Sunday, November 2, 2008

fMRI: The Argument of Authority

Science in America has replaced religion. Not in all aspects – science will never be held in people’s hearts like religion, but the two tread on the same ground, by some arguments they stab at the same questions. Both are paradigms for explanation, and they’re competing for space - science’s gains in status speak more to scientific progress than to religious decline. In a funny way though, science’s rise in power has inherited it some of religion’s warts. Science in America has adopted an air of superiority and objectivity, which for centuries was reserved for Christianity. The curious rise in the use of fMRI – functional magnetic resonance imaging, used to tap brain activity - is an interesting example of this. It’s a scientific technique that may have more objectivity and authority than substance.

The argument of authority is the weakest argument of all. This is a stance put forward by St. Thomas Aquinas (who, ironically, was rather authoritative himself). As the Church’s authority changed and grew with the times, this became a common criticism of doctrine. Nietzsche, though, first revealed authority - or at least, how authority was perceived by the masses - for what it really was: a power grab.

His line of thought was that people are going to declare whatever they want to declare and they’re going to use any means to do so. The largest historical example of this is the Church – who go so far as to claim backing by the word of God in order to hold captive the public.
But Nietzsche didn’t stop there. He damned objectivity as part of the same game. This is theology, this is bodies and bodies of literature using the bible to form public opinion. Authority and objectivity have a synergistic effect, and this is what kept the Church in place. In 397 AD St. Augustine wrote The Confessions and in 1227 St. Thomas Aquinas wrote The Summa Theologica. In the 800 years in between, there weren’t really any other intellectual breakthroughs in the Western world. This worked.

Democracy heralded a new age of decentralization in the West. People not only stopped trusting authority, they were smarter. Smarter in an academic sense. More intellectual, more opinionated, individualistic, they felt their voice should be heard because it deserved to be heard. The academic sphere – which used to center around religion and authority – now focuses more on objectivity. With an air of objectivity, it is earier to win over the modern mind. Modern day science holds a similar role - in power and policy - as religion used to, but it’s traded a bit of authority for some more objectivity: The latter is built on the pillars of the scientific method and peer review; while authority still persists in premier research institutions and "Ivory Towers", but overall the value of authority is still sinking. Here, though, Nietzsche still stands: Objectivity, yes, but objectivity for what?

Moving onto fMRI's, this post was largely sparked by a presentation I saw about neuroimmaging by Robert Poldrack. He’s documented his skepticism behind the widespread use of fMRI. On the surface, the technology, as used in most research, is simple enough: Participants do activities while their hemodynamic responses from different brain areas are measured. This gives us pretty images like this:The results are the changes in brain activity across tasks that have been carefully selected by scientests. The tasks involve turning on/off a certain thoughts or stimuli (e.g., viewing a shape versus a piece of art). Empirical results from fMRI studies are centered around very simplified and controlled changes in the lab and corresponding changes in brain activity. That’s it.

Poldrack raises the point that fMRI images are very sensitive and they’re very nonspecific. In other words, your brain lights up from almost any activity, and the areas that light up aren’t always specific to the activity you’re doing. You could be pondering the world or having sex, a lot of the same areas of your brain will light up. This becomes a problem when scientific studies pinpoint areas of the brain that are tied to some distinct activity and/or use fMRI to distinguish between two populations.

For the better or worst, these sorts of studies can't simply look at the whole brain. In the world of science, it’s preferred to keep studies limited in scope, and this particularly applies to brain imaging. Too much data is hard to interpret, and in technical terms it’s…a mess. Unfocused studies have a higher chance of finding spurious results. This has a statistical explanation, but really it’s just that if you look at tons of stuff, you’re bound to find stuff that appears interesting, on an empirical level, but is actually just occurring by chance. This gets worse though with fMRI’s, because they spit out millions of pixels, each of which is a data point that is analyzed. As technology makes fMRI’s more resolute, they give out even more data, increasing the chances of finding a mess on your hands.

As participants do the required experimental actions, researchers focus on distinctive parts of the brain. When that part of the brain lights up across their sample, the authors attribute whatever action they have the participant do to that part of the brain. It seems reasonable, and that's often why you always hear about the executive part of the brain, the emotional part, etc. But the issue of high sensitivity and low specificity calls most of that logic into question: Due to high sensitivity, those areas in the brain might have lighten up in response to any other task; and due to non-specificity, many other areas of the brain likely respond to that activity as well.
An example: Poldrack brought up an area of the brain called the anterior cingulate cortex, often summarized as the decision making part of the brain. However, this area lights up from so many other tasks: reading fake words versus real ones, pushing your tongue against the roof of your mouth versus resting it, viewing certain patterns versus letters, and doing simple versus complex memory tasks, to name a few. Nonetheless, whenever researchers find that this area lights up, they'll specifically attribute it to their experimental task. This sort "reverse inference", as Poldrack calls it, runs rampant in the field.

