Whole human brain mapped in 3D
nature.com
nature.com
They can already do a full 3d map of blood vessels and neurons (with stains) in a mouse brain within a few days and store it on a TB hard drive (I'm told an equivalent for the human brain would be a petabyte but their slices might be thinner). This is a procedure that would take months if not years to do by hand (they do a full analysis on all of the slices to reproduce a 3d model afterwards).
This paper was done mostly by hand but soon we'll be able to do it quickly and automatically.
It's okay, Nature, the word terabyte doesn't scare people and is indeed now part of common parlance...
(Though seriously, Wikipedia is about as accurate as the Encyclopedia Brittanica, at least for science articles: http://www.nature.com/nature/journal/v438/n7070/full/438900a...)
Don't trust a wikipedia page that has zero citations.
I was not aware at that time that Wikipedia actually contradicted itself, but that was a very easy way to demonstrate my point in a followup post. But the particular flaws in that article were never my main point.
The real megabyte page says that it has multiple meanings, and the mebibyte page says that "it was designed to replace the megabyte" and that "it is not commonly used". And I'll assume the sources listed are suitable for the moment.
as confirmed here:
http://www.sciencemag.org/content/suppl/2013/06/19/340.6139....
Hell yeah, free science requires free software!
If possible, this would open a huge ethical can of worms: how can we tell such a simulation is not conscious? Would deleting its runtime data after however many simulation cycles be tantamount to murder?
Edit: I am not saying that the above concerns should stop us from working towards developing human brain simulations since the potential benefits of those are just too great. Rather, it is something we have to have in mind as they get more complex and closer to the real thing.
Then again, it will likely be many years still before that actually comes up.
This will certainly be useful for attempts to recreate the functionality of a brain in silico - big research efforts such as the blue brain project [1] have probably been using even early forms of this data.
Having said that, in some ways it won't provide the useful information that will enable the functionality to be restored to the connections.
heres why.
Current efforts involving simulated brains rely both on older, less precise versions of what this nature article talks about - let's call that the roadmap, as it is a map of where all the neurons sit and where they connect to. This project drastically increases the resolution of this roadmap.
However the additional information needed is what traffic is carried by each road. The brain as we understand it today consists not just of the connections between the neurons but also that each neuron, and each different network of the brain, secretes it's own neurotransmitter. Because some of these neurotransmitters are depolarising and some are inhibitory, and they connect widely across the brain and are much more closely related to the actual information processing, we need to have this information before we will be able to better approximate a brain.
In all likelihood this is information gathering is probably underway right now. From what I understand the 'BigBrain' project aims to do for the human brain what the Allen Brain atlas did for mouse brains, that is not only provide a map of the connections but also stain for gene expression and (from memory) neurotransmitter presence.
With this added information we will be closer to our goal of getting skynet sentient.
It's not just about mapping the topology of the brain, just having a neural network of 1e10 vertices and 1e12 links will not give you an artificial intelligence. It's just not that simple. The connectome paradigm is not sufficient. It is hip because of computer scientists using artificial neuron networks to achieve awesome stuff. But that doesn't mean that the complexity of the human brain only resides in the number of neurons and interactions. It's not guaranteed that we are getting closer of the goal just by adding billions of neurons and connections.
I find this wannabe holistic approach a bit confusing as it is horizontal whereas I am convinced that what we need is a vertical approach : up from graph topology down to an accurate biophysical understanding of synapses and information transmission, all across multiple scales, from the angström up to microns.
That's the key : multiscale modeling, not single-huge-scale modeling.
There are other exciting developments that map not just neuroanatomical structure but also the distribution of proteins and gene expression [2],[3]
[1] http://eyewire.org/ [2] http://med.stanford.edu/ism/2013/april/clarity.html [3] http://smithlab.stanford.edu/Smithlab/Array_Tomography.html
"I'd love for a neuroscientist to weigh in on this - what is the possibility that something like this could be used to generate an artificial neural network which imitates, even crudely, the functions of the human brain?"
Pretty much zero. Because it really just focussed on the organisation of the neurons, and ignores the complexity of the neurons themselves and the chemical/electrical/etc. communication between 'em. Neurons themselves are pretty complex beasts, and we're still learning things about them and the level of "processing" that is happening within neurons, as opposed to between 'em.
For example as recently as ten years ago everybody knew that most of the computation was implicit in the neural connectivity of the synapses. We now know that there is significant computation within individual neurons - in the dendrites of all things (previously thought to be pretty much passive carriers of output from other cells - just wires basically).
(See http://www.annualreviews.org/doi/abs/10.1146/annurev.neuro.2... ).
Don't get me wrong - it's useful work. But nowhere close to the level of detail needed to run people-sims.
- 100 billion vertices, 100 trillion edges
- 2.08 mNA · bytes^2 (molar bytes) adjacency matrix
- 2.84 PB adjacency list
- 2.84 PB edge list
[1]: http://www.pdl.cmu.edu/SDI/2013/slides/big_graph_nsa_rd_2013...And, of course, it isn't even near to what we could call a "working model". Just a mapping of every neuron of some particular brain specimen. No one understands how it works yet. There are detailed description in textbooks of how each kind of cells in the brain works, but still can't see the mind among neurons.))
EDIT: Perhaps its similar to google maps, where 3D "tiles" are loaded as required as you zoom in or out.