© Bryan Olson

A few years ago, the Geneva researchers asked 50 multilingual students to lie in a brain scanner and carry out a series of language exercises. In one subjects merely listened to a sentence and said nothing. Another involved the students repeating the sentence in the same language. The third was the most onerous: subjects were asked to repeat what they were hearing, this time translating it into another language.

In cognitive terms this seems like a big step up. Initially the students just had to listen, and then to repeat. Task three required them to think about meaning and how to translate it: to interpret simultaneously. But the scans didn’t reveal any neural fireworks. “There wasn’t a huge amount of additional engagement,” says Hervais-Adelman. No extra activity in regions that handle comprehension or articulation, for example. “It was just a handful of specific regions that were handling the extra load of the interpreting.” These included areas that control movement, such as the premotor cortex and the caudate. Interpretation, in other words, may be about managing specialised resources rather than adding substantially to them.

This idea remains unconfirmed, but the Geneva team added weight to it when they invited some of the same students back into the fMRI scanner a little over a year later. During that period 19 of the returnees had undergone a year of conference interpretation training, while the others had studied unrelated subjects. The brains of the trainee interpreters had changed, particularly parts of the right caudate, but not in the way you might expect – activity there lessened during the interpretation task. It is possible that the caudate had become a more efficient coordinator, or had learned how to farm out more of the task to other structures.

“It could be that as people become more experienced in simultaneous interpretation there’s less need for the kind of controlled response provided by the caudate,” says David Green, a neuroscientist at University College London who was not involved in the Geneva work. “The caudate plays a role in the control of all sorts of skilled actions. And there’s other work showing that as people get more skilled at a task you get less activation of it.”

The story that is emerging from the Geneva work – that interpretation is about coordinating more specialised brain areas – seems to gel with interpreters’ descriptions of how they work. To be really effective, for example, a simultaneous interpreter needs a repertoire of approaches. “The process has to adapt to varying circumstances,” says Moser-Mercer, who still does 40 to 50 days of interpretation a year, mainly for UN agencies. “There could be poor sound quality, or a speaker with an accent, or it might be a topic I don’t know much about. For instance, I wouldn’t interpret a fast speaker in the same way I would a slow one. It’s a different set of strategies. If there isn’t time to focus on each and every word that comes in you have to do a kind of intelligent sampling.” It may be that the flexible operation of the brain networks underpinning interpretation allows interpreters to optimise strategies for dealing with different types of speech. And different interpreters listening to the same material may use different strategies.

The results from the Geneva group also fit with a wider theme in neuroscience. When fMRI became widely available in 1990s, researchers rushed to identify the brain areas involved in almost every conceivable behaviour (including, yes, sex: several researchers have scanned the brains of subjects experiencing an orgasm). But on their own those data didn’t prove terribly useful, partly because complex behaviours don’t tend to be controlled by individual brain areas. Now the emphasis has shifted to understanding how different areas interact. Neuroscientists have learned that when we consider a potential purchase, for example, a network of areas that includes the prefrontal cortex and insula helps us decide whether the price is right. Interplay between another set of brain areas, including the entorhinal cortex and the hippocampus, helps store our memories of routes between places.

This more sophisticated understanding has been made possible in part by improvements in scanning technology. In the case of the caudate, activity there can now be distinguished from that in other parts of the basal ganglia, the larger brain area within which it is located. The finer-grained scans have revealed that the caudate is often involved in networks that regulate cognition and action, a role that puts it at the heart of an extraordinarily diverse range of behaviours. As a team of British researchers noted in a 2008 review, studies have shown that the caudate helps control everything from “a rat’s decision to press a lever to a human’s decision about how much to trust a partner in a financial exchange”.

One of the review’s authors was John Parkinson of Bangor University in Wales. I ask him if he would have predicted that the caudate would be involved in simultaneous interpretation. He says that at first he wouldn’t have. “The caudate is involved in the intentionality of an action, in its goal-directedness. Not so much in carrying it out but in why you’re doing it.” Then he thought about what interpreters do. Computers translate by rote, often with risible results. Humans have to think about meaning and intent. “The interpreter must actually try to identify what the message is and translate that,” says Parkinson. He agrees that the involvement of the caudate makes sense.

Given that the Geneva research is based partly in a department tasked with training interpreters, it’s natural to wonder if their scientific findings might eventually find a direct practical application. Moser-Mercer and her colleagues are careful to avoid extravagant claims, and rule out suggestions that brain scanners might be used to assess progress or select candidates with an aptitude for interpreting. But even if studying simultaneous interpretation doesn’t lead to immediate applications, it has already extended our knowledge of the neural pathways that link thinking with doing, and in the future it may help neuroscientists gain an even deeper understanding of the networked brain. The Geneva team wants next to explore the idea that some high-level aspects of cognition have evolved from evolutionarily older and simpler behaviours. The brain, they suggest, builds its complex cognitive repertoire upon on a lower level of what they call “essential” processes, such as movement or feeding. “This would be a very efficient way to do things,” Moser-Mercer and her colleagues tell me in an email. “It makes sense for the brain to evolve by reusing or by adapting its processors for multiple tasks, and it makes sense to wire the cognitive components of control directly into the system that will be responsible for effecting the behaviour.” Simultaneous interpreting, with its close back-and-forth relationship between cognition and action, may be an ideal test bed for such thinking.