Simulating 1 second of real brain activity takes 40 minutes and 83K processors • Hacker News Board

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#81

Post by sgentle » Mon, Aug 05, 2013, 5:16 AM UTC

JamesArgo wrote: post #78

dekhn wrote: post #56

Earlier quoted context omitted.

Generally, the people doing brain simulations like to claim that they can use a massively reduced representation (little more than a graph model that pushes signals around with some constants) and yet, somehow, the simulation is inherently capable of reproducing something complex about thought. I'm not sure how they get to this conclusion, but it's a massive reductionism. It would be nice if it were true- it would me…

When did reductionism become a dirty word?

I've noticed this too. I blame a combination of Zen and the Art of Motorcycle Maintenance and not knowing what the word actually means.

From my observation, it appears people assume "reductionist" means "simplistic" as opposed to "representing a complex system as no more than the sum of its components". To be honest, I think it's just an etymological problem: "reduction" sounds bad, so "reductionism" sounds bad.

The grandparent here follows this pattern. Using the actual meaning, it would be paradoxical for an approximation to be reductionist. In fact, it's quite the opposite. A reductionist would hold that the most accurate high-level model of a brain would be the most low-level model of a brain. If we could model each atom precisely then we would, necessarily, model the whole brain precisely.

The whole thing is pretty amusing when you take into account that anyone who manipulates software or systems in any serious way needs to engage in reductionism to be able to work. It's not as if "first, we write module A, then module B, then a system magically appears from the ether" is a viable architecture. At least, not since we stopped taking neural nets seriously.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#82

Post by smosher » Mon, Aug 05, 2013, 5:20 AM UTC

jonmrodriguez wrote: post #67

smosher wrote: post #64

Earlier quoted context omitted.

> something complex about thought Can you elaborate on this class of 'something'? There are intelligent behaviours that can be reproduced this way, so without more specifics I feel like you're making the same mistake you're condemning.

For example, the glial cells are now believed to be vital to the brain's processing, but most "brain simulations" are still modeling neurons only, not glia. http://shahamlab.rockefeller.edu/pdf/CTDB_69_C_69003.pdf

Not helpful. My question demands an answer from the person making the claim, unless you happen to know what they're thinking. Besides, this sounds nothing like what they're talking about.

Worse, I don't think you're prepared to prove that a mostly pure-neuron simulation is incapable of giving rise to that certain complex quality apparently far removed from the level of the simulation.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#83

Post by coldarchon » Mon, Aug 05, 2013, 6:03 AM UTC

pervycreeper wrote: post #4

anigbrowl wrote: post #2

Unfortunately, that's only for a number of cells equivalent to 1% of a human brain. A full brain's worth of simulation would take 2.5 days....although that much is probably not necessary. It will fall soon enough, though.

The thought that we are maybe two decades away from having the computing power to simulate a human brain in realtime (and much more than that subsequently) is astounding, even in this age of technological wonder.

add another decade until we have the right software then ..

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#84

Post by pixie_ » Mon, Aug 05, 2013, 6:34 AM UTC

hannibal5 wrote: post #48

pygy_ wrote: post #44

These attempts at brain simulation perplex me to no end. Simulating a lump of tissue is definitely useful, it's when they start talking about simulating a complete brain that I get lost. A brain doesn't happen overnight. It is the result of a long developmental process encompassing embryology, learning and experience acquisition. How do they plan to wire the whole thing? Micro- and macroscopic connections are well un…

They use it to understand brain. So they wire it like the brain is wired. If they simulate cortex, they wire arrange it into cortical columns (size of each column is between 50,000 and 100,000 neurons and there is over two million of them). Those columns have many different layers and neuron types. Understanding how cortical columns and minicolumns work is very important.

Each neuron is growing, making decisions about it's environment, reacting to a multitude of neurotransmitters with a mulititude of complex reactions. Deciding where are when to make a new connection. If each node is a little computer system how do we even begin to emulate its probably extensive and convoluted 'programming.'

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#85

Post by ars » Mon, Aug 05, 2013, 7:00 AM UTC

ggreer wrote: post #14

csallen wrote: post #6

Earlier quoted context omitted.

Even if you are a simulation, would you prefer not to exist? What, really, is the difference between reality and a perfectly-executed simulation? It's hard to condemn one without condemning the other.

