Neuroscientists discover long-term potentiation in the olfa...( CLEVELAND May 3 2009 Ben W. Strowbr...)

CLEVELAND May 3, 2009 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 t
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