Factor structure and clinical applicability of new semantic tasks in Alzheimer's disease and aphasia

Semantic tasks are frequently used when examining language functions in patients with acquired disorders such as Alzheimer's disease (AD) and aphasia. Little is known about the possible covariation between different types of tasks or their factor structure in healthy adults. Additionally, few studies have examined semantic task performances in different patient groups. The aims of this data-driven study were to examine the factor structure in a wide range of semantic tasks in healthy older adults, the possible differences in factor variables between healthy controls, patients with AD and patients with stroke aphasia, as well as the clinical applicability of tasks in differentiating the two patient groups from controls. Participants included 59 healthy older adults, 13 patients with AD and 14 patients with aphasia. The results indicated a four-factor solution for the semantic task variables: (1) the Semantic association factor, (2) the Time factor, (3) the Verbal factor and (4) the Synonym factor. The Verbal factor was the only distinguishing factor between the two patient groups. Three factors reliably discriminated between the controls and the AD patients, and the Verbal factor reliably discriminated between the controls and the aphasia patients. In addition, a few single task variables showed outstanding discrimination for both patient groups. This study supports the notions of semantic tasks tapping into more than one cognitive subcomponent and a more general semantic impairment in AD than in aphasia. In clinical assessment, choosing appropriate semantic tasks is crucial in order to reliably detect the characteristics of the impairment.

Influence of Respiratory Tract Infections on Vocabulary Growth in Relation to Child's Sex: The STEPS Study

Common health issues have been less examined in studies of early language development, particularly in relation to the child's sex. Respiratory tract infections, often complicated by acute otitis media, are common in children during the first years of life, when early vocabulary development takes place. The present study, conducted in Finland, aimed to investigate whether possible associations between recurrent respiratory tract infections, background factors, and vocabulary growth differ in boys and girls aged 13 to 24 months. The participants (N = 462, 248 boys and 214 girls) were followed for respiratory tract infections and acute otitis media from 0 to 23 months of age. The parents completed daily symptom diaries of respiratory symptoms, physician visits, and diagnoses. The expressive vocabulary was measured with parental reports. We found that recurrent respiratory tract infections were not associated with slower vocabulary development in boys or girls. In fact, boys with recurrent respiratory tract infections had more vocabulary growth during the second year than boys who were less sick. We found that vocabulary growth was associated differently with respiratory tract infections and background factors as a function of the child's sex. The vocabulary growth of boys seems to be more influenced by environmental factors than that of girls.

Recurrent respiratory tract infections or acute otitis media were not a risk factor for vocabulary development in children at 13 and 24 months of age

AIM

This study examined associations between recurrent respiratory tract infections (RTI) and acute otitis media (AOM) during the first one and two years of life and vocabulary size at 13 and 24 months of age.

METHODS

We studied 646 children born between January 2008 and April 2010 and followed up from birth to two years of age with daily diary and study clinic visits during RTIs and AOM. The families were recruited from maternity health care clinics or delivery wards in south-west Finland. Parents completed the MacArthur Communicative Development Inventory at 13 and 24 months, and the vocabularies of children with high rates of RTIs or AOM were compared to children without recurrent issues.

RESULTS

Of the 646 children, 9.6% had recurrent RTIs and 9.9% had recurrent AOM from 0 to 24 months. Children with high rates of RTIs or AOM did not have smaller vocabularies than children without recurrent RTIs or AOM. Girls had larger vocabularies and higher parental socioeconomic status was associated with a larger expressive vocabulary at 24 months.

CONCLUSION

The child's gender and parental socioeconomic status played a more critical role in vocabulary development in the first two years than a high burden of RTIs or AOM.

Event-Related Potentials Reflect Deficits in Lexical Access: The N200 in Prematurely Born School-Aged Children

OBJECTIVES

Children born preterm have a high prevalence of neurocognitive deficits early in life. We examined whether the neural correlates of lexical access are atypical in 9-year-old children born preterm, and whether the findings of acoustic mapping correlate with language- and attention-related skills.

