When words fail
Brain surgery on a patient who is awake is common nowadays. While the surgeon is working, the patient has to perform several linguistic tests. These serve to figure out which parts of our brain produce language.
RUG linguist Roelien Bastiaanse’s research ensured that in addition to the ‘normal words’, verbs and grammar also remain intact during brain surgery.
She developed tests for ‘awake’ operations. She also researched how someone with verb and sentence aphasia can best communicate.
Each language has a basic order, says Bastiaanse. Deviation from this order is problematic for aphasia patients.
In Dutch, the verb comes at the end of the sentence. ‘Ik zie dat Jan een bal gooit’ (I can see Jan throwing a ball) is therefore easier than ‘Jan gooit een bal’ (Jan is throwing a ball).
Bastiaanse also researches the basic order in different languages. In the Ghanaian language Akan, for example, the pitch denoting past tense is quite difficult.
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Well, what do you know: while the brain surgeon is preparing to remove a tumour from your brain, you are joined by a linguist. The top of your skull has been removed so the surgeon can do their job, but you are conscious. While an electrode is sending small electric shocks to certain parts of your brain, the linguist is showing you pictures: a dog, a house, a helicopter.
It does not hurt. After all, the brain has no nerve endings that can transmit pain. But you do notice that you are suddenly incapable of pronouncing the word ‘helicopter’. Or you have forgotten which day follows Monday.
The tests serve to figure out which parts of your grey matter produce language. When a small electric shock disrupts this, the surgeon knows not to cut there: otherwise, their patient could end up with aphasia, a condition that affects the brain’s ability to produce language.
It is a shame, though, when during the operation you have no trouble naming the days of the weeks or distinguishing helicopters from boats when afterwards, you have lost all your verbs. They have been cut out.
More than a picture
Only several years ago, this was still a real risk. The fact that this is no longer true is due in large part to Roelien Bastiaanse and her research into the way the human brain processes language.
She has been fascinated with language her entire life. That is also why after graduation she worked with aphasia patients for a while. These people often have a hard time recalling words or forming sentences. ‘Back then, they thought that the temporal lobe housed the words and the frontal lobe housed sentences, and that brain damage in those areas caused aphasia. But it’s much more complicated. It also concerns the connections between landing sites that transmit signals.’ Resigned, she says: ‘Forty years ago, we knew everything. Now, we hardly know anything.’
Think of something simple, like ‘apple’. The word is an image and a combination of sounds, but it also evokes associations with smell, taste and the sensation of holding it in your hand. All of that is to say that, according to Bastiaanse, language is more than an image.
And verbs – her own speciality – are even more interesting. The word ‘cycling’ is not just some guy pedalling along. ‘You have to know how to use the word, where it goes in a sentence, and in which tense the event is happening.
Bastiaanse is researching how the brain processes all these different elements. She pursues this task together with her colleagues, PhD students, and regular students at the international research master for clinical linguistics. ‘And we don’t just research Dutch. We have an international master’s programme that three universities participate in – Potsdam, Joensuu in Finland, and Groningen. It allows us to research the most amazing languages. We just got a student who speaks Arabic, which is great. I don’t know anything about Arabic!’
It’s a very complicated language, says Tom Abuom, who worked with Bastiaanse for five years. That is especially true of verbs. ‘A singe verb, such as nimekupenda, can be translated into English as a complete sentence: I have loved you.’
In research where he compared the simple English and the complex Swahili, Abuom expected that English would be simpler for aphasia patients. That did not turn out to be the case, however. ‘English actually caused them more problems.’ The cause? English is simple, but it has a lot of strong verbs, while Swahili has complex but extremely regular verbs.
Passive sentences that do not conform to the basic order – ‘or verbs that form sentences about past events’ – are the most difficult for aphasia patients who speak Swahili.
These are the ideal circumstances for Bastiaanse to test and expand upon the most important hypothesis of her career: that each language has its own basic order. ‘When you deviate from that order, it gets more difficult for the brain. That’s when aphasia patients get into trouble. And this also goes for Swahili, Russian, Indonesian. You name it.’
Therefore, it is important to figure out each language’s basic structure. Only then can you develop a language test that can help prevent aphasia caused by brain surgery, or – when the damage has already been done by a brain haemorrhage or simply cannot be prevented – with which you can help people to communicate to the best of their ability.
The right direction
For years, speech therapists trained people suffering from ‘agrammatism’, the type of aphasia that mainly affects people’s grammar, to speak in short sentences. For example, ‘Jan throws a ball’. ‘They thought it would be easier’, says Bastiaanse.
However, she showed that this thought was wrong. ‘For Dutch, the basic order is: subject, object, verb’, says Bastiaanse. And that means that the order of the clause [Ik zie dat] Jan een bal gooit ([I can see] Jan throwing a ball) is much easier for an aphasia patient than Jan gooit een bal (Jan throws a ball). The verb has to be at the end.’
