Greater syntactic impairments in native language in bilingual Parkinsonian patients

Subcortical Involvement in Formulaic Language: Studies on Bilingual Individuals With Parkinson's Disease

Purpose An impoverished production of routinized expressions, namely, formulaic language, has been reported for monolingual speakers with Parkinson's disease (PD). Little is known regarding how formulaic expressions might be manifested in individuals with neurological damage who speak more than one language. This study investigated the processing of formulaic language across first language (L1) and second language (L2) in bilingual individuals with PD. Method Eleven Korean-English bilingual speakers with PD, who acquired Korean as L1 and English as L2, were recruited for this study. Two matched control groups composed of 11 healthy Korean-English bilingual individuals and 11 healthy native English speakers were included for comparison. Their performance on three structured tasks (comprehension, completion, and judgment-correction) and conversational speech was measured and compared across groups for analyses. Results The bilingual speakers with PD had significantly impaired comprehension of formulaic language in L1 and had lower proportions of formulaic expressions in their L1 conversational speech compared with the bilingual controls. Regarding L2, both bilingual groups with and without PD were comparable in their English performance across all tasks. Both groups performed significantly poorer in L2 structured tasks than the native English speakers. Spontaneous production of formulaic language in English (L2 for bilingual individuals) was similar across all three groups. Conclusions The results of this study contribute to the growing body of literature on impoverishment of formulaic language production following subcortical dysfunction. Additionally, findings here demonstrate a selective impairment of formulaic language performance in L1 but not L2 for bilinguals with PD, further supporting the role of the basal ganglia in native language.

How words ripple through bilingual hands: Motor-language coupling during L1 and L2 writing

The speed of our hand movements can be affected by concurrent processing of manual action verbs (MaVs). Whereas this phenomenon is well established for native languages (L1s), it remains underexplored in late foreign languages (L2s), especially during highly automatized tasks. Here we timed keystroke activity while Spanish-English bilinguals copied MaVs, non-manual action verbs, and non-action verbs in their L1 and L2. Motor planning and execution dynamics were indexed by first-letter lag (the time-lapse between word presentation and first keystroke) and whole-word lag (the time-lapse between first and last keystroke), respectively. Despite yielding no effects on motor planning, MaVs facilitated typing execution in L1 but delayed it in L2, irrespective of the subjects' typing skills, age of L2 learning, and L2 competence. Therefore, motor-language coupling effects seem to be present in both languages though they can arise differently in each. These results extend language grounding models, illuminating the role of embodied mechanisms throughout life.

A dissociation between syntactic and lexical processing in Parkinson's disease

Parkinson's disease (PD), which involves the degeneration of dopaminergic neurons in the basal ganglia, has long been associated with motor deficits. Increasing evidence suggests that language can also be impaired, including aspects of syntactic and lexical processing. However, the exact pattern of these impairments remains somewhat unclear, for several reasons. Few studies have examined and compared syntactic and lexical processing within subjects, so their relative deficits remain to be elucidated. Studies have focused on earlier stages of PD, so syntactic and lexical processing in later stages are less well understood. Research has largely probed English and a handful of other European languages, and it is unclear whether findings generalize more broadly. Finally, few studies have examined links between syntactic/lexical impairments and their neurocognitive substrates, such as measures of basal ganglia degeneration or dopaminergic processes. We addressed these gaps by investigating multiple aspects of Farsi syntactic and lexical processing in 40 Farsi native-speaking moderate-to-severe non-demented PD patients, and 40 healthy controls. Analyses revealed equivalent impairments of syntactic comprehension and syntactic judgment, across different syntactic structures. Lexical processing was impaired only for motor function-related objects (e.g., naming 'hammer', but not 'mountain'), in line with findings of PD deficits at naming action verbs as compared to objects, without the verb/noun confound. In direct comparisons between lexical and syntactic tasks, patients were better at naming words like 'mountain' (but not words like 'hammer') than at syntactic comprehension and syntactic judgment. Performance at syntactic comprehension correlated with the last levodopa equivalent dose. No other correlations were found between syntactic/lexical processing measures and either levodopa equivalent dose or hypokinesia, which reflects degeneration of basal ganglia motor-related circuits. All critical significant main effects, interactions, and correlations yielded large effect sizes. The findings elucidate the nature of syntactic and lexical processing impairments in PD.

