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Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

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Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#11

Post by monocasa »

KingMob wrote: post #8

Former neuroscientist here. I have no idea why this paper is at the top of HN, other than that the former founder of Palm is the lead author. Setting aside that it hasn't been published or accepted, the only remotely novel thing seems to be they suggest that location information is represented in each column, and this occurs everywhere in the neocortex. Well, what does the actual biology do? On the one hand, it's wel…

> On the other hand, the entire medical history of restricted lesions and targeted deficits (Broca's area, Wernicke's area, patient HM's hippocampal anterograde amnesia, visual scotomas, etc etc etc) indicate some brain areas really are specialized for some things more than others.

Wouldn't the evolutionary history of the brain imply that information is encoded in two different ways in a lot of cases. Ie. that the components of the older 'lizard brain' (if you'll excuse the issues with that term) have a rather fixed function, but the neocortex evolved overrides to those functions?

Like sure, we've got a much better understanding of grid cells and place cells in the hippocampus, but does that mean that there isn't similar information being stored in a different way in the neocortex?

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#12

Post by sqeaky »

hyperion2010 wrote: post #5

So the implication in the title is almost certainly false. There are columns and layers in areas of cortex that are responsible for processing sensory modalities that are not inherently 3d in nature. If I had to guess (from my vague recollection of the literature) the current thinking is that laminar structures are a nice way to build things developmentally, and columns arise in part from development but also because…

I interpreted the headline as though they meant that the neurons were in a 3d structure and part of the world.

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#13

Post by AndrewKemendo »

monocasa wrote: post #11
KingMob wrote: post #8

Former neuroscientist here. I have no idea why this paper is at the top of HN, other than that the former founder of Palm is the lead author. Setting aside that it hasn't been published or accepted, the only remotely novel thing seems to be they suggest that location information is represented in each column, and this occurs everywhere in the neocortex. Well, what does the actual biology do? On the one hand, it's wel…

> On the other hand, the entire medical history of restricted lesions and targeted deficits (Broca's area, Wernicke's area, patient HM's hippocampal anterograde amnesia, visual scotomas, etc etc etc) indicate some brain areas really are specialized for some things more than others. Wouldn't the evolutionary history of the brain imply that information is encoded in two different ways in a lot of cases. Ie. that the co…

but the neocortex evolved overrides to those functions?

In ideal circumstances that might be true but in fact it's usually the other way around. Kahneman's type 1 and type 2 thinking theory expresses this most succinctly:

The key theme of the book is that the human mind has two distinct systems of thought. The first, which Kahneman labels System 1, is fast, reflexive, intuitive and automatic. It is the primitive part of thinking that evolved to allow us to survive in a dangerous world.

System 2 is slow, rational and deliberative. It is the part of our thinking that we can consciously “observe” and is used for analysis, logical reasoning and deliberate calculations. System 2 can sometimes act as rational governor, overriding judgements or decisions made by System 1. However, the main takeaway from Kahnemen’s life work is that System 2 can be “lazy”, allowing System 1 to lead us to irrational conclusions.

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#14

Post by svara »

amelius wrote: post #10
bmcooley wrote: post #2

Question from someone who is not knowledgeable in ML or AI: Do current implementations of ANNs allow trying out these different types of organizations/structures? Is the structure and workings of neurons sufficiently similar to ANNs that the architecture transfers, or are there huge differences that make understanding and development orthogonal?

And another question on top of that: is there any biological theory that corresponds to backpropagation?

A really interesting question. It would seem far fetched at first that backpropagation could be used by the brain, because it's unclear what the mechanism for transmitting the error at every synapse backwards, to the synapses in the previous layer, would look like physically.

This is a really interesting lecture given by Geoffrey Hinton (https://www.youtube.com/watch?v=VIRCybGgHts) where he discusses the various issue commonly raised with "biological backpropagation" and proposes a solution based on Spike Timing Dependent Plasticity (STDP). Basically he argues that you can interpret the STDP learning rule as a derivative filter on a firing rate and get backpropagation in this way. This is just on wild idea though and has not been shown to work experimentally or through simulations.

There are also a couple of interesting pointers in this Stackexchange thread: https://cogsci.stackexchange.com/questions/16269/is-back-pro...

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#15

Post by etiam »

KingMob wrote: post #9
neuronexmachina wrote: post #7

For some context, this paper is from Numenta, Jeff Hawkins' company. Hawkins was the founder of Palm/Handspring back in the 90s. Afterwards he became quite interested in neuroscience and neural networks, and pulled a Wolfram in his 2004 book "On Intelligence" with claims that he had a unified theory of how the brain works. https://en.wikipedia.org/wiki/Jeff_Hawkins

As a former neuroscientist, the majority of people who claim to have grand unified theories of the brain are those who haven't studied it enough to know how far we still have to go.

Well, Hawkins isn't one of them.

neuronexmachina's flippant comment misrepresents Hawkins and On Intelligence, which lays out in popular form a scientific theory of neocortical function, with perfectly sane perspective on what that means in the context of the whole brain, due references to neuroscience, suggestions for experimental tests and obvious awareness that the theory may prove wrong or incomplete.

