Dr. David Eagleman

But if I turn around, I'll feel that on my right hip and so on.

And people get really good at being able to detect which way north is.

Just as one example, it's really easy to add new senses, like magnetoreception in this case, and people can figure this stuff out.

Let me answer that second part first.

We're not sure about that.

I ask people all the time who are aphantasic or hyperphantasic about their dreams.

It's hard to tell.

I don't see something obvious there, which is to say when there's dreams, you're getting this activity blasted into your visual cortex.

So it's like vision.

So let me back up to answer the question about my new theory about why we dream, because this has everything to do with brain plasticity.

So here's where this got started.

By about 2013, some of our colleagues at Harvard did this experiment where they put people in the scanner and they blindfolded them tightly and they were looking at what was going on in the brain and, you know, with touch and with sounds.

And it turns out that if you're blindfolded after about an hour, you start seeing a little bit of activity in the visual cortex when you are touched or when you hear something.

Now, this was crazy because we know that if somebody goes blind, hearing and touch will take over that territory.

But we thought that was on the scale of years.

And here what they were demonstrating is that within 60 to 90 minutes, you start seeing little blips of activity.

Why?

It's because you've got all this cross-modal wiring.

In other words, you've got neurons, let's say, in the auditory cortex that actually reach all the way over to the visual cortex.

And same with touch neurons and so on.