Scientists at The University of Arizona have added another piece of the puzzle of how the brain processes memory.
Bruce McNaughton, a professor of psychology and physiology, and his colleague David Euston have shown that, during sleep, the reactivated memories of real-time experiences are processed within the brain at a higher rate of speed. That rate can be as much as six or seven times faster, and what McNaughton calls “thought speed.”
Their results are published in the Nov. 16 issue of the journal Science.
Memory stores patterns of activity in modular form in the brain’s cortex. Different modules in the cortex process different kinds of information – sounds, sights, tastes, smells, etc. The cortex sends these networks of activity to a region called the hippocampus. The hippocampus then creates and assigns a tag, a kind of temporary bar code, that is unique to every memory and sends that signal back to the cortex.
Each module in the cortex uses the tag to retrieve its own part of the activity. A memory of having lunch, for example, would involve a number of modules, each of which might record where the diner sat, what was served, the noise level in the restaurant or the financial transaction to pay for the meal.
But while an actual dining experience might have taken up an hour of actual time, replaying the memory of it would only take 8 to 10 minutes. The reason, McNaughton said, is that the speed of the consolidation process isn’t constrained by the real world physical laws that regulate activity in time and space.
The brain uses this biological trick because there is no way for all of its neurons to connect with and interact with every other neuron. It is still an expensive task for the hippocampus to make all of those connections. The retrieval tags the hippocampus generates are only temporary until the cortex can carry a given memory on its own.
So people who have poor memory are poor dreamers. There should be classes in dreaming. I'd like to get a degree in dreaming.
