Being able to treat the pattern of someone's brain as software to be run on a computer, perhaps in parallel or at a large speedup, would have a huge impact, both socially and economically. Robin Hanson thinks it is the most likely route to artificial intelligence. Anders Sandberg and Nick Bostrom of the Future Of Humanity Institute created out a roadmap for whole brain emulation in 2008, which covers a huge amount of research in this direction, combined with some scale analysis of the difficulty of various tasks.
Because the human brain is so large, and we are so far from having the technical capacity to scan or emulate it, it's difficult to evaluate progress. Some other organisms, however, have much smaller brains: the nematode C. elegans has only 302 cells in its entire nervous system. It is extremely well studied and well understood, having gone through heavy use as a research animal for decades. Since at least 1986 we've known the full neural connectivity of C. elegans, something that would take decades and a huge amount of work to get for humans. At 302 neurons, simulation has been within our computational capacity for at least that long. With 25 years to work on it, shouldn't we be able to 'upload' a nematode by now?
Reading through the research, there's been some work on modeling subsystems and components, but I only find three projects that have tried to integrate this research into a complete simulation: the University of Oregon's NemaSys (~1997), the Perfect C. elegans Project (~1998), and Hiroshima University's Virtual C. Elegans project (~2004). The second two don't have web pages, but they did put out papers: [1], [2], [3].
Another way to look at this is to list the researchers who seem to have been involved with C. elegans emulation. I find:
- Hiroaki Kitano, Sony [1]
- Shugo Hamahashi, Keio University [1]
- Sean Luke, University of Maryland [1]
- Michiyo Suzuki, Hiroshima University [2][3]
- Takeshi Goto, Hiroshima Univeristy [2]
- Toshio Tsuji, Hiroshima Univeristy [2][3]
- Hisao Ohtake, Hiroshima Univeristy [2]
- Thomas Ferree, University of Oregon [4][5][6][7]
- Ben Marcotte, University of Oregon [5]
- Sean Lockery, University of Oregon [4][5][6][7]
- Thomas Morse, University of Oregon [4]
- Stephen Wicks, University of British Columbia [8]
- Chris Roehrig, University of British Columbia [8]
- Catharine Rankin, University of British Columbia [8]
- Angelo Cangelosi, Rome Instituite of Psychology [9]
- Domenico Parisi, Rome Instituite of Psychology [9]
This seems like a research area where you have multiple groups working at different universities, trying for a while, and then moving on. None of the simulation projects have gotten very far: their emulations are not complete and have some pieces filled in by guesswork, genetic algorithms, or other artificial sources. I was optimistic about finding successful simulation projects before I started trying to find one, but now that I haven't, my estimate of how hard whole brain emulation would be has gone up significantly. While I wouldn't say whole brain emulation could never happen, this looks to me like it is a very long way out, probably hundreds of years.
Note: I later reorganized this into a blog post, incorporating some feed back from these comments.
Papers:
[1] The Perfect C. elegans Project: An Initial Report (1998)
[2] A Dynamic Body Model of the Nematode C. elegans With Neural Oscillators (2005)
[3] A model of motor control of the nematode C. elegans with neuronal circuits (2005)
[4] Robust spacial navigation in a robot inspired by C. elegans (1998)
[5] Neural network models of chemotaxis in the nematode C. elegans (1997)
[6] Chemotaxis control by linear recurrent networks (1998)
[7] Computational rules for chemotaxis in the nematode C. elegans (1999)
[9] A Neural Network Model of Caenorhabditis Elegans: The Circuit of Touch Sensitivity (1997)
I would respectfully disagree with Dr. Hayworth.
I would challenge him to show a "well characterized and mapped out part of the mammalian brain" that has a fraction of the detail that is known in c. elegans already. Moreover, the prospect of building a simulation requires that you can constrain the inputs and the outputs to the simulation. While this is a hard problem in c. elegans, its orders of magnitude more difficult to do well in a mammalian system.
There is still no retina connectome to work with (c. elegans has it). There are debates about cell types in retina (c. elegans has unique names for all cells). The gene expression maps of retina are not registered into a common space (c. elegans has that). The ability to do calcium imaging in retina is expensive (orders of magnitude easier in c. elegans). Genetic manipulation in mouse retina is expensive and takes months to produce specific mutants (you can feed c. elegans RNAi and make a mutant immediately).
There are methods now, along the lines of GFP (http://en.wikipedia.org/wiki/Green_fluorescent_protein) to "read the signs of synapses". There is just very little funding interest from Government funding agencies to apply them to c. elegans. David Hall is one of the few who is pushing this kind of mapping work in c. elegans forward.
What confuses this debate is that unless you study neuroscience deeply it is hard to tell the "known unknowns" apart from the "unknown unknowns". Biology isn't solved, so there are a lot of "unknown unknowns". Even with that, there are plenty of funded efforts in biology and neuroscience to do simulations. However, in c. elegans there are likely to be many fewer "unknown unknowns" because we have a lot more comprehensive data about its biology than we do for any other species.
Building simulations of biological systems helps to assemble what you know, but can also allow you to rationally work with the "known unknowns". The "signs of synapses" is an example of known unknowns -- we can fit those into a simulation engine without precise answers today and fill them in tomorrow. The statement that no one should start simulating the worm based on the current data has no merit when you consider that there is a lot to be done just to get to a framework that has the capacity to organize the "known unknowns" so that we can actually do something useful with them once they have them. More importantly, it makes the gaps a lot more clear. Right now, in the absence of any c. elegans simulations, data are being generated without a focused purpose of feeding into a global computational framework of understanding c. elegans behavior. I would argue that the field would be much better off collecting data in the context of adding to the gaps of a simulation, rather than everyone working at cross purposes.
That's why we are working on this challenge of building not just a c. elegans simulations, but a general framework for doing so, over at the Open Worm project (http://openworm.googlecode.com).