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PubMed2005

Visuospatial deficits in patients with early left-hemispheric lesions and functional reorganization of language: consequence of lesion or reorganization?

INTRODUCTION: Patients with early left-hemispheric lesions have repeatedly been reported to show spared language functions (which are then mediated by the right hemisphere), but exhibit deficits in visuospatial functions. The "crowding hypothesis" explains these deficits by a neuronal scarcity in the right hemisphere for the original right hemispheric functions. An alternative hypothesis suggests direct lesion effects as the sole reason for the visuospatial impairments. The scope of this study was to examine the relations between visuospatial skills and hemispheric preference for language, and between visuospatial skills and cerebral lesion size. METHODS: In a sample of young adults with pre- or perinatally acquired focal lesions of the left hemisphere and unilateral spastic cerebral palsy on the right side, we assessed intelligence and neuropsychological functions in the verbal and visuospatial domains. The behavioural data was correlated with structural MRI information and language preference as assessed using fMRI. RESULTS: Patients with right hemispheric language production were impaired in visuospatial functions, compared not only to normal controls, but also to patients without right hemispheric language preference. Additionally, the degree of right hemispheric language correlated negatively with performance in visuospatial tasks. Lesion size correlated negatively only with performance IQ, which again correlated negatively with motor impairment of the patients and thus does not seem to reflect true cognitive deficits. CONCLUSION: Visuospatial deficits in patients with early left-hemispheric lesions are a consequence of lesion-induced right hemispheric language organization, thus lending further support to the "crowding hypothesis".

Adolescent↗

PubMed2006

Language outside the focus of attention: the mismatch negativity as a tool for studying higher cognitive processes.

Which aspects of language and cognitive processing take place irrespective of whether subjects focus their attention on incoming stimuli and are, in this sense, automatic? The Mismatch Negativity (MMN), a neurophysiological brain response recorded in the EEG and MEG, is elicited by attended and unattended stimuli alike. Recent studies investigating the cognitive processes underlying spoken language processing found that even under attentional withdrawal, MMN size and topography reflect the activation of memory traces for language elements in the human brain. Familiar sounds of one's native language elicit a larger MMN than unfamiliar sounds, and at the level of meaningful language units, words elicit a larger MMN than meaningless pseudowords. This suggests that the MMN reflects the activation of memory networks for language sounds and spoken words. Unattended word stimuli elicit an activation sequence starting in superior-temporal cortex and rapidly progressing to left-inferior-frontal lobe. The spatio-temporal patterns of cortical activation depend on lexical and semantic properties of word stems and affixes, thus indicating that the MMN can give clues about lexico-semantic information processing stored in long term memory. At the syntactic level, MMN size was found to reflect whether a word string conforms to abstract grammatical rules. This growing body of results suggests that lexical, semantic and syntactic information can be processed by the central nervous system outside the focus of attention in a largely automatic manner. Analysis of spatio-temporal patterns of generator activations underlying the MMN to speech may be an important tool for investigating the brain dynamics of spoken language processing and the activated distributed cortical circuits acting at long-term memory traces.

Acoustic Stimulation↗

PubMed2005

Written language skills in children with benign childhood epilepsy with centrotemporal spikes.

PURPOSE: The goal of this work was to study written language skills in children with benign childhood epilepsy with centrotemporal spikes (BCECTS) in the absence of atypical clinical or electroencephalographic (EEG) features (n = 32), as compared with controls (n = 36). METHODS: BCECTS patients (7-16 years), attending regular school, without cognitive or behavioral regression, or atypical EEG patterns, completed four tests assessing written language skills and one nonverbal cognitive test. School performance information was recorded. Seizure types, duration, and frequency; awake and sleep interictal EEG findings; and medication status were documented. Epilepsy and educational outcome was recorded for a period of 1-5 years after diagnosis. RESULTS: As a group, BCECTS patients performed significantly worse than controls in spelling, reading aloud, and reading comprehension; presented dyslexic-type errors; and frequently had below-average school performance. Among 11 with poor written language performance, 4 had developmental dysfunctions before school and seizure onset and, as a group, demonstrated low performance on a nonverbal cognitive test. Even though 65.6% were on anticonvulsants due to frequent seizures and/or seizures while awake, none belonged to the atypical BCECTS spectrum with respect to clinical or EEG findings. Increased epilepsy duration and seizure frequency were less represented in patients with no or mild written language problems than in those with poor performance. Otherwise, clinical course and EEG findings in this group were no different than those for the 11 children with severe written language problems. Clinical follow-up indicated that learning problems appear persistent and several children require remedial classes and/or tutoring after the epilepsy has resolved. CONCLUSIONS: Children with severe but not atypical BCECTS performed, as a group, significantly worse than controls in written language skills, specifically in spelling, reading, aloud and reading comprehension; they also presented many difficulties also found in children with dyslexia. However, poor written language performance was not considered specific to BCECTS because it occurred in children with generally low cognitive capacity and/or preexisting developmental dysfunctions. Moreover, a dissociation between epilepsy outcome and learning problem outcome, in the subgroup with poor performance, casts doubt on the existence of a possible causal link between BCECTS and educational performance.

