6 ms·

The article is pretty light on the details, so I'll try to add to it. In my prior career as a cognitive neuroscientist, I analyzed an fMRI data set on blindsigh

by KingMob 14y ago

The article is pretty light on the details, so I'll try to add to it. In my prior career as a cognitive neuroscientist, I analyzed an fMRI data set on blindsight patient GY, and read up on the blindsight literature at the time. The neurons in the retina don't go straight to the occipital (primary visual) cortex; they all synapse onto the thalamus first. From there, the vast majority of exiting neurons go on to occipital cortex, but a few percent go off to other regions, such as the superior colliculus, amygdala, MT and FEF. It's been shown in diffusion studies that people with damage in thalamus or prior to it, don't show blindsight effects, while people with post-thalamic or occipital damage can. Now, the really interesting part is that, these non-occipital signals are enough to help people perform tasks at above-chance levels, but not enough for them actually be aware. Nobody knows for sure why. Conscious awareness is one of the biggest unsolved mysteries of neuroscience. Top candidates are information integration theory, higher-order thought theories, and signal-detection-based theories.

ktizo 14y ago
After hearing about those parasitic brain bugs that you can catch from cats I started to wonder if conscious awareness could be merely the collective experience of some kind of bug we caught that has just hitched along for the ride and that hasn't actually really got much of a control over anything really, but just believes that it is the creature it is inhabiting, because it is a bit stupid. Perhaps you could cure someone of it and not even be able to tell the difference. These are the kind of thoughts that keep me awake at night ;)
- KingMob 14y ago
  Well, this would explain the internet's fondness for cat photos...
  - ktizo 14y ago
    See, there's evidence and everything!
- stephth 14y ago
  That's funny, I had the almost same sci-fi scenario thoughts during one night. The thought of the nature of our minds being defined by a disease that we caught at some point in time and now completely identify with it, that that disease made us forget our true nature. It's pretty great as a sci-fi scenario, but I now believe it has a deep truth to it. I later discovered the writings of Eckhart Tolle. According to him, we are diseased in the sense that we identify with our mind/ego, instead of realizing what it actually is: a tool. Part of the problem is we often don't know what exists underneath. We are 100% convinced we are our mind. But obviously we're not - if we were, we wouldn't be able to observe it. Once we realize we're not our mind, we're free of its control. Until we do, we're in a way, severely ill. We're actually not disfunctional in our true nature - but we're unenlightened. At least that's what Eckhart Tolle says. I personally find it disarmingly logical - and reasonably easily provable within my perception, not to mention deeply liberating/changing. Finding out you can stop your thoughts and not only still be aware, but become the most aware you can be, that's quite a doozy of a realization.
  - thisduck 14y ago
    >> we're not our mind Okay, what does this mean?
    - KingMob 14y ago
      "Mind" is a very poorly defined term, unfortunately. To determine what you are or aren't, consider this for an exercise: You are a view point, yes? What you can observe is not part of your identity because you can observe it, and therefore it must be external to "you". This is obvious when it comes to things like your body parts; you could cut off your hand, but that wouldn't cut off a part of your "you-ness". The interesting bit comes when you start to examine your mind itself. Normally, we think of our thoughts as part of our identity. But with a little practice, you can watch thoughts arise, at which point they seem more "separate" and less "you". I always liken them to those biplanes at the beach with a banner fluttering behind them. So, if you can observe thoughts and not identify with them, then they're not "you". What makes up "you", then? The more you observe, the fewer candidates for "you" there are, no? ;)
- BoppreH 14y ago
  You may like the short science fiction story Learning To Be Me, by Greg Egan. The idea is that people put a microchip in their brain (the "jewel") that learns to mimic the brain's signals, so when the brain fails the microchip can take over. The interesting question is: "am I the jewel?"
- TimJRobinson 14y ago
  When I first read animorphs I thought the same thing. That maybe I was actually a yeerk controlling a human host and I didn't know it...
  - sreyaNotfilc 14y ago
    Isn't it kinda like .. in a way Krang from the Teenage Mutant Ninja Turtles? He had this exo-body that he was able to hop in freely. The body was just a dumb machine that needed him to control. It was merely a tool, jet it had a head, harms, legs and can shoot missiles. Well, we can't do that just yet. But in away, our bodies are just tools to that brain/consciousness uses to do things. If we loose a limb, we just build another one. Sure, we haven't mastered replaced limb awareness (touch, feel), but we're getting close. Like a machine, we need fuel (food), maintenance (doctors appointment, exercise), periods of rest and recovery (sleep). I'm trying to figure out how sex, anger, and jealousy comes in, but we are essentially tools. And I guess the brain is really a complex OS that runs our bodies. Some brains/OS are, of course, have a better way of processing tasks/programming/apps than others.
