Neurophilosophy

IN the 1860s, the French physician Paul Broca treated two patients who had lost the ability to speak after suffering strokes. When they died, he examined their brains, and noticed that both had damage to the same region of the left frontal lobe. About a decade later, neuropsychiatrist Carl Wernicke described a stroke patient who was unable to understand written words or what was said to him, and later found in this patient’s brain a lesion towards the back of the left temporal lobe. 

Thus was established the classical neurological model, in which language is localized to two specific areas of the left hemisphere. Recently though, researchers have found evidence that some components of language are encoded in other brain regions. Furthermore, it is still unclear how the brain represents language in bilingual people. Some studies suggest that both languages are represented in the same set of laguage areas, while others point to distinct neural substrates for the first and second languages.

A unique case study published in the open access journal Behavioral and Brain Functions sheds some light on this matter. The study, by Raphiq Ibrahim, a neurologist at the University of Haifa, describes a bilingual Arabic-Hebrew speaker who incurred brain damage following a viral infection. Consequently, the patient experienced severe deficits in one language but not the other. The findings support the view that specific components of a first and second language are represented by different substrates in the brain.

The patient, referred to as M.H., is a 41-year-old high school biology teacher. A native Arabic speaker, he learned Hebrew at an early age (4th grade) and later used it competently both professionally and academically. He was proficient enough in the language to graduate from an Israeli university, at which he was taught in Hebrew. In 2004, M.H. was admitted to the local hospital with with a sudden onset of fever and confusion. His cerebrospinal fluid tested positive for Herpes simplex virus, and he was given the antiviral drug Zovirax. Two days later, he suddenly began to experience headaches, vomiting and disturbances of consciousness.

A CT scan showed that he had suffered a massive hemorrhage in the left temporal lobe, which was compressing the tissue on both sides of the central sulcus, the prominent gfissure which separates the frontal and parietal lobes. A craniotomy was performed to relieve the pressure, and afterwards another scan showed moderate hemorrhage and herpes encephalitis in the left temporal lobe, and another hemorrhage beneath the outer membrane (the dura) lying over the right frontal lobe. He began to recover, but two days after the operation became lethargic, and was sent to another hospital for rehabilitation. During his 2 month stay there, he developed epileptic seizures which originated in the left temporal lobe, and amnestic aphasia (an inability to name objects or to recognize their written or spoken names). 

After the rehabilitation period, a series of linguistic tests was administered to determine the extent of his speech deficits. M.H. exhibited deficits in both languages, but the most severe deficits were seen only in Hebrew. In this language he had a severe difficulty in recalling words and names, so that his speech was non-fluent and interrupted by frequent pauses. He had difficulty understanding others’ spoken Hebrew, and also had great difficulty reading and writing Hebrew. In Arabic, his native language, all of these abilities were affected only mildy. Differences were also seen in the effects of intensive language therapy. Although the therapy led to improvements in both languages, the improvements in Arabic were seen in all linguistic abilities; in Hebrew, by contrast, there was only mild improvement in his spontaneous speech and comprehension, and his ability to name objects remained unchanged.Similarly, his ability to read and write Arabic, but not Hebrew, improved significantly.

Most previous studies of bilinguals have used participants who speak English and one other Western European language. This is the first to investigate bilingualism in the Semitic languages, which differ markedly in structure from Indo-European languages. Nevertheless, it it provides valuable evidence about the mechanisms of lanuage processing in the bilingual brain. The results support a neurolinguistic model in which the brain of bilinguals contains a semantic system (which represents word meanings) which is common to both languages and which is connected to independent lexical systems (which encode the vocabulary of each language). The findings further suggest that the second language (in this case, Hebrew) is represented by an independent subsystem which does not represent the first language (Arabic) and is more susceptible to brain damage.

Related:


Ibrahim, R. (2009). Selective deficit of second language: a case study of a brain-damaged Arabic-Hebrew bilingual patient. Beh. Brain Funct. 5: 17 [Full text].

Comments

  1. #1 Muse142
    July 10, 2009

    The varying and sundry aphasias and agnosias are really fascinating, in part because they tease out the various dissociations between tasks in the brain. Nice piece!

  2. #2 Roland Branconnier, MA
    July 11, 2009

    “The findings further suggest that the second language (in this case, Hebrew) is represented by an independent subsystem which does not represent the first language (Arabic) and is more succeptible [sic] to brain damage.”

    One could posit a parsimonious explanation based on Ribot’s Law.

