Publications
Background
It has been demonstrated that reference to the past is difficult for individuals with agrammatic aphasia, leading to the formulation of the PAst DIscourse LInking Hypothesis (PADILIH). Many of the previous studies have focused on Indo-European languages, in which time reference is expressed through verb inflection. The current study examined the PADILIH in Thai, a language that does not use verb inflection but instead uses aspectual markers to refer to time.
Aims
We aimed to evaluate the pattern of impairment of time reference in Thai speakers with agrammatic aphasia, by investigating how grammatical reference to past, present, and future was processed.
Methods and Procedures
A total of 15 Thai agrammatic speakers and 18 Thai non-brain-damaged (NBD) speakers participated in a sentence production task and an auditory sentence-to-picture matching comprehension task, both of which probed past, present, and future time reference.
Outcomes and Results
While the NBD participants performed close to ceiling in both production and comprehension, the agrammatic speakers showed significantly more difficulty in conditions requiring reference to the future in both modalities. In production, however, the agrammatic speakers replaced the target future time reference construction with negation (a construction that can be used as an alternative means for future reference). When responses using negation were counted as correct, the individuals with agrammatic aphasia showed equal impairment across conditions.
Conclusions
The results of this study were inconsistent with the PADILIH predictions: Thai agrammatic speakers experienced more vulnerability in reference to the future than the present and the past. This suggested that impairments of time reference may differ depending on the structure of the language. We hypothesized that the problems with producing future time reference in Thai may be influenced by the grammatical status of the future marker. In addition, the use of negation in place of the target word might have been because this negative construction reduces the processing load for Thai agrammatic speakers.
The objective of this systematic review is to create an overview of the literature on the comparison of navigated transcranial magnetic stimulation (nTMS) as a mapping tool to the current gold standard, which is (intraoperative) direct cortical stimulation (DCS) mapping. A search in the databases of PubMed, EMBASE, and Web of Science was performed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and recommendations were used. Thirty-five publications were included in the review, describing a total of 552 patients. All studies concerned either mapping of motor or language function. No comparative data for nTMS and DCS for other neurological functions were found. For motor mapping, the distances between the cortical representation of the different muscle groups identified by nTMS and DCS varied between 2 and 16 mm. Regarding mapping of language function, solely an object naming task was performed in the comparative studies on nTMS and DCS. Sensitivity and specificity ranged from 10 to 100% and 13.3–98%, respectively, when nTMS language mapping was compared with DCS mapping. The positive predictive value (PPV) and negative predictive value (NPV) ranged from 17 to 75% and 57–100% respectively. The available evidence for nTMS as a mapping modality for motor and language function is discussed.
Background: The important role of phonological processing for reading has been demonstrated by many studies. The purpose of this research was to investigate the role of phonological processing for reading in Russian. Specifically, we tested whether the overall complexity of a phonological task predicts reading fluency and reading comprehension.
Method: We used seven phonological tests ranked according to the number of linguistic processes involved in each task. We examined the relative difficulty of the tests and the relationship between phonological processing and reading skills (reading fluency and comprehension of simpler and more difficult texts) in 90 typically developing 7 to 11 years-of-age Russian-speaking children.
Results: Phonological tests that involved more linguistic processes had lower response accuracies. At the individual level, a greater estimated cost of adding a linguistic process to a phonological test was associated with a reliable decrease in reading fluency, but not reading comprehension.
Conclusions: Our findings confirmed the substantial role of phonological processing in reading acquisition, while stressing a higher predictive value of more complex phonological tests for reading fluency. The relationship between phonological processing and reading comprehension, in Russian, needs further investigations.
The left frontal aslant tract (FAT) has been proposed to be relevant for language, and specifically for spontaneous speech fluency. However, there is missing causal evidence that stimulation of the FAT affects spontaneous speech, and not language production in general. We present a series of 12 neurosurgical cases with awake language mapping of the cortex near the left FAT. Tasks for language mapping included the commonly used action picture naming, and sentence completion, tapping more specifically into spontaneous speech. A task dissociation was found in 10 participants: while being stimulated on specific sites, they were able to name a picture but could not complete a sentence. Overlaying of these sites on preoperative white-matter tract reconstructions revealed that in each individual case they were located on cortical terminations of the FAT. This corroborates the language functional specificity of the left FAT as a tract underlying fluent spontaneous speech.
