Trauma Alters Brain Function… So What?

By Neuroskeptic | September 8, 2009 11:15 pm

According to a new paper in the prestigous journal PNAS, High-field MRI reveals an acute impact on brain function in survivors of the magnitude 8.0 earthquake in China.

The earthquake, you’ll remember, happened on 12th May last year in central China. Over 60,000 people died. The authors of this paper took 44 earthquake survivors, and 32 control volunteers who had not experienced the disaster.

The volunteers underwent a “resting state” fMRI scan; survivors were scanned between 13 and 25 days after the earthquake. Resting state fMRI is simply a scan conducted while lying in the scanner, not doing anything in particular. Previous work has shown that fMRI can be used to measure resting state neural activity in the form of low-frequency oscillations.

The authors found differences in the resting state low-frequency activity (ALFF) between the trauma survivors and the controls. In survivors, resting state activity was increased in several areas:

“The whole-brain analysis indicated that, vs. controls, survivors showed significantly increased ALFF in the left prefrontal cortex and the left precentral gyrus, extending medially to the left presupplementary motor area… [and] region of interest (ROI) analyses revealed significantly increased ALFF in bilateral insula and caudate and the left putamen in the survivor group…

They also reported correlations between resting activity in some of these areas and self-reported anxiety and depression symptoms in the survivors.

Finally, survivors showed reduced functional connectivity between a wide range of areas (“a distributed network that included the bilateral amygdala, hippocampus, caudate, putamen, insula, anterior cingulate cortex, and cerebellum.”) Functional connectivity analysis measures the correlation in activity across different areas of the brain – whether the areas tend to activate at the same time or not.

Now – what does all this mean? And does it help us understand the brain?

The fact that there are differences between the two groups is neither informative nor surprising. “Resting state” neural activity presumably reflects whatever is going through a person’s mind. Recent earthquake survivors are going to be thinking about rather different things compared to luckier people who didn’t experience such trauma. It doesn’t take a brain scan to tell you that, but that’s all these scans really tell us.

But these weren’t just any differences – they were particular differences in particular brain regions. Does that make knowing about them more interesting and useful?

Not as such, because we don’t know what they represent, or what causes them. So living through an earthquake gives you “Increased ALFF in the left prefrontal cortex” – but what does that mean? It could mean almost anything. The left prefrontal cortex is a big chunk of the brain, and its functions probably include most complex cognitive processes. Ditto for the other areas mentioned.

The authors link their findings to previous work with frankly vague statements such as “The increased regional activity and reduced functional connectivity in frontolimbic and striatal regions occurred in areas known to be important for emotion processing”. But anatomically speaking, most of the brain is either “fronto-limbic” or “striatal“, and almost everywhere is involved in “emotion processing” in one way or another.

So I don’t think we understand the brain much better for reading this paper. Further work, building on these results, might give insights. We might, say, learn that decreased connectivity between Regions X and Y is because trauma decreases serotonin levels, which prevents signals being communicated between these areas, which is why trauma victims can’t use X to deliberately stop recalling traumatic memories, which is what Y does.

I just made that up. But that’s a theory which could be tested. Much of today’s neuroimaging research doesn’t involve testable theories – it is merely the exploratory search for neural differences between two groups. Neuroimaging technology is powerful, and more advanced techniques are always being developed. What with resting state, functional connectivity, pattern-classification analysis, and other fancy methods, the scope for finding differences between groups is enormous and growing. I’m being rather unfair in criticizing this paper; there are hundreds like it. I picked this one because it was published last week in a good journal.

Exploratory work can be useful as a starting point, but at least in my opinion, there is too much of it. If you want to understand the brain, as opposed to simply getting published papers to your name, you need a theory sooner or later. That’s what science is about.

ResearchBlogging.orgLui, S., Huang, X., Chen, L., Tang, H., Zhang, T., Li, X., Li, D., Kuang, W., Chan, R., Mechelli, A., Sweeney, J., & Gong, Q. (2009). High-field MRI reveals an acute impact on brain function in survivors of the magnitude 8.0 earthquake in China Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0812751106

  • reasonsformoving

    “almost everywhere is involved in “emotion processing” in one way or another.”

    Doesn't that have powerful implications for all of the psychopathy fMRI studies?

    I hope you do a post soon on those studies. For instance, the big deal now is dysfunction in the the amydala which is associated with emotional processing – yet haven't their been similar findings in schizophrenia? Yet, no one is claiming that people with schizophrenia are incapable of remorse.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Yep, also “amygdala dysfunction” has been reported in autism, depression, healthy people taking antidepressants… etc.