Adolescent↗

PubMed1997

Piracetam as an adjuvant to language therapy for aphasia: a randomized double-blind placebo-controlled pilot study.

OBJECTIVE: To determine whether piracetam 4.8 g/day together with intensive language therapy improved language function more than language therapy alone. DESIGN: Double-blind, placebo-controlled parallel group study. SETTING: Referral speech and language clinic of a university department of neurology. PATIENTS: Sixty-six inpatients with aphasia present between 4 weeks and 36 months. INTERVENTIONS: Intensive language therapy for 6 weeks in all patients. Thirty-two patients received piracetam 4.8 g daily and 34 patients received placebo. MAIN OUTCOME MEASURE: The Aachen Aphasia Test (AAT), a standardized procedure for evaluating the severity of aphasia, was performed at baseline and after 6 weeks' treatment. RESULTS: In 50 patients evaluated for efficacy, a trend toward improvement in the active group was observed in all subtests of the AAT. This trend was statistically significant for absolute differences in recovery of "written language" and "profile level." CONCLUSION: Piracetam appears to have a positive adjuvant effect on the recovery of aphasia in patients receiving intensive language therapy.

Adult↗

PubMed2002

The role of abstract syntactic knowledge in language acquisition: a reply to Tomasello (2000).

In his paper "Do young children have adult syntactic competence?" Tomasello (Cognition 74 (2000) 209) interprets young children's conservatism in language production as evidence that early language use, and verb use in particular, are based entirely on concrete lexical representations, showing no evidence of abstract syntactic categories such as "verb" or "transitive sentence". In this reply, I argue that Tomasello's interpretation depends on three questionable premises: (a) that anyone with a robust grammatical category of verbs would use new verbs in unattested sentence constructions; (b) that there are no reasons other than lack of syntactic competence for lexical effects in language use; and (c) that children always interpret a new verb presented in the context of an action on an object as a causal action verb, and therefore as one they should use transitively. I review evidence against all of these assumptions. Tomasello's data, among others', show that children indeed learn item-specific facts about verbs and other lexical items - as they must, to become competent speakers of their native language. However, other data suggest that more abstract descriptions of linguistic input also play a role in early language use. To achieve a complete picture of how children learn their native languages, we must explore the interactions of lexical and more abstract syntactic knowledge in language acquisition.

Child, Preschool↗

PubMed2002

Form is easy, meaning is hard: resolving a paradox in early child language.

A developmental paradox is discussed: studies of infant processing of language and language-like stimuli indicate considerable ability to abstract patterns over specific items and to distinguish natural from unnatural English sentences. In contrast, studies of toddler language production find little ability to generalize patterns over specific English words or constructions. Thus, infants appear to be abstract auditory or language processors whereas toddlers appear to be non-abstract, item-specific language users. Three resolutions are offered to this paradox. The first, that no resolution is necessary because only the toddler findings come from language use in a communicative context and so only the toddler findings are relevant to linguistic knowledge, is rejected. The second, that the contradictions are rooted in the differing methodologies of the two sets of studies (comprehension vs. production), is found to explain important aspects of the contradictory findings. The third, that the contractions come from the differing content of the stimuli in the studies, is also found to be explanatory and is argued to carry greater weight. Resolution 3 suggests that the patterns that infants extract from their linguistic input are not yet tied to meaning; thus, toddlers do not lose these earlier-abstracted forms but their use of them is limited until they have been integrated with meaning. It is argued that in language acquisition, learning form is easy but learning meaning, and especially linking meanings and forms, is hard.

