Dr. Matthew Walker

So PGO waves are unique.

PGO waves don't simply just hit the back of your brain, that we've now measured them in all sorts of different cortical areas, and they seem to light up.

The lightning splits, as it were, and it strikes all sorts of cortical areas.

So then the question was, well, let's take humans and let's put them inside of brain scanners.

Let's allow them to fall into REM sleep, and then we'll start scanning the brain.

What did we find?

It was very interesting.

When you look at the brain during REM sleep compared to, let's say, non-REM sleep, you see motor regions of the brain lighting up.

You see visual regions of the brain lighting up, just as we described.

You see memory-related structures lighting up, like the hippocampus.

And you see emotional-related structures, like the amygdala and something called the anterior cortex, the anterior cingulate cortex, I should say.

If I were to just show you an expert, a brain imaging map with memory centers related in terms of their activity, emotion centers, visual centers, motoric centers, and I were to say to you, Andrew, this is a scan that we got from an individual.

Just describe the type of experience that you think this person was having in the scanner.

You would probably look at it and say, well,

They were probably recollecting things from their past memory structures.

They seemed to be having a visual experience, but there was also probably movement involved in that brain scanning experiment.

And also there seems to be some degree of emotionality to it.

That sounds strikingly similar to what we know dreams are like.

With one exception though, another part of the brain bucked the trend of increased activation during REM sleep.

That part of the brain where the far left and right sides of your frontal lobe, something that we call the dorsolateral prefrontal cortex, terrible mouthful word salad, essentially just means the far left and right sides of your prefrontal cortex,