Transcript

Avoir un mot sur le bout de la langue... et ne pas le trouver ! | Clémence Chausse | TEDxNouméa

Translator: Catherine Dean
Reviewer: Robert Tucker Have you ever had a word
on the tip of your tongue? You know, that slightly annoying sensation where the word is there,
just between your lips, burning. You can almost taste it,
but you’re unable to say it. It often happens when we’re tired. We can’t find the words: each sentence
becomes long and complicated. One day, my father
suddenly stopped speaking. It was after a bike accident,
a fall and a head injury. In fact, he could speak, but he struggled
to initiate the movement of speech. It was strange because, from the outside,
this struggle was invisible. But he stopped speaking
and we didn’t understand. Then the bleeding in his head diminished,
and my father started speaking again. But this time, he couldn’t say
the right words. Things like: "Can you get me some yogurt from the... from the... the oven?" He knew that the words
coming out of his mouth weren’t the ones he wanted to say. So, he gave it a go. But it was a strange phenomenon. Don’t you think? In fact, speaking is far
from a simple action. By the way, who has ever wondered what happens in our brains when we speak? It seems so simple in our daily lives. But what goes on in our heads? Scientists don’t agree on the details of the various steps that take place
in our brains when we speak. However, this is my favourite theory. It’s the one that the most closely matches
the clinical observations I have made as a speech therapist. The brain is able to generate an idea,
to think of a concept. That’s quite a lot. From there, one connection follows another and the brain searches my semantic memory, this is the memory that stores
my knowledge of the world, and selects the desired word,
related to its meaning. It searches in a catalogue, the catalogue containing the vocabulary
I know and have already used. In this process,
looking for the right word, my brain activates all the mental
images of the word, and the ideas associated with it. A whole host of words present themselves, but my brain looks for the chosen one. Well, fortunately, my brain blocks,
suppresses all the useless ideas that take up too much space in my head. If I think of an apple and look for the word "apple, several ideas can emerge: "pear", "apple tart",
"fruit", "crunch", "bible", "Adam and Eve", "snake". But my brain sorts through it all, and is able to keep one word: the word. Once it has selected the right word, it activates what we call
"phonological trails". Phonology includes everything
that is related to sounds of language and the representations we have of them. We have all learnt to hear, recognise, pronounce the various sounds of a language when we learnt how to speak. These representations are stored in a box and enable us to know
what these sounds resemble and how they are made
in terms of motor production: movements of the tongue, of the mouth. If these representations are altered, we are no longer able to know
whether we are making the right sounds. We speak, we speak,
we think we’re saying the right words, but we use the wrong sounds. People don’t understand what we say, and we don’t understand
why others don’t understand. Not only do we need to be able
to use the right sounds, we also have to be able
to put them in the right order. And one type of small memory
exists just for that purpose. This memory also includes all the small words that enable us
to create sentences, words like "but", "where", "and",
"so", "yet", "or", "because". But all the others too: "of", "by", "for". These words are very small
and are related to syntax, to grammar. Their meaning isn’t as strong
as words like "chair" or "pen", or even "philosophy",
which is an abstract word, but which is related to concrete actions
from our daily lives: books, rationales. These small words have their place,
they are anchored in the brain. If this part of the brain is injured, the person will be unable
to say these small words that are essential
when creating sentences. If this small memory if affected, it can also become more difficult to put the sounds of the word
in the correct order. To perform speech movements - the movement of the vocal cords,
of the tongue, the lips - a whole host of neurological signals
must be activated. In order to not get confused and activate the neurological signals
in the correct order, my brain makes a plan. This is the motor system. And at the same time
it must remember the sounds, their representation, their order. And it’s not so easy. So, fortunately, with practice, my brain has several small
prestored motor systems. Great. But errors are still possible. We can get tongue-tied, for example. If everything isn’t perfectly coordinated, we can even forget to open our mouths
before saying a word. Yes, it happens. Being able to say: "she sells seashells on the seashore", is a very difficult exercise. Once the brain has set out a plan,
what we call the motor system, it’s time to initiate the movement. And it’s the motor cortex that does this. It activates the movements
of the larynx and the vocal cords, as well as breath, the lips,
the tongue, the cheeks, the soft palate. In short, all the movements of the face,
the throat, and the chest. You don’t realise it, but when I talk, my motor cortex
is continuously giving orders. Imagine: just for my vocal cords, they are constantly moving
without me realising it. For example, for the sound "a",
