4 ms·

Remember that a lot of 'standard' movements aren't fully controlled from the brain. Instead, the brain generators modulating signals to structures/systems lower

Remember that a lot of 'standard' movements aren't fully controlled from the brain. Instead, the brain generators modulating signals to structures/systems lower in the spinal - ie increasing or decreasing your rate of walking. There's lots of evidence of these 'Central Pattern Generators' being located below the brain - which would reduce signal lag. For a somewhat disturbing example of this, here's a 'decerberated' cat on a treadmill. https://www.youtube.com/watch?v=wPiLLplofYw https://www.youtube.com/watch?v=wPiLLplofYw That said, the fact that any vertebrae (even our selves) are able to move and react so well is pretty amazing, given that our own neural lag is in the ~100ms range. It's really a testament to the robustment of the multi-tier control that we (animals in general.. but especially large animals) have evolved.

chiph 12y ago
Warning: don't watch if you're squeamish or a pet owner.
- ars 12y ago
  Why not? You don't see anything except a cat walking.
  - chiph 12y ago
    "Decerebrated" means the cat has had it's brain removed. Zombie cat. On a treadmill.
scrumper 12y ago
Fascinating (if a little hard to stomach) video. This seems to imply that bipedal locomotion is learned, while quadrupeds have the skill hardwired into lower-level structures. (Certainly, having watched my eldest figure it out, it doesn't seem to be an innate ability in humans.)
- icegreentea 12y ago
  Just because the structure resides below the brain, doesn't mean that it's simply 'innate'. For example, while deer fawn are famously able to start walking right away, a kitten is actually pretty terrible at walking for many weeks - they still have to learn. Perhaps part of the difference between the 'apparent' skill of quadrapedal and bipedal learning is that a) quadrupedal is inherently easier (its more stable, more forgiving of small deficiencies), b) bipedal 'failure' is a lot more drastic (especially when you have the proportions of a child.. you don't have a lot of leg to catch yourself), and c) we're simply more familiar with bipedal motion, and therefore more critical of flaws on observation. In addition, there is suggestive evidence that human bipedal motion is CPG driven [1]. I think a reasonable analogy to draw is that at birth a CPG is kind of a lower level controller, all hooked up, but not yet programmed. It takes time and practice to tune and program the controller to generate useful output. [1] http://brain.oxfordjournals.org/content/117/5/1143.abstract http://brain.oxfordjournals.org/content/117/5/1143.abstract
  - scrumper 12y ago
    Interesting - thanks.

chiph 12y ago

Warning: don't watch if you're squeamish or a pet owner.

ars 12y ago
Why not? You don't see anything except a cat walking.
- chiph 12y ago
  "Decerebrated" means the cat has had it's brain removed. Zombie cat. On a treadmill.

scrumper 12y ago

Fascinating (if a little hard to stomach) video. This seems to imply that bipedal locomotion is learned, while quadrupeds have the skill hardwired into lower-level structures. (Certainly, having watched my eldest figure it out, it doesn't seem to be an innate ability in humans.)

icegreentea 12y ago
Just because the structure resides below the brain, doesn't mean that it's simply 'innate'. For example, while deer fawn are famously able to start walking right away, a kitten is actually pretty terrible at walking for many weeks - they still have to learn. Perhaps part of the difference between the 'apparent' skill of quadrapedal and bipedal learning is that a) quadrupedal is inherently easier (its more stable, more forgiving of small deficiencies), b) bipedal 'failure' is a lot more drastic (especially when you have the proportions of a child.. you don't have a lot of leg to catch yourself), and c) we're simply more familiar with bipedal motion, and therefore more critical of flaws on observation. In addition, there is suggestive evidence that human bipedal motion is CPG driven [1]. I think a reasonable analogy to draw is that at birth a CPG is kind of a lower level controller, all hooked up, but not yet programmed. It takes time and practice to tune and program the controller to generate useful output. [1] http://brain.oxfordjournals.org/content/117/5/1143.abstract http://brain.oxfordjournals.org/content/117/5/1143.abstract
- scrumper 12y ago
  Interesting - thanks.