Peggy S. Conner

Language Disorders in Multilingual and Multicultural Populations.

We review the characteristics of developmental language disorders (primary language impairment, reading disorders, autism, Down syndrome) and acquired language disorders (aphasia, dementia, traumatic brain injury) among multilingual and multicultural individuals. We highlight the unique assessment and treatment considerations pertinent to this population, including, for example, concerns of language choice and availability of measures and of normative data in multiple languages. A summary of relevant, recent research studies is provided for each of the language disorders selected.

Asymmetric inhibitory treatment effects in multilingual aphasia

Findings from recent psycholinguistic studies of bilingual processing support the hypothesis that both languages of a bilingual are always active and that bilinguals continually engage in processes of language selection. This view aligns with the convergence hypothesis of bilingual language representation. Furthermore, it is hypothesized that when bilinguals perform a task in one language they need to inhibit their other, nontarget language(s) and that stronger inhibition is required when the task is performed in the weaker language than in the stronger one. The study of multilingual individuals who acquire aphasia resulting from a focal brain lesion offers a unique opportunity to test the convergence hypothesis and the inhibition asymmetry. We report on a trilingual person with chronic nonfluent aphasia who at the time of testing demonstrated greater impairment in her first acquired language (Persian) than in her third, later learned language (English). She received treatment in English followed by treatment in Persian. An examination of her connected language production revealed improvement in her grammatical skills in each language following intervention in that language, but decreased grammatical accuracy in English following treatment in Persian. The increased error rate was evident in structures that are used differently in the two languages (e.g., auxiliary verbs). The results support the prediction that greater inhibition is applied to the stronger language than to the weaker language, regardless of their age of acquisition. We interpret the findings as consistent with convergence theories that posit overlapping neuronal representation and simultaneous activation of multiple languages and with proficiency-dependent asymmetric inhibition in multilinguals.

Age-related differences in idiom production in adulthood

To investigate whether idiom production was vulnerable to age-related difficulties, we asked 40 younger (ages 18–30) and 40 older healthy adults (ages 60–85) to produce idiomatic expressions in a story-completion task. Younger adults produced significantly more correct idiom responses (73%) than did older adults (60%). When older adults generated partially correct responses, they were less likely than younger participants to eventually produce the complete target idiom (old: 32%; young: 70%); first-word cues after initial failure to retrieve an idiom resulted in more correct idioms for older (24%) than younger (15%) participants. Correlations between age and idiom correctness were positive for the young group and negative for the older group, suggesting mastery of familiar idioms continues into adulthood. Within each group, scores on the Boston Naming Test correlated with performance on the idiom task. Findings for retrieving idiomatic expressions are thus similar to those for retrieving lexical items.

Use of tDCS in Aphasia Rehabilitation: A Systematic Review of the Behavioral Interventions Implemented With Noninvasive Brain Stimulation for Language Recovery

Purpose The purpose of this article is to review the behavioral treatments used in aphasia rehabilitation research that have been combined with transcranial direct current stimulation (tDCS). Although tDCS in aphasia treatment has shown promise, the results have not been conclusive, and their interpretation is further compounded by the heterogeneity of study characteristics. Because implementing a behavioral task during brain stimulation has been shown to be pivotal to the adjuvant effects of tDCS, we analyze the behavioral treatments that have been paired with tDCS. Method A computerized database search (PubMed) was completed to document and review aphasia treatment studies that combine behavioral treatment with noninvasive brain stimulation in the form of tDCS. Two authors reviewed each aphasia tDCS article published between 2008 and 2015 and evaluated (a) the behavioral interventions for aphasia that have been combined with tDCS, and (b) the methodological variables that may have influenced language outcomes in the tDCS aphasia literature. Conclusions A review of the behavioral treatments implemented in tDCS aphasia rehabilitation studies highlights several methodological considerations for future investigations. Impairment-focused and pragmatic treatments have been implemented in tDCS aphasia research studies. No one behavioral approach stands out as the best treatment to combine with tDCS for the promotion of language recovery.

The role of language proficiency and linguistic distance in cross-linguistic treatment effects in aphasia

ABSTRACT Current findings from intervention in bilingual aphasia are inconclusive regarding the extent to which levels of language proficiency and degree of linguistic distance between treated and non-treated languages influence cross-language generalisation and changes in levels of language activation and inhibition following treatment. In this study, we enrolled a 65-year-old multilingual speaker with aphasia and administered treatment in his L1, Dutch. We assessed pre- and post-treatment performance for seven of his languages, five of high proficiency and two of lower proficiency. We asked whether treatment in L1 would generalise to his other languages or increase interference among them. Forty hours of treatment were completed over the course of five weeks. Each language was tested three times at pretreatment and at post-treatment. Testing included measures of narrative production, answering questions, picture description and question generation. Dependent measures examined language efficiency, defined as Correct Information Units (CIUs)/min, as well as language mixing, defined as proportion of code-mixed whole words. We found that our participant’s improved efficiency in Dutch was mirrored by parallel improvement in the four languages of high proficiency: English, German, Italian and French. In contrast, in his languages of lower proficiency, Norwegian and Spanish, improved efficiency was limited. An increase in code-mixing was noted in Spanish, but not in Norwegian. We interpret the increased code-mixing in Spanish as indication of heightened inhibition following improvement in a language of close linguistic proximity, Italian. We conclude that an interaction of language proficiency and linguistic similarity affects cross-language generalisation following intervention in multilingual aphasia.