PATIENTS AND METHODS

The subjects were fourteen 9-year-old children born preterm and 14 full-term, typically developing controls. Two auditory event-related potential (ERP) components, the N200 and the N400, were used to assess discrimination response and word recognition. A set of behavioral tests (naming ability, auditory attention, phonological processing, pseudoword repetition, and comprehension of instructions) was performed, and the results were compared with the amplitudes, latencies, and scalp distribution of the ERP results.

RESULTS

In prematurely born children, neurophysiological deficits were associated with difficulties in auditory discrimination. The N200 amplitude correlated significantly with auditory attention and pseudoword repetition. The scalp distribution of both the N200 and the N400 was broader in children born preterm than in the controls. Low scores in the neuropsychological tasks referred to difficulties in auditory processing and memory.

CONCLUSIONS

Children born preterm have difficulties in lexical access together with memory- and attention-related processes, which may have a longstanding impact on their school outcomes and academic skills.

Identification of biological and environmental risk factors for language delay: The Let's Talk STEPS study

The aim of this population-based study was to identify demographic factors for language delays at an early age. The risk analysis covered 11 biological and 8 environmental factors. The mothers' concerns regarding language development were also examined. A total of 226 children from a Finnish cohort study were invited to participate in language assessments at 36 months. The test results for word finding and language comprehension were compared with parental questionnaires about children's vocabulary at 13 and 24 months. Regression analysis revealed that the father's social class (t=-2.79, p=0.006) and working full time (t=-2.86, p=0.005) significantly predicted children's language delay. In addition, language comprehension was significantly predicted by the mother's social class (t=-2.06, p=0.041) and by gender, with an advantage to girls (t=-2.71, p=0.008). Vocabulary at 24 months was a powerful predictor for lexical development (t=4.58, p<0.0001) and language comprehension (t=4.85, p<0.0001) at 36 months. Mothers' concerns were correlated with children's limited lexicons as early as 24 months (r=0.31, p<0.0001) and poor language comprehension (r=-0.35, p<0.0001) at 36 months. Mothers were especially concerned if the parents needed special education during school years. At the population-level, gender was the most powerful biological factor in predicting language delays. Similarly, both parents' social status had predictive value for the child's language development. In addition, it was found that the mother's concern about her child's slow language acquisition should be taken into account when making decisions regarding special support.

Electrophysiological correlates of cross-linguistic semantic integration in hearing signers: N400 and LPC

We explored semantic integration mechanisms in native and non-native hearing users of sign language and non-signing controls. Event-related brain potentials (ERPs) were recorded while participants performed a semantic decision task for priming lexeme pairs. Pairs were presented either within speech or across speech and sign language. Target-related ERP responses were subjected to principal component analyses (PCA), and neurocognitive basis of semantic integration processes were assessed by analyzing the N400 and the late positive complex (LPC) components in response to spoken (auditory) and signed (visual) antonymic and unrelated targets. Semantically-related effects triggered across modalities would indicate a similar tight interconnection between the signers׳ two languages like that described for spoken language bilinguals. Remarkable structural similarity of the N400 and LPC components with varying group differences between the spoken and signed targets were found. The LPC was the dominant response. The controls׳ LPC differed from the LPC of the two signing groups. It was reduced to the auditory unrelated targets and was less frontal for all the visual targets. The visual LPC was more broadly distributed in native than non-native signers and was left-lateralized for the unrelated targets in the native hearing signers only. Semantic priming effects were found for the auditory N400 in all groups, but only native hearing signers revealed a clear N400 effect to the visual targets. Surprisingly, the non-native signers revealed no semantically-related processing effect to the visual targets reflected in the N400 or the LPC; instead they appeared to rely more on visual post-lexical analyzing stages than native signers. We conclude that native and non-native signers employed different processing strategies to integrate signed and spoken semantic content. It appeared that the signers׳ semantic processing system was affected by group-specific factors like language background and/or usage.