I think the GP is talking about current simulations, not future ones. Current simulations don't have sensory organs, and I doubt the simulated neurons accurately reflect a real brain at this stage. Most likely, early simulated minds would be insane and in great pain, with no way to communicate. Considering we experiment on animals to reduce human suffering (heck, we kill and eat them just because they're tasty), runn…

> early simulated minds would be insane and in great pain

Insane maybe, but why in pain? Why would you add pain signals without also communication?

Even currently existing lower animals (lobsters and down) don't feel pain - why would you expect a simulation to do so?

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#86

Post by kingkawn » Mon, Aug 05, 2013, 7:02 AM UTC

Recent research has shown glial cells, the uncelebrated insulator of the axon, in fact provide significant chemical signaling and modulation to the process of neural activity. Only phenotypical changes have been observed, it's not understood yet. Suffice to say that computational limits aside, we still couldn't simulate a brain because we wouldn't know what to make.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#87

Post by dnautics » Mon, Aug 05, 2013, 7:29 AM UTC

jfoutz wrote: post #39

moocowduckquack wrote: post #36

Earlier quoted context omitted.

How would you plan on simulating all the variety of states, reactions and solutions involving plain old water without worrying about hydrogen and oxygen atoms?

Again, i would assert that a cell is 70% water. some tiny fraction of water that's actually used in a reaction would just be special cased, and modeled independently. My understanding of "solution" is stuff floating in water. If there's some value in breaking out each atom, i'm all for it, but i kind of suspect the spherical cow is good enough in that case. Even if i'm wrong there, each atom would introduce at least…

The interior of a cell does not follow solution dynamics at all in the way that you would like for it to, and this is why:

http://mgl.scripps.edu/people/goodsell/illustration/mycoplas...

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#88

Post by ibudiallo » Mon, Aug 05, 2013, 7:34 AM UTC

Maybe we are simply taking the wrong approach.

How many gears from a mechanical computer does it take to simulate a micro processor?

If we were to one day to closely simulate the brain, I am sure the method will not involve computers as we know them today.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#89

Post by lukifer » Mon, Aug 05, 2013, 8:10 AM UTC

Dylan16807 wrote: post #31

lukifer wrote: post #20

Earlier quoted context omitted.

It isn't a big leap to imagine a debate between aliens about whether the hairless apes on the third rock from Sol should be considered "sentient", or merely clever animals. I'd rather err far on the side of assuming sentience and personhood if there is a shadow of a doubt, simulated or otherwise.

Why would they debate? It's very easy to test for [sentience or fake sentience programmed by a sentient]. Unless the aliens think we're robots they can do a mirror test or something. But such a test does not work in a possibly-tainted environment. A neural net that seems to communicate might just have a hidden encoding of ELIZA. You can err on the side of assuming sentience if you want, but don't think it's out of se…

We choose the definition of sentience so that it includes us. There's no reason to believe that an alien species might not do the same, and that we might not make the cut. Hell, some of the worst racist rhetoric on the planet involves seeing other humans as non-sentient.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#90

Post by slacka » Mon, Aug 05, 2013, 8:43 AM UTC

Xcelerate wrote: post #49

The title statement is almost meaningless. It would be better just to say "simulating reality takes a LONG time". My research is in molecular dynamics. I simulate systems up to 1 billion atoms on Kraken & Titan. HUGE approximations are made in simulating these systems, but depending on what exactly it is you're studying, these simulations still provide useful results. That is the key to all these studies: how well do…

For all the reasons you listed, if we’re going to crack the problem of strong AI in the next century, we’re not going to be doing it by simulating the brain at the atomic or molecular level. However the lower level simulations are important because we still don’t have deep understanding of how neurons work.

An overwhelming amount of neuroscience research data points to the neocortex reusing the same functional unit composed of 100's-1000's of neurons called a cortical column. For example one patient was able to regain her balance by rerouting the signal from her vestibular system to her tongue. So the cortical column is the layer of abstraction we should be shooting for.

Hopefully we'll move away from the 1950’s style perceptron, whose mathematical simplicity has attracted researchers but has been a major distraction to AI as they share almost nothing in common with their biological counterparts. If we don’t want to see a 3rd AI winter, we need to move to more biologically inspired approaches.