The neurosciences of … Language | Technological networks

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In this article, the last in our series “The Neuroscience of …”, we study recent and dominant theories on the emergence of language, the surprising phenomena that correlate with or may have preceded language, and what this means. for our place in the Animal Kingdom.

The uniqueness of human language


Over 7,000 different human languages ​​are spoken in the world today. And yet, human language is a unique phenomenon. No other animal can do it as well as us.

Humans can create abstract and arbitrary symbols for words and juggle them in our heads to create a meaningful story or convey emotion to others. Monkeys and other primates cannot. We can create recursive sentences, continually embellishing short sentences into more complex and descriptive sentences. Other animals can’t do it, even when researchers try to teach them.

It is clear that if we are to examine the age-old philosophical question, “What makes humans special?” ”, The analysis of the neurosciences of language seems to be a good starting point to begin the investigation.

What distinguishes human language?


Most animals have the innate ability to transmit emotions through communication. However, there is a strong consensus among researchers and linguists that none of these non-human animal communication systems come close to human language.

What sets us apart from our animal cousins? There are five characteristics of human language that make it unique in the animal kingdom:

  1. Our lexicon (vocabulary) is huge – and keeps growing and changing

  2. We use abstract words that only have meaning in relation to other words (if, that, but, and, or …)

  3. We can refer to the past and the future

  4. We use metaphors, analogies and other tools of figurative language

  5. Our language uses flexible and recursive syntax (ie we can keep adding adjectives or clauses in a sentence and it will still make sense. For example: “The big dog jumped over the fence “→” The big one yellow dog with floppy ears jumped over the high fence “→” The big yellow dog with floppy ears that hung under his muzzle jumped up mightily on the big one white stake fence “, etc …)

Perhaps a common misconception, there is no such thing as a “language region” of the brain. Human language is a symphony of different regions of the brain playing their role perfectly. In fact, it is believed that much of the neurology underlying different elements of language evolved first for other more primitive functions, independently of each other. The neuroscience of semantics versus syntax is a prime example.

The building blocks of language: lexicon, semantics, syntax


Speaking verbally is so natural for most of us that we don’t even think about it. No matter which language you examine, you will find that there are three key elements, each with their own important role to play in imparting ideas and understanding:

  1. Lexicon (scattered throughout the cortex): the actual words we use, the vocabulary (eg “switch”)

  2. Semantics (domain of Wernicke): the meaning of the words we use (for example, if we mean the lever that turns the light on and off, or the act of swapping places / objects)

  3. Syntax (Broca area): grammatical rules that hold the structure of language together into something understandable

In order for language to have meaning, we need to make sure that the words we use convey the meaning we put on them, while structuring them in a way that makes sense to the recipient. The Wernicke and Broca estates work together to orchestrate this complex executive function. However, their activity remains separate, since damage to one area does not interfere with the activity of the other.

Wernicke’s area gives meaning to words


Located in the left temporal lobe, Wernicke’s area deals with the semantics of language. Patients with lesions in this region of the brain are able to construct grammatically correct sentences that sound fluently (since their Broca’s area is functional), but are meaningless – a phenomenon known as Wernicke’s aphasia. . You can get an idea of ​​what it looks like from this video of a patient. An excerpt has been transcribed below:

“Well, it’s quite viable in jealousy. You don’t get it, but if the buzz and they get it wrong, three of each other from there and it’s from the country house, you see. Paul, you hundred, you see it goes up and finally, get out here and get out. “

Broca’s area constructs grammatically correct sentences


Broca’s domain, on the other hand, concerns the syntax of language. Damage to this region of the brain leads to patients who are unable to produce grammatically correct speech, but can retain some semblance of meaning in their ideas (because their Wernicke zone is unaffected). The loss of prepositions, articles and connecting words is very common, so “I took the dog for a walk” can become “I am walking the dog”. Some people with Broca’s aphasia do not speak at all. However, it can be incredibly frustrating because despite their difficulties in communicating, their understanding of others remains intact.

Where does human language come from?


Researchers aren’t sure exactly where language came from or how it evolved, but a few theories have been put forward – some more plausible than others. One of the most compelling is the “synaesthetic bootstrap” theory.