    Ribot’s Law of retrograde amnesia was proposed by Théodule Ribot in 1881. Ribot’s Law states that there is a time-gradient in retrograde amnesia. Recent memories are more likely to be lost than the more remote memories.

    The above findings that the older, primary language Arabic was better preserved than the newer, secondary language Hebrew is consistent with this well established Law in neuropsychology.

  3. #3 Ruth Seeley
    July 11, 2009

    My father had several cerebral hemorrhages as a result of an aberrant form of cerebral amyloid angiopathy (which wasn’t preceded by dementia). After the first, he had to be taught to read and write again, and did so with very little difficulty, leading his neurologists to conclude that he had mixed brain dominance (this was in 1987, 1988 or so) as a result of being left-handed – or maybe not (he had broken his right collarbone just as he was about to start school and they had allowed him to use his left hand, unusual for 1926 in North America). He had severe anomia, although he became a master of circumlocution (he once described chick peas/garbanzo beans as ‘those little round animals we never used to eat till you came to stay with us’ – I knew precisely what he meant. :)

    After his second stroke however, I was amazed to come down a hallway at the Montreal Neurological Institute and hear him speaking fluent French – which he had studied in an immersion course 15 years earlier – but which he had by no means mastered. In fact, he was doing so badly in his French immersion course that he had to seek a unilingual position because he wasn’t going to pass the course. I’m not sure how this fits in with Ribot’s Law (it would seem to contradict it). In my father’s case I concluded that right brain damage had lowered his inhibitions to some extent, and that explained why he was suddenly willing to speak French. And that he had always been able, just disinterested in learning the language.

  4. #4 Vaughan
    July 11, 2009

    Hi Mo,

    Great write-up! I’m no aphasia expert but one fascinating phenomenon for me is ‘alternating antagonism’ where through the recovery process bilingual patients have alternating access to their languages. Only one, then only the other, then only the first again, and so on, until the difficulties resolve.

    There are a few case studies in the literature (one of which is between Farsi and German).

    This strikes me as interesting as it suggests that everything is ‘intact’ but there are access problems. I don’t know enough about neurolinguistics to make a stab at what this tells us about the structure of language but I think it’s interesting that languages can be impaired without seeming to damage their core mechanisms or resources.

    Another good one Mo, thanks!

  5. #5 Mo
    July 11, 2009

    Roland: I shouldn’t think Ribot’s Law applies here, as the second language was acquired at such an early age. Your definition of it is exactly the same as Wikipedia’s. Did you copy it from there? And thanks for pointing out the typo; I like how you did that…

    Ruth: Fascinating story about your father – thanks for sharing it. It’s true that some left-handed people have a bilateral representation of speech. As a result, they often have milder symptoms and better prognosis following stroke than right-handed people. Thanks also for feeding my vocabulary with a new word (cirumlocution; brilliant!).

    Vaughan: Thank you! I didn’t know about alternating antagonism – it’s certainly remarkable. Unfortunately I, like you, don’t know enough about neurolinguistics to fully understand the implications.

  6. #6 Dr X
    July 11, 2009

    @ Muse142

    “The varying and sundry aphasias and agnosias are really fascinating, in part because they tease out the various dissociations between tasks in the brain.”

    Indeed. Excellent post, Mo!

  7. #7 MB
    July 12, 2009

    Interesting post. For individuals with lexical access issues, the resilience of vocabulary to brain damage, and the success in therapy, may be due to frequency of usage as well as age of acquisition. It would have been nice to know more details about the therapy…

  8. #8 Chris Phoenix
    July 14, 2009

    Sometimes, in young children with intractable epilepsy, an entire hemisphere of their brain is removed. I’ve read (in popular writeups, not source papers) that they can grow up more or less normal, mentally.

    Surely this implies that language (and many other cortical functions) are not always embedded in the same location in the brain in every person. No doubt various areas are specialized for certain functions. But if those areas become unavailable at an early age, other areas can be recruited to perform the same functions. It seems that culture (in the broad sense) is a strong enough influence, and brain is sufficiently plastic, that we don’t actually need those areas to learn to (e.g.) speak.

  9. #9 Sokratis
    July 14, 2009

    Really a very good post! I’m not a specialist by any way, but I think that the difference between the two languages is that the one was the mother tongue, while the other was not. Mother tongue is learnt while one is an infant, something that includes listening to the language from the very first days of existence. I can imagine that this process is different brain-wise. A language that is being learnt after the age of 5-6 years old is actually learnt in a different way than ones mother tongue and I expect another brain process is at work.