    There are also cases of people who suffer serious amygdala damage for various reasons, and they experience various effects but to my knowledge none have become psychopaths.

    This doesn't mean that the amygdala isn't disturbed in psychopathy, but it suggests the picture is more complex than it's often thought.

    I'll write a post on this at some point…

  • http://www.blogger.com/profile/02919372687833171031 togliatti

    This is a very good point and it almost made me relieved as not being the only whiner in the town. I am very new in neuroscience area, and it is one of the things has been perplexing to me as I read more and more papers. Difference, difference and difference. I have been asking very same question: So what?

    Thanks for the great post!

  • http://www.blogger.com/profile/06832177812057826894 pj

    Also, when does a very small difference in mean BOLD signal in some area between two groups (or even worse, difference in the correlation in BOLD signal between two areas) equal 'dysfunction'?

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    pj: I think that started around about when technology advanced such that it requires less effort to detect differences than to characterise or explain them.

  • dearieme

    Is that “trauma” as in having received blows to the body in the earthquake, or “trauma” as in having been dreadfully upset or frightened?

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Oh, sorry. It's psychological trauma, they were medically not injured.

    They also didn't meet criteria for psychiatric disorders such as PTSD.

    “All survivors were recruited within 25 days (range 13–25 days; mean ± SD: 21 ± 3) after the start of the Wenchuan earthquake from the most affected regions, where seismic intensity ranged from 9 to 11 on the Mercalli intensity scale. In these regions, thousands of people were buried and dead under collapsed buildings, and survivors were still afraid of intense aftershocks. The inclusion criteria for survivors included: (i) physically experiencing the earthquake, (ii) no personal medical injury, and (iii) personally witnessing death, serious injury, or the collapse of buildings. Participants underwent Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV (SCID) interview to rule out a current diagnosis of psychiatric disorder. “

  • dearieme

    Ta.

  • http://www.blogger.com/profile/05690938219773877575 Nora Miller

    “So living through an earthquake gives you “Increased ALFF in the left prefrontal cortex” – but what does that mean?”

    Unlike folks steeped in up-to-the-minute neuroscience, a lot of people who work with trauma patients do not necessarily understand, accept or even know about the (to-us) unquestioned connection between “mind” and brain. Despite a growing body of research that I believe absolutely refutes the “mind-body” dualism of old, research has shown that many psychiatrists, psychologists and other mental health workers still subscribe to the notion. The more research that connects real-world events with brain changes the better, in my view. Studies which document that emotional trauma causes actual changes in the brain may help such people feel and express more empathy for victims, and to recognize that victims won't just “get over it” if they just “put it behind them”.

  • http://saradenning.com Dr.D

    Thank you for being a 'clinical' skeptic. I am one of those psychologists who gets that the mind/brain is what we have to work with and not separate dishes served up for each diagnosis. When I first looked at fMRIs I keep looking at parts and trying to find how they worked individually. Looks like a symphony now.. and some sections may not play as well as others. To ask only which part is traumatized doesn't work.

  • Psychoskeptic

    Re 'mind-body' stuff – accepting the 'mind' and 'brain' is probably linked doesn't mean we can claim 'psychogenic' explanations for any somatic conditions that cannot be easily or fully 'explained' by current scientific knowledge (a problem with 'mind-body' approaches), for example. Part of the problem, even in those claiming to 'transcend dualism', is that they actually often do subscribe to notions of 'mind over matter' to absurd degrees when it comes to human bodies. We get it, emotions cause biochemical changes in the brain, in everyone. Doesn't mean cbt will 'grow' grey (or was it white? I forget) matter though, a recently implied claim based on a small scanning project of 'CFS' patients. And some dude is claiming he can cure 'CFS' by 'retraining the amygdala' now.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Nora: OK, that's fair, but this was published in a scientific journal – what I was criticising was the fact that it doesn't really advance our scientific understanding. Although, as I said, it could potentially act as a starting-off point for further work.

    Psychoskeptic: That's absolutely true, in certain circles there is much excitement over the idea that “you can change your brain” (and they have the MRI scans to prove it!) which is silly. We are all changing our brains every moment of our lives, it doesn't mean we have the power to will away any obstacle. “Neuroplasticity” is becoming a buzzword for some people.

  • http://www.blogger.com/profile/14608995629056535796 SleepRunning

    Scientists are callow careeists and all around human.

    New technologies, data and bodies of knowledge are usually more “wrong” than “right.”

    Human knowledge is really, really imperfect and often just dum!!

    These trival observations are worth a whole blog?! Oh well….

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Not the whole blog… I also review horror movies.

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Neuroskeptic

No brain. No gain.

About Neuroskeptic

Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

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