Polinsky and Scontras (Polinsky & Scontras), in their thought-provoking keynote article, bring together two perspectives on heritage languages, i.e., of theoretical linguistics and of psycho- linguistics, and show how they interact and enrich each other. The authors list three causes of differences (transfer from the dominant language, attrition, divergent attainment) and out- comes (avoidance of ambiguity, resistance to irregularity, shrinkage of structure) of how the heritage languages differ from their baselines, but say that they do not know whether there is “agency on the part of heritage speakers” with regards to these outcomes. In this commen- tary, we provide psycholinguistic evidence that supports Polinsky and Scontras’ idea of how important it is for psycholinguistics and the linguistic theory of heritage languages to feed each other. We show that (a) heritage speakers’ processing can diverge from the baseline in online but not offline measures, (b) transfer from the dominant language does not always hap- pen, and (c) heritage speakers can actively shape their processing that can contribute to heri- tage language restructuring in a chain reaction fashion.
Background
Implicit-statistical learning (ISL) research investigates whether domain-general mechanisms are recruited in the linguistic processes that require manipulation of patterned regularities (e.g. syntax). Aphasia is a language disorder caused by focal brain damage in the left fronto-temporal-parietal network. Research shows that people with aphasia (PWA) with frontal lobe lesions manifest convergent deficits in syntax and ISL mechanisms. So far, ISL mechanisms in PWA with temporal or parietal lobe lesions have not been systematically investigated.
Aims
We investigated two complementary hypotheses: 1) the anatomical hypothesis, that PWA with frontal lesions display more severely impaired ISL abilities than PWA with posterior lesions and 2) the behavioural hypothesis, that the magnitude of impairment in ISL mechanisms correlates to syntactic deficits in aphasia.
Methods
We tested 13 PWA, 5 with frontal lesions and 8 with posterior lesions, and 11 non-brain-damaged controls on a visual statistical learning (VSL) task. In addition, all PWA completed several linguistic tasks. Reaction times, obtained in the VSL task, were analyzed using linear mixed-effects model. Correlational statistics were used to assess the relationship between VSL task performance and linguistic measures.
Results and Discussion
We did not find support for the anatomical hypothesis as patients with spared frontal regions also manifested impaired ISL mechanisms. This is attributed to a) ISL mechanisms being vulnerable to other cognitive dysfunctions and/or b) ISL mechanisms anatomically extending to the posterior brain regions. Notably, ISL mechanisms were impaired, but not absent in aphasia. With regards to the behavioural hypothesis, we provide empirical evidence of correlation between ISL mechanisms and syntactic, but not lexical impairment in aphasia. We discuss both the theoretical contributions to the debate of domain-independence of ISL mechanisms and clinical implications for implicit language therapy.
The frontal aslant tract (FAT) is a white-matter tract connecting the inferior frontal gyrus (IFG) and the supplementary motor complex (SMC). Damage to either component of the network causes spontaneous speech dysfluency, indicating its critical role in language production. However, spontaneous speech dysfluency may stem from various lower-level linguistic deficits, precluding inferences about the nature of linguistic processing subserved by the IFG-SMC network. Since the IFG and the SMC are attributed a role in conceptual and lexical selection during language production, we hypothesized that these processes rely on the IFG-SMC connectivity via the FAT. We analysed the effects of FAT volume on conceptual and lexical selection measures following frontal lobe stroke. The measures were obtained from the sentence completion (SC) task, tapping into conceptual and lexical selection, and the picture-word interference (PWI) task, providing a more specific measure of lexical selection. Lower FAT volume was not associated with lower conceptual or lexical selection abilities in our patient cohort. Current findings stand in marked discrepancy with previous lesion and neuroimaging evidence for the joint contribution of the IFG and the SMC to lexical and conceptual selection. A plausible explanation reconciling this discrepancy is that the IFG-SMC connectivity via the FAT does contribute to conceptual and/or lexical selection but its disrupted function undergoes reorganisation over the course of post-stroke recovery. Thus, our negative findings stress the importance of testing the causal role of the FAT in lexical and conceptual selection in patients with more acute frontal lobe lesions.
