1Week 11b. Neurolinguistics andbilingualism, continuedCAS LX 400Second Language AcquisitionRecall…• How is language represented in the brain?• What are the differences between thelanguage representations found inmonolingual speakers and in bilingualspeakers (of varying degrees of L2proficiency)?So far…• Brain divided into two hemispheres.• Primary language functions (syntax, phonology,morphology) appear to be mostly dealt with by theleft hemisphere.• Looking at linguistic deficits (aphasias) and thecorresponding physiological causes (lesions) canhelp determine what parts of the brain appear to befunctionally responsible for what parts of thelanguage system.Broca’s area and “function areas”Lichtheim (1885)ConceptsVerbal motor memoryAcoustic word memorySome attested aphasia types• L1 and L2 seem to be able to recoverindependently.• It appears to sometimes make a difference whetherthe language was learned by reading or speaking(implicit vs. explicit long term memory?)• Cases so far: recovering non-communicationlanguages first, differential effects from the samelesion, pathological code-mixing, alternatingantagonism.Child aphasia• Acquired aphasia during childhood is almost neverfluent (mutism), but they recover rapidly (lastingeffects generally only slight word-finding andvocabulary difficulties).• Recovery is faster, better than in adult acquiredaphasia, but not complete.• Early enough, right hemisphere can take overlanguage functions after a serious loss in the lefthemisphere, but it doesn’t do as good a job.2Child aphasia• Lenneberg’s summary of the results of lefthemisphere lesions as a function of age:– 0-3mo: no effect– 21-36mo: all language accomplishments disappear;language is re-acquired with repetition of all stages.– 3-10ye: aphasic symptoms, tendency for full recovery– 11ye on: aphasic symptoms persist.• Basis for his view that lateralization was tied tocritical period.Translation• Aphasic deficits in translation capabilities suggestthat translation too might be a separate system.• Reported cases of loss of ability to translate(though retaining some abilities in each language).• Other reported cases of loss of ability not totranslate; Case: Perecman (1984): patient wouldalways spontaneously translate German (L1)sentences uttered into English (L2) immediateafterward, yet could not perform translation taskon request.Translation• Sometimes this can happen even withoutcomprehension; Case: Veyrac (1931):patient (English L1, French dominant L2),could not understand simple instructions inFrench, but when instructed in Englishwould spontaneously translate them toFrench and then fail to carry them out.Paradoxical translation• Case: Paradis et al. (1982). Patient switched(by day) between producing Arabic andproducing French. When producing onlyArabic, she could only translate fromArabic into French; when producing onlyFrench, she could only translate fromFrench into Arabic.Gomez-Tortosa et al. (1995)• 22 yo, RH woman raised until 10 in Bolivia(Spanish L1), in US for past 12 years (fluentEnglish L2). Had a brain problem which requiredsurgery in a language area. Wada test in Englishshowed LH dominance.• 2mo: Had trouble finding words in Spanish,frequently used nonwords approximating Spanishwords. No noticable problems with English. Testsconfirmed.• Conclude: both languages in dominant hemisphere.Each language in different area?Bilingual representation• A number of dissociated phenomena in bilingualaphasia studies.– Sometimes only one language returns, not always the L1– production and comprehension and translation seem to beseparable, and even by language.– Monolingual aphasia studies seem to correlate lesionlocalization with function.– Not much evidence for localization differences betweenmultiple languages per se.– Some evidence for localization differences between typesof learning? (written, conscious vs. unconscious, implicitvs. explicit memory?)3Bilingual representation• Given the postmortem studies showing no realmorphological differences between monolingualsand polyglots, the most consistent picture seems tobe one of shared neural architecture withinhibition between languages.• Choice of language A inhibits access to grammar,vocabulary of language B during production.• Comprehension is often spared even in the face ofproduction inability, suggesting that the same kindof inhibition does not hold of comprehension.Bilingual representation• Many of the aphasic symptoms in productioncan be described in terms of changinginhibitions; the lesion disrupts the balance ofinhibition and excitation between neuralstructures, leading to:– loss of inhibition (pathological mixing)– heightened invariant inhibition (fixation)– shifting inhibition (alternating antagonism)– psychological inhibition (repression)Subsystems• There also seem to be several subsystems whichcan be individually impaired.– Naming, concepts– Fluency of production– Ability to retain and repeat– Translation from L1 to L2– Translation from L2 to L1• Some of these seem to correlate with localizationdifferences.More modern methods andresults• Recording electrical activity in the brain can alsohelp us see which parts are used in language tasks– Electroencephalogram (EEG)– Event-related potentials (ERP).– Magnetoencephalogram (MEG)• Functional brain imaging– Computer axial tomography (CT) (X-rays)– Positron emission tomography (PET)– Functional magnetic resonance imaging (fMRI)MEG4ex. Pylkkänen, Stringfellow, Kelepir, & Marantz (2000)BELLRTstimulusM180: A visual responseunaffected by stimulusproperties such as frequency(Hackl et al, 2000), repetition(Sekiguchi et al, 2000, Pylkk änenet al 2000) and phonotacticprobability/density. Clearlyposterior dipolar pattern.M250: A component betweenthe M180 and M350. Alsoinsensitive to variations instimulus properties that affectlexical access. Clearly distinctfrom the M350 as these tworesponses have oppositepolarities. Processing oforthographic forms?M350: The first MEG component sensitive tomanipulations of stimulus properties affecting lexicalactivation. Working hypothesis: this componentreflects automatic spreading activation of the lexicon –at signal maximum all the competitors are activated.Postlexical processesincluding the word/nonworddecision of the lexicaldecision task.More modern methods andresults• Wada test. Sodium amytal causing temporaryneural