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  Would you like some chips with your brains?Jun 24, 2011 3:26 AM PDT | url
Added 1 new A* page:
"A* has set the standard for greatness in webcomics. As a reader, I am very impressed. As a webcomic producer, I am insanely jealous."
-- TonyDoug Wright, Champion City Comics

Before I launch into the third and final part of this week's foray into the neuroscience (or what little gloss I can glean of it) of Selenis' neural implants and doohickeys, I wanted to point you to an interesting article I just came across today, which talks about a new brain interface being developed of the ECoG type, which is short for "electrocorticography," "in which a grid of electrodes is surgically placed directly on the surface of the brain to monitor electrical activity. This technology is currently used for surgical planning in patients with uncontrolled epilepsy in order to find the origin of their seizures." But now they're talking about refined versions that can do much more, like control artificial limbs, and I thought the part describing how patients learn to use it was pretty interesting:
"Tests of more than 20 patients have shown that people can quickly learn to move a cursor on a computer screen using their brain activity. Researchers first ask patients to imagine performing a certain action, such as moving a computer cursor to the left. They then identify changes in the frequency of electrical signals that correlate with that movement and use those to control the computer. The patient learns to more precisely control his or her brain activity and hence more reliably performs the task within half an hour."
So the connection between brain activity and result doesn't necessarily have to be hard-wired--you just give the interface to the subject and let them teach it to themselves on the go!
Okay anyway onto the third neuroscience part proper, which has to do with memory: Selenis' many lives in cloned bodies are made possible in large part by the transfer of memories--or at least sensory data, but ideally both...--from her past clones into the newest clone. Is that possible? Can memories be transformed into digital signals, stored and transferred, and then at some point be put back into a brain in a form the brain can use?
As far as I could tell when I tried to comb Wikipedia about this, human memory is one of the things that neuroscience doesn't know very much about--its exact mechanical operation, anyway. The most I was able to come up with--and now I'm not sure where this was, but maybe it's somewhere I'm currently overlooking in the page I'm going to link shortly--was a suggestion that memory actually consists of synaptic connections and receptors, or something like that, that have become streamlined...or this was vague and my own memory is pretty bad :P...through repeated use under a certain configuration.
That doesn't sound like much, but when you consider that there are maybe about one billion neurons in the human brain, with maybe something like one hundred trillion synapses connecting them (and that's down from ten times that, one quadrillion synapses, in a three-year-old child--the number of synapses decays from that point, stabilizing in adulthood), maybe it starts to add up to something.
And maybe that huge tangle of neurons and synapses would be pretty darn tough to read and write to artificially; it certainly isn't something that can be done on anything like a large scale with our current technology. But--
Ah hold on, I found that memory mechanism I was stumbling over. It's called long-term potentiation, and it's basically a phenomenon, first artificially induced (accidentally) and observed in 1966, of "a long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously. It is one of several phenomena underlying synaptic plasticity, the ability of chemical synapses to change their strength. As memories are thought to be encoded by modification of synaptic strength, LTP is widely considered one of the major cellular mechanisms that underlies learning and memory."
It still isn't know exactly how that all works on a molecular level, but it does work. So in theory, if you got really good and efficient at stimulating individual neurons, and could also *read* the signal transmission levels between neurons on a wide scale--or at least knew where to put patterns you wanted to lay down, anyway--*maybe* there's some sort of mechanism for transferring memory there.
On the other hand, a simpler solution might be simply to play back the sensory data that needed to be remembered--like a long burst of a super-sped-up-multi-sensory movie--directly into the appropriate areas of the brain, and let the brain do the re-wiring itself.
Partly because LTP was first observed there, it is thought that long-term potentiation and memory have a lot to do with the squiggly little bit of the brain known as the hippocampus:
image from Gray's Anatomy of the Human Body, 20th edition (source)
The hippocampus is one of the first places to suffer damage from Alzheimer's, for instance. So a lot of memory research involves poking around in hippocampi, and the claimed results of a USC study on rat hippocampi published just last week sound like quite a breakthrough.
The hippocampus has been connected with the conversion of short-term to long-term memory, so the researchers, having trained rats to press two levers in an alternating pattern, and having observed changes in the rats' brain activity between the two major internal divisions of the hippocampus, then gave the rats a drug that specifically inhibits activity between those two parts of the hippocampus, and observed the result: the rats could only remember which lever they had thrown first for 5-10 seconds.
But that's far from the most interesting part of this study. See, having studied the intra-hippocampic brain activity of the rats while they were learning, the researchers were able to gain an understanding of the hippocampus' short-to-long-term memory encoding process sufficiently to be able to program it into an electronic device which, when implanted into other rats, actually improved their long-term learning capability: they could remember the lever-pressing sequence with longer and longer delays between lever presses. And not only that, but when they triggered the artificial hippocampus sequence on memory-inhibited rats, the drugged rats were then able to "remember" the correct pattern.
So they've been able to put the algorithm our brains (or rat brains, at least) use for converting data into long-term memory onto a computer chip, which you can see here. That's not only mind-blowing, it's mind-restoring!
So maybe this stored-memory system Selenis uses to bring her new clones up to speed isn't quite as far-fetched as I had secretly feared. Whew!
There's a specific biological aspect of her whole longer-living-through-clones procedure whose feasibility I sometimes, in my darker moments, begin to doubt, and which I hinted at on A*'s Facebook page earlier today. So I need to study up on that one, and hopefully it will turn out as well as the neuroscience part has! Or at least, it'll still be a scientific gray area. >_>
And yes, that was a brainy pun. =PP
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