an enjoyable reading, indeed. I send my best to Caenorhabdites elegantes for
their scientific prowess.
Are your numbers correct? Is the brain-"wiring" length indeed 170 trillion
microns long? (I took 1.7 km for a mile).
And for the synapses: I was modest and took only 10 billion neurons to a
brain, which accounts for 20,000 synapses per neuron if there are 100
trillions of them. (2 axons to 1 s)
I am not an expert in these topics, but the drawings I saw would not
facilitate that much.
I think I counted the zeros correctly.
S.Hameroff and Penrose had a piece in an early issue of Journal of
Consciousness Studies (UK) about "How to feel to be a worm" - counting with
1000 neurons per earthworm (It was a follow-up to Nagel's "What is it to be
like a bat?") of which my reflection denied any conclusions if one is not
thinking "worm"-ly, i.e. by the complexity of an earth worm-like mentality.
We try to understand primitive construct using our very sophisticated
(complex) structures and there is no way to play it down to a lesser complex
level - we just have a complex mentality, terms/thoughts. We may pretend to
understand a lower level.
I feel similar troubles in a computer-evaluation of the 302 neuron chap by a
'base-structure' built (by and for) in 10 billion neuronal complexity
brains, or - as some AI fans state: for even an exceeding of such. I find it
not believable to properly downgrade.
The study, however, is relevant and appreciable. Thanks again.
On Tue, Jun 21, 2011 at 2:47 PM, Rex Allen <rexallen31...@gmail.com> wrote:
> Brain uploading for worms...
> Caenorhabditis elegans, as the roundworm is properly known, is a tiny,
> transparent animal just a millimeter long. In nature, it feeds on the
> bacteria that thrive in rotting plants and animals. It is a favorite
> laboratory organism for several reasons, including the comparative
> simplicity of its brain, which has just 302 neurons and 8,000
> synapses, or neuron-to-neuron connections. These connections are
> pretty much the same from one individual to another, meaning that in
> all worms the brain is wired up in essentially the same way. Such a
> system should be considerably easier to understand than the human
> brain, a structure with billions of neurons, 100,000 miles of
> biological wiring and 100 trillion synapses.
> The biologist Sydney Brenner chose the roundworm as an experimental
> animal in 1974 with this goal in mind. He figured that once someone
> provided him with the wiring diagram of how 302 neurons were
> connected, he could then compute the worm’s behavior.
> The task of reconstructing the worm’s wiring system fell onJohn G.
> White, now at the University of Wisconsin. After more than a decade’s
> labor, which required examining 20,000 electron microscope cross
> sections of the worm’s anatomy, Dr. White worked out exactly how the
> 302 neurons were interconnected.
> But the wiring diagram of even the worm’s brain proved too complex for
> Dr. Brenner’s computational approach to work. Dr. Bargmann was one of
> the first biologists to take Dr. White’s wiring diagram and see if it
> could be understood in other ways.
> After studying the little animal for 24 years, she believes she is
> closer to understanding how its nervous system works.
> Why is the wiring diagram produced by Dr. White so hard to interpret?
> She pulls down from her shelves a dog-eared copy of the journal in
> which the wiring was first described. The diagram shows the electrical
> connections that each of the 302 neurons makes to others in the
> system. These are the same kind of connections as those made by human
> neurons. But worms have another kind of connection.
> Besides the synapses that mediate electrical signals, there are also
> so-called gap junctions that allow direct chemical communication
> between neurons. The wiring diagram for the gap junctions is quite
> different from that of the synapses.
> Not only does the worm’s connectome, as Dr. Bargmann calls it, have
> two separate wiring diagrams superimposed on each other, but there is
> a third system that keeps rewiring the wiring diagrams. This is based
> on neuropeptides, hormonelike chemicals that are released by neurons
> to affect other neurons.
> The neuropeptides probably help control the brain’s general status, or
> mood. A strong hint of how they work comes from the npr-1 gene, which
> makes a protein that responds to neuropeptides. When the npr-1 gene is
> active, its neuron becomes unavailable to its local circuit.
> That may be a reason why the worm’s behavior cannot be computed from
> the wiring diagram: the pattern of connections is changing all the
> time under the influence of the worm’s 250 neuropeptides.
> The connectome shows the electrical connections, and hence the
> quickest paths for information to move through the worm’s brain. “But
> if only a subset of neurons are available at any time, the connectome
> is ambiguous,” she says.
> The human brain, too, has neuropeptides that set mood and modify
> behavior. Neuropeptides are probably at work when the pain pathways
> are cut off in acute crises, allowing people to function despite
> serious wounds.
> The human brain, though vastly more complex than the worm’s, uses many
> of the same components, from neuropeptides to transmitters. So
> everything that can be learned about the worm’s nervous system is
> likely to help with the human system.
> Though the worm’s nervous system is routinely described as simple,
> that is true only in comparison with the human brain. The worm has
> 22,000 genes, almost as many as a person, and its brain is a highly
> complex piece of biological machinery. The work of Dr. Bargmann’s and
> other labs has deconstructed many of its operational mechanisms.
> What would be required to say that the worm’s nervous system was fully
> understood? “You would want to understand a behavior all the way
> through, and then how the behavior can change,” Dr. Bargmann says.
> “That goal is not unattainable,” she adds.
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