What the brain's wiring looks like
bbc.com
bbc.com
The connectome at the cellular level is massive. I think part of the mouse visual cortical connectome has been mapped out, and the data is on the order of tens of terabytes.
https://www.nature.com/nature/journal/v420/n6915/full/nature...
Take a bunch of source code. Compile it, obfuscate it, compress it, and encrypt it with AES such that the result is a 160MB blob. Now see how long it takes to figure out what it does, given a computer that costs a lot of money just to load your program and a long time to give you a result. The upper bound on the complexity of DNA as it relates to the complete expression of an organism phenotype is insanely high.
Like, the connectome for C. elegans has been mapped out; it's can be written down as a 2 megabyte ascii text file. Just the connectivity is not enough to actually reproduce the behavior of the worm, you would also need data about the weight of each connection, but it's still a lot less data than the worm genome (about 25 megabytes---I hope I got the number right this time!). The worm genes also need to contain a lot of additional stuff to build functioning cells internals, etc, stuff which hopefully is irrelevant to the actual cognition.
I cannot adequately put the insane laugh required as response to that into text form. So I will only write this and be just as right: going by physics the brain of a mouse can be adequately approximated by a perfect sphere.
"A Turing machine ... manipulates symbols on a strip of tape according to a table of rules"
Whichever programming language you are fond of ultimately reduces to this mode of computation. However, with DNA, RNA, and Proteins, that is not the case. The way that we compute is simplistic compared with the way that biology computes. Thus: the crude analogy in fact hinders understanding, and should be discarded.
How complicated does a brain have to become in order to understand itself?
Could a brain exist that is so complicated that it could not understand itself, or does a brain's understanding always scale up with its complexity?
Does "understanding of the brain" mean, that we can construct or simulate a brain? An artificial brain, which reproduce our intelligence and consciousness?
There is no reason to believe, that we can't do this. A brain is part of our world, governed by physics.
However, we will never be able to understand the thought process down to each individual activation of the neuron.
That's like trying to "understand" and follow the movement of each atom in my coffee next to me.
How do you know consciousness is "governed" by our contemporary understanding of physics?
If it's the latter, then the project to explain everything in scientific terms is doomed, because it will always leave something out. If it's the former, then subjectivity is not fundamental, but arises from the objective world. How this is so is a difficult matter (no pun intended).
Either way, there is no magic involved, just a question of where philosophical assumptions begin. You can start with matter or the mind and see where it takes you.
IMO science is doomed to always leave something out as you say.. it will reach a fundamental building block that simply exists, can not be expressed in terms of something else and might as well be called God. But i just haven't heard any convincing arguments that consciousness can't be understood before we reach that point.
Pain is also "subjective", but we understand pain, who it develops and moves in the body, etc.
Plus, that consciousness is subjective is another way of saying we haven't mapped it specifically, so this is a kind of circular logic.
The "subjective" part is just a set of states of an objective construct (the brain, which is a physical object).
Once we know enough to create a synthetic brain, it really doesn't matter what its subjective experience is, we will judge it the same way we judge our fellow humans.
And this is fine since we have no way to truly know the subjective experience of say color for any other human either. Yet we don't question each others claim of consciousness.
It's enough that we can both say "blue" to name the ~ 490–450nm wavelength of light regardless of our personal subjective experience of it.
It doesn't mean we can experience the subjective states of a synthetic brain or another human, but we can definitely replicate the physical aspects of the brain that produce them.
Update:
I'm not sure I'd say supernatural. I think consciousness is different in kind from the rest of how we understand the universe to work. It seems likely that it's a fundamental property of the universe.
I see this all pretty much the same way that the philosopher David Chalmers does. He probably does a better job of explaining it than me. It's worth looking at his thinking on the matter.
Edit:
I think all that philosophy is going to have to be updated when we eventually start having conversations with synthetic brains that can tell us about their sense of consciousness ;-)
Edit 2:
If we had a device that could instantly make a carbon-copy (unintended pun) of a human (let's say me), identical down to the last atom, what you're saying is that copy would NOT be conscious. That it is not enough to capture the physical nature of someone to capture the state of consciousness.. that it is beyond physical. I just don't know how to come to terms with that idea. To me consciousness simply must be a product of our physical bodies and thus within the purview of rational study and comprehension.