The goal of the present study was to investigate the interaction between different senses of polysemous nouns (metonymies and metaphors) and different meanings of homonyms using the method of event-related potentials (ERPs) and a priming paradigm. Participants read two-word phrases containing ambiguous words and made a sensicality judgment. Phrases with polysemes highlighted their literal sense and were preceded by primes with either the same or different – metonymic or metaphorical – sense. Similarly, phrases with homonyms were primed by phrases with a consistent or inconsistent meaning of the noun. The results demonstrated that polysemous phrases with literal senses preceded by metonymic primes did not differ in ERP responses from the control condition with the same literal primes. In contrast, processing phrases with the literal sense preceded by metaphorical primes resulted in N400 and P600 effects that might reflect a very limited priming effect. The priming effect observed between metonymic and literal senses supports the idea that these senses share a single representation in the mental lexicon. In contrast, the effects observed for polysemes with metaphorical primes characterize lexical access to the word’s target sense and competition between the two word senses. The processing of homonyms preceded by the prime with an inconsistent meaning, although it did not elicit an N400 effect, was accompanied by a P600 effect as compared to the control condition with a consistent meaning of the prime. We suppose that the absence of the N400 effect may result from inhibition of the target meaning by the inconsistent prime, whereas the P600 response might reflect processes of reanalysis, activation, and integration of the target meaning. Our results provide additional evidence for the difference in processing mechanisms between metonymies and metaphors that might have separate representations in the mental lexicon, although they are more related as compared to homonyms.
This chapter deals with segmentation, definition of reference units and annotation of the first corpus of Russian narratives by individuals with brain damage – people with aphasia and right hemisphere damage – and neurologically healthy speakers. We show that such parameters as pause length and intonation contours cannot be used for segmentation of impaired speech. Instead, we use syntactic criteria for identification of the reference, or – as they are called in this paper – elementary discourse units (EDUs). The Russian CliPS (Clinical Pear Stories) corpus contains multi-layer annotation of audio- and video-recordings, performed on micro- and macro-linguistic level, and can be used as a source for qualitative and quantitative research on various aspects of speech in aphasia and right hemisphere damage.
Handedness is the most prominent trait of functional asymmetry in humans, associated with lateralized cognitive functions and considered in relation to mental disorders. However, the neuroanatomical correlates of handedness are still unclear. It has been hypothesized that the structural properties of sub-regions of the corpus callosum (CC) are linked to handedness. Nevertheless, tractography studies of the relation between directly measured structural properties of CC subregions and handedness are lacking. The Constrained Spherical Deconvolution (CSD) approach enables full reconstruction of the sub-regions of the CC. The current study aimed to investigate the relation between the structural properties of the CC, such as volume and the CSD metric, referred to as hindrance modulated orientational anisotropy (HMOA), and handedness. Handedness was considered in two dimensions: direction (right-handed, ambidextrous, left-handed) and degree (the absolute values of Handedness quotient). We found no association between 1) volume or HMOA as a proxy of microstructural properties, namely the axonal diameter and fiber dispersion, of each sub-region and 2) either the direction or the degree of handedness. These findings suggest the absence of a direct relation between sub-regions of the CC and handedness, demonstrating the necessity of future tractography studies.
People with aphasia (PWA) often demonstrate verb and sentence processing impairments, in production as well as in comprehension modalities. Meanwhile, patterns of impairment are typically studied at the group level, in groups of PWA with specific aphasia types (e.g., Broca's aphasia), or in case-series with small sample sizes. Our aim was to investigate if there are consistent patterns of impairment on the Russian version of the Verb and Sentence Test (Bastiaanse et al., 2000) in a large group of PWA (N = 54). We used a data-driven classification method that does not require information about aphasia types - k-means cluster analysis - and compared the results with the clinical diagnoses of the PWA. As a follow-up analysis, we used Crawford's single case methodology (Crawford et al., 2010) to further investigate patterns of impairment within the revealed clusters.
Background: Languages of the world have several ways of expressing time reference. Many languages such as those in the Indo-European group express time reference through tense. Languages such as Chinese and Standard Indonesian express time reference through aspectual adverbs, while Akan does so through grammatical tone. Previous studies have found that time reference is selectively impaired, with reference to the past being more impaired than reference to the non-past. The PAst DIscourse LInking Hypothesis (PADILIH) posits that pastime reference is difficult because it requires discourse linking.
