Wednesday, February 18, 2009

Remixing memories

I'm thinking that The Globe and Mail has been checking out my blog, seeing this article from earlier in the week talking about the things from my last post. Particularly how other countries are pumping money into research while Canada is cutting. Interestingly, they interviewed my PhD supervisor, who is apparently "one of Canada's top scientists".

I'm pleased how closely his opinions follow mine, and that they're publishing them in the Globe and Mail. I'm a bit disturbed about being so similar to my boss, though. I'm also disturbed that he apparently has fantasies of moving to Signapore...

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A genetic therapy approach to treating AIDS that I blogged about last summer is currently recruiting for its first clinical trial. This is pretty incredibly quick, but it seems very safe - take some of a patient's blood, take out the T-cells, culture them, insert the gene, grow a whole pile of the modified cells, and then return them to the patient. This follows on the footsteps of another successful trial of gene therapy for AIDS treatments.

The risks of these treatments seem minimal. The gene transfer isn't contagious to other cells, and the T-cells come from the patient's own body so there should be no risk of rejection. Assuming the cells aren't grown in an animal serum, which could induce a rejection response in patients. But I imagine these guys know what they're doing.

Of course, the guys injecting a Russian boy with stem cells also knew what they were doing, and they knew the risks. Turns out they lost this bet - the kid developed extensive tumours throughout his nervous system. While this was a predicted potential side effect, I don't think anyone was expecting this to go so spectacularly wrong.

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If there's one thing I've been wanting to blog about this week, it's this story about using a heart medication (propranalol, a beta-blocker) to "block bad memories." People are going buck-wild about this - I even saw it on Facebook (I have some geeky friends). But the study is not all it's cracked up to be.

The researchers conditioned people to be "afraid" of spiders by showing them pictures of spiders and then shocking them, a Pavlovian paradigm that couples a neutral stimulus (spider) to an averse stimulus (shock), and transfers the unpleasant feeling associated with the shock to the spider. The drug was able to reverse this conditioning, so people no longer had an adverse response to the spiders. And now it's being touted as a treatment for PTSD and anxiety disorders.

First of all, I would like someone to explain to me and a couple of war veterans exactly how shocking someone while looking at pictures of spiders is anything remotely like traumatic experiences like losing a limb in a firefight or having your friend's brains blown out all over you. Or even like being in a car crash.

Secondly, even something like a phobia against an object (say, spiders) isn't like a conditioned association. In fact, it's the opposite. The reason it's a phobia is precisely because it's an unconditioned and irrational fear of an object. Show me a trial with arachnophobics on propanalol viewing pictures of tarantulas and I don't think we'll see such stunning claims being made.

The idea is that when we remember things, we take the representation out of long-term storage in our brains and move it into "working memory," a sort of RAM buffer memory for your brain. When we're done with it, it gets re-programmed back into the long-term storage. If we can remove the bad associations from the memory before we code it back into long-term storage, then we can remove some of the anxiety and pathology that comes from remembering it.

I, for one, am not sure that this will work. I think that removing a simple conditioned association is a lot different from removing the particularly vivid memories that many PTSD patients have, and that the emotional component of these memories is much more intense than a simple shock to the finger. I think the biochemical underpinnings are significantly more complicated than simple noradrenaline release as well. That being said, we can condition men to respond sexually to an old boot, but again I would argue that this neither a complex behaviour nor particularly difficult to accomplish. Now if we could do it in women, then we'd be on to something.

I'm not sure what it will take to "erase" these memories, but I refer you back to an earlier post I made on memory manipulation and Joe Tsien's quote: "All memories, including the painful emotional memories, have their purposes. We learn great lessons from those memories or experiences so we can avoid making the same kinds of mistakes again, and help us to adapt down the road."

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My other blog, for those who are interested, is up. The first post is enititled "Douglas Zombies Need Brains." And if that doesn't pique your interest, then I don't want you reading it anyways.

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