However, there is no reason future computers will be limited to current (Turing) technology instead of being a collection of many co-processors with differing capabilities.
The main point though, is that since consciousness is housed in the physical brain, we can dissect, understand, and recreate fully-functional synthetic versions. While each person is in their own subjective world, the brain which is responsible for it is an objective object that is open to study.
That would violate the Church-Turing thesis, which is pretty widely accepted, unless the universe itself is a hypercomputer that we can leverage to perform computation.
But they do, and we can copy them, what is the problem with making a synthetic brain? Why is the natural brain an allowed exception, but the one we make is not allowed?
Edit:
On the one hand you want to use Church-Turing to invalidate the possibility of us creating non-Turing based technology, and yet in a previous post you claimed the human brain likely violates Church-Turing. So which is it? Is reality allowed to violate Church-Turing or is it not?
If you honestly believe that the human brain violates Church-Turing, then you have to explain why you also believe that we can not copy the brain and achieve the same result ourselves.
I do think that I actually agree with your earlier point that once we have a functioning synthetic brain, we can ignore subjective experience itself and just focus on its functional implications for the entire system.
Why?
Any sufficiently advanced technology is indistinguishable from magic.
Is consciousness?
How do you know that this is true?
Our brains are part of this universe, and conciousness is dependent on our brains.
This is neither a logical/mathematical proof, nor an empirically established fact. So how do you know? Why are you making statements of faith in what seems to be the scientific worldview, when the actual scientific worldview is that we should never make statements of faith?
Roughly 68% of the observable universe cannot be explained by physics ("dark matter").
Lets assume there is some sort of physical process involved that we don't understand or even know about (unlikely), it would still be part of the physics that govern our universe.
You're begging the question. Why is "some sort of physical process" the only hypothesis space you're considering?
If the feeling of beeing a clock, winds up a spring in the clock that works a mechanism that feels like fear on beeing predictable (aka exploitable) - that does not make the clock less observable.
What grounds do we have for asserting as certain that consciousness is not a foundational thing-that-simply-is, but must definitely be composed from sub-systems that are themselves non-conscious?
I for once believe that at the neuronal level, the sugar is spun into little pixies that fly around in the brain transfering information.
Dementia is occuring when somebody does no longer believe in fairys - and the little sugar elves die. So its always good to start any conversation on this with "I-do-believe-in-fairys" to keep the memory fresh.
Sure. But not necessary governed by current physics..
Is there any reason for the operations of brain to be limited to those involving P' only?
That means that even if exotic particles existed, they wouldn't have a practical effect on everyday matter, and thus, to our brain.
This all, of course, lies on the assumption that the symmetry property of QFT is correct. It's very likely to be (at least in everyday conditions, such as in a slab of fat in 37 C heat bath) – after all, QFT is the most experimentally precise scientific theory ever discovered in the history of science.
Is that true in general, or are you specifically talking about human brains?
At time index 586578382342us the cell no 15547349 got activated which led to a slightly improved electric charge around the axon of neuron no 68342. The connection strength, as you remember, from time index 3870127106 is now 1% higher ..... one billion pages later ..... but the atom here is slightly misaligned to its counterpart, ...... one billion pages later .... noise coming from dentride no 496839 .... one billion pages later .... let to a decreased potential at muscle cell no 9678402 and hence a millimeter shift of the finger tip no 3. ......
Do you want to here the exciting story about my semimenbranous muscle at time index 4386702121us :)
Do we understand the brain when we have this information? What I want to say is, that our brain cannot store so much information and handle it. Hence, we cannot "understand" the brain on this level. ("The person did this, because .... ")
In order to reason about the emergent phenomena, you have to "zoom out" - look at bigger pieces, not the individual atoms or neurons.
The tricky part here is that it seems that there is no particular reason for the bigger pieces to be separated into easy to reason about "modules". It could of course be the case, but I don't really see the evolutionary advantage between a "mess of wires" that works well enough and a system that is modularised.
So, if the brain is a modularised system, then there is hope of understanding it, as you can understand a computer that another commenter mentioned as well.
