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A Nanoscale Look At a Complete Fly Brain (cemag.us)
An anonymous reader quotes a report from Controlled Environments Magazine: Two high-speed electron microscopes. 7,062 brain slices. 21 million images. For a team of scientists at the Howard Hughes Medical Institute's Janelia Research Campus in Ashburn, Virginia, these numbers add up to a technical first: a high-resolution digital snapshot of the adult fruit fly brain. Researchers can now trace the path of any one neuron to any other neuron throughout the whole brain, says neuroscientist Davi Bock, a group leader at Janelia who reported the work along with his colleagues on July 19 in the journal Cell.
The fruit fly brain, roughly the size of a poppy seed, contains about 100,000 neurons (humans have 100 billion). Each neuron branches into a starburst of fine wires that touch the wires of other neurons. Neurons talk to one another through these touchpoints, or synapses, forming a dense mesh of communication circuits. Scientists can view these wires and synapses with an imaging technique called serial section transmission electron microscopy. First, they infuse the fly's brain with a cocktail of heavy metals. These metals pack into cell membranes and synapses, ultimately marking the outlines of each neuron and its connections. Then the researchers hit slices of the brain with a beam of electrons, which passes through everything except the metal-loaded parts. "It's the same way that x-rays go through your body except where they hit bone," Bock explains. The resulting images expose the brain's once-hidden nooks and crannies.
The fruit fly brain, roughly the size of a poppy seed, contains about 100,000 neurons (humans have 100 billion). Each neuron branches into a starburst of fine wires that touch the wires of other neurons. Neurons talk to one another through these touchpoints, or synapses, forming a dense mesh of communication circuits. Scientists can view these wires and synapses with an imaging technique called serial section transmission electron microscopy. First, they infuse the fly's brain with a cocktail of heavy metals. These metals pack into cell membranes and synapses, ultimately marking the outlines of each neuron and its connections. Then the researchers hit slices of the brain with a beam of electrons, which passes through everything except the metal-loaded parts. "It's the same way that x-rays go through your body except where they hit bone," Bock explains. The resulting images expose the brain's once-hidden nooks and crannies.
Much progress has been made at understanding C. elegans. The OpenWorm project has simulated the neuron to muscle pathway, and they estimate they are about 30% of the way to a complete simulation.
Simulating a fly brain will be a big step beyond that.
Unless the OpenWorm project is also simulating the astrocytes ...
They are. OpenWorm is a project to digitally simulate the entire organism at the biochemical level. All the cells. Every chemical pathway.
Worms first. Then flies. Then humans.