Aims: The goal of this study was first to examine whether pastime reference is impaired also in languages that do not use grammatical affixes but rather tone, to make time reference. Second, this study aims to decouple the effect of tone from the effect of temporal reference on Akan verbs.
Method and Procedures: Ten Akan agrammatic speakers and 10 non-brain-damaged speakers (NBDs) participated in this study. An Akan adapted version of the Test for Assessing Reference of Time (African TART), for both production and comprehension was used. The TART focuses on the future, present (habitual) and the pastime frames. Additionally, five of the agrammatic speakers performed two tonal discrimination tasks: a non-linguistic and a linguistic (lexical) one.
Outcomes and Results: While the NBDs scored at ceiling, the agrammatic speakers made errors, and these affected past more than present and the future time references, in both comprehension and production tasks. However, the comprehension data showed a dissociation between the present habitual and the future. The substitution error analysis revealed a preference for the present. The five agrammatic speakers showed an intact performance on non-linguistic tonal discrimination task.
Conclusion: The conclusion is that regardless of how time reference is expressed, whether through inflectional morphology or grammatical tone, reference to the past is problematic for individuals with agrammatic aphasia. The fact that the agrammatic speakers could perceive the non-linguistic tonal differences demonstrates that it is not tone in general that is disrupted, but rather time reference, particularly reference to the past, as predicted by the PADILIH.
Purpose
Corpus analyses of spontaneous language fragments of varying length provide useful insights in the language change caused by brain damage, such as caused by some forms of dementia. Sample size is an important experimental parameter to consider when designing spontaneous language analyses studies. Sample length influences the confidence levels of analyses. Machine learning approaches often favor to use as much language as available, whereas language evaluation in a clinical setting is often based on truncated samples to minimize annotation labor and to limit any discomfort for participants. This article investigates, using Bayesian estimation of machine learned models, what the ideal text length should be to minimize model uncertainty.
Method
We use the Stanford parser to extract linguistic variables and train a statistic model to distinguish samples by speakers with no brain damage from samples by speakers with probable Alzheimer's disease. We compare the results to previously published models that used CLAN for linguistic analysis.
Results
The uncertainty around six individual variables and its relation to sample length are reported. The same model with linguistic variables that is used in all three experiments can predict group membership better than a model without them. One variable (concept density) is more informative when measured using the Stanford tools than when measured using CLAN.
Conclusion
For our corpus of German speech, the optimal sample length is found to be around 700 words long. Longer samples do not provide more information.
We report results from a self-paced silent reading study and a self-paced reading-aloud study examining ambiguous forms (heteronyms) of Russian animate and inanimate nouns which are differentiated in speech through word stress, e.g. uCHItelja.TEACHER.GEN/ACC.SG and uchiteLJA.TEACHERS.NOM.PL1. During reading, the absence of the auditory cue (word stress) to word identification results in morphologically ambiguous forms since both words have the same inflectional marking, -ja. Because word inflection is a reliable cue to syntactic role assignment, the ambiguity affects the level of morphology and of syntactic structure. However, word order constraints and frequency advantage of the GEN over both the NOM and the ACC noun forms with the -a/-ja inflection should pre-empt two different syntactic parses (OVS vs SVO) when the heteronym is sentence-initial. We inquired into whether the parser is aware of the multi-level ambiguity and whether selected conflicting cues (case, word order, animacy) can prime parallel access to several structural parses. We found that animate and inanimate nouns patterned differently. The difference was consistent across the experiments. Against the backdrop of classical sentence processing dichotomies, the emergent pattern fits with the serial interactive or the parallel modular parser hypothesis.
Background: The distribution of pronouns varies cross-linguistically. This distribution has led to conflicting results in studies that investigated pronoun resolution in agrammatic indviduals. In the investigation of pronominal resolution, the linguistic phenomenon of “resumption” is understudied in agrammatism. The construction of pronominal resolution in Akan presents the opportunity to thoroughly examine resumption.
Aims: To start, the present study examines the production of (pronominal) resumption in Akan focus constructions (who-questions and focused declaratives). Second, we explore the effect of grammatical tone on the processing of pronominal (resumption) since Akan is a tonal language.