Child Language↗

PubMedDate not supplied

A language learning model for finite parameter spaces.

This paper shows how to formally characterize language learning in a finite parameter space, for instance, in the principles-and-parameters approach to language, as a Markov structure. New language learning results follow directly; we can explicitly calculate how many positive examples on average ("sample complexity") it will take for a learner to correctly identify a target language with high probability. We show how sample complexity varies with input distributions and learning regimes. In particular we find that the average time to converge under reasonable language input distributions for a simple three-parameter system first described by Gibson and Wexler (1994) is psychologically plausible, in the range of 100-150 positive examples. We further find that a simple random step algorithm-that is, simply jumping from one language hypothesis to another rather than changing one parameter at a time-works faster and always converges to the right target language, in contrast to the single-step, local parameter setting method advocated in some recent work.

Adult↗

PubMedDate not supplied

Speech and language outcomes of children with bronchopulmonary dysplasia.

UNLABELLED: A prospective follow-up of very low birth weight infants (VLBW) with (n = 89) and without (n = 71) bronchopulmonary dysplasia (BPD) and Term control children (n = 93) was conducted at 8 years of age. Groups were compared on measures of articulation, receptive and expressive language, verbal and performance IQ, oral motor skills and gross and fine motor skills. The BPD group demonstrated reduced articulation, receptive language skills, performance IQ, and overall gross and fine motor skills when compared to VLBW and Term groups. The BPD and VLBW groups did not differ on expressive language, oral motor skills, or verbal IQ. The groups also differed in enrollment in special classes and speech-language therapy, with almost half (48%) of the BPD group enrolled in speech-language therapy compared to 21% of the VLBW group, and 9% of the Term group. These results suggest that BPD may have adverse effects on speech development as well as on performance IQ, motor skills, and receptive language over and above the effects of VLBW. LEARNING OUTCOMES: (1) As a result of this activity the reader will be able to describe what BPD is and how it impacts speech and language. (2) As a result of this activity the reader will be able to discuss how children with VLBW with BPD differ from children with VLBW without BPD in their developmental outcomes.

Bronchopulmonary Dysplasia↗

PubMed1998

Effects of resective surgery for left-sided intracranial tumours on language function: a prospective study.

BACKGROUND: Although language disorders occur in about 50% of patients with a left hemispheric tumour and are a significant cause of morbidity, the effects of resective neurosurgery and their relation to tumour pathology are unclear. We report the immediate effects of resective surgery on language functions in a heterogeneous group of patients with left-sided intracranial tumours. METHODS: 40 patients were studied. The Western Aphasia Battery (WAB) and Boston Naming Test (BNT) were administered preoperatively and before discharge following resective neurosurgery. Dexamethasone dose at time of testing was recorded, as was time taken to complete the tests, and tumour neuropathology. FINDINGS: 15 patients with normal aphasia quotients and language quotients before resective surgery all had normal quotients postoperatively. 25 who were dysphasic (ie, aphasia quotient <93.8) preoperatively showed significant postoperative improvements in both their mean aphasia quotient (from 81.8 to 89.1, p=0.004) and their mean language quotient (from 73.4 to 85.4, p=0.001), though 13 remained dysphasic. Two of the 25 dysphasic patients had their WAB scores lowered by tumour resection. The findings and postoperative changes in BNT scores were almost identical to the pattern of those in WAB scores. At second assessment, dexamethasone therapy was significantly (p<0.01) lower than preoperative dose (reduction from mean 10.3 mg/day to 0.7 mg/day in the dysphasic group). Patients with glioblastoma were more likely to have lower aphasia quotients, language quotients, and BNT scores than patients with anaplastic glioma, metastasis, or meningioma. Although the glioblastoma group had the greatest improvements in WAB operative scores, 57% remained dysphasic after resective surgery. Two additional patients declined postoperative assessment. INTERPRETATION: Resective surgery for left-sided intracranial tumours significantly improves language function in dysphasic patients, and is unlikely to impair language functions in non-dysphasic patients. Dysphasia and its response to resective surgery are related to the tumour neuropathology.