Rethinking the Neural Basis of Prosody and Non-literal Language: Spared Pragmatics and Cognitive Compensation in a Bilingual With Extensive Right-Hemisphere Damage

Above and beyond the critical contributions of left perisylvian regions to language, the neural networks supporting pragmatic aspects of verbal communication in native and non-native languages (L1s and L2, respectively) have often been ascribed to the right hemisphere (RH). However, several reports have shown that left-hemisphere activity associated with pragmatic domains (e.g., prosody, indirect speech, figurative language) is comparable to or even greater than that observed in the RH, challenging the proposed putative role of the latter for relevant domains. Against this background, we report on an adult bilingual patient showing preservation of pragmatic verbal skills in both languages (L1: Spanish, L2: English) despite bilateral damage mainly focused on the RH. After two strokes, the patient sustained lesions in several regions previously implicated in pragmatic functions (vast portions of the right fronto-insulo-temporal cortices, the bilateral amygdalae and insular cortices, and the left putamen). Yet, comparison of linguistic and pragmatic skills with matched controls revealed spared performance on multiple relevant tasks in both her L1 and L2. Despite mild difficulties in some aspects of L2 prosody, she showed no deficits in comprehending metaphors and idioms, or understanding indirect speech acts in either language. Basic verbal skills were also preserved in both languages, including verbal auditory discrimination, repetition of words and pseudo-words, cognate processing, grammaticality judgments, equivalent recognition, and word and sentence translation. Taken together, the evidence shows that multiple functions of verbal communication can be widely spared despite extensive damage to the RH, and that claims for a putative relation between pragmatics and the RH may have been overemphasized in the monolingual and bilingual literature. We further discuss the case in light of previous reports of pragmatic and linguistic deficits following brain lesions and address its relation to cognitive compensation in bilingual patients.

Embodied Semantics in a Second Language: Critical Review and Clinical Implications

The role of the sensorimotor system in second language (L2) semantic processing as well as its clinical implications for bilingual patients has hitherto been neglected. We offer an overview of the issues at stake in this under-investigated field, presenting the theoretical and clinical relevance of studying L2 embodiment and reviewing the few studies on this topic. We highlight that (a) the sensorimotor network is involved in L2 processing, and that (b) in most studies, L2 is differently embodied than L1, reflected in a lower degree or in a different pattern of L2 embodiment. Importantly, we outline critical issues to be addressed in order to guide future research. We also delineate the subsequent steps needed to confirm or dismiss the value of language therapeutic approaches based on embodiment theories as a complement of speech and language therapies in adult bilinguals.

The Affective Nature of Formulaic Language: A Right-Hemisphere Subcortical Process

Formulaic expressions naturally convey affective content. The unique formal and functional characteristics of idioms, slang, expletives, proverbs, conversational speech formulas, and the many other conventional expressions in this repertory have been well-described: these include unitary form, conventionalized and non-literal meanings, and reliance on social context. Less highlighted, but potent, is the intrinsic presence of affective meaning. Expletives, for example, signal strong emotion. Idioms, too, inherently communicate emotional connotations, and conversational speech formulas allow for empathetic bonding and humor. The built-in affective content of formulaic expressions, in combination with their other unique characteristics, is compatible with the proposal that brain structures other than those representing grammatical language are in play in producing formulaic expressions. Evidence is presented for a dual process model of language, whereby a right hemisphere-subcortical system modulates formulaic language.

Neural basis of bilingual language control

Acquiring and speaking a second language increases demand on the processes of language control for bilingual as compared to monolingual speakers. Language control for bilingual speakers involves the ability to keep the two languages separated to avoid interference and to select one language or the other in a given conversational context. This ability is what we refer with the term "bilingual language control" (BLC). It is now well established that the architecture of this complex system of language control encompasses brain networks involving cortical and subcortical structures, each responsible for different cognitive processes such as goal maintenance, conflict monitoring, interference suppression, and selective response inhibition. Furthermore, advances have been made in determining the overlap between the BLC and the nonlinguistic executive control networks, under the hypothesis that the BLC processes are just an instantiation of a more domain-general control system. Here, we review the current knowledge about the neural basis of these control systems. Results from brain imaging studies of healthy adults and on the performance of bilingual individuals with brain damage are discussed.