- itmag 14y ago
  These are the kind of thoughts that keep me awake at night ;) Then you probably don't want to read Thomas Ligotti's "The conspiracy against the human race". It's a philosophical and neuroscientific treatise on existentialism written by a lovecraftian horror writer... http://www.amazon.com/The-Conspiracy-Against-Human-Race/dp/098242969X http://www.amazon.com/The-Conspiracy-Against-Human-Race/dp/0...
- pessimizer 14y ago
  That's a legitimate approach: https://en.wikipedia.org/wiki/Epiphenomenalism https://en.wikipedia.org/wiki/Epiphenomenalism
nitrogen 14y ago
The neurons in the retina don't go straight to the occipital (primary visual) cortex; they all synapse onto the thalamus first. From there, the vast majority of exiting neurons go on to occipital cortex, but a few percent go off to other regions, such as the superior colliculus, amygdala, MT and FEF. I wonder if there's a similar explanation for some people (like myself) who sometimes have difficulty reading facial expressions by instinct, and have to rely on conscious interpretation and training to determine others' emotional state.
- KingMob 14y ago
  Well, that would be a bit like the opposite of blindsight, being forced to do something consciously that most of us do unconsciously. I'm not sure which regions subserve facial expression recognition (probably amygdala, FFA and others), but it could be a deficit in those regions. Alternatively, if you think you have Asperger's/ASD, they tend to have general deficits in emotion-reading and theory-of-mind-type tasks.
- algorias 14y ago
  maybe related to http://en.wikipedia.org/wiki/Prosopagnosia http://en.wikipedia.org/wiki/Prosopagnosia ?
  - KingMob 14y ago
    It might involve similar regions, such as the Fusiform Face Area (FFA), but people with prosopagnosia don't necessarily have difficulty with identifying facial emotions; what they have difficulty with is in distinguishing and remembering faces from each other. It's a bit like the way most of us couldn't tell one sheep from another in a flock. Prosopagnosics tend to rely on things like voice, gait, haircuts, facial hair, and name badges.
- lusr 14y ago
  You may want to read Oliver Sacks' "The Man Who Mistook His Wife for a Hat" and "The Minds' Eye".
adamio 14y ago
Now, the really interesting part is that, these non-occipital signals are enough to help people perform tasks at above-chance levels, but not enough for them actually be aware. Nobody knows for sure why. Without the non-occipital signals, are the visual cortex signals alone enough to perform tasks?
- KingMob 14y ago
  Oh, certainly. If the signal is reaching your occipital/visual cortex, then you have the experience of seeing. There would be other deficits (weakened orienting responses, cross-modal congruency effects, diminished RT to dangerous/frightening stimuli), but nothing quite as major as no longer "seeing".
finisterre 14y ago
Blindsight seems to be a powerful demonstration of how a brain can perform high order actions - e.g. respond to social stimuli such as facial expressions - without consciousness. It's a reminder that many things we think inseparable from self awareness and consciousness are no such thing. Perhaps you could consider a person with blindisight to have been "downgraded" to the condition of a mammal without consciousness.
- maebert 14y ago
  I think it's a bit more complicated, since mammals without consciousness (ouh, vague concepts ftw) still show immediate reaction to visual stimuli, where as patient TN and others can react and act upon to visual stimuli, although the traditional "chain of command" is broken.
boothead 14y ago
I read Jeff Hawkins book On Intelligence recently. Would these observations fit with the idea of visual data being passed up the hierarchy of the cortex far enough to be recognising objects as obstructions, but not far enough to be conscious of them?
- maebert 14y ago
  The term "recognising" is a bit misleading here. Blindsight is in fact a very nice case where traditional cognitive science and AI paradigms suggesting a hierarchy of processing (bottom up of primal stimuli until they end up as meaningful concepts, top down of thoughts until they turn into actions (roughly)) doesn't quite fit.
  - boothead 14y ago
    Yes perhaps categorising would be better?
- KingMob 14y ago
  People into higher-order and SDT-based theories of consciousness have argued similar things. One problem with the hierarchy model, though, is that the brain does not use layers as cleanly separated as in software. So, it's quite possible that after exiting the thalamaus and entering area MT or the amygdala, the signal goes on to "higher" regions such as the prefrontal cortex. So even though it's reaching the region, it's still insufficient. It could be because it's not stimulating enough neurons, but it's also possible that there's some qualitative difference as well. For example, sheer numbers of neurons don't guarantee awareness. The cerebellum has half the total number of neurons in the brain, but they're arranged in a very repetitive manner and seem to have nothing to do with awareness. If you had your cerebellum removed (say, for cancer), you would have difficulty with fine motor control, but not much else. It wouldn't alter your awareness, even though you've just lost half your brain's neurons. If you believe the information integration theorists, what matters is heterogeneity and interconnectivity, rather than mere numbers.

