Dr. Matthew Walker

It's a great demonstration of the uniqueness of your brain.

I mean, essentially what we're asking is, this is your brain on dreams.

Explain.

And REM sleep has many different brain features to it.

The first of which is, as we spoke in the first episode, your electrical brainwave activity at the top of the brain, the cortex, looks almost identical to that which you have when you're awake, which is stunning because you're not conscious.

You're lying completely still, no presence of muscle tone whatsoever, yet your brain seems to be just as on fire with electrical activity as it is when you're awake.

Coming down a step though, there are these unique pulses of electrical, almost like lightning bursts that come up from the brainstem up to this sensory relay center in your brain called the thalamus.

And then they were initially recorded out in the back of the brain in the visual cortex.

Hence, this PGO waves describes the three sites that I've just mentioned.

It goes from the brainstem, the pons, up to the thalamus, a part of it called the geniculate, and then out to the back of the brain called the occipital cortex, PGO.

What they found was that those bursts of PGO wave activity were very much linked to these rapid eye movements.

So once you got this burst of a PGO wave, this sort of brainstem up into the brain burst, then you got one of these rapid eye movements.

So it was linking something there with the eye movements.

And I told you that when you're having these eye movements, that's a state where there's a high probability of dreaming.

And is it a surprise then that the final destination of that lightning bolt where it sort of strikes is at the back of the brain in the visual cortex?

Probably not.

There's also been some links with those PGO waves and learning.

Not so much that those PGO waves seem to consolidate memories.

In other words, they may not be critical for sleep after learning, but they seem to be related almost to sleep and initial learning.

And the more that animals learn, the greater the amount of PGO wave activity they have when they go to sleep.