Traumatic Brain Injury

Following the death of Natasha Richardson from a head injury, MSNBC is running a bit of information about Traumatic Brain Injury that they pulled from the CDC. It’s some good info for anyone who is interested in brain trauma.

Sunday Sessions

I feel like crap. I’ve got some sort of upper-respiratory thing (I thought those would go away when I quit smoking!) and my head feels like it’s swimming. I’m getting cold chills. Basically, it feels like a fever, except the thermometer doesn’t read over 98.5. I don’t care what it says. I would have an argument with it, but at this point I’m afraid it would win.

So, here’s a couple of quickies for Sunday (and to prove how messed up I am, it’s technically Monday).

Is Genius Inherited? Time asks this question. The answer is “yes and no,” and, while I appreciate coverage of anything psychologically-related in the national press, I have to ask… Really? Haven’t we pretty much settled this one by now?

Anatomy of Thought Neurophilosophy has some beautiful engravings of the human brain.

I Love This Website

Polite Dissent. It’s medical reviews of comic books and House. It’s a geek’s best friend.

More on propanolol

I’m not going to reproduce his whole post, but Ed Young over at Not Exactly Rocket Science has compiled the good, bad, and ugly of the media’s reporting on the propanolol study I blogged about last night.

The Boston Globe has a piece that Ed points to as an example of a media outlet that got it right. Here’s the last few lines:

So can beta-blockers be used to erase our fearful memories? “We have a long way to go before this finding can be clinically applied. We still need to identify all the factors that influence memory,” she says.
BOTTOM LINE: Propranolol may play a role in disrupting the process that encodes and re-stores a fearful memory in the brain.
CAUTIONS: It’s unclear whether the three-day findings apply to a memory created over the long term.
WHAT’S NEXT? Researchers plan to vary the duration of exposure to fearful stimuli to see if the results hold.
WHERE TO FIND IT: Nature Neuroscience, Feb. 15, 2009.

This is the best I’ve read, but I still don’t like the “erase memories” thing in the first line. Again, the drug doesn’t erase fearful memories, but disassociates the fear response from the memory.

A Pill to Erase Bad Memories? Not Quite…

I heard it during a news commercial during House, “a pill to remove bad memories.” I thought, “I should watch that. It sounds too good to be true,” but I didn’t. Then I see the headline in The Huffington Post, Pill to Erase Bad Memories: Ethical furor over drugs “that threaten human identity and I knew I had to check this out because it sounded too good to be true. And it is.

The research article that the news media is mangling is a study from the University of Amsterdam by Kindt, Soeter, and Vervliet (2009), Beyond extinction: Erasing the human fear response and preventing the return of fear published in Nature Neuroscience. (Actually, it’s pre-press.) In this experiment, the authors performed a double-blind test in which they first stimulated a fear response to spiders by pairing images of spiders with electric shocks. On the second day, they gave the control group a placebo and the experimental group propranolol, a β-adrenergic receptor antagonist, or beta blocker, and re-exposed them to the spiders, measuring potentiation of the eye blink startle reflex to a loud noise as a test of fear response. What they found was that subjects given propranolol were calmer and less likely to startle. On the third day the researchers attempted the startle test again after the beta blocker was gone from the system and found that the subjects stayed calm.

As an extra test, they tried just giving beta blockers without reintroducing the fear response. Those subjects remained fearful, so it appears that the mechanism only works by combining the drug with exposure.

Beta blockers block androgens like testosterone, which are implicit in the fight or flight response.

What this treatment apparently does, and more studies are certainly warranted for a finding of this magnitude, is to remove the fear response that is paired with a particular memory. What it certainly does not do is “erase bad memories.” The researchers are clear on this:

Notably, the propranolol manipulation left the declarative memory for the acquired contingency between the conditioned and unconditioned stimulus intact, but this knowledge no longer produced emotional effects. Our finding that propranolol eliminated the fear response, without affecting declarative memory, is consistent with the observed double dissociation of fear conditioning and declarative knowledge relative to the amygdala and hippocampus in humans (Kindt, Soeter, & Vervliet, 2009, p. 3).

However, it appears that not everyone bothered to read the article:

Paul Farmer, chief executive of the mental-health charity Mind, said he was concerned about the ‘fundamentally pharmacological’ approach to problems such as phobias and anxiety.

He told Channel 4 News that the unintended consequences ‘could include the eradication of positive memories’.

Not quite, because it doesn’t eradicate memories.

I am not a neuroscientist. Reading neuroscience is a bit of a hobby, but I am by no means an expert. However, I think it would be fair to say that there are different mechanisms in the amygdala to pair memories with different emotions. And it wouldn’t be too far of a stretch to believe that a drug may affect one aspect (say, fear) without affecting another (happiness). Also, remember that we don’t know the mechanism behind this yet. The authors propose that beta blockers affect the amygdala, the brain’s emotion center, but not the hypocampus, where facts and events are stored. The amygdala is also active in the process of learning, and that might have something to do with the mechanism of action. But the key point is that no one is advocating throwing this treatment out there without adequate testing. If they do find it effective with low side effects, this could be a major breakthrough. After all, every talking therapy is essentially trying to do this: remove the fear response from a patient’s memory of feared events and trauma.

The Internet is wonderful for science news, but it is hard to differentiate the real story from the media’s version. It took three articles before I found the source of this story and was able to read the evidence for myself. If you find something that looks too good to be true, try to do a little digging.

UPDATE: Ed Young over at Not Exactly Rocket Science got to this story and tore the media’s version apart before I was out of bed this morning. Unfortunately, I didn’t see it. Credit where credit is due.

Merel Kindt, Marieke Soeter, Bram Vervliet (2009). Beyond extinction: erasing human fear responses and preventing the return of fear Nature Neuroscience DOI: 10.1038/nn.2271