A core avenue for transcultural research on dementia: on the cross-linguistic generalization of language-related effects in Alzheimer's disease and Parkinson's disease

OBJECTIVE

Language is a key source of cross-cultural variability, which may have both subtle and major effects on neurocognition. However, this issue has been largely overlooked in two flourishing lines of research assessing the relationship between language-related neural systems and dementia. This paper assesses the limitations of the evidence on (i) the neuroprotective effects of bilingualism in Alzheimer's disease and (ii) specific language deficits as markers of Parkinson's disease.

DESIGN

First, we outline the rationale behind each line of research. Second, we review available evidence and discuss the potential impact of cross-linguistic factors. Third, we outline ideas to foster progress in both fields and, with it, in cross-cultural neuroscience at large.

RESULTS

On the one hand, studies on bilingualism suggest that sustained use of more than one language may protect against Alzheimer's disease symptoms. On the other hand, insights from the embodied cognition framework point to syntactic and action-verb deficits as early (and even preclinical) markers of Parkinson's disease. However, both fields share a key limitation that lies at the heart of cultural neuroscience: the issue of cross-linguistic generalizability.

CONCLUSION

Relevant evidence for both research trends comes from only a handful of (mostly Indo-European) languages, which are far from capturing the full scope of structural and typological diversity of the linguistic landscape worldwide. This raises questions on the external validity of reported findings. Greater collaboration between linguistic typology and cognitive neuroscience seems crucial as a first step to assess the impact of transcultural differences on language-related effects across neurodegenerative diseases. Copyright © 2017 John Wiley & Sons, Ltd.

Coprolalia in aphasic patients with stroke: a longitudinal observation from the BLAS2T database

The BLAS₂T (bilingual aphasia in stroke-study team) initiative has been a multi-center attempt to investigate longitudinal changes in language function in a cohort of stroke subjects. This report discusses linguistic performance in four cases from the BLAS₂T database who demonstrated coprolalia as an irresistible urge to say obscene words.  Coprolalia was found to partly resolve in a 30-day follow-up in three cases. Recognition of coprolalia and language recovery patterns in bilingual aphasic patients with stroke would potentially lead to their even better individualized care and neurolinguistic/cognitive rehabilitation.

Action-semantic and syntactic deficits in subjects at risk for Huntington's disease

Frontostriatal networks play critical roles in grounding action semantics and syntactic skills. Indeed, their atrophy distinctively disrupts both domains, as observed in patients with Huntington's disease (HD) and Parkinson's disease, even during early disease stages. However, frontostriatal degeneration in these conditions may begin up to 15 years before the onset of clinical symptoms, opening avenues for pre-clinical detection via sensitive tasks. Such a mission is particularly critical in HD, given that patients' children have 50% chances of inheriting the disease. Against this background, we assessed whether deficits in the above-mentioned domains emerge in subjects at risk to develop HD. We administered tasks tapping action semantics, object semantics, and two forms of syntactic processing to 18 patients with HD, 19 asymptomatic first-degree relatives, and sociodemographically matched controls for each group. The patients evinced significant deficits in all tasks, but only those in the two target domains were independent of overall cognitive state. More crucially, relative to controls, the asymptomatic relatives were selectively impaired in action semantics and in the more complex syntactic task, with both patterns emerging irrespective of the subjects' overall cognitive state. Our findings highlight the relevance of these dysfunctions as potential prodromal biomarkers of HD. Moreover, they offer theoretical insights into the differential contributions of frontostriatal hubs to both domains while paving the way for innovations in diagnostic procedures.

Language Deficits as a Preclinical Window into Parkinson's Disease: Evidence from Asymptomatic Parkin and Dardarin Mutation Carriers

OBJECTIVES

The worldwide spread of Parkinson's disease (PD) calls for sensitive and specific measures enabling its early (or, ideally, preclinical) detection. Here, we use language measures revealing deficits in PD to explore whether similar disturbances are present in asymptomatic individuals at risk for the disease.