Aphasia↗

PubMed2004

Are English- and Chinese-language versions of the SF-6D equivalent? A comparison from a population-based study.

OBJECTIVE: The goal of this study was to assess the equivalence of English- and Chinese-language versions of the SF-6D (a 6-dimensional health classification system based on the 36-Item Short Form Health Survey) using a model of equivalence proposed previously. METHODS: We analyzed data from a previously published, cross-sectional, population-based survey of ethnic Chinese in Singapore, using linear regression models to adjust for the influence of potential confounding variables. Based on equivalence clinical trial methods, measurement (ie, scale) and item equivalence were assessed by comparing 90% CIs of differences in scores due to language with predefined equivalence margins, that corresponded to the minimum clinically important difference for SF-6D utility and item scores. RESULTS: Data from 2,558 respondents (aged 21-65 years; 48.8% completed the English-language version) were analyzed. The utility scores of respondents using the English- or Chinese-language versions of the SF-6D had similar distribution patterns, with a mean (SD) utility score of 0.8 (0.12). Adjusted 90% CIs for differences in utility and item scores due to language fell within predefined equivalence margins, suggesting measurement and item level equivalence. The 90% CI for scale scores was -0.0089 to 0.0065 (range, 0.0154; equivalence margin, 0.033); the 90% CI for item scores varied from -0.0046 to -0.0020 (range, 0.0026; equivalence margin, 0.0036) for vitality to -0.0024 to 0.0037 (range, 0.0061; equivalence margin, 0.0088) for social functioning. Functional equivalence was suggested because the various aspects of equivalence proposed previously were demonstrated in this study. CONCLUSIONS: English- and Chinese-language versions of the SF-6D demonstrated item, measurement, and functional equivalence in this population-based study comparing 2 widely used languages with very different linguistic structures. This suggests that English and Chinese SF-6D scores can be pooled, thus increasing the representativeness and power of studies using the SF-6D, and providing a basis for studies to value health by obtaining SF-6D utility scores in Asian populations.

Adult↗

PubMed2001

The correlation between languages and genes: the Usko-Mediterranean peoples.

The usko-Mediterraneans peoples are defined as ancient and present day populations that have lived in the Mediterranean/Middle-East/Caucasus area and have spoken a Basque related language. The present day existing populations show an HLA genetic relatedness which is more or less close according to geographical distance. The Greek sample is an outlying in all genetic analyses, because Greeks have a significant genetic input from sub-Saharan Ethiopians and Blacks. This probably occurred in Pharaonic times. Present day comparisons between genes and languages show a lack of correlation: Macedonian, Palestinians, Kurds, part of Berbers, Armenians, and Turks belong to the old Mediterranean substratum, but they do not speak a language included in the old Mediterranean Dene-Caucasian group. This is due to an "elite"-imposed culture and language. Other ethnic groups speak an "old Mediterranean language" or "usko-Mediterranean language" modified by Roman Latin (i.e., Spanish, Italians), or by other not fully explained processes (Jews). Therefore, the correlation between genes and languages may exist at a macrogeographical level, but not when more precise microgeographical studies are done, as shown in the present "usko-Mediterranean" peoples model.

Africa South of the Sahara↗

PubMed2001

Language lateralization in schizophrenia, an fMRI study.

Anatomical studies have shown that cerebral asymmetry is reduced in schizophrenia. Functional asymmetry appears to be reduced also, as was shown with dichotic listening studies. These studies, however, have not revealed whether reduced lateralization is the result of decreased language activity of the left hemisphere or whether it is the consequence of increased language-related activity in the right hemisphere. To elucidate this, we examined hemispheric dominance for language processing by means of functional MRI. Twelve schizophrenic patients and twelve healthy controls were scanned while they were engaged in a verb-generation and a semantic decision task. Activation was measured bilaterally in the frontal, temporal and temporo-parietal language areas, and a laterality index was derived from activity in these regions of interest in the left and the right hemispheres. Clinical symptoms were rated at the time of scanning. The results indicate that language processing is less lateralized in patients than in controls (a mean laterality index of 0.35 versus 0.63, respectively, difference p<0.01). Analysis of variance of the extent of activity, i.e. numbers of active voxels, revealed a significant hemisphere by group interaction (F(1,22)=11.2, p<0.001), which was due to increased activation in the right hemisphere of the patients (post hoc t-test p<0.05). We found no evidence of reduced activity in the left hemisphere. Further analysis of clinical symptoms rated prior to scanning revealed that decreased language lateralization was associated with more severe hallucinations (r=-0.54, p<0.05). We postulate that decreased language lateralization in schizophrenia may result from failure to inhibit the right hemisphere.

