
Why Is the Human Brain So Efficient? Massive Parallelism - nbmh
http://nautil.us/issue/59/connections/why-is-the-human-brain-so-efficient
======
iandanforth
"a professional tennis player can follow the trajectory of a tennis ball after
it is served at a speed as high as 160 miles per hour"

This is false or at least highly misleading. A reader might imagine that the
player's eyes track the ball in flight. This is not what happens. A pro player
reads the position of the serve and begins moving before the ball is hit. The
predictive power of the brain is much more important than the speed and
precision the author was trying to highlight here.

~~~
21
The way other articles describe it, a pro player is not really aware of the
incoming ball, lower level non-conscious (reflex) systems track the
environment and react before you are aware of it, just like when a regular
person dodges a sudden obstacle coming at them and only a bit later they
realize what's going on.

~~~
BLKNSLVR
Sounds like one of the concepts that inspired the book Blindsight by Peter
Watts. The subconscious 'reptile brain' is able to process certain old-school
dangers, like an object moving quickly towards us, faster than our conscious
brain, and can cause involuntary, potentially life-saving, reactions to the
stimulus.

The conscious mind processing these things can often get in the way but, in
the case of sports, alter the instinctive behaviour into something
advantageous. An augmentation of the conscious and subconscious into better
performance.

A converse example, being conflict between conscious and sub-conscious, is if
you drop a mug of boiling water, the instinctive reaction is to try and catch
'thing you dropped', but the conscious reaction is 'don't burn yourself' so
don't catch it and jump backwards to not get splashed.

Very interesting stuff.

[https://www.goodreads.com/book/show/48484.Blindsight](https://www.goodreads.com/book/show/48484.Blindsight)

[https://en.wikipedia.org/wiki/Blindsight_(Watts_novel)#Consc...](https://en.wikipedia.org/wiki/Blindsight_\(Watts_novel\)#Consciousness)

Beware (or since it's the HN crowd, Recommended!): hard sci-fi.

~~~
dlwdlw
One thing that has always bothered me about many AI approaches is that instead
of having multiple layers that deal with different levels of urgency
everything is delegated to a "rational" mind that thinks vs a combination of
thinking predicting and reacting.

The parallel is this obsession with rationality over intuition. Though
somewhat ironic because black box AI is just accepted.

~~~
BLKNSLVR
Building something that mimic how it appears to work, as opposed to how it
does work. Like building the symptoms whilst assuming we're building the
disease.

Having said that, however, gotta start somewhere. Having said that, however,
we might have done a decade of work in the wrong direction by the time we find
out what direction it should go...

'tis a conundrum.

------
nootropicat
I recently realized the (obvious in hindsight) fact that general intelligence
better that brute force doesn't exist, as intelligence is equivalent to
compression.

Given the recent discoveries about neurons using mRNA capsids to communicate
[0] it's not that farfetched to posit that we are really dna computers [1].
The processing time (for new problems) seems human-like: "The slow processing
speed of a DNA-computer (the response time is measured in minutes, hours or
days, rather than milliseconds)"

The evolutionary argument: as DNA computing is already used by microbes [2]
how could the nervous system made of (relatively) dumb neurons compete with
that? Synapses still make sense - as a way to request a rna packet and/or
inform that it's coming and from where.

One neuron with capability of ~10M pattern matches per second (encoded in
dna/rna) would mean that the human brain executes ~2^60 pattern-matching
operations per second, utilizing zettabytes of imperfectly copied data. Enough
to brute force its way through lots of problems.

Memory as dna would explain high-level memory quirks: each read would be
destructive, by splitting dna into rna, interacting with other rna under the
presence of appropriate enzymes, then copying and disseminating the resulting
rna, transforming the memory each time it's retrieved.

It would also explain urban legends about people's personalities changing to
resemble their organ donors in some way - as a donor's memory packets that
somehow ended up on the donor's organ and, with the help of
immunosuppressants, managed to infect the receiver's brain.

[0]
[https://www.nature.com/articles/d41586-018-00492-w](https://www.nature.com/articles/d41586-018-00492-w)

[1]
[https://en.wikipedia.org/wiki/DNA_computing](https://en.wikipedia.org/wiki/DNA_computing)

[2]
[https://en.wikipedia.org/wiki/Microbial_intelligence](https://en.wikipedia.org/wiki/Microbial_intelligence)

~~~
justifier
> general intelligence better that brute force doesn't exist

What do you mean by this?

It sounds like you are assuming nature requires exactness and are really
making a philosophical argument about the nature of computation, namely an np
solution in p 'doesnt exist'

> Memory as dna would explain high-level memory quirks

If we are conjecturing than so too could approximate results 'explain high-
level memory quirks'

we already have many approximate algorithms that are significantly better than
brute force, and I would argue that any read procedure would necessarily be
algorithmic, which then would require an explanation as to why this natural
process failed to evolve over time

If such an explanation is simply, though arguably counterfactual, 'nature
requires exactness' and so is unable to utilize the incremental improvement of
evolving algorithms for approximate results, I would argue this implies p!=np
because otherwise I think, if it were able, nature would tend toward improving
on exactness over the 13B+ years it's been expressing mathematical truths

Being as my intended inference in regard this specific unsolved problem is to
develop an algorithm to show p=np, I wonder if the process we refer to as
conciousness may be such an algorithm

> neurons using mRNA capsids to communicate

I wonder if the rna is raw memory data or architectural plans for nuerons
which, when constructed, express memory

~~~
nootropicat
>What do you mean by this?

