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Medicine Software Science Technology

A Nanoscale Look At a Complete Fly Brain (cemag.us) 73

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.

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A Nanoscale Look At a Complete Fly Brain

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  • 100k neurons only (Score:5, Insightful)

    by hcs_$reboot ( 1536101 ) on Tuesday July 24, 2018 @12:06AM (#56998492)
    And yet the fly adapts to so many different situations, flies,"eats", copulates etc.... that emphasizes how powerful the 3D brain structure is, and how our current AI is not.
  • by aberglas ( 991072 ) on Tuesday July 24, 2018 @12:21AM (#56998512)

    It has about 300 neurons, 1000 cells all up (so about a third are neurons). Its connectome (wiring diagram) has been known for decades, and unlike human brains is identical in each worm. But how it actually thinks remains a mystery.

    So good work to understand a fruit fly, and no doubt useful. But do not mistake it for understanding.

    While understanding neurons might be helpful for building an AI, I think it is unlikely that an AI will be any direct mapping. Aeroplanes are not built out of feathers.

    • by ShanghaiBill ( 739463 ) on Tuesday July 24, 2018 @12:48AM (#56998574)

      Much progress has been made at understanding C. elegans. The OpenWorm project [wikipedia.org] 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.

      • by raftpeople ( 844215 ) on Tuesday July 24, 2018 @01:22AM (#56998656)
        Unless the OpenWorm project is also simulating the astrocytes that modulate and manage synapse activity, it's probably not going to be successful. For further info, google astrocyte tripartite synapse and you will find that neuroscientists now consider the astrocyte to be managing/controlling the synapse, (responding to neurotransmitters and signalling neurons on either side of the synapse as well as other glial cells).
        • Interesting information, but did you read the linked article? The project's ultimate goal is simulating all of the cells, and the post you replied to claims they are 30% of the way there.

          BTW, C. Elegans only has 50 glial cells [nih.gov].

          • by raftpeople ( 844215 ) on Tuesday July 24, 2018 @12:24PM (#57001038)
            I'm very aware of the OpenWorm project and I think it's a great idea to start with the smallest brain rather than others that think they can jump right into simulating a rat brain or a human brain.

            Having said that, they will first need to figure out how the astrocytes performs their computations and neuroscientists are absolutely nowhere near that level of information. In addition, even in the neuron, DNA is involved in computations (synapse strength is altered by turning on/off genes via epigenetic mechanisms and those alternations are what sustain the synapse at the current strength). So, OpenWorm idea is good but they are a looooong way off from having enough info to simulate the computations that happen.
        • Re: (Score:3, Interesting)

          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.

          • simulate the entire organism at the biochemical level

            I call BS. Every chemical reaction in the entire organism is simulated? Cells replicate? Proteins fold and unfold? Enzymes trigger chemical reactions? The organisms reproduce? Suuuuuure.

          • OpenWorm is a project to fantasize about simulating the entire organism

            FTFY.
            There is zero reason to believe that this will be achieved anytime this century.

    • But how it actually thinks remains a mystery.

      How much time do you think C. elegans spends contemplating "does existence precede essence?"

    • We won't be successful with a real AI until we return to analog computing. The brain in biological organisms is analog and operates roughly equivalent to a pokey 600mhz. The difference is the 100 billion connections with upwards of dozens of routing paths per neuron and analog communication. We are a long way from being able to create something similar. Although we wouldn't need the full 100 billion because much of the brains computing power is devoted not to inteligence but simply managing living processe

  • I'm not sure I want to do it this way. There seems to be an awful lot of slicing involved, and then there's a ton of heavy metal poisoning on top of it.

    I think I might just wait for a less lethal method.

  • Actual size!

  • This article, and the description of what they have to go through just to map a paltry 1x10^5 neurons (as compared to the 1x10^11 in a human brain), is an excellent example of one of the problems with understanding how a biological brain, like humans posess, produces phenomena like sentience, self-awareness, cognition, and real ability to think. For starters, they can't map it without killing the host first, because they have to dismantle the brain in order to map it. Furthermore, since a living brain is ex
  • The world depicted in Ghost in the Shell is approaching

"What man has done, man can aspire to do." -- Jerry Pournelle, about space flight

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