Adult↗

PubMed1997

Is schizophrenia the price that Homo sapiens pays for language?

The dichotomy between schizophrenia and manic-depressive illness is, as E. Kraepelin suspected, flawed; no unequivocal separation can be achieved. There are no categories of psychosis, but only continua of variation. However, the definition of nuclear symptoms by K. Schneider reveals the fundamental characteristics of the core syndrome--it is independent of the environment and constant in incidence across populations that have been separated for thousands of years. The associated genetic variation must be as old as Homo sapiens and represent a component of diversity that crosses the population as a whole. The fecundity disadvantage that accompanies the syndrome requires a balance in a substantial and universal advantage; this advantage, it is proposed, is the speciation characteristic of language; language and psychosis have a common evolutionary origin. Language, it is suggested, originated in a critical change on the sex chromosomes (the 'speciation event'--the genetic change that defined the species) occurring in East Africa between 100 and 250 thousand years ago that allowed the two hemispheres to develop with a degree of independence. Language can be understood as bi-hemispheric with one component function--a linear output sequence--confined to the dominant hemisphere--and a second--parallel distributed sampling occurring mainly in the non-dominant hemisphere. This mechanism provides an account of the generativity of language. The significance of nuclear symptoms is that these reflect a breakdown of bi-hemispheric coordination of language, perhaps specifically of the process of 'indexicalisation' (the distinction between 'I' and 'you') of self- versus other-generated references. Nuclear symptoms can be described as 'language at the end of its tether'; the phenomena and population characteristics of the nuclear syndrome of schizophrenia thus yield clues to the origin of the species.

Biological Evolution↗

PubMed1994

[Event-related potentials and language processing].

The contribution of cognitive event-related potentials (ERPs) and particularly of the N400 component to the study of language processing is considered. After a general presentation of the various components of cognitive evoked potentials which are differentiated from early potentials (sensitive to perceptive parameters), the neurophysiological and psychological correlates of ERPs are discussed. Before the presentation of the main studies concerned with the correlation between specific late components and linguistic processes, it is proposed an introduction to some theoretical models of language processing which serve as conceptual framework supporting most of the experimental approaches in this field. The results of EPs studies devoted to functional asymetries in language processing are briefly mentioned. Then a number of studies are analysed, these demonstrate the sensitivity of event-related potential measures to linguistic manipulations. Finally, the studies concerned with the N400 are reviewed, this potential appears to be the more specifically language-related ERP component, even if its connection with specific linguistic processes or its differentiation from N200 are still under debate. Nevertheless language-related electrophysiological investigations may become in the near future a useful complementary approach to our understanding of language processing and language disorders.

Brain↗

PubMed2003

Quantitative fMRI assessment of the differences in lateralization of language-related brain activation in patients with temporal lobe epilepsy.