The goal is to reduce n bits of data to x<n bits. Because there are less
variables you gain predictive capability of n-x bits. Or stated differently,
the goal is to get closer to the kolmogorov complexity of whatever you're
trying to model.

Yet it's not possible to compress n bits in the general case. That's because
the kolmogorov complexity is a function of your assumed knowledge
(assumptions). All you can do is start checking every possible transformation
from your assumption starting with the most probable one - the probabilities
are based on your knowledge itself.

>we already have many approximate algorithms that are significantly better
than brute force

Yes - but that means the algorithm itself, along with its execution, is the
shortest (in the used metric, which can include execution time) answer for a
particular problem. How do you generate the algorithm in the first place?

~~~
justifier
> Yet it's not possible to compress n bits in the general case.

Abstract bits sure, 2^4 objects are unable to represent 2^5 objects, simply
due to 16!=32

But what does it have to do with'general intelligence' and brute force?

We were originally talking about rna communication.. where does kolmogrov come
in? In the data representation in the rna? But what of it when the mechanism
that encodes and decodes is unrestricted in its upper bound complexity? If the
disparity between the upper bound of memory being encoded and the mechanism
encoding it are great enough then that system could 'compress n bits in the
general case'

> All you can do is start checking every possible transformation from your
> assumption starting with the most probable one - the probabilities are based
> on your knowledge itself.

This just sounds like you're saying every algorithm is brute force but with
different possible states due to assumptions

Would you call Euclid's gcd 'brute force with assumptions'? I would argue
algorithm is antonym to brute force

> How do you generate the algorithm in the first place?

Ah, I think I see what you're saying.. are you conjecturing the process of
evolving conciousness was itself a brute force process?

Where understanding it's underlying process and being able to implement it
ourselves, perhaps even more thermodynamically efficient, is inconsequential
due to our efforts being only possible by the original conjectured brute force
process that allowed us to abstract to such a degree..? This process being the
'assumption' to be appended to the proof?

But this again seems like a philosophical debate.. one of life and negative
entropy

How do you define general intelligence? How do you defend the statement that
'intelligence is equivalent to compression.'?

If you would have to consider all of existence as assumption, then a bitwise
representation of our own intelligence would be a significantly small subset
of the bitwise representation of all things; expressing this would seem to
imply some process substantially more efficient than brute forcing every
possible state, or luck is real?, or we underestimate the complexity of
'general intelligence' and in actuality the search is ongoing? Or some
undiscussed other?

------
fallingfrog
The article seems to be about how it is that the brain can process so much
information at so slow a cycle speed, but it doesn't really address power
efficiency at all. Even assuming 100% parallel operation, our current chip
designs use something like a factor of a million more energy to do the same
amount of computation. I wish I knew why- it's not like we're ignoring power
efficiency. Depolarization of an axon must be incredibly power efficient.

~~~
dlwdlw
I think it's about context. If I say "order pizza" a ton of information is
transferred via shared environmental context. I'm not transferring information
directly but manipulating contextual levers to map certain types of
information.

An example is if I say something to you in say japanese, I also need to teach
you japanese in the same phrase unless there is shared context. computers run
on a very impotent form of language, logic, that is rigorous and general
purpose but has no "escape hatch". (basically the sentiment of Godem, Escher,
Bach with regards to rigorous systems. )

~~~
fallingfrog
Oh ok you're talking about data compression. That's also not what efficiency
means, in a strict sense.

------
nitwit005
We don't know what operations the brain is actually doing, so declaring that
it is performing them efficiently is pure speculation.

Similarly, the brain surely has limits to parallelism, for the same sorts of
reasons a computer does. You only have one mouth, so if two parts of the brain
tried to speak, fully parallelized, you'd get nonsense at best. They have to
agree on what to say, which is effectively serialization.

~~~
antris
The mouth as an example with regarding to speech doesn't work very well.
People can say one thing, but say it in a way that means the complete
opposite. So already we have tone incorporated into our speech. Who knows what
kind of subconscious thoughts we embed into our speech that are not yet
understood well.

