Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Long-Term Potentiation in the Olfactory Bulb

05.05.2009
Case Western Reserve University School of Medicine researchers are the first to discover a form of synaptic memory in the olfactory bulb, the part of the brain that processes the sense of smell.

Ben W. Strowbridge, Ph.D, associate professor of Neuroscience and Physiology/Biophysics, and Yuan Gao, a Ph.D. student in the neurosciences program at Case Western Reserve University School of Medicine, are the first to discover a form of synaptic memory in the olfactory bulb, the part of the brain that processes the sense of smell.

Their study, entitled “Long-term plasticity of excitatory inputs to granule cells in the rat olfactory bulb” will be published in the June 2009 issue of Nature Neuroscience and is currently available online.

In the 1970s, scientists discovered that elemental connections between brain cells, called synapses, could change their strength following brief periods of activity. This process, called long-term potentiation (LTP), is the leading candidate to explain how we store information about specific places, names and events. While laboratories around the world have found LTP in nearly every part of the mammalian brain there was one glaring exception: the part of the brain that first processes the sense of smell, the olfactory bulb.

Gao, a fourth-year graduate student, had learned that damaging olfactory sensory pathways prevents sheep from forming selective bonds with her own lambs, causing them to adopt lambs from other mothers. This cued her curiosity as to how a mother ewe forms such a selective bond with her lamb within several hours of parturition, a bond that is primarily dependent on olfactory sensory recognition.

Using an innovative home-built laser microscope, Strowbridge and Gao were able to determine that the olfactory bulb does in fact have LTP. This specialized microscope used an advanced imaging technique called “2-photon excitation” which enabled the researchers to see entire brain cells and then test whether different types of inputs to the cell could mediate olfactory memory.

“The real surprise in the study was the specific brain connection that changed following experience. It was a rarely-studied brain projection from the cortex back to the olfactory bulb” said Strowbridge.

Neuroscientists commonly believe that the way the brain processes information is similar to climbing a pyramid—starting from the bottom and working up to the top. All of the sensory systems have a large number of low-level cells that do very simple things (forming the base of the pyramid), and then they feed their results to brain areas higher up the pyramid. The brain cells in these “higher” regions begin to reflect abstract concepts, such as the shape of human faces, in the visual system or melodies in the auditory system. The brain areas related to our conscious perception of the world are presumably at the top of pyramid.

However, the Case Western Reserve University researchers found that the brain circuit had the ability to change with experience was unexpectedly a connection from high in the pyramid (the olfactory cortex) back to a lower level (the olfactory bulb).

One of the implications of Strowbridge and Gao’s work is that the brain may learn about different smells by having higher brain areas first make a prediction about which scent it might be, and then test that prediction against the actual sensory data coming into the brain.

“Our work suggests that there is much more talking back-and-forth between higher and lower brain areas during olfactory learning,” continued Strowbridge. “We are just beginning to explore the function of the feedback circuits that inform low-level parts of the brain, like the olfactory bulb, about predictions made by higher-order brain regions. The 2-photon microscope used in this study is an ideal tool to ask what these different brain circuits are actually doing.”

Previous studies had suggested that the circuit changes associated with olfactory learning, such as sheep learning to recognize their own lambs though their characteristic scents, involved changes in the olfactory bulb. Strowbridge and Gao discovered that certain olfactory brain circuits can change with experience. This discovery provides a possible explanation for how animals can form memories of particular scents.

In 2006, Strowbridge’s grouped discovered a new type of brain cell, the Blanes cell, in the olfactory bulb, also using the same home-built 2-photon microscope. Ramón y Cajal, an important Spanish anatomist, had drawn pictures of these cells and named them for one of his medical students in the late 1800s. They stayed a curiosity item in very old textbooks until Strowbridge’s laboratory found that they represented a very important cell type in the brain. Using 2-photon imaging, the CWRU group showed that Blanes cells have unusual properties that may help the brain maintain memories of smells and also opened a new approach to understanding the basis of memory impairment in Alzheimer’s disease. That study was published in the March 16, 2006 issue of the journal Neuron.

This study was funded by the National Institutes of Health. The 2-photon laser microscope used in the study was constructed with support from the Mount Sinai Health Care Foundation.

About Case Western Reserve University School of Medicine
Founded in 1843, Case Western Reserve University School of Medicine is the largest medical research institution in Ohio and is among the nation’s top medical schools for research funding from the National Institutes of Health. The School of Medicine is recognized throughout the international medical community for outstanding achievements in teaching. The School’s innovative and pioneering Western Reserve2 curriculum interweaves four themes--research and scholarship, clinical mastery, leadership, and civic professionalism--to prepare students for the practice of evidence-based medicine in the rapidly changing health care environment of the 21st century. Eleven Nobel Laureates have been affiliated with the school.

Annually, the School of Medicine trains more than 770 M.D. and M.D./Ph.D. students and ranks in the top 25 among U.S. research-oriented medical schools as designated by U.S. News and World Report “Guide to Graduate Education.”

The School of Medicine’s primary clinical affiliate is University Hospitals Case Medical Center and is additionally affiliated with MetroHealth Medical Center, the Louis Stokes Cleveland Department of Veterans Affairs Medical Center, and the Cleveland Clinic, with which it established the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University in 2002.

Christina DeAngelis | Newswise Science News
Further information:
http://www.case.edu
http://casemed.case.edu

More articles from Life Sciences:

nachricht Immune Defense Without Collateral Damage
23.01.2017 | Universität Basel

nachricht The interactome of infected neural cells reveals new therapeutic targets for Zika
23.01.2017 | D'Or Institute for Research and Education

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>