Listen up guys, because this just came in. Hot off the press and everything. Today I received quite an impressive e-mail submission from one of the authors of the paper from the MRC National Institute for Medical Research in London. He was also kind enough to share one of their figures with us. I personally think he did an excellent job at summing up the importance and novelty of this new tracing technique so I encourage you to read below and check out the original research article. Thanks Bruno!
Breakthrough in Neuroscience ā new method allows characterization ofĀ Ā neuronal networks on single-cell level An international team led by neuroscientist Troy Margrie has developedĀ Ā a new method, which will shape the future of cellular neuroscience.Ā Ā The researchers from MRC National Institute for Medical Research inĀ Ā London, Columbia University in New York and Max-Planck-Institute forĀ Ā Medical Research in Heidelberg succeeded in determining the functionĀ Ā of individual nerve cells in the brain and identify those neurons fromĀ Ā which a given cell receives its signals. āThe new method enables usĀ Ā for the first time to identify a neuronal networks on the level ofĀ Ā individual cells and characterize it functionallyā, explains EdeĀ Ā Rancz. This study is now published in Nature Neuroscience. A genetically modified rabies virus leads the way The scientists combined two existing methods, āwhole-cell patch clampĀ Ā recordingā and āmonosynaptic retrograde virus tracingā. They use theĀ Ā patch-clamp technique to determine the exact stimuli to which a givenĀ Ā brain cell responds. Through the glass micropipette, which is used toĀ Ā record electrical signals, they simultaneously inject plasmid DNA intoĀ Ā this cell. In the vicinity of the cell they later inject a rabiesĀ Ā virus, which is lacking proteins necessary for entering a cell andĀ Ā spreading through neuronal pathways. These missing proteins areĀ Ā provided by the plasmid DNA injected previously into the cell.Ā Ā Therefore, the virus can only infect this single cell and then spreadĀ Ā across synapses to only those neurons which are exactly one stepĀ Ā upstream in the signaling chain. There it stops because theseĀ Ā presynaptic cells do not contain the necessary plasmid DNA, which theĀ Ā modified virus needs for spreading. Cellular networks in the living organism The plasmid DNA and the virus both produce fluorescent proteins, whichĀ Ā are then visualized through specialized microscopes. In this way, theĀ Ā functionally characterized cell as well as its connected āneighboursā,Ā Ā from which the cell receives information - let them be in closeĀ Ā proximity or in a different brain area -can be identified. As thisĀ Ā technique can be used in a living organism, cellular networks can beĀ Ā identified and then subjected to further experiments. The researchersĀ Ā are convinced that this method opens up the door for answering aĀ Ā plethora of very important but previously unapproachable questions. The original paper is available online: http://www.nature.com/neuro/journal/vaop/ncurrent/abs/nn.2765.html Short video clips of original microscopy images are available at: http://www.youtube.com/watch?v=6spZuxsJOcU http://www.youtube.com/watch?v=Tujh2YH6rK8 Contact: Prof. Troy Margrie http://www.nimr.mrc.ac.uk/research/troy-margrie/
