Monday, November 06, 2006

Dreaming about Dreams

I woke up at 3 a.m. almost unable to go back to sleep.

I had been dreaming.

No, it was not a nightmare. It was far better. I was dreaming about dreaming.

"Freud was an idiot," I often say. Sure it's an overgeneralization. Sure he helped advance the field a lot. But mostly, an idiot.

Along these lines, dream interpretation is more akin to "ESP" and "UFOs" than any legitimate science.

However, you do dream. And something is going on in your head when you see Abe Lincoln and that beaver (I am tired of that ad, too).

Here's what I think it is. I think dreaming has a lot to do with memory consolidation. You see, humans have the capability to do two pretty cool things: learn quickly and remember stuff for a long time.

When you attempt to build a simple artificial neural network, it can do one of those two things. But it cannot do both. If you learn fast, you forget old stuff. However, most of us still remember the name of our kindergarten teacher, and we can learn new stuff.

But how?

I subscribe to a theory of memory that conceives of the human brain as a two-step learner. The hippocampus and other structures in the medial temporal lobe are quick learners. Your isocortex (more often called neocortex or just cortex) is a slow learner that remembers for a long time.

Research done by neuroscientist Larry Squire and colleagues suggests that the hippocampus "plays back" your new experiences to your isocortex while you are asleep. And it does this in parallel, thus memories cross over.

It is quite possible that dreams are simply amalgamations of memory consolidation. And the super cool thing is that last night I had a dream about these theories of memory consolidation. So I was dreaming about how dreams occur.

Yes, I know I am a terrible nerd.

To learn more about this theory, please read:

McClelland, J. L., McNaughton, B. L., & O'Reilly, R. C. (1995). Why there are complementary learning systems in the hippocampus and neocortex: Insights from the successes and failures of connectionist models of learning and memory. Psychological Review, 102, 419-457.

To learn more about evidence of this playback, please read:

Skaggs, W. E., & McNaughton, B. L. (1996). Replay of neuronal firing sequences in rat hippocampus during sleep following spatial experience. Science, 271(5257), 1870-1873.

To learn more about interruption of consolidation, please read:

Squire, L. R., Chace, P. M., & Slater, P. C. (1976). Retrograde amnesia following electroconvulsive therapy. Nature, 260(5554), 775-777.


Post a Comment

<< Home