Memories processed seven times faster than reality
Scientists have show that when rats sleep, they play back memories as much as seven times faster than the events really transpired. The research, conducted at the University of Arizona, may shed light on how memories are processed. From a University of Arizona press release:
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.Link
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, (professor Bruce) 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.
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Kick ass... so when we get our direct-to-brain inputs, we can experience 35 minutes of reality in just 5 minutes of real time!
Well, provided our brains run at rat-speed or better.
Quite. It's interesting to see that the concept of "speed of thought" has basis in reality.
It is pretty intuitive that the processing of our memories are not constrained by the same things that the experiencing of reality are. Our memories are designed to contain a lot less information, and are not anything like the full experience of reality. This is not so much because the hippocampus cannot connect to every neuron (that is misleading because it is widely accepted that memories are not stored in a single neuron but a large and distributed network of them) but because our senses filter out so much of the incoming information.
Memories that are exact representations of reality would be an enormous, and completely unnecessary burden.
When do we get to see movies of our dreams?
I'm itching to see what happens when the unconscious becomes conscious in its totality.
If the hippocampus could process all of that information at once as one long continuous projection transferred via some kind of wetware/hardware interface we could slow it down and watch it with popcorn, or with an air sickness bag, whichever is most fitting.
It's a very interesting study (Euston, Tatsuno & McNaughton just published it in Science), but this article way overstretches what we know about hippocampal function or what this study found. That barcode business is very speculative (though a reasonable enough theory), and why exactly certain patterns of activity are played back during sleep and why this would be faster than the awake patterns is also unknown...