METHODS

We administered executive, semantic, verb-production, and syntactic tasks to sporadic PD patients, genetic PD patients with PARK2 (parkin) or LRRK2 (dardarin) mutation, asymptomatic first-degree relatives of the latter with similar mutations, and socio-demographically matched controls. Moreover, to detect sui generis language disturbances, we ran analysis of covariance tests using executive functions as covariate.

RESULTS

The two clinical groups showed impairments in all measures, most of which survived covariation with executive functions. However, the key finding concerned asymptomatic mutation carriers. While these subjects showed intact executive, semantic, and action-verb production skills, they evinced deficits in a syntactic test with minimal working memory load.

CONCLUSIONS

We propose that this sui generis disturbance may constitute a prodromal sign anticipating eventual development of PD. Moreover, our results suggest that mutations on specific genes (PARK2 and LRRK2) compromising basal ganglia functioning may be subtly related to language-processing mechanisms. (JINS, 2017, 23, 150-158).

The role of executive control in bilingual language production: A study with Parkinson's disease individuals

The basal ganglia are critically involved in language control (LC) processes, allowing a bilingual to utter correctly in one language without interference from the non-requested language. It has been hypothesized that the neural mechanism of LC closely resembles domain-general executive control (EC). The purpose of the present study is to investigate the integrity of bilingual LC and its overlap with domain-general EC in a clinical population such as individuals with Parkinson's disease (PD), notoriously associated with structural damage in the basal ganglia. We approach these issues in two ways. First, we employed a language switching task to investigate the integrity of LC in a group of Catalan-Spanish bilingual individuals with PD, as compared to a group of matched healthy controls. Second, to test the relationship between domain-general EC and LC we compared the performances of individuals with PD and healthy controls also in a non-linguistic switching task. We highlight that, compared to controls, individuals with PD report decreased processing speed, less accuracy and larger switching costs in terms of RT and errors in the language switching task, whereas in the non-linguistic switching task PD patients showed only increased switching cost in terms of errors. However, we report a positive correlation between the magnitudes of linguistic and non-linguistic mixing costs in individuals with PD. Taken together, these results support the notion of a critical role of the basal ganglia and connected structures in LC, and suggest a possible link between LC and domain-general EC.

Reading comprehension in Parkinson's disease

PURPOSE

Although individuals with Parkinson's disease (PD) self-report reading problems and experience difficulties in cognitive-linguistic functions that support discourse-level reading, prior research has primarily focused on sentence-level processing and auditory comprehension. Accordingly, the authors investigated the presence and nature of reading comprehension in PD, hypothesizing that (a) individuals with PD would display impaired accuracy and/or speed on reading comprehension tests and (b) reading performances would be correlated with cognitive test results.

METHOD

Eleven adults with PD and 9 age- and education-matched control participants completed tests that evaluated reading comprehension; general language and cognitive abilities; and aspects of attention, memory, and executive functioning.

RESULT

The PD group obtained significantly lower scores on several, but not all, reading comprehension, language, and cognitive measures. Memory, language, and disease severity were significantly correlated with reading comprehension for the PD group.

CONCLUSION

Individuals in the early stages of PD without dementia or broad cognitive deficits can display reading comprehension difficulties, particularly for high- versus basic-level reading tasks. These reading difficulties are most closely related to memory, high-level language, and PD symptom severity status. The findings warrant additional research to delineate further the types and nature of reading comprehension impairments experienced by individuals with PD.

How does the bilingual experience sculpt the brain?

The ability to speak two languages often marvels monolinguals, although bilinguals report no difficulties in achieving this feat. Here, we examine how learning and using two languages affect language acquisition and processing as well as various aspects of cognition. We do so by addressing three main questions. First, how do infants who are exposed to two languages acquire them without apparent difficulty? Second, how does language processing differ between monolingual and bilingual adults? Last, what are the collateral effects of bilingualism on the executive control system across the lifespan? Research in all three areas has not only provided some fascinating insights into bilingualism but also revealed new issues related to brain plasticity and language learning.

