From: Stathis Papaioannou (stathisp@gmail.com)
Date: Thu Nov 15 2007 - 03:53:43 MST
On 15/11/2007, Adam Safron <asafron@gmail.com> wrote:
> This seems like a fallacy of composition. Simple brain function? All
> of these phenomena are dependent upon functional relationships between
> neurons. But this does not mean that we will be able to understand
> more complex configurations–by "complex", I'm referring to difficulty
> of understanding and not necessarily structural/functional complexity–
> just because we understand simpler configurations. Neuroscientists
> have detailed mechanistic explanations of basic perceptual processes.
> They have had nowhere near this kind of success when it comes to
> things like "executive functions". It may have to do with the fact
> that the nature of information processing is more idiosyncratic (self-
> organizing in a complex way) in the frontal lobe of the brain. Bottom
> up perceptual processes are topographic and map the external world in
> a fairly tractable manner. Consequently, we have fairly detailed
> models going down to the neuronal level. We don't have this for
> higher-order cognition.
>
> We could emulate the human brain by modeling the activity of different
> neural regions, but this would be an extremely limited form of reverse
> engineering. Emulation isn't understanding. Ideally, we would like
> detailed understanding of the engineering principles underlying
> cognition. Without this, we will be limited in our abilities to
> anticipate the emergent properties of the emulated brains. If you
> achieve a super-intelligence using this sort of method (the ethics of
> which are questionable), I don't see how we will be able to ensure
> benevolence (which is important if you're a non super-intelligence).
To emulate the behaviour of neurons in a brain would involve
calculating all the outputs from a volume of neural tissue given all
the inputs from the surrounding tissue. If we could do that, we would
be able to calculate what signals the brain would send to the vocal
apparatus after receiving any given input from the auditory nerve. The
only obstacles to doing this, given an adequate neural model, would be
having sufficiently fine-grained information about brain state and
sufficient computational resources to run the model. It would require
resolution and simulation down to at least the molecular level, and it
is hard to imagine that we would be able to pull off such a feat
without understanding and copying higher level cognitive functions
first; rather like building a flying machine by emulating a bird's
wings, muscles, cardiovascular and nervous system before being able to
build a rubber band-powered ornithopter.
-- Stathis Papaioannou
This archive was generated by hypermail 2.1.5 : Wed Jul 17 2013 - 04:01:00 MDT