Everything gets messier when comparing different people. (You might remember the recent news item that Democrats think with different parts of their brains than Republicans.) Inevitably, many fMRI studies do this, but things get tricky with the introduction of a new demographic or person-based variable.

For example, a study might compare responses to certain stimuli - say, threatening versus neutral stimuli - in anxious versus normal people. So they’re dealing with two versuses: The first – based on the task – produces those sensitive and non-specific responses in the brain; and the second – the person-centered comparison – brings into the equation differences between people, which is a complex area in its own right.

One pitfall (of many) in this common experimental design: Different clinical conditions are related to different amounts of baseline brain activity. Going back to our example, this is likely the case in anxiety, which is a state of hyper-vigilance. So the noise of the anxious person’s brain is already turned up. This leaves less room for their brain to respond to tasks (causing a ceiling effect). Studies in fact often conclude that clinical groups are less responsive to changes in stimuli, because a specific brain area lit up less in response to a certain activity in clinical populations than in normal ones. Again though, this might be due to differences in resting brain activity. Or it might be due to non-theoretical differences between the populations - for example, anxiety tends to be higher among women or in insomniacs. Or it might be due to non-theoretical differences in responses to the stimuli that the researchers used (e.g., the color of a certain card) which were picked up in the sensitive brain reading. In other words, it's easily possible that such a typical study isn't teaching us much about anxiety or the brain.

I apologize for the long and technical discussion of fMRI, but the resulting situation is rather interesting, albeit not because of what it teaches you about the brain. Imagine if every question you could ask about the brain were answered in the positive, regardless of the true answer. That’s much like this field.

Since every study finds what it wanted to, you get this mishmash of absurdly complicated theories about neural correlates, brain circuits, specific activities linked to specific areas of the brain. It reminds me of reading theology, where I'd have to step back and ask myself whether the sheer complexity of the subject matter ever matched its underlying content. Every research question is answered with a yes, and consequentially it's said to deserve further research, which means even more finely detailed study. You end up getting these very complicated theories about how specific activities affect very specific brain areas in different types of people. The word complex is used very often even within scientific circles to summarize these theories. (There’s even a blog called The Neurotic completely devoted to unveiling society’s brain-imaging-based misconceptions.)

Not that all of science is going to hell in a hand basket. There’s no mistaking true scientific advancement for anything but – and we’ve been a fortunate and smart enough society to have experienced much of it. Likewise, despite Nietzsche’s musing about the church and power, there’s a true underlying glow of religion which fits the human soul so perfectly and like a key. But inevitably there are ways to exploit any man-made system, and fMRI’s maybe a unique example of this exploitation in science. They provide a veil of objectivity necessary for academic clout, justification for future grants – in a word, power.


Media (in order of appearance)

Photo (1) The Majesty of Law, statue on Independence Avenue Washington, DC, 09/19/2008, by Kimberly Faye; (2) Portrait of Fredrich Nietzsche (1844-1900); (3) Christianity, 08/29/2007, by OdedG; (4) Triumph of Christianity, by Tommaso Laureti (1530-1602), Sala di Costantino, Vatican Palace (5) Stained Glass Tower of Ivory, window in St. Ignatius Church, Chestnut Hill, MA, 05/17/2006, by John Workman; (6) fMRI, 03/08/2004, by Washington Irving; (7) Varian4T, fMRI scanner from Helen Wills Neuroscience Institute at University of California Berkley; (8) Artistic Mess Cormacphelan; (9) Anterior Cingulate Cortex; (10) Activation of Brain Region Predicts Autism, Scott Huettel, Duke University Photography Jim Wallace; (11) Hawkan Lau by Dr. Pat, 07/18/2005; (12) Nietzsche's Will to Power - Bar, 05/01/2008, by Sharon Hagenbeek

Video (1) some of them were superstitious, AlGorey91's channel, music by the band Midlake, from the album Bamnan and Silvercork, released 07/06/2004
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  1. I like your style.

    I've got a few comments to make about this when I find some time. It may appear as a post on my blog.

  2. Thanks, & glad it stimulated some thought! Looking forward to reading it Jake.



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