  10. #10 IP
    August 4, 2009

    It is very interesting the post, as usual, I could say.
    However, I agree with the last person who comments that the second language was learned already at more advanced age (if 4th gradeers can be called like that…).
    I was wondering if there are studies involving “true” bilinguals, meaning those who learn two languages from infancy. My children learned two languages as their father and I have different mother language. My son asked me the other day: what if I will forget Spanish? (now, he is learning in school in a third language). I told him, he can’t forget mother language(s) (in his case, mother and father language :) ). It seems to be a correct answer, but is it?

  11. #11 Pablo Mayrgundter
    August 6, 2009

    A perhaps related phenomena to the distinction between mother and learned tongue.

    First, try listening to a professional news broadcast spoken in a language you don’t know. You catch inflection, tone, etc. no problem, but have no idea what is being said. Next, listen at barely audible volume.

    Next, listen to a professional news broadcast in a learned language, but do so again at the normal and then the low volume. In my experience, you can easily slip in and out of “recognition mode” where you do or don’t understand what’s being said, because the base listening conditions are so poor.

    Next – and only attempt this after experiencing the slippage described above – listen to a to a professional news broadcast in your native language, both at normal and then barely audible levels. I have found that even at barely audible levels, it is almost impossible to “hear” it without “hearing” it. Meaning that, the volume is either so low I simply can’t hear it, or it’s loud enough to understand what is being said. There’s very little in between. But! there is an in between, and it feels very weird. There is a volume level at which I can with great difficulty hear spoken english the same way I hear spoken.. German: meaning such that I hear it as a foreign language, as if the person is speaking something that is nonsense to me. But then when it slips back in to English, I’m amazed that I have not understood it all along.

    I think this kind of experimental condition is ripe for exploitation.. wish this were my field! :)

  12. #12 j
    August 14, 2009

    Just to let you know that I found this article fascinating and have linked to it from my blog,which would be of no interest whatsoever to scence bods.Not too sure about ‘netiquette’ – didn’t want to ‘steal’ without saying thanks.

  13. #13 farhadalishah
    August 22, 2009

    Hello I am Sha!
    Assalam-o-Alaikum!
    I really like & love the arabic as a “Language”.
    The impression I got immediately after I
    completed MA English was that I should have
    studied “Arabic”.
    I have grown a strong passion and attachment
    for Arabic and the Arabs. How much it can last?
    This is what i don’t know nor am much sure about
    but if your gals and guys out there help me, my
    love might become fruitful for me.
    Why do i like and love arabic and the Arabs?
    This is sort of expansive questions.
    I only know that Arabic is soft, smooth
    and melodius.
    The Arabs are loving, sincere and sobre.
    Well, what I don’t know is if they are
    lovers of their language too or not.
    I aspire to someday talk fluently in arabic.
    Talk to my friends. But can i attract Arabic
    -speakers to my self by speaking their lang-
    uage is yet another thing to be experienced
    still.
    Arabic is the language of the Muslims but i do
    believe ALLAH will hear and help me even when
    i speak my mother tongue to ask him. I am
    sensitive to the degree that if i like something
    just for the sake of some good and great point
    in it and I am not answered positively…. I
    really begin to hate that thing. Well i don’t
    know why should i do it but still here i am to
    do it. I like to chat, sing, speak, think, write
    and argue in Arabic. I have no intention to
    visit an Arabic speaking country as yet but
    can it be helpful enough in learning a language to
    personally visit the country where it is spoken?
    Because we have been in this country of ours for
    since our birth but still we haven’t got command
    and control over the national language spoken
    here. Does it go to say that it doesn’t matter
    a lot to visit a country for the solitary purpose
    of learning a language spoken there? I like the
    h sound of Arabic and also I like it for not
    having the clattering sounds of t,d etc. I
    want to have good really good arabic language
    friends. I can teach you English “only and only
    if you think you need it”. I should thank you
    in advance if you think my love for Arabic and
    the Arab is something valuable.
    With best regards it is farhad (underscore)
    alishah (at) yahoo (dot) com
    my cell number is zerozeroninetwothreeonetwo
    fivezerotwozeroeighteighteight
    Wassalam-o-Alaikum Wa Rahmatullah!
    ( I shall be really anxiously waiting for
    the language friend of my dreams.
    How can i say in Arabic
    “The lover and Admirer of Arabic as a Language”
    Bubye thanks

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