Parallel deterioration to language processing in a bilingual speaker

The convergence hypothesis [Green, D. W. (2003). The neural basis of the lexicon and the grammar in L2 acquisition: The convergence hypothesis. In R. van Hout, A. Hulk, F. Kuiken, & R. Towell (Eds.), The interface between syntax and the lexicon in second language acquisition (pp. 197-218). Amsterdam: John Benjamins] assumes that the neural substrates of language representations are shared between the languages of a bilingual speaker. One prediction of this hypothesis is that neurodegenerative disease should produce parallel deterioration to lexical and grammatical processing in bilingual aphasia. We tested this prediction with a late bilingual Hungarian (first language, L1)-English (second language, L2) speaker J.B. who had nonfluent progressive aphasia (NFPA). J.B. had acquired L2 in adolescence but was premorbidly proficient and used English as his dominant language throughout adult life. Our investigations showed comparable deterioration to lexical and grammatical knowledge in both languages during a one-year period. Parallel deterioration to language processing in a bilingual speaker with NFPA challenges the assumption that L1 and L2 rely on different brain mechanisms as assumed in some theories of bilingual language processing [Ullman, M. T. (2001). The neural basis of lexicon and grammar in first and second language: The declarative/procedural model. Bilingualism: Language and Cognition, 4(1), 105-122].

The role of subcortical structures in recited speech: Studies in Parkinson's disease

The role of subcortical structures in language function is complex and dependent on language task, with studies increasingly showing subcortical involvement for the production of formulaic language, including recited speech. Individuals with Parkinson's disease (PD), with (n = 6) and without (n = 7) surgical treatment, deep brain stimulation (DBS), were compared to healthy adults (n = 14) to determine whether individuals with subcortical dysfunction produce more errors during a recitation speech task. Participants were asked to recite poems, prayers, and rhymes familiar to them in order to determine the effects of subcortical disease on recited speech ability. When compared with healthy controls, the DBS-OFF group produced significantly more error words, suggesting that deficits in recitation arise with severe states of subcortical dysfunction. Individuals with DBS in the ON or OFF conditions did not differ significantly during the recited speech task. Results support a model of language where large units of overlearned language are at least partially modulated by subcortical structures.

Language and syntactic impairment following stroke in late bilingual aphasics

PURPOSE

Bilingual aphasia generally affects both languages. However, the age of acquisition of the second language (L2) seems to play a role in the anatomo-functional correlation of the syntactical/grammatical processes, thus potentially influencing the L2 syntactic impairment following a stroke. The present study aims to analyze the influence of late age of acquisition of the L2 on syntactic impairment in bilingual aphasic patients.

METHODS

Twelve late bilingual participants (speaking French as L2 and either English, German, Italian or Spanish as L1) with stroke-induced aphasia participated in the study. The MAST or BAT aphasia batteries were used to evaluate overall aphasia score. An auditory syntactic judgement task was developed and used to test participants syntactic performance.

RESULTS

The overall aphasia scores did not differ between L1 and L2. In a multiple case analysis, only one patient had lower scores in L2. However, four patients presented significantly lower performances in syntactic processing in the late L2 than in their native language (L1). In these four patients the infarct was localized, either exclusively or at least partially, in the pre-rolandic region.

CONCLUSION

This pilot study suggests that, in late bilingual aphasics, syntactic judgment abilities may be more severely impaired in L2, and that this syntactic deficit is most likely to occur following anterior lesions.

Primary progressive aphasia in a bilingual speaker: a single-case study

We report on the case of an elderly bilingual woman presenting with a diagnosis of primary progressive aphasia. The participant's native language was Friulian (L1), a predominantly oral Romance language, and her second language was Italian (L2), formally learned at primary school in oral and written forms. We investigated her linguistic abilities by means of the Bilingual Aphasia Test ( Paradis, M., & Libben, G. (1987). The assessment of bilingual aphasia. Hillsdale, NJ: Lawrence Erlbaum Associates), which is specifically devised for studying language levels and skills in bilingual/polyglot individuals with aphasia. Specifically, we focused on different tasks extracted from the Bilingual Aphasia Test, targeting phonology, morphology, syntax and lexical semantics. Results show that both languages were affected to a clinically significant degree, but with different profiles in terms of linguistic levels, suggesting the presence of greater phonological, morphological, grammatical and syntactic impairments in L2. Results are discussed in terms of possible dissociations both within the language system of each language and between languages, within the Procedural/Declarative theoretical framework of language acquisition in bilinguals.

