Biology Forums - Study Force

I just want to facilitate a little discussion, get peoples minds thinking, keep it fun and don't look it up :)

A guy names Sharington had a cat, to make a long story short he cut the cats brain stem from its spinal cord so cognitively the cat was still there and alive, but essentially paralyzed from the neck down. Sharington then suspended the cat in a harness on a treadmill. When he started the treadmill the cat began to walk, and when he increased the speed the cat began to run. How do you think this is possible? how can a paralyzed cat run? and how can this be applied to humans?

Why did you name him Sharington :-:) lol

Sharington is the guy who did the experiment. I don't think the cat had a name. Study was done in the 40s I think.

I really want to know the answer. The only thing that comes to mind is a robotic exoskeleton that fits on the cat, but I'm pretty sure that's not it ;)

Haha nope, nothing mechanically moving the cat. I'll give you a hint: has something to do with the spinal cord and reflexes.

I'm going to come clean and say I looked it up; actually, I looked up Sherrington's Wikipedia page and it explained it only briefly. Mind sharing how the cat miraculously was able to walk again after a broken neck? :-\

Bio man ! come on ! haha but alright I'll spill the beans. basically his research proved that walking is an innate and automatic reflex. Basically every animal is born with the ability to walk. it is a survival mechanism. Everyone has seen this before, a horse gets born and not 30 seconds later it is running along side it's mom. If the horse had to learn how to run it would get left behind and die. Even humans have this ability. Babies, if you put something against their feet they will begin to walk, this quickly disappear because humans get fat as babies and a babies muscle can't over come the weight of the limb.

SO how does this relate to the cat. Well basically you don't need your brain to walk it is all controlled by the spinal cord as a reflex. Which is how the cat was able to walk and run without brain control. You can think of walking like pulling your hand away from a hot stove. you don;t think about pulling your hand away you just do it. It took no cognitive processing to respond to the hot surface it was a protective reflex. Same with walking, it is a survival reflex. If you stop moving you die.

Where does the brain fit into this? The brain does play a role in adapting gait. So walking over un even surfaces requires a lot of cognitive processing. So if you put an obstacle on the treadmill with the cat, the cat would fall over it.

Didn't know that (I'm mind blown :joy:). Now, in terms of what you wrote here:


Why do paraplegics exist, in other words, why is it when a person's spine is severed, they lose their ability to walk?

This is even cooler, so the same things happen to adults as babies. when you un-weight them on a treadmill and start the treadmill they do step. Is it coordinated? No. Is it functional? No. The reflex is still there to walk, but it is useless to our function, the muscles cannot support weight and need external activation (like a treadmill moving) so there is no initiation of mvmt and no adaptation.

To put it simply they still have the ability, but the weight of the limbs prevents them from moving, as well as the lack of initiation. But if you un-weight them they will walk (just not well)

Making sense now.

Othello2, what about people who are paraplegics though, sorry for my ignorance but I don't think you covered it

So paraplegics lose the ability to voluntarily control their  legs. Paraplegics have the same injury as the cat only lower on the spinal cord, so the result is the same. The brain cannot get info to the legs and consciously tell them to move, but the legs still have the ability to move, the muscles are fine and all the nerves below the injury are fine too. So you suspend a paraplegic in a harness and put them on a treadmill their legs will try to step. they HAVE to be unweighted though. The same reflex arc occurs in all animals, humans are no exception.

I didn't expect that, thank you for explaning

 I hope that makes a little more sense, it is kind of a hard topic to explain. it is kind of a weird thing to wrap your head around at first.