But, if not, then it might be the case that indeed a human brain will not be able to understand it by itself. If there is an underlying structure that's just intermixed with the other parts, then perhaps with the help of computers we can separate them logically.
There is of course the possibility that modularisation is simply not possible, because of (almost) full connectedness and interactions. Mr Penrose for example suggests the case of quantum entanglement leading to consciousness and if that really is the case, then there is essentially no way to "understand" why a certain decision was reached by the brain.
Finding a bug is usually starting from a very high degree of knowledge about the designed function of the system and verifying at ever higher resolution that it actually performs according to those designed parameters. That's different from trying to understand what a computer does starting from an electron micrograph of the chips and not having access to the software or the wiring diagram. That might lead to useful insights but it wouldn't be understanding.
Can a computer compute itself?
So in the strict sense, not only can a computer compute itself, but it can compute its (more capable) successor generation.
Practically, this now occurs in large server farms, so it takes a large number of computers to compute themselves and/or progeny. But this is very much what happens.
The brain may be the only object with this property.
Your statement sounds like mysticism, trying to soften the emotional coldness of the materialist view of the universe.
so the question is, where does the line between animate and inanimate lie?
It’s an interesting line of questioning. What makes “someone?”
Is a living but braindead/comatose human body someone?
Many may be inclined to say yes, yet a statue or other inanimate likeness of a human wouldn’t be considered someone..
How about a thing that doesn’t resemble a human at all but gives the exact same responses to inputs that a human brain would? Say, on a computer screen?
If you were told that a real person is sitting somewhere and sending these responses, you’d say it was someone, but probably not if you were told that it’s an AI...
It’s mostly all subjective and we just pick the definition that’s convenient for us to work with and comprehend.
[0] https://www.amazon.com/Infinity-Mind-Philosophy-Infinite-Pri...
Is there any reason to get the most recent version (says "with a new preface by the author") over the $2 paperback?
Would be interesting to know how much better this model is.
It is not exactly "hot news", as it is already in research use for several years already (in the US, at MGH). It is, still, however, pretty unique in a way that it was optimized for human in-vivo diffusion MRI (tracing of white matter pathways in alive human subjects :-).
Diffusion MRI scans which can be obtained by this scanner are of exceptionally high quality and resolution (spatial and angular), and contain lots of data that can be fed to mathematical models to infer fiber crossings, etc.
However, despite the high spatial and angular resolution it is still at least an order of magnitude short of what is necessary to capture local axonal connections and this type of imaging certainly does not tell you the direction the signal is flowing.
Still an important progress IMO.
In fact, 3T Connectom A is actually more optimized for Diffusion MRI / white matter tract tracing compared to the available 7T scanners due to its enormous 300 mT/m gradient.
In theory, the best of both worlds would be a 7T+ scanner with ultra strong gradient system such as the one developed by the HCP team, but such device does not exist yet AFAIK.
I wouldn't have guessed that it would look so linear. I was expecting a much more tangled appearance.
[0] https://28oa9i1t08037ue3m1l0i861-wpengine.netdna-ssl.com/wp-...
Check out this article for a pretty cool overview of the brain: https://waitbutwhy.com/2017/04/neuralink.html
Forests are brains.
https://aeon.co/essays/your-brain-does-not-process-informati...
Yes, humans are certainly different than our PCs today, but that does not mean that the principles are so different. E.g. humans seem to use a lot of lossy 'compression' while that is something we try to avoid in software in recent years. So we use computers for the things humans cannot do very well and therefore it appears that we are different.
I think the whole discussion about putting the human mind into computer terminology is more about accepting that humans are just biological machines versus believing that humans are special because they have a soul and are different than any other animal.
Similarly, the brain is like a computer. Until it's not.
Interesting how nobody runs it the other way. A computer is like the brain. Why don't we? Probably because we understand computers a lot better than brains, and use that analogy to make sense of something otherwise mysterious.
None of this has anything to do with a soul, btw. It's all a matter of how we think about things.
The mistake is when we take our metaphors literally and try to make domain B fit into domain A, despite obvious differences. Then we end up with a convoluted view of B that's been distorted by being mapped onto A.