Capacity of the Catalan and Spanish versions of the Bilingual Aphasia Test to distinguish between healthy aging, mild cognitive impairment and Alzheimer's disease

This study analysed the capacity of the Catalan and Spanish versions of the Bilingual Aphasia Test (BAT) to distinguish between normal and pathological aging. Both versions of the test were administered to 45 bilingual subjects: 15 healthy aging subjects, 15 patients with mild cognitive impairment and 15 patients with Alzheimer's disease. To explore which combination of subtests was best suited to differentiate the three study groups, stepwise discriminant analyses were performed using each version of the Bilingual Aphasia Test separately and together. The percentages of properly classified subjects were as follows: 93.3% when the Spanish version was administered, 88.9% when the Catalan version was administered and 95.6% when both versions were used. The subtests that best classified the subjects were of the lexical-semantic type but also related to metalinguistic capacity and language organisation skills. The performance of each group in Catalan and Spanish was more similar than different.

Principles underlying the Bilingual Aphasia Test (BAT) and its uses

The Bilingual Aphasia Test (BAT) is designed to be objective (so it can be administered by a lay native speaker of the language) and equivalent across languages (to allow for a comparison between the languages of a given patient as well as across patients from different institutions). It has been used not only with aphasia but also with any condition that results in language impairment (Alzheimer's, autism, cerebellar lesions, developmental language disorders, mild cognitive impairment, motor neuron disease, multiple sclerosis, Parkinson's, vascular dementia, etc.). It has also been used for research purposes on non-brain-damaged unilingual and bilingual populations. By means of its 32 tasks, it assesses comprehension and production of implicit linguistic competence and metalinguistic knowledge (which provide indications for apposite rehabilitation strategies). Versions of the BAT are available for free download at www.mcgill.ca/linguistics/research/bat/.

Paradoxical recovery in a bilingual patient with aphasia after right capsuloputaminal infarction

We report the case of a bilingual dextral patient, who presented with an uncommon pattern of aphasic deficit following a right capsulo-putaminal infarction. In this patient, the linguistic deficit concerned the use of her mother tongue (Galician, L1) much more than the lesser practised second language (Spanish, L2). Our patient presented spontaneous fluent speech in L2 but not in L1, automatic translation into L2, and impaired repetition in L1, whereas comprehension was spared in both L1 and L2. Reading and writing were less valuable due to educational interference (reduced schooling). Spontaneous speech 16 months after the stroke showed the stability of the impairment. This is the first reporting of a crossed subcortical aphasia in a bilingual patient.

Characteristic functional networks in high- versus low-proficiency second language speakers detected also during native language processing: an explorative EEG coherence study in 6 frequency bands

An EEG coherence study was performed with a twofold objective: first, to scrutinize the theoretical concept of "cortical efficiency" in connection with second language (L2) acquisition and, second, to detect cooperations between cortical areas in specific frequency bands indicative for highly proficient L2 processing. Two groups differing only in their level of L2 proficiency were contrasted during presentation of natural language videos in English (L2) and German (native language, L1), with explorative coherence analysis in 6 frequency bands (0.5-31.5 Hz). The coherence brain maps revealed more pronounced and widespread increases in coherences in the alpha1-band (8-10 Hz) in low-proficiency than in the high-proficiency L2 speakers. Surprisingly, this difference was obtained also during L1 processing and corroborated for both languages by multivariate permutation tests. These tests revealed additional differences between the low- and the high-proficiency group also for coherences within the beta1- (13-18 Hz) and the beta2-band (18.5-31.5 Hz), again during L2 and L1 processing. Since the same group differences were observed during L1 and L2 processing, our high-proficiency group might have profited from a more generic advantage in language or text processing strategy. This strategic advantage was most evident at alpha1 frequencies, possibly related to a specific way of processing internal mental states (top-down processing).