Dr. David Berson

If your eyes were closed, you'd sense it.

If your ears were plugged and your eyes were closed, you'd still know it.

Anything that jostles you out of the current position you're in right now will be detected by

the vestibular system pretty much.

It's basically in your inner ear, hairy cells, they got little cilia sticking up off the surfaces.

And depending on which way you bend those, the cells will either be inhibited or excited.

But then they talk to neurons with a neuron-like process and off you go.

Now you've got an auditory signal if you're sensing things bouncing around in your cochlea, which is sympathetically the bouncing of your eardrum, which is sympathetically the sound waves in the world.

But in the case of the vestibular apparatus, evolution has built a system that detects the motion of, say, fluid going by those hairs.

And if you put a sensor like that in a tube that's fluid-filled, now you've got a sensor that will be activated when you rotate that tube around the axis that passes through the middle of it.

Right, three hula hoops.

Right, one the other way.

Three directions.

So three axes.

of encoding, just like in the cones of the retina.

Yeah, the puppy head tilt.

That's the other one.

So the point is that your brain is eventually going to be able to unpack what these sensors are telling you about how you just rotated your head.

Now you can tell if you're rotating your head left or right, up or down.

That's the sensory signal coming back into your brain