put your hand on your larynx. Go on! (Laughter) Just below your Adam’s apple. And all together, say: "a". Audience: A... Well, this vibration, it’s your vocal cords coming together. But, conversely, for the sound "p". Audience: P, p, p. (Laughter) There is no vibration. Your vocal cords move apart. This movement is controlled
by your motor cortex at all times. Fascinating, isn’t it? And all this, is just for one word. So, imagine a whole sentence, that at the same time requires an analysis
of the syntax and fluidity between words. And you have to keep an idea in mind
throughout this process, and not be distracted by what we see, by what we are doing at the time:
walking, driving. Not be overwhelmed
by our associated thoughts. All of this is so we can speak. But, for the opposite path,
understanding what we are being told, it is just as complicated. You have to listen to the sounds,
sort through them, associate them. Moreover, the catalogue of words
used when listening is not the same
as the one used when speaking. This is easy to see in children, who understand more words
than they can say. But that’s not all. When we talk to someone,
as well as speech, our brains analyse all the signals, including non-verbal language. You know, facial and body movements, the emotions that come through
subtly, or not so subtly. Our brains analyse them, organise and prioritise them,
while staying aware of what is being said. And at the same time,
you have to keep in mind, the ideas, the sounds,
their representation. My brain allows me
to adapt to my interlocutor. It allows us not to be rude, to not say everything
that goes through our minds, to let the other speak, to choose the appropriate volume
for the situation. Communication isn’t just verbal language, it’s a whole host of behaviours. My brain allows me
to read silences, coded language, and it allows me to understand
irony, humour and things said implicitly. In fact, my brain thinks
and analyses while I listen, it thinks and analyses while I speak. And if that wasn’t complex enough, let’s add emotion management: knowing how to read and convey emotions. Not become overwhelmed. Having a tight throat. It’s crazy how complex the mechanisms
in play in language are. And so we can imagine
all the possible expectations. There can be issues
with the semantic memory, concepts that are in the wrong place,
not correctly connected to each other, or maybe even absent. There can be issues in the catalogues, the catalogues of words
that have been heard or said, issues with the ability to match sounds, to know what they are like. Or there could be issues
in the motor system or even in the mechanical
process of the movement. It’s like a small electrical circuit
that orders a light bulb to turn on. When the bulb doesn’t turn on as expected, there could be many reasons: the batteries, the switch, defective soldering, the wire, the wire insulation could be damaged
and cause a short circuit. Only one of these elements
needs to be affected for the light bulb
to not turn on as expected. It can stay off, it can flash on and off, it can shine too brightly, too weakly, it can crackle. Etc. It doesn’t turn on as expected. Learning a language and then losing it
because of a brain injury, this difficulty is called aphasia. Being confronted
with language difficulties, it’s a bit like travelling
to a foreign country of which you don’t know the language. Speaking becomes exhausting. We don’t always understand
what we are being told. Very quickly, we feel socially awkward. We get frustrated because we can’t
go further in our conversations. We have to stay focused all day. And even though we might
usually have a sense of humour, we are not always able
to understand the joke. We have all pretended to laugh
at a joke we didn’t really understand. Well, this awkwardness that tries to say: "I’m not stupid. But at the same time,
I didn’t really understand this joke." (Laughter) Well, this is how people
with aphasia feel every day, but for simple statements, from their family, in their own home, and with no escape. My job is the rehabilitation of aphasia. Language can be lost in many ways: Strokes, head trauma,
brain tumour, dementia. The brain is so complex that there are
as many aphasias as there are cases depending on where the injury is. But, if we only consider how it manifests, what we can see, we quickly conclude that a person
with aphasia is crazy or stupid. And this is far from the truth. My father recovered from his aphasia. Well, from the outside, because when
a person with aphasia has a brain injury, they can’t recover completely. But, because my brain
is an extraordinary machine, it’s possible to recover partially,
alleviate fatigue, compensate. Sometimes, the issue is only slight
but the restlessness and fatigue incurred, although they may be invisible, do exist. The invisibility of this handicap
is a dual sentence, because, socially, we feel judged, subject to various
interpretations about us, and we are afraid
of how others perceive us. When a person has aphasia, they must be able to let go
of the social image they had for many years. An image that they built while watched by others and by themselves. Letting go of this can be very painful,
especially with regard to their family, because language allows us to think, it allows us to be who we are. This is why it is
so important to understand the complexity of what is at stake, because we could all be affected by this,
through a family member or simply when we encounter
a person with aphasia. Thank you. (Applause)