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 – new method allows characterization of
neuronal networks on single-cell level
An international team led by neuroscientist Troy Margrie has developed
a new method, which will shape the future of cellular neuroscience.
The researchers from MRC National Institute for Medical Research in
London, Columbia University in New York and Max-Planck-Institute for
Medical Research in Heidelberg succeeded in determining the function
of individual nerve cells in the brain and identify those neurons from
which a given cell receives its signals. “The new method enables us
for the first time to identify a neuronal networks on the level of
individual cells and characterize it functionally”, explains Ede
Rancz. This study is now published in Nature Neuroscience.
A genetically modified rabies virus leads the way
The scientists combined two existing methods, “whole-cell patch clamp
recording” and “monosynaptic retrograde virus tracing”. They use the
patch-clamp technique to determine the exact stimuli to which a given
brain cell responds. Through the glass micropipette, which is used to
record electrical signals, they simultaneously inject plasmid DNA into
this cell. In the vicinity of the cell they later inject a rabies
virus, which is lacking proteins necessary for entering a cell and
spreading through neuronal pathways. These missing proteins are
provided by the plasmid DNA injected previously into the cell.
Therefore, the virus can only infect this single cell and then spread
across synapses to only those neurons which are exactly one step
upstream in the signaling chain. There it stops because these
presynaptic cells do not contain the necessary plasmid DNA, which the
modified virus needs for spreading.
Cellular networks in the living organism
The plasmid DNA and the virus both produce fluorescent proteins, which
are then visualized through specialized microscopes. In this way, the
functionally characterized cell as well as its connected ‘neighbours’,
from which the cell receives information - let them be in close
proximity or in a different brain area -can be identified. As this
technique can be used in a living organism, cellular networks can be
identified and then subjected to further experiments. The researchers
are convinced that this method opens up the door for answering a
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/
