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> But much of a human brain is a uniform matrix that self-programs. Speaking as a neuroscience PhD ... no. Not remotely close, sorry.

by dmd 10y ago

JoeAltmaier 10y ago
The cortex? How would you describe it then? There are not enough genes in our genome to wire every connection, so self-organizing.
- tormeh 10y ago
  The visual system is basically a deep neural net of the type we are already building, but it's self-contained. Generally it seems like our brain is composed of a lot of fixed-function neural nets (and other algorithms) which are then integrated by less specialized units. That's my impression anyway. I think maybe our artificial visual nets are too general, actually, in comparison to natural ones. It not only describes what it sees, but tries to analyze it too. Showing a picture of a dog results in "dog", rather than "big four-legged furry thing". Expecting a visual system to know that a chihuahua and a German shepherd is the same thing is maybe a case of grouping tasks that shouldn't be grouped.
  - sounds 10y ago
    In order to build an artificial visual system, humans must grasp what their own visual system does. In order to describe what the human visual system does we use words like "dog" -- and I would agree with you, "big four-legged furry mammal" might be better, but artificial visual systems work more at the level of "80% probability of dog," "2% probability of brick," "90% probability of chihuahua," and they don't really know that chihuahua must always imply dog. In order to describe the function of the visual system, a fundamental change really must happen in the way the system's output is described. Using plain written words as output may work as a system but it is not an exact replica of a human visual system. It is more of a trained animal act: when you see dog-like images, press the button labelled "dog" (does the animal even comprehend what a dog is?) In order to rethink the way we describe output, we will have to come up with a very precise description of the inside potentials and activations in mammalian brains. We are just barely creating tools to describe what an artificial neural net "is thinking." So I guess we're starting to look in that direction.
- LeifCarrotson 10y ago
  Genes encode some of the rules by which the the neurons self-organize, or "grow". Further growth from an initial cell is partially controlled by environmental factors. This is not a novel or unique application, literally all living things grow by using the rules encoded in DNA and environmental factors. Consider the demo scene, where 64 kilobytes of code generates a fascinating video with deep complexity. You could not encode a 64k demo as a series bitmapped frames in 64k, or probably in 64 megabytes. But that doesn't mean that you can generate one by stuffing together a bunch of RGB pixels and hoping they self-organize.
Balgair 10y ago
I'm going to echo this and add a bit more context. Look at the cerebellum for example. That lump at the bottom of your rear skull has ~50% of all your neurons. It is extremely important for motor control. When you grab a cup of coffee as you dash out the door in the morning, your cerebellum is what is responsible for you being able to do that without looking at the cup as you reach for it. You 'know' the cup is there and you don't have to tell every nerve to fire every muscle and to extend your forearm and then grab it with only 3 fingers and then adjust for the decrease in weight with every sip. You just do it, naturally. Your cerebellum is what is responsible for that. It is a dedicated portion of your brain that really only does those kinds of things. Your hippocampus also deals with short term memory. HM was a famous patient that had his hippocampus removed, basically, and then lost all of his short term memory. Poof, gone forever. In short, your brain has dedicated areas in it that only do certain things, it is NOT some FPGA that gets re-wired on the fly. Your intelligence is not dependent on the number of connections or neurons.
- dmd 10y ago
  And it develops this way, controlled by DNA. If the brain were really a "uniform matrix that self-programs", think how unlikely it would be that the same functions are performed in the same areas in every person. Everyone's language area (to use a rough term) is in the same place in the brain. Everyone's visual cortex is in the same place. And this holds for even fuzzier concepts like, say, 'concepts', to a point. And this holds for even non-primates - take a squirrel, and you'll find its visual cortex right where you'd expect it.

> But much of a human brain is a uniform matrix that self-programs. Speaking as a neuroscience PhD ... no. Not remotely close, sorry.

by dmd 10y ago

> But much of a human brain is a uniform matrix that self-programs. Speaking as a neuroscience PhD ... no. Not remotely close, sorry.

JoeAltmaier 10y ago

The cortex? How would you describe it then? There are not enough genes in our genome to wire every connection, so self-organizing.

tormeh 10y ago
The visual system is basically a deep neural net of the type we are already building, but it's self-contained. Generally it seems like our brain is composed of a lot of fixed-function neural nets (and other algorithms) which are then integrated by less specialized units. That's my impression anyway. I think maybe our artificial visual nets are too general, actually, in comparison to natural ones. It not only describes what it sees, but tries to analyze it too. Showing a picture of a dog results in "dog", rather than "big four-legged furry thing". Expecting a visual system to know that a chihuahua and a German shepherd is the same thing is maybe a case of grouping tasks that shouldn't be grouped.
- sounds 10y ago
  In order to build an artificial visual system, humans must grasp what their own visual system does. In order to describe what the human visual system does we use words like "dog" -- and I would agree with you, "big four-legged furry mammal" might be better, but artificial visual systems work more at the level of "80% probability of dog," "2% probability of brick," "90% probability of chihuahua," and they don't really know that chihuahua must always imply dog. In order to describe the function of the visual system, a fundamental change really must happen in the way the system's output is described. Using plain written words as output may work as a system but it is not an exact replica of a human visual system. It is more of a trained animal act: when you see dog-like images, press the button labelled "dog" (does the animal even comprehend what a dog is?) In order to rethink the way we describe output, we will have to come up with a very precise description of the inside potentials and activations in mammalian brains. We are just barely creating tools to describe what an artificial neural net "is thinking." So I guess we're starting to look in that direction.
LeifCarrotson 10y ago
Genes encode some of the rules by which the the neurons self-organize, or "grow". Further growth from an initial cell is partially controlled by environmental factors. This is not a novel or unique application, literally all living things grow by using the rules encoded in DNA and environmental factors. Consider the demo scene, where 64 kilobytes of code generates a fascinating video with deep complexity. You could not encode a 64k demo as a series bitmapped frames in 64k, or probably in 64 megabytes. But that doesn't mean that you can generate one by stuffing together a bunch of RGB pixels and hoping they self-organize.

Balgair 10y ago

I'm going to echo this and add a bit more context. Look at the cerebellum for example. That lump at the bottom of your rear skull has ~50% of all your neurons. It is extremely important for motor control. When you grab a cup of coffee as you dash out the door in the morning, your cerebellum is what is responsible for you being able to do that without looking at the cup as you reach for it. You 'know' the cup is there and you don't have to tell every nerve to fire every muscle and to extend your forearm and then grab it with only 3 fingers and then adjust for the decrease in weight with every sip. You just do it, naturally. Your cerebellum is what is responsible for that. It is a dedicated portion of your brain that really only does those kinds of things. Your hippocampus also deals with short term memory. HM was a famous patient that had his hippocampus removed, basically, and then lost all of his short term memory. Poof, gone forever. In short, your brain has dedicated areas in it that only do certain things, it is NOT some FPGA that gets re-wired on the fly. Your intelligence is not dependent on the number of connections or neurons.

dmd 10y ago
And it develops this way, controlled by DNA. If the brain were really a "uniform matrix that self-programs", think how unlikely it would be that the same functions are performed in the same areas in every person. Everyone's language area (to use a rough term) is in the same place in the brain. Everyone's visual cortex is in the same place. And this holds for even fuzzier concepts like, say, 'concepts', to a point. And this holds for even non-primates - take a squirrel, and you'll find its visual cortex right where you'd expect it.