
Paul Allen believes a tipping-point is near in brain research - robg
http://www.economist.com/theworldin/displayStory.cfm?story_id=12494720&d=2009
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jaytee_clone
I'm very grateful for this work. However, saying that this contribution alone
brings the tipping-point closer is rather pompous.

First of all, since gene expressions are such upstream information, knowing it
won't give us the whole picture (or even come close to it.)

It's like knowing the code of a program, which has syntax you have never seen
before, and you have no idea what the compiler does, not to mention the
machine code describes an astronomical non-linear computation.

Second of all, gene expression dependents on age, environment, behavior, and
probably things we don't even know. I haven't look at the data, but I assume
it's just the mouse's brain in one instant. Otherwise it will be a VERY
resource intensive job. Not to mention that you have to freeze the brain in
order to slice it and map the gene (unless they got better technology now), so
even if you get a different instant of the brain it won't be the same mouse.

However, a step towards the goal is a step towards the goal. And that's what
this project was. Great work.

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davi
The Allen Brain Atlas, as currently realized, is likely to be very useful for
disease research & basic biology. But, explaining how the brain works by
profiling gene expression... I don't think so. Certainly not sufficient, maybe
not necessary.

Generaly, though, applying high throughput imaging methods to different
problems in neuroscience is going to be very fruitful. So in this sense, maybe
we're near a tipping point. I don't really think quite yet, though; maybe in a
decade or two.

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anewaccountname
Just curious, with current imaging techniques, can computers even distinguish
inhibitory neurons from excitatory neurons?

~~~
davi
There are plenty of microscopic techniques to distinguish inhibitory from
excitatory cells. Computers can tell the difference if given appropriate
microscopy images as input and the software to process those images. Not too
hard.

But these are dynamic objects. Google 'rebound excitation' for some
counterintuitive effects of inhibitory input. Hard to dissect how circuits of
these objects work.

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anewaccountname
Couldn't make much sense of the results =). You should add a snippit to the
wikipedia page <http://en.wikipedia.org/wiki/IPSP> on it =).

~~~
davi
You're right, that was a pretty crummy suggestion. I looked at the wikipedia
IPSP page and didn't like it much, either. A little deeper googling gave me
this:

[http://icwww.epfl.ch/~gerstner/SPNM/node15.html#SECTION02133...](http://icwww.epfl.ch/~gerstner/SPNM/node15.html#SECTION02133100000000000000)

To help parse figure 2.12:

'Resting potential' = voltage between inside and outside of the neuron in the
absence of any excitatory or inhibitory input. It is generated constitutively
by ion pumps in the cell.

When cell receives inhibitory input, its voltage drops and it become
'hyperpolarized'. This causes a certain type of calcium ion channel, the
'T-type', to gain the capability of opening (it stops being 'inactivated').
When the inhibitory input ceases, the cell's constitutive ion pumps return it
to its resting potential. As the voltage of the cell increases, some T-type
channels begin to open, leading to an influx of calcium ions (there are more
calcium ions outside the cell than inside), which in turn leads to the cell's
voltage to increase further. Now the cell's voltage shoots _above_ its resting
potential, and voltage-dependent sodium channels begin to open. Sodium ions
rush in, and a spike is generated.

And the payoff to me for trying to a little bit better job of answering your
question is that I discovered what looks to be a pretty good resource:

<http://icwww.epfl.ch/~gerstner/SPNM/SPNM.html>

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robertk
Does anyone know how to get into diamond mechanosynthesis as a hobby
(computational chemistry methods of course, not lab work)? I'm a pure math
student, but the applications of that field are so vast (molecular nanotech?).

~~~
robertk
This looks promising!

<http://www.molecularassembler.com/Nanofactory/DMS.htm>

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logjam
Executive summary: lottery winner writes self-congratulatory article with
over-promising title for non-technical rag on lottery winner's funding an
anatomical and genetic database of the nervous system -- the data least likely
to yield a "tipping point" in how brains fundamentally work.

~~~
ryanwaggoner
Off-topic, but your repeated use of the phrase "lottery winner" annoys me.
Every self-made billionaire is a lottery winner in that none of them got where
they are without luck. But none of them got there through luck alone. To
characterize their success as pure luck indicates either ignorance or
jealousy.

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Allocator2008
I wonder if Paul Allen thinks having a gene map of the human brain will help
him get reservations to Dorsia.

(Also, even if he can get into Dorsia, he should stay away from that bimbo
Allison Poole, whose liason with Sen. Edwards caused such a fuss...)

