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4 HN mentions · mentioned in 4 months, 2014–2023
0:23 · 636K views · Apr 30, 2010
An old lab video of a decerebrate cat walking on a treadmill and shifting between gait patterns as the speed changes. It is used to illustrate that much locomotion control comes from the spinal cord and body mechanics rather than the brain.
Used as a vivid example of spinal pattern generators and morphological control in locomotion discussions.
4 comments from Hacker News
Uhm... all kinds of animals actually, but you need ethics approval if you use vertebrates. And I don't think you will find non-crazy volunteers for the invasive experiments... I took neuroscience courses - and a lot of what I learned was made possible by such experiments, so I'm not against them. However, the cost for the animals that get selected is high. You can't do that with humans, only the most benign experiments. But many experiments involves cutting open the head. inserting electrodes at the very least, sometimes you want to see the brain too - there are things you can do, like two-photon microscopy (example: [LINK] -- you have to expose the brain), or inject dyes, and other options). A possible setup (for invasive experiments) is that the animal is drugged, the brain exposed, electrodes inserted, the head fixated. Now you can, stimulate the retina, or the ears, or whiskers, and follow what happens in the living brain. Here is an example for what you get from such an experiment: [LINK] > Mice were head-fixed using a titanium head postimplant... For implantation, mice were anesthetized with isoflurane..., and maintained at 37°C body temperature on a thermal blanket (Harvard Apparatus). Following a local injection of Marcaine (50 μl), the scalp and periosteum over the dorsal surface of the skull were removed. The skull was then coated with a thin layer of cyanoacrylate adhesive (Krazy Glue, Elmer's Products).... (etc.) What sane human would allow an experiment like this
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. this video 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.
If the babies don't see objects, they don't "develop" object permanence. Yeah, here we can summon the "use it or use it" copeout, but then the nativist account becomes unfalsifiable. Being able to crawl within minutes (and even somewhat run within hours as horses do) is mostly due to anatomy and "reflex pathways". E.g. a cat can walk without brains [1], as can famosly headless chicken. Human babies too have these kinds of reflexes but they are "abandoned" well before the baby learns to walk. [1] this video
the decerebrate cat experiments illustrate this perfectly (although perhaps people dont like to talk about it because of the ethics of the experiments) this video