Then there's the combination of tone and the words, accent, body language and
every other context embed into our language that produces a very complex
meaning, even for one word.

~~~
nitwit005
It doesn't matter what was factored into the speech, you still can't speak in
parallel. It's not physically possible. At some point you need to get
agreement as to what the output should be.

------
nojvek
The brain definitely has an edge on compute power. The computer has an edge on
storage power. I would bet the brain doesn’t store more than a Terabyte of
information.

We just need more cores without spiking energy usage.

~~~
reubenswartz
The human brain has over 100 trillion synapses, which is somewhat analogous to
storage or memory (in both senses). Some estimates for the storage capacity of
the brain are as low as a terabyte. Others are an order of magnitude or two
higher.

Being electrochemical, the brain is “slow” compared to a computer (around
10hz). But it’s massively parallel and an interesting combination of digital
and analogue.

------
Arthanari
A brain is not equal to a computer or a processor.

You will never get the answer if you look at it from a narrow minded
perspective.

A brain is equal to billions of processors connected in a highly naturally
efficient network functioning almost effortlessly.

Something along these lines seems like a plausible comparison to a brain.

What is a brain is not equal to a processor but a neuron is equal to a
processor?

------
amelius
How many milliseconds does it take for one layer of neurons to adjust its
output? Let's call this number X.

Can we conclude that if a task takes a human Y milliseconds, then a neural
network with Y/X layers is sufficient for that task?

~~~
blattimwind
AIUI/AIBT there aren't really discrete layers in brains and even the same type
of neuron can act in very different ways, so I wouldn't be surprised if this
question doesn't translate to brains.

------
partycoder
The side-to-side comparison is not very accurate.

The brain consists of many structures, many of them involved in non-cognitive
tasks.

~~~
blattimwind
The "speed of basic operation" column is given as "10 GHz" for a computer and
1 kHz for a human brain, but later is clarified that the 1 kHz refers to the
maximum observed frequency of a neuron's output. Arguably these are unrelated
metrics. I don't think a thing like "speed of basic operation" can even be
defined for a human brain, because fundamentally it's a programmable computer
metric that simply doesn't transfer to a brain.

Of course, one could go ahead and simply compare the conscious compute power
of a human to that of a computer (e.g. FLOPS), but then that number would be
something like "1/100 to 5 FLOPS".

~~~
partycoder
Another problem with the analogy in this article is that there is no division
between memory and processing element in a nervous system. They're essentially
the same.

Imagine running a program on a computer where everything is somehow memoized,
on a system that is always powered on.

------
timvisee
I wonder how this would compare against quantum computing, as that allows
maximum parallelism too if in correct.

~~~
rfw
Quantum computing is not parallel computing:
[https://physics.stackexchange.com/a/3400](https://physics.stackexchange.com/a/3400)
briefly talks about the mechanism of quantum computing and how it is not
general parallelism.

------
whatever1
Question: Has there been a comprehensive study on the activation function of a
single (biological) neuron?

~~~
gimagon
Yes, see the Hodgkin Huxley model [1].

[1]
[https://en.wikipedia.org/wiki/Hodgkin%E2%80%93Huxley_model](https://en.wikipedia.org/wiki/Hodgkin%E2%80%93Huxley_model)

------
tabtab
My brain isn't efficient. I forget basic things sometimes.

------
pranjal1029
Human brain mechanism is a mystery

------
coss
I feel like there must be some way to 'clean' our brains. As we get older it
must accumulate 'gunk' that slow it down or weaken connections.

I guess sleep is the closest thing we have but to me that's like saying drink
water to fix tooth decay.

~~~
rmwaite
Drinking water (instead of sugary and/or acidic drinks) is actually a very
good way to prevent tooth decay.

~~~
Retra
Even if you drink sugary/acidic drinks, water helps dilute them and rinse them
away.

------
posterboy
Like a quantum computer, computing thousand calculations at once and the true
answer is what remains? I guess there's a ... parallel there. And I know some
people don't like this diductic reduction, analogy, metaphor,
callitwhatyouwant. I'd welcome corrections.

~~~
dsr_
The problem with trying to correct this is that it's not wrong, because it
doesn't really state a hypothesis.

Are you trying to say that brains are quantum computing devices? Maybe, but we
don't have any particular evidence for that, so it's on a par with saying "The
Flying Spaghetti Monster has a tiny noodly appendage that reaches through
hyperspace into each neuron, and that's how we think."

We can observe brains in a lot of different ways - active electromagnetics,
chemical sampling, microscopy, MRI... and we can say that injuring certain
areas of the brain will impede certain functions. We know that excesses or
droughts of some chemicals are associated with emotions, depression, and some
diseases.

But we don't have a good model for how brains think, and among the good models
we don't have, quantum computing is one of them.

~~~
posterboy
I was being sarcastic, but then wasn't sure whether the comparison was
actually wrong.