I'm disturbed to see that two of the early comments here contribute nothing of value and amount to little more that personal attacks by way of misinformation.

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#16

Post by KingMob »

monocasa wrote: post #11
KingMob wrote: post #8

Former neuroscientist here. I have no idea why this paper is at the top of HN, other than that the former founder of Palm is the lead author. Setting aside that it hasn't been published or accepted, the only remotely novel thing seems to be they suggest that location information is represented in each column, and this occurs everywhere in the neocortex. Well, what does the actual biology do? On the one hand, it's wel…

> On the other hand, the entire medical history of restricted lesions and targeted deficits (Broca's area, Wernicke's area, patient HM's hippocampal anterograde amnesia, visual scotomas, etc etc etc) indicate some brain areas really are specialized for some things more than others. Wouldn't the evolutionary history of the brain imply that information is encoded in two different ways in a lot of cases. Ie. that the co…

In some ways that's true, though the more recent areas tend to cooperate/elaborate, not replace.

E.g., both the superior colliculus in the midbrain and the frontal eye fields in neocortex are responsible for making eye movements, but the FEF doesn't override the SC. Even in this case, it's not like eye gaze/movement info is dispersed throughout all the cortex, it's limited to a short list.

We also know that the receptive fields (which part of a scene a neuron fires in response to) increase in size as you go up the visual hierarchy. V1 neurons will response to tiny parts of a scene, whereas V4/MT and V5 will response to huge swathes of your vision, indicating they become less location-sensitive. Object-identifying neurons may well respond to the object anywhere in your vision, suggesting they're not location-sensitive at all.

I guess Hawkins might argue that it's different neurons in association cortex columns that encode location, but frankly, the argument from biology is poor. There are cortical areas mapped out like this... but I can't imagine why Hawkins thinks this is a governing principle for the whole cerebrum.

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#17

Post by deepsun »

KingMob wrote: post #9
neuronexmachina wrote: post #7

For some context, this paper is from Numenta, Jeff Hawkins' company. Hawkins was the founder of Palm/Handspring back in the 90s. Afterwards he became quite interested in neuroscience and neural networks, and pulled a Wolfram in his 2004 book "On Intelligence" with claims that he had a unified theory of how the brain works. https://en.wikipedia.org/wiki/Jeff_Hawkins

As a former neuroscientist, the majority of people who claim to have grand unified theories of the brain are those who haven't studied it enough to know how far we still have to go.

Nevertheless I appreciate his efforts and just bought his book, because having an idea is way different from putting own money in it. He puts his own money to neuroscience, and does not compete with real scientists for government grants.

Other millionaires may buy yachts, or just spread "novel" ideas (e.g. Hyperloop idea by St. Elon) without investing their own money.

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#18

Post by paladin314159 »

deepsun wrote: post #17
KingMob wrote: post #9

Earlier quoted context omitted.

As a former neuroscientist, the majority of people who claim to have grand unified theories of the brain are those who haven't studied it enough to know how far we still have to go.

Nevertheless I appreciate his efforts and just bought his book, because having an idea is way different from putting own money in it. He puts his own money to neuroscience, and does not compete with real scientists for government grants. Other millionaires may buy yachts, or just spread "novel" ideas (e.g. Hyperloop idea by St. Elon) without investing their own money.

I appreciate and agree with your perspective on putting your money where your mouth is, but Elon is the last person to criticize in that context. He quite literally put all of his money into the problems that he thinks are the most valuable to work on (whether you agree with him or not).

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#19

Post by [deleted] »

paladin314159 wrote: post #18
deepsun wrote: post #17

Earlier quoted context omitted.

Nevertheless I appreciate his efforts and just bought his book, because having an idea is way different from putting own money in it. He puts his own money to neuroscience, and does not compete with real scientists for government grants. Other millionaires may buy yachts, or just spread "novel" ideas (e.g. Hyperloop idea by St. Elon) without investing their own money.

I appreciate and agree with your perspective on putting your money where your mouth is, but Elon is the last person to criticize in that context. He quite literally put all of his money into the problems that he thinks are the most valuable to work on (whether you agree with him or not).

[deleted]

Re: Why Does the Neocortex Have Layers and Columns, Learning the World's 3D Structure

#20

Post by deepsun »

paladin314159 wrote: post #18
deepsun wrote: post #17

Earlier quoted context omitted.

Nevertheless I appreciate his efforts and just bought his book, because having an idea is way different from putting own money in it. He puts his own money to neuroscience, and does not compete with real scientists for government grants. Other millionaires may buy yachts, or just spread "novel" ideas (e.g. Hyperloop idea by St. Elon) without investing their own money.

I appreciate and agree with your perspective on putting your money where your mouth is, but Elon is the last person to criticize in that context. He quite literally put all of his money into the problems that he thinks are the most valuable to work on (whether you agree with him or not).

False. He didn't put a single dollar into Hyperloop (idea that was researched since 100 years ago, and general conclusion is that it's not worth it, too expensive to maintain).
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