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Archive - Oct 6, 2014

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Nobel Prize Awarded for Discovery of GPS in Brain

The Nobel Assembly at Karolinska Institutet has today (October 6, 2014) decided to award The 2014 Nobel Prize in Physiology or Medicine with one half to John O´Keefe, Ph.D. (photo), in the UK, and the other half jointly to the wife-husband team of May-Britt Moser, Ph.D., and Edvard I. Moser, Ph.D., in Norway, for their discoveries of cells that constitute a positioning system in the brain. How do we know where we are? How can we find the way from one place to another? And how can we store this information in such a way that we can immediately find the way the next time we trace the same path? This year´s Nobel Laureates have discovered a positioning system, an “inner GPS” in the brain that makes it possible to orient ourselves in space, demonstrating a cellular basis for higher cognitive function. In 1971, Dr. O´Keefe discovered the first component of this positioning system. He found that a type of nerve cell in an area of the brain called the hippocampus was always activated when a rat was at a certain place in a room. Other nerve cells were activated when the rat was at other places. Dr. O´Keefe concluded that these “place cells” formed a map of the room. More than three decades later, in 2005, Drs. May-Britt and Edvard Moser discovered another key component of the brain’s positioning system. They identified another type of nerve cell, which they called “grid cells,” that generate a coordinate system and allow for precise positioning and pathfinding. Their subsequent research showed how place and grid cells make it possible to determine position and to navigate. The discoveries of Drs.

Glia-Secreted Exosomes Play Key Role in Functioning of Nerve Cells

Tiny vesicles containing protective substances which they transmit to nerve cells apparently play an important role in the functioning of neurons. As cell biologists at Johannes Gutenberg University Mainz (JGU) have discovered, nerve cells can enlist the aid of mini-vesicles of neighboring glial cells to defend themselves against stress and other potentially detrimental factors. These vesicles, called exosomes, appear to stimulate the neurons on various levels: they influence electrical stimulus conduction, biochemical signal transfer, and gene regulation. Exosomes are thus multifunctional signal emitters that can have a significant effect in the brain. The scientists reported these results in the September 2014 issue of The Philosophical Transactions of the Royal Society B (Biological Sciences). The researchers in Mainz already observed in a previous study that oligodendrocytes release exosomes on exposure to neuronal stimuli. These exosomes are absorbed by the neurons and improve neuronal stress tolerance. Oligodendrocytes are a type of glial cell and they form an insulating myelin sheath around the axons of neurons. The exosomes transport protective proteins such as heat shock proteins, glycolytic enzymes, and enzymes that reduce oxidative stress from one cell type to another, but also transmit genetic information in the form of ribonucleic acids. "As we have now discovered in cell cultures, exosomes seem to have a whole range of functions," explained Dr. Eva-Maria Krämer-Albers. By means of their transmission activity, the small bubbles that are the vesicles not only promote electrical activity in the nerve cells, but also influence them on the biochemical and gene regulatory level. "The extent of activities of the exosomes is impressive," added Dr. Krämer-Albers.