4 ms·

This is inaccurate. We understand much of how it works, how vision, speech, etc work but we don't understand consciousness which is quite different.

arendtio 8y ago
Well, maybe it just doesn't exist and my Roomba is as conscious as me.
- Brifer 8y ago
  This made me ponder.
mattkrause 8y ago
Nonsense. I’m an actual, working neuroscientist and if we’ve solved any of these things, it would be news to me (and everyone else at my institute). We have good, if coarse, knowledge of which structures are critical for which functions—-at least under some conditions. Our knowledge of how they do this is even cruder: neither the representations nor the algorithms are known with much certainty, let alone how they arise. Let me give you a very concrete example of where we are. There’s a small nemode called C. elegans. It’s about a millimeter long and has 302 neurons. We know its complete wiring diagram, its genome, and the origin and fate of every cell (not just the neurons) in its tiny, simple body. Its behavior has been studied extensively. And yet...we can’t accurately simulate the damn thing—-and it’s not like it does a lot to begin with. The human brain has about 86B neurons, and we know an awful lot less about them. Neither vision nor speech is remotely close to “solved” or understood. Consciousness, even in the very limited sense of “why do we fall asleep—-or need to?” is a mote off in the distance.
- zipzap324 8y ago
  Where did I say anything about simulating? Are you really saying that we understand nothing about how vision works? Also a 10 second google search pulls up papers with plenty of details about vision in the brain so I don't know why you're talking about it as if its some great mystery. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4574956/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4574956/ A 1800 Page textbook on Vision Neuroscience. I'll leave it to HN to decide if we "Understand" Vision. Arbitrarily high requirements for understanding are being thrown about that would leave modern science in shambles if applied. https://mitpress.mit.edu/books/visual-neurosciences-2-vol-set https://mitpress.mit.edu/books/visual-neurosciences-2-vol-se...
  - thereisnospork 8y ago
    We understand lots about how the brain behaves, we understand next to nil about how it behaves that way. we can't describe how vision, eg, is processed at a molecular or even cellular level, ergo we know nothing.
  - mattkrause 8y ago
    I have a PhD in visual neuroscience, so yeah, I’m pretty comfortable saying we don’t know how it works. We know a lot of facts, and we have some ideas about how various small things are implemented, but in terms of grand unifying theories, we’re nowhere close. For example, suppose I showed you two gratings (think zebra stripes): a small patch and a larger one. Under some circumstances, you’ll have a harder time determining which way the big patch is oriented vs. the small one. This is true even though there’s extra information in the big patch. We think this is related to a phenomena called surround suppression, but they’re not exactly the same....and no one can agree on how surround suppression is implemented, let alone what it’s good for. This happens in primary visual cortex, which is probably the simplest—-and most extensively studied—of the visual cortical areas.
    - 0-_-0 8y ago
      It's quite unrelated, but I've been wondering something about neuroscience grammar: Why is it "in primary visual cortex" and not "in _the_ primary visual cortex"?
      - primo44 8y ago
        And just regular grammar. "Phenomena" is plural.
        mattkrause 8y ago
        Got nothing for that one :-)
      - mattkrause 8y ago
        I'm not sure! Your innocuous question has kicked off a pretty feisty debate on my floor about whether it is 'primary' as in first (either in the circuit or evolutionarily) or primary as in most important. If it's the former, adding a "the" seems to add some unwarranted emphasis. I think there's probably some parallelism too. Primary visual cortex is also called "V1" (as in the first cortical area involved in vision) or "Area 17" (according to a map that defines areas based on their cellular organization). While "in the primary visual cortex" sounds fine, "in the V1" and "in the Area 17" sound barbarous.
wuliwong 8y ago
You responded to hyperbole with with a vague and imprecise statement. I will admit it is more accurate since "much" is somewhere between "everything" and "nothing".

arendtio 8y ago

Well, maybe it just doesn't exist and my Roomba is as conscious as me.

Brifer 8y ago
This made me ponder.

mattkrause 8y ago

Nonsense. I’m an actual, working neuroscientist and if we’ve solved any of these things, it would be news to me (and everyone else at my institute). We have good, if coarse, knowledge of which structures are critical for which functions—-at least under some conditions. Our knowledge of how they do this is even cruder: neither the representations nor the algorithms are known with much certainty, let alone how they arise. Let me give you a very concrete example of where we are. There’s a small nemode called C. elegans. It’s about a millimeter long and has 302 neurons. We know its complete wiring diagram, its genome, and the origin and fate of every cell (not just the neurons) in its tiny, simple body. Its behavior has been studied extensively. And yet...we can’t accurately simulate the damn thing—-and it’s not like it does a lot to begin with. The human brain has about 86B neurons, and we know an awful lot less about them. Neither vision nor speech is remotely close to “solved” or understood. Consciousness, even in the very limited sense of “why do we fall asleep—-or need to?” is a mote off in the distance.

zipzap324 8y ago
Where did I say anything about simulating? Are you really saying that we understand nothing about how vision works? Also a 10 second google search pulls up papers with plenty of details about vision in the brain so I don't know why you're talking about it as if its some great mystery. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4574956/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4574956/ A 1800 Page textbook on Vision Neuroscience. I'll leave it to HN to decide if we "Understand" Vision. Arbitrarily high requirements for understanding are being thrown about that would leave modern science in shambles if applied. https://mitpress.mit.edu/books/visual-neurosciences-2-vol-set https://mitpress.mit.edu/books/visual-neurosciences-2-vol-se...
- thereisnospork 8y ago
  We understand lots about how the brain behaves, we understand next to nil about how it behaves that way. we can't describe how vision, eg, is processed at a molecular or even cellular level, ergo we know nothing.
- mattkrause 8y ago
  I have a PhD in visual neuroscience, so yeah, I’m pretty comfortable saying we don’t know how it works. We know a lot of facts, and we have some ideas about how various small things are implemented, but in terms of grand unifying theories, we’re nowhere close. For example, suppose I showed you two gratings (think zebra stripes): a small patch and a larger one. Under some circumstances, you’ll have a harder time determining which way the big patch is oriented vs. the small one. This is true even though there’s extra information in the big patch. We think this is related to a phenomena called surround suppression, but they’re not exactly the same....and no one can agree on how surround suppression is implemented, let alone what it’s good for. This happens in primary visual cortex, which is probably the simplest—-and most extensively studied—of the visual cortical areas.
  - 0-_-0 8y ago
    It's quite unrelated, but I've been wondering something about neuroscience grammar: Why is it "in primary visual cortex" and not "in _the_ primary visual cortex"?
    - primo44 8y ago
      And just regular grammar. "Phenomena" is plural.
      - mattkrause 8y ago
        Got nothing for that one :-)
    - mattkrause 8y ago
      I'm not sure! Your innocuous question has kicked off a pretty feisty debate on my floor about whether it is 'primary' as in first (either in the circuit or evolutionarily) or primary as in most important. If it's the former, adding a "the" seems to add some unwarranted emphasis. I think there's probably some parallelism too. Primary visual cortex is also called "V1" (as in the first cortical area involved in vision) or "Area 17" (according to a map that defines areas based on their cellular organization). While "in the primary visual cortex" sounds fine, "in the V1" and "in the Area 17" sound barbarous.

wuliwong 8y ago

You responded to hyperbole with with a vague and imprecise statement. I will admit it is more accurate since "much" is somewhere between "everything" and "nothing".