Cohort profile: Steps to the healthy development and well-being of children (the STEPS Study)

The STEPS Study aims to search for the precursors and causes of problems in child health and well-being by using a multidisciplinary approach. The cohort consists of all mothers (Finnish or Swedish speaking) who had live deliveries in the Hospital District of Southwest Finland from January 2008 to April 2010 and their children (n=9811 mothers, n=9936 children). Of these, 1797 mothers and their 1827 children were recruited to an intensive follow-up group during the first trimester of pregnancy or soon after delivery. Information about the whole study cohort is based on pregnancy follow-up data from maternity clinics, National Longitudinal Census Files and child welfare clinics. Data from multiple sources are used to obtain a picture of the overall well-being of the child and the family. After birth, study visits include several clinical examinations. Collaboration is encouraged, and access to the data will be available when the data set is complete.

Deficient language acquisition in children with single suture craniosynostosis and deformational posterior plagiocephaly

PURPOSE

This study examined early language acquisition in children with single suture craniosynostosis (SSC) and in children with deformational posterior plagiocephaly. Our purpose was to determine whether infants with SSC have normal language acquisition at the age of 3 years, and whether infants with deformational posterior plagiocephaly demonstrate parallel development when compared with children with SSC.

METHODS

The study population includes 61 infants. Twenty of them had synostosis of the sagittal suture, 12 synostosis of other suture and 29 deformational posterior plagiocephaly. Forty-nine of them were operated on a mean age of 10.6 months, and 12 were non-operated children with deformational posterior plagiocephaly. Language skills of participants were prospectively evaluated at the mean age of 3 years 4 months.

RESULTS

About one half of the subjects (49%) had normal linguistic development, 30% had slight developmental problems and 21% had severe disorders in speech-language-related skills. These figures showed the prevalence of severe language disorders to be three times higher in our study population when compared with the general population. Children with sagittal synostosis managed better in all language skills compared with other types of SSC. Defective language development was found in deformational posterior plagiocephaly, both operated and non-operated.

CONCLUSIONS

We found a noticeable developmental risk for specific language impairment in children with nonsyndromic SSC, and that the deviant language development is observable already in early infancy. Contrary to previous beliefs, the developmental risk for defective language development in deformational posterior plagiocephaly was found in both operated and non-operated subjects.

Semantic representation of speech and signing in codas and interpreters: Behavioral patterns of interaction

Lexical representation of natural signed language in interrelation to speech was explored by analyzing hearing signers’ and non-signers’ behavioral response patterns to a within- and across-language semantic decision task. Native hearing signers, non-native sign language interpreters and sign-naïve controls had to decide whether two lexical items (speech-speech or speech-sign) were antonymic or not. Aim of this study was to examine whether sign language and speech are interacting with each other on the semantic level. Response patterns indicate semantic effects on within-language conditions in all three groups, whereas clear semantically motivated responses to cross-language conditions were only apparent in the two signing groups, though with different functional distribution. Our data demonstrate how tightly signing and speech can be interconnected at the semantic level. This linkage is at least partly learned and connected with language usage.

Processing of affective speech prosody is impaired in Asperger syndrome

Many people with the diagnosis of Asperger syndrome (AS) show poorly developed skills in understanding emotional messages. The present study addressed discrimination of speech prosody in children with AS at neurophysiological level. Detection of affective prosody was investigated in one-word utterances as indexed by the N1 and the mismatch negativity (MMN) of auditory event-related potentials (ERPs). Data from fourteen boys with AS were compared with those for thirteen typically developed boys. These results suggest atypical neural responses to affective prosody in children with AS and their fathers, especially over the RH, and that this impairment can already be seen at low-level information processes. Our results provide evidence for familial patterns of abnormal auditory brain reactions to prosodic features of speech.

Similarities in the phenotype of the auditory neural substrate in children with Asperger syndrome and their parents

Asperger syndrome (AS) is a developmental disorder of brain function characterized by deficits in social interaction including difficulties in understanding emotional expressions. Children with AS share some of the behavioural characteristics with their parents and AS seems to run particularly in the male members of the same families. The aim of the present study was to determine whether similarities could be found between children with AS and their parents at central auditory processing. It was found that in children with AS the sound encoding, as reflected by the exogenous components of event-related potentials, was similarly abnormal as in both their mothers and fathers. However, their abnormal cortical auditory discrimination, as indexed by the prolonged latency of the mismatch negativity, resembled that of their fathers but not that of their mothers. The present results suggest that complex genetic mechanisms may contribute to auditory abnormalities encountered in children with AS.