by KingMob 14y ago

ktizo 14y ago

After hearing about those parasitic brain bugs that you can catch from cats I started to wonder if conscious awareness could be merely the collective experience of some kind of bug we caught that has just hitched along for the ride and that hasn't actually really got much of a control over anything really, but just believes that it is the creature it is inhabiting, because it is a bit stupid. Perhaps you could cure someone of it and not even be able to tell the difference. These are the kind of thoughts that keep me awake at night ;)

KingMob 14y ago
Well, this would explain the internet's fondness for cat photos...
- ktizo 14y ago
  See, there's evidence and everything!
stephth 14y ago
That's funny, I had the almost same sci-fi scenario thoughts during one night. The thought of the nature of our minds being defined by a disease that we caught at some point in time and now completely identify with it, that that disease made us forget our true nature. It's pretty great as a sci-fi scenario, but I now believe it has a deep truth to it. I later discovered the writings of Eckhart Tolle. According to him, we are diseased in the sense that we identify with our mind/ego, instead of realizing what it actually is: a tool. Part of the problem is we often don't know what exists underneath. We are 100% convinced we are our mind. But obviously we're not - if we were, we wouldn't be able to observe it. Once we realize we're not our mind, we're free of its control. Until we do, we're in a way, severely ill. We're actually not disfunctional in our true nature - but we're unenlightened. At least that's what Eckhart Tolle says. I personally find it disarmingly logical - and reasonably easily provable within my perception, not to mention deeply liberating/changing. Finding out you can stop your thoughts and not only still be aware, but become the most aware you can be, that's quite a doozy of a realization.
- thisduck 14y ago
  >> we're not our mind Okay, what does this mean?
  - KingMob 14y ago
    "Mind" is a very poorly defined term, unfortunately. To determine what you are or aren't, consider this for an exercise: You are a view point, yes? What you can observe is not part of your identity because you can observe it, and therefore it must be external to "you". This is obvious when it comes to things like your body parts; you could cut off your hand, but that wouldn't cut off a part of your "you-ness". The interesting bit comes when you start to examine your mind itself. Normally, we think of our thoughts as part of our identity. But with a little practice, you can watch thoughts arise, at which point they seem more "separate" and less "you". I always liken them to those biplanes at the beach with a banner fluttering behind them. So, if you can observe thoughts and not identify with them, then they're not "you". What makes up "you", then? The more you observe, the fewer candidates for "you" there are, no? ;)
BoppreH 14y ago
You may like the short science fiction story Learning To Be Me, by Greg Egan. The idea is that people put a microchip in their brain (the "jewel") that learns to mimic the brain's signals, so when the brain fails the microchip can take over. The interesting question is: "am I the jewel?"
TimJRobinson 14y ago
When I first read animorphs I thought the same thing. That maybe I was actually a yeerk controlling a human host and I didn't know it...
- sreyaNotfilc 14y ago
  Isn't it kinda like .. in a way Krang from the Teenage Mutant Ninja Turtles? He had this exo-body that he was able to hop in freely. The body was just a dumb machine that needed him to control. It was merely a tool, jet it had a head, harms, legs and can shoot missiles. Well, we can't do that just yet. But in away, our bodies are just tools to that brain/consciousness uses to do things. If we loose a limb, we just build another one. Sure, we haven't mastered replaced limb awareness (touch, feel), but we're getting close. Like a machine, we need fuel (food), maintenance (doctors appointment, exercise), periods of rest and recovery (sleep). I'm trying to figure out how sex, anger, and jealousy comes in, but we are essentially tools. And I guess the brain is really a complex OS that runs our bodies. Some brains/OS are, of course, have a better way of processing tasks/programming/apps than others.
itmag 14y ago
These are the kind of thoughts that keep me awake at night ;) Then you probably don't want to read Thomas Ligotti's "The conspiracy against the human race". It's a philosophical and neuroscientific treatise on existentialism written by a lovecraftian horror writer... http://www.amazon.com/The-Conspiracy-Against-Human-Race/dp/098242969X http://www.amazon.com/The-Conspiracy-Against-Human-Race/dp/0...
pessimizer 14y ago
That's a legitimate approach: https://en.wikipedia.org/wiki/Epiphenomenalism https://en.wikipedia.org/wiki/Epiphenomenalism