So Bastiaanse designed training that would lead patients – and speech therapists – in the right direction. They are exercises that always have the same goal: for people to maintain the basic order of language. An app for this training is currently in development, so you can easily do it at home on your iPad.
At the same time, she and her PhD. students and the students at the international master are working on designing diagnostics tests for languages other than Dutch. Because each language has its quirks. English, for example, has a fairly simple order: subject, finite verb, object. But if you deviate from it, Bastiaanse knows, aphasia patients get into trouble. John throws the ball is usually quite easy, but Does John throw the ball? can present immense difficulties.
One of the most interesting characteristics of Turkish is that you can use the grammar to express whether someone actually experienced the events or has only heard about them, says Seçkin Arslan. Together with Bastiaanse, he researched how sensitive bilingual speakers are to this phenomenon. ‘That means the English sentence John came home can be translated in either of two ways: one where the speaker saw John coming home and one where they were only told about it. That makes it really difficult in lie in Turkish.’
Another thing that makes Turkish special: you can express many different things simply by adding a suffix to the end of the verb. ‘An English speaker has to change the word order to make a passive sentence. In Turkish, the suffix does all the work.’
And in Turkish, placement does not matter, because the ending and case indicate who does what. ‘Some languages have endless conjugations and others, such as Indonesian, don’t use them at all’, she says.
The best way to test someone’s linguistic capabilities during an awake brain surgery is to make them come up with ‘difficult words’. In Dutch, ‘helicopter’ is more difficult than ‘ball’. But what about patients who speak Chinese?
‘In Mandarin Chinese, every syllable is a word. It’s not like Dutch, where some syllables don’t mean anything.’ That fairly limits the available options, which is why the Chinese make up for this with four tones: up, down, flat, and a little ‘dip’.
‘Mother’ is ‘horse’
Bastiaanse laughs: ‘One time we were travelling through China and our driver was called ‘horse’. It wasn’t until the end of the trip that we realised we had been using the wrong tone and had been calling him ‘mother’ this whole time. Really embarrassing.’
But the question is: how do you make a difficult word in Chinese? Or the Ghanaian tonal language Akan? There, tones makes things more difficult. While in Dutch, ‘werkte’ (worked) is more difficult than ‘werkt’ (works), the brain has more trouble with the tone that denotes that a verb is in the past tense in Akan.
And then there’s Swahili. ‘The verbs in that language are half a meter long and contain just about everything’, says Bastiaanse. ‘Negation, tense, the personal pronouns. So you’d think there are a lot of ways that can go wrong, but it turns out that’s not the case. The verbs might be complex, but they’re also very regular. For aphasia patients it’s much easier than English, which has a lot of strong verbs.’
Indonesian is a very special language, says Bernard Jap. ‘It’s called a zero-marking language: it has no grammatical constructions such as object verb agreement or any indication of gender.’
In Groningen, Jap worked on the understanding and formation of sentences in Indonesian aphasia patients, among other things. ‘Especially the object-cleft construction – ‘It is the ball we’re looking for’ as opposed to ‘We’re looking for the ball’ – is hard to understand for people suffering from grammatical aphasia.’
It is also remarkable that Indonesian aphasia patients often use the passive form, even if it’s difficult for them. Jap discovered that that is probably because the passive form is used abundantly in Indonesian: it is used to denote respect – like the Dutch formal ‘you’. Whether the frequency causes the Indonesian aphasia patients to be able to ‘reach’ the construction or whether it is a pragmatic solution cooked up by the brain is not yet clear.
Bastiaanse and her associates’ task is to develop a balanced test for these different languages with all their quirks that ensure that patients come out of surgery with their verbs intact.
That’s no simple task. After all of these scientific insights have been gained, a host of practical problems remain. ‘You have to be able to properly represent the word to ensure that everyone who sees the image comes up with the same word.’
After all, one person might see a walking man, while another thinks the man is running. In other words: it is not as simple as it looks.
The chosen words must also be carefully balanced. How frequently they are used and when in your life you learned them are both important. They need to contain both transitive and intransitive verbs, instrumental cases, and so on.
Out of 600 possibilities, you might only approve 88, says Bastiaanse. The images need to be drawn up, and then there is the first actual testing moment. While the brain surgeon is preparing to remove the tumour from the brain, you sit down with the patient whose skull has just been opened. ‘And then you present them with a picture of a bald head with a bird… pecking on it’, says Bastiaanse.
She shrugs. ‘That one should perhaps be removed. Not that anyone’s complained about it, but… the association is a bit grim.’
Want to know more about aphasia tests and awake brain surgery? This fall, the university will start an MOOC with the subject ‘Language testing an awake brain surgery’.