The Acting Brain!

The BBC promises us a look

Inside an actor's brain during a performance

Actress Fiona Shaw had an fMRI scan. Parts of her brain were more active while she was reading a poem by T. S. Eliot featuring dialogue than when she was merely counting. So what?

The fact that different parts of Shaw's brain were active whilst reading Eliot than when counting out loud is unsurprising. Different parts of the brain do different things - this is not news - and reading poetry is certainly very different from counting. This doesn't mean that "Fiona Shaw's brain appears to be adapted to acting", as the article says. If your brain was adapted to acting it would look like this:

All dressed up, skull in hand, ready to portray Hamlet - "Alas, poor Yorick..." Actually, brains generally do carry skulls around with them, so maybe there's something in it.

In fact, Shaw's brain presumably is adapted to acting - she's an actress. If you're able to do something, your brain must be able to do it, because you are your brain after all. In just the same way, my brain is adapted to being a neuroscientist and Barack Obama's brain is adapted to being President. This is not news either. However, the fMRI scan doesn't tell us anything about how Shaw's brain is adapted to acting.

We are told which areas of Shaw's brain lit up while she was reading poetry, and what this means -

Towards the front of the brain there is a part associated with "higher order" control of behaviour. Towards the top of the brain is a section which controls the movement of the hands and arms - even though she wasn't waving her arms about, she was apparently thinking about doing so.

And towards the back of the head is an area associated with complex visual imagery, even though she wasn't performing a complex visual task. The scan backs up work with professional impressionists, whose brains also conjure up visual images of the people they're imitating.

All very plausible - this is a nice convincing story to explain what these brain areas are doing while reading a passage of poetry in which people are talking to each other. It makes perfect sense. But the problem is, so would anything else.

Suppose that Shaw's hippocampus had lit up as well. That's involved in memory. She's remembering having read T. S. Eliot before! What if she's never read him? Well, the hippocampus must be forming a new memory. Her medial prefrontal cortex is activating? Clearly, that's the emotional impact of reading this masterpiece of modernist poetry. And so on. These areas did not, in fact, light up, but if they had, it would have made perfect sense too.

The point is that we all know what kinds of things go on in our heads while reading poetry - visual imagery, memories, emotions etc. And each brain region has numerous functions, many of which are sufficiently vague ("social cognition", "emotion") to cover almost anything, especially if you allow that a brain area can activate whenever someone is merely thinking about doing something rather than actually doing it. So whatever blobs appear on the brain, it's easy to invent a story linking these to the whatever task is going on.

It's like astrology. Astrological "readings" always seem accurate because they can be made to fit anyone. Actress Fiona Shaw is a Leo and Leo's have "a flair for drama. In fact, many Leos are attracted to the theatre, the performing arts and public relations". It fits so well! Actually, I made a mistake with my dates, she's a Libra. No problem, "Libra is among the most sociable of the signs...drawn toward creative endeavours." - obviously a born actress. And so on. (She's actually a Cancer.)

Perhaps it's unfair to criticize this experiment. It was a demonstration of fMRI technology for the "Wellcome Collection's new exhibition on identity". The scan was for educational purposes only, it wasn't meant to be proper science.

The problem is that a lot of what is meant to be rigorous science consists of this kind of thing. The Discussion sections of many fMRI papers are full of stories linking whatever brain regions happened to be activated to whatever the task in the experiment was. Most fMRI studies today are more sophisticated than simply scanning normal people doing some task, but the same kind of post-hoc storytelling can be applied to areas of the brain that light up differently in mentally ill people compared to healthy people, or areas that light up in response to a drug, etc.

Of course this doesn't mean that these stories are false. Shaw's visual cortex probably did activate because she was mentally imagining the people and the scene she was reading about - that explanation's good enough for me. The point, though, is that we don't really know, because whatever the fMRI data was, we could have made an equally convincing story having seen it.

What we need are hypotheses made up before doing the experiment, which can then be tested and verified, or falsified, on the basis of the data. As I wrote a couple of months back:

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... the scope for finding differences between groups is enormous and growing.

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 you need a theory sooner or later. That's what science is about.