Neurologists VS Ramachandran and EM Hubbard postulated in a monumental 2001 article that language emerged as a byproduct of cross-mapping in the brain, much like the cross-mapping seen in people with synesthesia. Synaesthetes experience one sense through another, such as seeing shapes while hearing certain sounds, or tasting textures while eating. The most common type of synesthesia is grapheme-color synesthesia, when subjects see numbers as colors – and always in the same combination (e.g. four is always red, five is always green, etc.).

Is it a coincidence that the area of ​​the brain that processes numbers and the part that processes colors are located next to each other? The simplest explanation for this grapheme-color synesthesia is then a kind of cross-wiring between these two areas, so that the experience of a number cannot be dissociated from the experience of a color. This is what Ramachandran and Hubbard maintain.

You might be wondering what this talk about synesthesia has to do with language development. There is some evidence to suggest that the type of cross-wiring seen in synesthesia may also have given rise to language, and that the verbal sounds we associate with objects may not be as arbitrary as they initially seem.

Understanding metaphors

Bouba and Kiki, Credit: By Monochrome version June 1, 2007 by Bendž Vectorized with Inkscape –Qef (talk) 21:21, June 23, 2008 (UTC) – Drawn by Andrew Dunn, October 1, 2004 Originally uploaded on En Wiki – 07:23, October 1, 2004. . : en: User: Solipsist. . 500 × 255 (5,545 bytes), CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19653163

Consider this simple psychology experiment created and then explored by Kohler and later by Werner – the Bouba-Kiki effect. In the Martian language, one of the above forms is called “bouba” and the other, “kiki”. In the survey, 95% of Tamil and American speakers said the form on the right is “bouba”, and the form on the left is “kiki”.

This suggests that the sounds we associate with shapes are not arbitrary, but come from something innate. Ramachandran and Hubbard argue that this innateness is a cross-wiring between the visual, audio, and motor regions of the brain.

People generally associate “bouba” with the shape on the right because the shape our mouth takes when we say the word mimics the roundness of the shape. “Bouba” also sounds sweet, just as the movement of our tongue is soft and smooth inside our mouth when we say the word associated with the shape. In contrast, the “kiki” sound has a sharpness which is mimicked both by the peaks of the image and by the inflection of the tongue during pronunciation.

This suggests that our brains have the ability to recognize abstract qualities through various senses, including sight, sound, and muscle movements (sharpness, smoothness, plumpness, etc.). It is no exaggeration how this kind of intermodal abstraction and the inferior parietal lobule (IPL) – where it takes place in the brain (which also happens to be the intersection of the tactile, auditory and visual parts of the brain ), could give rise to metaphors in language – one of the five key characteristics of human language described above. Fun fact: Synesthesia, which also relies on this type of cross-wiring of different regions of the brain, is much more common among writers, poets, and creative people than in the general population.

Finally, it is interesting to note that while 95% of the people in the initial study agreed that the round shape corresponds to “bouba”, this number drops to 56% in the autistic population, showing perhaps a lower capacity. to perform an intermodal abstraction. Is it a coincidence that people with autism also have difficulty understanding metaphors and other figurative languages?

Linking all of this together, it seems that language emerged in a non-arbitrary fashion. The verbal cues we associate with objects and ideas seem to mimic some abstract quality of the object or idea, and this cross-wiring in the brain might also allow us to identify these patterns, as well as to create and understand metaphors.

Conclusion


In conclusion, language is one of the main identifiers that separate humans from the rest of the animal kingdom. Different regions of the brain have evolved to handle different functions associated with language, such as Wernicke’s area for semantics and Broca’s area for syntax.

In addition, the lexicon that we have developed does not seem arbitrary. IPL – the intersection of the tactile, visual and auditory parts of the brain – has been identified as playing a key role in identifying the abstract multisensory qualities of objects or ideas, and associating them with words that correspond to these qualities. abstract, as shown by the Bouba-Kiki effect.

This intermodal abstraction is believed to be the same mechanism that underlies synesthesia and our ability to grasp metaphors. Coincidentally, people on the autism spectrum have a hard time grasping imagery and do not attribute the same abstractions to Bouba and Kiki as the rest of the population, suggesting that IPL might be involved in one way or another. another in the development of autism.

Language continues to be one of the biggest question marks in modern neuroscience. Very little is known about it yet, but it is evident that any learning we acquire will lead to a better understanding of other regions of the brain, their functions and our human potential.


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