Defining language lateralization is important to minimize morbidity in patients treated surgically for temporal lobe epilepsy (TLE). Functional magnetic resonance imaging (fMRI) offers a promising, noninvasive, alternative strategy to the Wada test. Here we have used fMRI to study healthy controls and patients with TLE in order to (i) define language-related activation patterns and their reproducibility; (ii) compare lateralization determined by fMRI with those from of the Wada test; and (iii) contrast different methods of assessing fMRI lateralization. Twelve healthy right-handed controls and 19 right-handed preoperative patients with TLE (12 left- and seven right-TLE) were studied at 3T using fMRI and a verbal fluency paradigm. A Wada test also was performed on each of the patients. Greater activation was found in several areas in the right hemisphere for the left-TLE group relative to controls or right-TLE patients. Relative hemispheric activations calculated based on either the extent or the mean signal change gave consistent results showing a more bihemispheric language representation in the left-TLE patients. There was good agreement between the Wada and fMRI results, although the latter were more sensitive to involvement of the nondominant right hemisphere. The reproducibility of the fMRI values was lowest for the more bihemispherically represented left-TLE patients. Overall, our results further demonstrate that noninvasive fMRI measures of language-related lateralization may provide a practical and reliable alternative to invasive testing for presurgical language lateralization in patients with TLE. The high proportion (33%) of left-TLE patients showing bilateral or right hemispheric language-related lateralization suggests that there is considerable plasticity of language representation in the brains of patients with intractable TLE.

Adolescent↗

PubMed2003

How atypical is atypical language dominance?

Atypical, right-hemisphere language dominance is poorly understood. It is often observed in patients with brain reorganization due to lesions early in life. It can also be encountered in seemingly normal individuals. We compared the patterns of neural language activation in 7 individuals with left- and 7 with right-hemisphere language dominance, none of whom had any evidence of brain lesions. We speculated that incongruencies in the activation patterns in atypical, right-hemisphere language dominance could indicate a reorganized neural language system after undetected early brain damage. Functional magnetic resonance imaging analysis of brain activation during phonetic word generation demonstrated (1). no increased activation in the subdominant hemisphere in right compared to left language dominance, (2). a similar variability in the pattern of activation in both groups, and (3). a mirror reverse pattern of activation in right- compared to left-hemisphere dominant subjects. These findings support the view that in individuals with an unrevealing medical history right-hemispheric dominance constitutes a natural rather than an abortive variant of language lateralization.

Adult↗

PubMed2003

Functional MRI study of semantic and phonological language processing in bilingual subjects: preliminary findings.

The objective of the study was to explore differences in regional fMRI activation topography and lateralization between semantic and phonological tasks performed in English and Spanish in bilingual individuals. Eight bilingual (primary Spanish and secondary English-speaking) individuals performed fMRI noun-verb association and rhyming tasks in both Spanish and English. Functional dataset analysis within Statistical Parametric Mapping (SPM99) with overlay on T1-weighted anatomic images was performed. Significantly higher laterality indices were noted in the semantic tasks as compared with the phonological tasks in the anterior regions of interest comprising the frontal and superior temporal lobes. A task subtraction analysis demonstrated right hemispheric (inferior frontal gyrus and supramarginal gyrus) foci of significantly increased activation in the combined language phonological tasks compared to the combined language semantic tasks; similarly prominent right hemispheric activation was seen in the English phonological-English semantic subtraction, but the analogous Spanish task subtraction revealed no task-related differences. This divergence in activation topography between semantic and phonological tasks performed in the nonnative language, but not in the primary language, suggests that neural networks utilized for phonological and semantic language processing in the nonnative language may not be as similar as those in the primary language.

Adult↗

PubMed2005

Atypical language lateralization and early linguistic development in children with focal brain lesions.

The effects of congenital, unilateral, focal brain lesions on early linguistic development and hemispheric lateralization for language were investigated longitudinally in 24 preschool children with hemiplegia (14 males, 10 females), 12 with left hemisphere damage (LHD) and 12 with right hemisphere damage (RHD). A comprehensive linguistic assessment was performed at 2 and 3 years of life; cerebral lateralization for language was measured by the Fused Dichotic Words Listening Test. An early left-side specificity for language was indicated by the presence of lexical and grammatical delay in most children with LHD. In the dichotic listening test all 12 children with LHD showed a shift of language lateralization from the left to the right hemisphere. Atypical lateralization coefficients (lambda), i.e. values falling more than two standard deviations from the mean of a normative sample, were associated with a delay in lexical and grammatical development, especially after LHD. In addition, cortical-subcortical-periventricular lesions rather than solely periventricular damage, and larger lesions rather than small, were associated with the most atypical lateralization coefficients, irrespective of lesion side. Results of this study suggest that language and lateralization data are closely related and that reallocation of language functions in alternative regions of the brain has a cost in terms of a slow rate of language acquisition.

Brain Diseases↗