.D., program director at the NINDS.

Jules Asher | Eurek Alert!
Further information:

Further reports about: Health LTP NIH NIMH UCSD evidence long-term memories neurons synapses targeting

More articles from Studies and Analyses:

nachricht Climate study finds evidence of global shift in the 1980s
26.11.2015 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Network analysis shows systemic risk in mineral markets
16.11.2015 | International Institute for Applied Systems Analysis (IIASA)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

Im Focus: Quantum Simulation: A Better Understanding of Magnetism

Heidelberg physicists use ultracold atoms to imitate the behaviour of electrons in a solid

Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...

All Focus news of the innovation-report >>>



Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Art Collection Deutsche Börse zeigt Ausstellung „Traces of Disorder“

21.10.2015 | Event News

Latest News

Siemens to supply 126 megawatts to onshore wind power plants in Scotland

27.11.2015 | Press release

Two decades of training students and experts in tracking infectious disease

27.11.2015 | Life Sciences

Coming to a monitor near you: A defect-free, molecule-thick film

27.11.2015 | Materials Sciences

More VideoLinks >>>