Methods & Procedures: First, we tested the ability to distinguish linguistic and non-linguistic tone in Akan agrammatic speakers. Then, we administered an elicitation task to five Akan agrammatic individuals, controlling for the structural variations in the realization of resumption: focused who-questions and declaratives with (i) only a resumptive pronoun, (ii) only a clause determiner, (iii) a resumptive pronoun and a clause determiner co-occurring, and (iv) neither a resumptive pronoun nor a clause determiner.
Outcomes & Results: Tone discrimination both for pitch and for lexical tone was unimpaired. The production task demonstrated that the production of resumptive pronouns and clause determiners was intact. However, the production of declarative sentences in derived word order was impaired; wh-object questions were relatively well-preserved.
Conclusions: We argue that the problems with sentence production are highly selective: linguistic tones and resumption are intact but word order is impaired in non-canonical declarative sentences.
The purpose of this study was to systematically investigate language comprehension in individuals with left and right temporal lobe epilepsy (TLE) at different language levels— single word (noun and verb), sentence, and discourse. Neither of the groupswith TLE showed difficulties with noun comprehension, whereas verb comprehension performance was significantly lower in individuals with left, but not right TLE as compared to healthy controls. In contrast, sentence and discourse comprehension was overall impaired, irrespective of the lateralization of the epileptogenic focus. Education level and age at seizure onset were also found correlating with language comprehension in our tested cohort. The results, firstly, confirm that the verb comprehension task is more sensitive for assessment of single-word comprehension in individuals with TLE. Secondly, they indicate that language comprehension in left and right TLE is mostly impaired at the sentence and discourse levels, which may be associated with low working memory capacities.
ABSTRACT
Background: The Aphasia Rapid Test (ART) is a screening test developed for fast speech/language assessment of people in the acute stroke period. This test has been developed for French and English and was recently adapted for Portuguese and Italian. Nowadays, such a standardised screening test is in a great need at clinics with Russian-speaking patients. To fill this gap, the ART was adapted for Russian.
Aims: The current study investigated whether the Russian ART meets all the psychometric standards, and whether it is suitable for detecting speech/language disorders and estimating their severity, as well as for the evaluation of improvement in the acute post-stroke period.
Methods & Procedure: First, we evaluated the validity, sensitivity, specificity, accuracy, test-retest reliability, inter-item consistency and inter-rater reliability of the test in a group of people with chronic speech/language disorders (N = 55) and in an age-matched control group of non-brain-damaged individuals (N = 50). Participants performed the Russian ART, and their linguistic status was confirmed by the Russian e-version of the Token Test. Second, to test the appropriateness of the Russian ART in the acute post-stroke period, a clinical group of such individuals (N = 43) performed the ART and the Token Test, as well as the Vasserman’s scale which is widely used in Russian clinics. Finally, 16 people in the acute stroke period performed the Russian ART twice to prove that the test can detect early changes in an acute patient’s linguistic status.
Outcomes & Results: The results showed that the Russian ART can be considered as a valid, sensitive, specific, and accurate screening tool with the high test-retest reliability, inter-item consistency, and inter-rater reliability. In the acute post-stroke group, the correlation between the ART and the Token Test was high and significant; a moderate correlation and no significant correlation were found between the Vasserman’s scale and the Russian ART and the Token Test correspondingly. The Russian ART also allowed us to detect the improvement in speech/language status in the acute post-stroke period.
Conclusion: The study confirmed that the Russian ART meets all required standards to be suggested for usage in a Russian-speaking clinical population. This test was relevant for detecting the presence and severity of speech/language disorders and to measure the improvement in the acute post-stroke period.
This study investigates how PHONOLOGICAL NEIGHBORHOOD DENSITY (PND) affects word production and recognition in 4-to-6-year-old Russian children in comparison to adults. Previous experiments with English-speaking adults showed that a dense neighborhood facilitated word production but inhibited recognition whereas a sparse neighborhood inhibited production but facilitated recognition. Importantly, these effects are not universal because a reverse PND pattern was found in Spanish-speaking adults. Probably, PND effects depend on the morphological properties of language.
This study focuses on PND effects in word production and recognition in terms of facilitation and inhibition in Russian. Our results are consistent with those in Spanish: Russian-speaking adults produced words with dense neighborhoods more slowly and recognized them faster than words with sparse neighborhoods. Russian children showed the same PND effect in recognition and no effect was found in production. The findings support the hypothesis that PND effects in word production and recognition are influenced by the morphological system of language.