Neurophysiologic correlates of deficient phonological representations and object naming in prematurely born children

OBJECTIVE

The aim of this follow-up study was to evaluate the development of object naming ability and auditory processing in prematurely born children. Furthermore, we investigated whether the mismatch negativity (MMN) parameters at the age of 4 years correlate with the MMN parameters and naming ability at the age of 6 years.

METHODS

Twelve very low birth weight (VLBW) preterm children (mean age 5 years 7 months) and matched controls were studied. Object naming was measured by the Boston naming test. Auditory event-related potentials (ERPs), especially the MMN, were recorded for Finnish syllables (standard /taa/; deviants /ta/ and /kaa/) in an oddball paradigm.

RESULTS

VLBW preterm children scored significantly lower in the object naming test than their controls. The MMN amplitude for consonant change was significantly smaller in the preterm group compared to the controls. The MMN amplitude at the age of 4 years correlated with the MMN amplitude at the age of 6 years. Furthermore, absence of the MMN at the age of 4 years predicted naming difficulties at the age of 6 years.

CONCLUSIONS

VLBW preterm children with a difficulty to preattentively discriminate changes in syllables, as indexed by the diminished change detection response, MMN, seem to have sustained naming difficulty. Therefore, it is reasonable to record the MMN along with the language development from infancy, in order to identify the children at risk for language deficiencies and to provide appropriate rehabilitation.

Early and late mismatch negativity elicited by words and speech-like stimuli in children

In auditory perception the brain's attentional and preattentional mechanisms select certain stimuli for preferential processing and filter out irrelevant input. This study investigated nonattentive auditory processing in children. Event-related potentials (ERPs) provide a means to study neural correlates related to language and speech-sound processing. Mismatch negativity (MMN) is an ERP wave that indicates attention-independent perceptual change detection. In this study cortical ERPs were elicited by complex tones, naturally spoken words, and pseudowords, with each stimulus type containing equal acoustical elements. Tones elicited a bifurcated mismatch negativity (MMN), with early MMN (peaking at 150-200 ms) being more dominant. On the other hand, words elicited a strong late MMN, peaking at about 400-450 ms after stimulus onset. The MMN wave form was significantly weaker for pseudowords than for words. The late MMN wave, especially for word differences, was found to reflect summating MMN generators and memory trace formation on gestalt bases. Results suggest that the auditory processing, even nonattended, is highly associated with the cognitive meaning of the stimuli.

Mismatch negativity and late discriminative negativity in investigating speech perception and learning in children and infants

For decades, behavioral methods, such as the head-turning or sucking paradigms, have been the primary tools to investigate speech perception and learning of a language in infancy. Recently, however, new methods provided by event-related potentials have emerged. These are called mismatch negativity (MMN) and late discriminative negativity (LDN). MMN, the brain's automatic change-detection response in audition, has been intensively used in adults in both basic and clinical studies for longer than 20 years. LDN, on the other hand, was only recently discovered. There seem to be many differences between these two responses. MMN is developmentally quite stable and can be obtained even from preterm infants. LDN, however, can be obtained most reliably from young children, and its amplitude decreases as a function of age. New data suggest that both of these responses have a special role in language processing, although both of them can also be elicited by nonspeech stimuli.

Automatic auditory word perception as measured by 40 Hz EEG responses

OBJECTIVES

Here we report the existence of automatic speech perception in man, revealed by 40 Hz EEG responses.

METHODS

We presented to Finnish subjects the Finnish word /tu:li/(wind) as the standard stimulus and another Finnish word /tuli/(fire) as the deviant stimulus using a passive auditory oddball task. The experiment was also conducted with pseudowords as stimuli.

