Every Branch of every Brain Neuron exposed!
1/27/16 It took six years and 21 Harvard researchers to complete the model, but now they have the most detailed brain reconstruction to date. Even though it only represents a several billionths of a mouse brain! Even though the 3D model only represents a tiny fraction of the brain, it shows every branch of every neuron!
In a published article in Cell, researchers fed a micro sized piece of brain through a machine that sliced it very thinly. That machine then stuck the slices to a plastic tape to create a sort of film reel. A scanning electron microscope captured each frame digitally so researchers could use computers to trace what they saw. Then, focusing on an invisibly small, more manageable portion of their sample, they accounted for every cellular detail of each frame.
The resulting map includes every branch of every neuron, their mitochondria and supporting cells. The scientists created a spreadsheet giving locations of the 1,700 synapses (connections between neurons) plus which neurons they joined, and other data. A surprise emerged in how neurons’ branched arms connect with each other: Instead of synapsing with their conveniently close neighbors, as previously thought, two branches may seek each other out repeatedly amid the thicket of other cells. These deliberately reinforced connections might represent learning. The next step will be to learn more about the brain’s wiring by mapping an entire cubic millimeter of a brain slice!
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