Stathis Papaioannou wrote:
> Recent theory based on the work of Eric Kandel is that long term
> memory is mediated by new protein synthesis in synapses, which
> modulates the responsiveness of the synapse to neurotransmitter
> release; that is, it isn't just the "wiring diagram" that
> characterises a memory, but also the unique properties of each
> individual "connection".
.....
> This would be difficult enough to do if each neuron were considered in
> isolation, but in fact, there may be hundreds of synaptic connections
> between neurons, and the activity of each connected neuron needs to be
> taken into account, along with the activity of each of the hundreds of
> neurons connected to each of *those* neurons, and so on.
Stathis also wrote:
>I believe the level of detail required and the complexity of the
required models is grossly underestimated.
>Simply getting a 3D image of a brain down to electron microscopic
detail, including all the synaptic
>connections, would be an enormous task, and it probabaly wouldn't
tell us any more about the mind
>of the brain's owner than a picture of the books on a library
shelf would tell us about the book contents.
>I would bet more on mediaeval monks decoding the data on a DVD
sent back in time than I would
>bet on scientists decoding the contents of a human mind from
cryopreserved brain sections.
Let's cut through all this complexity and look at the functional
equivalent of a neuron or a group of neuron. I want to distinguish
between general architecture and particular architecture: general
architecture will provide the framework within which any human brain
could fit. Particular architecture is the architecture of a particular
brain.
1) General Architecture
The general architecture of the brain is a hot research project of the
scale and importance of the Genome Project and is currently being worked
on by major laboratories. We could speed up the functional
identification of neuronal groups or modules by using general
architecture apriori knowledge we have about these modules. For example
the architecture of the visual cortex is well defined. We could treat it
as a module with minor variations from individual to individuals due to
genetic differences such as Single Nucleotide Polymorphism SNP. SNPs.
Very soon we shall have the genetic map of all the human SNPs. We shall
also have the general architecture of the brain and all its nominal
variations.
2) Particular Architecture
Imagine using an advanced version of a functional Magnetic Resonance
Imaging (fMRI) device operating at the microscopic level on a slice of
brain tissue. Without knowing exaclty what is in the brain tissue black
box, it may be possible to identify their functional property and
recreate these in silicon or any other convenient substrate. By the way,
microscopic functional Magnetic Resonance Imaging is an existing
technology that is currently being used. This is what I got using Google.
Scholarly articles for functional magnetic resonance imaging microscop$
<
http://scholar.google.com/scholar?hl=en&lr=&biw=793&sa=X&oi=scholart&q=functional+magnetic+resonance+imaging+microscop%24>
The primate neocortex in comparative perspective using ...
<
http://www.google.com/url?sa=X&oi=scholarr&start=0&num=3&q=http://www.anthropology.emory.edu/FACULTY/ANTJR/JHE_1999.pdf>
- by Insel - 40 citations
Neuroimaging and neuropathology in epilepsy: With ...
<
http://www.google.com/url?sa=X&oi=scholarr&start=1&num=3&q=http://www.ingentaconnect.com/content/bsc/neu/1999/00000019/00000002/art00229>
- by Nishio - 1 citations
Evaluation by Contrast-Enhanced MR Imaging of the ...
<
http://www.google.com/url?sa=X&oi=scholarr&start=2&num=3&q=http://www.kjronline.org/abstract/files/v02n0121.pdf>
- by Jeong - 2 citations
3) Combining General and Particular Architectures
Fusing information to combine apriori knowledge of general architecture
brain functions, and particular architecture data obtained from in situ
functional measurements (e.g. fMRI), neurological and psychological
measurements, as well as self-analysis, it may be possible to
reconstruct a functional copy of the brain close enough as to be
indinstinguishable from the original by the owner. How does the owner
knows it is indistinguishable? This is a whole topic. He could for
example do a series of partial substitutions to find out if it feels
the same or not. For example, he could substitute in sequence the visual
cortex, the auditory cortex, some of the motor functions....
We may be closer to this goal than you think.
George
Received on Fri Jul 08 2005 - 16:07:51 PDT