RESULTS

We observed a global significant increase in 40 Hz EEG power at 600 ms after stimulus onset for words, but not for pseudowords.

CONCLUSIONS

Our results indicate that the memory representation of the standard verbal stimuli, even if unattended, might not merely be based on the physical features of the stimuli: if a semantic representation exists, then the brain processes it pre-attentively.

Abnormal frequency mismatch negativity in mentally retarded children and in children with developmental dysphasia

The auditory event-related potential waveform termed "mismatch negativity" was examined in 12 mentally retarded children with delayed development of speech and language (aged 5-8 years) and in 13 children with developmental dysphasia (aged 5-9 years). The mismatch negativity waves were elicited with pure sine-wave tone stimuli using the oddball paradigm. We measured the peak latency and peak amplitude of mismatch negativity responses to frequency (500/553 Hz) difference. The mismatch negativity patterns were compared with those of 10 children with normal development of linguistic skills (aged 5-9 years). In both the mentally retarded and dysphasic groups, the peak amplitude of the frequency mismatch negativity was significantly attenuated when compared with the control group, but no significant difference was observed between the mentally retarded and dysphasic groups. Attenuated frequency mismatch negativity was related to impairment of linguistic skills irrespective of the child's cognitive skills. Because the mismatch negativity response reflects central auditory processing and is modal specific for auditory stimuli, this change-specific response can serve as an objective tool to elucidate central auditory deficits in children.

Attenuated auditory event-related potential (mismatch negativity) in children with developmental dysphasia

An attention-independent negative wave-form termed 'mismatch negativity' (MMN) of the auditory event-related potentials (ERPs) was studied in ten children (3-6 years) with developmental dysphasia and in fourteen control children (3-7 years) with normal speech and language development. The MMNs were elicited with pure sine tone stimuli using the oddball paradigm. The peak latency and peak amplitude of MMN response to frequency (500/553 H2) difference was measured. The grand average amplitude of frequency MMN was significantly attenuated in dysphasic children as compared to controls, but no significant difference was observed in the latency of peak frequency MMN. The results indicate that dysphasic children have a defect in automatic auditory processing of frequency differences. Because the MMN response reflects central auditory processing and is modal specific for auditory stimuli we argue that the MMN method can serve as an objective tool to assess central auditory deficits in children.

Practical issues in the clinical application of mismatch negativity

The mismatch negativity (MMN) recordings provide an objective measure of the preattentive, automatic auditory discrimination function. This article deals with issues central to the recording of the MMN and the interpretation of the results for clinical and electrodiagnostic purposes. The methods of acquiring as pure an MMN response as possible, i.e., one not contaminated by auditory cortical responses reflecting other functions, are discussed first. Second, other technical questions associated with the recording are reported on, e.g., what MMN parameters should be recorded and how, what is the smallest recordable MMN response, and what is the repeatability of the MMN recordings. Then, the effect of various physiological factors on the MMN (age, alertness, gender, topographic distribution of the MMN) is considered. The correlation between auditory discrimination performance and the MMN amplitude, observed in normal population, is dealt with. Finally, there is a short concluding overview on clinical findings of MMN recordings and discussion on their electrodiagnostic applications.

Auditory ERP components and mismatch negativity in dysphasic children

Auditory event-related potentials (ERPs) and especially the mismatch negativity component (MMN) were examined in 14 dysphasic and 12 normal children (aged 7-13). The ERPs were elicited by sine tone stimuli using the passive oddball paradigm and short ISI (350 msec). We measured the peak latency and peak amplitude of MMN responses to frequency (500/553 Hz) and duration (50/110 msec or 50/500 msec) differences. In the dysphasic group the peak amplitude of the frequency MMN was significantly attenuated. The duration MMN showed a significant difference between the two groups only for stimuli with highly contrasting values (50/500 msec). In normal subjects we found a negative correlation between the peak latency of the frequency MMN and age. The maturational changes of long-latency ERPs were non-significant in dysphasic children. Evidence of differences in hemispheric asymmetry between the two groups was observed.