Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Team led by Carnegie Mellon University scientist finds first evidence of a living memory trace

15.11.2005


Results show neural reorganization occurs during short-term memory



An international team of scientists for the first time has detected a memory trace in a living animal after it has encountered a single, new stimulus. The research, done with honeybees sensing new odors, allows neuroscientists to peer within the living brain and explore short-term memory as never before, according to scientist Roberto Fernández Galán, a leading author on the report who is currently a postdoctoral research associate at Carnegie Mellon University.

Capturing these memory traces could ultimately provide a completely new way to understand how short-term memory works, stated Galán. The findings are scheduled for January publication in Neural Computation.


"Our findings show that an odor produces a memory trace of synchronized neural activity that lasts several minutes after a bee initially senses it," said Galán. "This is the first time anyone has revealed a short-term, stimulus-specific neural pulse within the living brain that occurs after exposure to a previously unknown stimulus."

"Future investigations along the lines of our study may reveal previously overlooked memory traces in many other neural systems," said C. Giovanni Galizia, Galán’s primary collaborator, who is now a professor at Konstanz Universität in Konstanz, Germany.

Galán performed the work as part of his dissertation research while in the research group of Andreas Herz at the Humboldt University in Berlin, Germany.

The report supports Hebb’s theory of learning, a 55-year-old proposition that "neurons that fire together wire together," thereby strengthening their connections. According to the theory, a stimulus activates some neurons while inhibiting others. Once this stimulus is removed, traces of that excitation/inhibition pattern – so-called Hebbian reverberations – should remain.

"We are the first to observe this phenomenon at the network level. We are also the first to detect a distinct signature, not only of a sensory short-term memory, but one that developed after a single exposure to a previously unknown stimulus, so that there is no context," said Galán. "All previous studies in this field have observed only a sustained, non-specific increase in neural activity after a living animal is repeatedly exposed to a stimulus. These investigations haven’t retrieved a signature of a stimulus, whereas we have."

The experiments were performed in the laboratory of Randolf Menzel, whose pioneering observational experiments in the 1970s and 1980s showed that honeybees exposed to an odor and rewarded with sugar could develop a memory of that odor and temporarily store it as "working memory." They also found that honeybees lost their working memory of a re-enforced odor if they were cooled down and then revived, suggesting that the memory wasn’t permanently stored.

This latest study is the first to combine fluorescent dye imaging developed by Galizia, and advanced image processing and mathematical data analysis developed by Galán to actually detect a working memory trace.

In the current research, the scientists studied clusters of neurons called glomeruli within the honeybee’s antennal lobe (AL), considered the invertebrate equivalent of the brain’s olfactory bulb. Team member Marcel Weidert placed fluorescent probes within different glomeruli, and imaged their activity using dyes sensitive to the opening and closing of calcium channels on neurons. The scientists created an imaging grid across the glomeruli and measured the ratio of fluorescence versus nonfluorescence over time.

Galán then used advanced mathematical techniques to process the images and create a matrix of the extent (or amplitude) of neuronal excitation and inhibition within glomeruli. He retrieved a spatial pattern of synchronized, correlated activity – the memory trace – from what appeared to be random fluctuations of neural activity.

"The trace is like a fingerprint that disappears over time. It’s strongest after the honeybee’s initial exposure to an odor, but you can still detect its signature features minutes afterwards," said Galán.

A future question that could be addressed using this research is addressing how short-term memory gets encoded as long-term memory over time, said Galán.

Lauren Ward | EurekAlert!
Further information:
http://www.cmu.edu

More articles from Life Sciences:

nachricht New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego

nachricht Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Gran Chaco: Biodiversity at High Risk

17.01.2018 | Ecology, The Environment and Conservation

Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials

17.01.2018 | Physics and Astronomy

Fraunhofer HHI receives AIS Technology Innovation Award 2018 for 3D Human Body Reconstruction

17.01.2018 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>