nitrogen 14y ago

The neurons in the retina don't go straight to the occipital (primary visual) cortex; they all synapse onto the thalamus first. From there, the vast majority of exiting neurons go on to occipital cortex, but a few percent go off to other regions, such as the superior colliculus, amygdala, MT and FEF. I wonder if there's a similar explanation for some people (like myself) who sometimes have difficulty reading facial expressions by instinct, and have to rely on conscious interpretation and training to determine others' emotional state.

KingMob 14y ago
Well, that would be a bit like the opposite of blindsight, being forced to do something consciously that most of us do unconsciously. I'm not sure which regions subserve facial expression recognition (probably amygdala, FFA and others), but it could be a deficit in those regions. Alternatively, if you think you have Asperger's/ASD, they tend to have general deficits in emotion-reading and theory-of-mind-type tasks.
algorias 14y ago
maybe related to http://en.wikipedia.org/wiki/Prosopagnosia http://en.wikipedia.org/wiki/Prosopagnosia ?
- KingMob 14y ago
  It might involve similar regions, such as the Fusiform Face Area (FFA), but people with prosopagnosia don't necessarily have difficulty with identifying facial emotions; what they have difficulty with is in distinguishing and remembering faces from each other. It's a bit like the way most of us couldn't tell one sheep from another in a flock. Prosopagnosics tend to rely on things like voice, gait, haircuts, facial hair, and name badges.
lusr 14y ago
You may want to read Oliver Sacks' "The Man Who Mistook His Wife for a Hat" and "The Minds' Eye".

adamio 14y ago

Now, the really interesting part is that, these non-occipital signals are enough to help people perform tasks at above-chance levels, but not enough for them actually be aware. Nobody knows for sure why. Without the non-occipital signals, are the visual cortex signals alone enough to perform tasks?

KingMob 14y ago
Oh, certainly. If the signal is reaching your occipital/visual cortex, then you have the experience of seeing. There would be other deficits (weakened orienting responses, cross-modal congruency effects, diminished RT to dangerous/frightening stimuli), but nothing quite as major as no longer "seeing".

finisterre 14y ago

Blindsight seems to be a powerful demonstration of how a brain can perform high order actions - e.g. respond to social stimuli such as facial expressions - without consciousness. It's a reminder that many things we think inseparable from self awareness and consciousness are no such thing. Perhaps you could consider a person with blindisight to have been "downgraded" to the condition of a mammal without consciousness.

maebert 14y ago
I think it's a bit more complicated, since mammals without consciousness (ouh, vague concepts ftw) still show immediate reaction to visual stimuli, where as patient TN and others can react and act upon to visual stimuli, although the traditional "chain of command" is broken.

boothead 14y ago

I read Jeff Hawkins book On Intelligence recently. Would these observations fit with the idea of visual data being passed up the hierarchy of the cortex far enough to be recognising objects as obstructions, but not far enough to be conscious of them?

maebert 14y ago
The term "recognising" is a bit misleading here. Blindsight is in fact a very nice case where traditional cognitive science and AI paradigms suggesting a hierarchy of processing (bottom up of primal stimuli until they end up as meaningful concepts, top down of thoughts until they turn into actions (roughly)) doesn't quite fit.
- boothead 14y ago
  Yes perhaps categorising would be better?
KingMob 14y ago
People into higher-order and SDT-based theories of consciousness have argued similar things. One problem with the hierarchy model, though, is that the brain does not use layers as cleanly separated as in software. So, it's quite possible that after exiting the thalamaus and entering area MT or the amygdala, the signal goes on to "higher" regions such as the prefrontal cortex. So even though it's reaching the region, it's still insufficient. It could be because it's not stimulating enough neurons, but it's also possible that there's some qualitative difference as well. For example, sheer numbers of neurons don't guarantee awareness. The cerebellum has half the total number of neurons in the brain, but they're arranged in a very repetitive manner and seem to have nothing to do with awareness. If you had your cerebellum removed (say, for cancer), you would have difficulty with fine motor control, but not much else. It wouldn't alter your awareness, even though you've just lost half your brain's neurons. If you believe the information integration theorists, what matters is heterogeneity and interconnectivity, rather than mere numbers.