Semantic processing in children with Cochlear Implants: A review of current N400 studies and recommendations for future research.

Deaf and hard of hearing children with cochlear implants (CI) often display impaired spoken language skills. While a large number of studies investigated brain responses to sounds in this population, relatively few focused on semantic processing. Here we summarize and discuss findings in four studies of the N400, a cortical response that reflects semantic processing, in children with CI. A study with auditory target stimuli found N400 effects at delayed latencies at 12 months after implantation, but at 18 and 24 months after implantation effects had typical latencies. In studies with visual target stimuli N400 effects were larger than or similar to controls in children with CI, despite lower semantic abilities. We propose that in children with CI, the observed large N400 effect reflects a stronger reliance on top-down predictions, relative to bottom-up language processing. Recent behavioral studies of children and adults with CI suggest that top-down processing is a common compensatory strategy, but with distinct limitations such as being effortful. A majority of the studies have small sample sizes (N < 20), and only responses to image targets were studied repeatedly in similar paradigms. This precludes strong conclusions. We give suggestions for future research and ways to overcome the scarcity of participants, including extending research to children with conventional hearing aids, an understudied group.

Selective Auditory Attention Associated With Language Skills but Not With Executive Functions in Swedish Preschoolers.

Associations between language and executive functions (EFs) are well-established but previous work has often focused more on EFs than on language. To further clarify the language-EF relationship, we assessed several aspects of language and EFs in 431 Swedish children aged 4-6, including selective auditory attention which was measured in an event-related potential paradigm. We also investigated potential associations to age, socioeconomic status (SES), bi-/multilingualism, sex and aspects of preschool attendance and quality. Language and EFs correlated weakly to moderately, indicating that relying on measures of vocabulary alone may overestimate the strength of the language-EF relationship. Contrary to predictions, we found no correlations between selective attention and EFs. There were however correlations between morphosyntactic accuracy and selective auditory attention which is in line with previous work and suggests a specific link between morphosyntax and the ability to suppress irrelevant stimuli. In Sweden, socioeconomic differences are rather small and preschool is universally available, but nevertheless, aspects of parental SES predicted children's performance on all measures. Bi-/multilingual children performed lower on language also when controlling for SES, highlighting the need for interventions to reduce inequalities in educational outcomes already in preschool. A female advantage was found for both language and EFs, whereas preschool attendance and quality were not significantly related to outcome measures. Future work should include longitudinal studies of language and EF development, include children from diverse SES backgrounds and contribute toward a theoretical framework that further clarifies the language-EF relationship.

Auditory event-related potentials and mismatch negativity in children with hearing loss using hearing aids or cochlear implants - A three-year follow-up study.

OBJECTIVES: The primary aim was to examine how event-related potentials (ERPs) and mismatch negativity (MMN) change and develop over time among children with hearing loss (HL) using hearing aids (HAs) or cochlear implants (CIs). Children with normal hearing (NH) were tested as a reference group. METHODS: This three-year follow-up study included 13 children with sensorineural HL (SNHL); 7 children using bilateral HAs and 6 children using CIs; and 10 children with NH as a reference group. ERPs were recorded at baseline and after three years. At time for the original study the children were approximately 5-8 years old and at the follow-up study 8-11 years old. ERP recordings and data processing were identical in both sessions. A standard stimulus alternated with five different deviants (gap, intensity, pitch, location and duration), presented in a pseudorandom sequence, thus following the multi-feature paradigm, Optimum-1. MMN was calculated from the average ERP of each deviant minus the standard stimuli. Repeated measures ANOVA was used for the statistical analyses and the results were based on samples within a specific time interval; 80-224 ms. RESULTS: There was a statistically significant difference in the obligatory responses between the NH and HA groups at baseline, but this difference disappeared after three years in our follow-up study. The children with HA also showed a significant difference in mean ERP at baseline compared to follow-up, and significant differences between the deviants at follow-up but not at baseline. This suggests an improvement over time among the children with HAs. On the other hand, the children with CIs did not differ from the NH children at baseline, but after three years their mean ERP was significantly lower compared to both the children with HA and NH, indicating a reduced development of the central auditory system in this age span among the children with CIs. Regarding MMN, there was an interaction between the duration deviant and time for the children with HA, also indicating a possible improvement over time among the HA children. CONCLUSIONS: This three-year follow-up study shows neurophysiological differences between children with HL and children with NH. The results suggest a delay in the central auditory processing among the HA children compared to children with NH, but a possible catch-up, over time, and this potential may be worth to be utilized. Regarding the CI children, similar improvement in this age span is missing, meaning there are differences between the subgroups of children with HL, i.e. the children with HAs vs. CIs. The results highlight the importance of distinguishing between subgroups of children with HL in further research.

N1 Repetition-Attenuation for Acoustically Variable Speech and Spectrally Rotated Speech.

The amplitude of the event-related N1 wave decreases with repeated stimulation. This repetition-attenuation has not previously been investigated in response to variable auditory stimuli, nor has the relative impact of acoustic vs. perceptual category repetition been studied. In the present study, N1 repetition-attenuation was investigated for speech and spectrally rotated speech with varying degrees of acoustic and perceptual category variation. In the speech condition, participants (n = 19) listened to stimulus trains consisting of either the same vowel exemplar (no variability condition), different exemplars of the same vowel (low variability condition), or different exemplars of two different vowels (high variability condition). In the rotated speech condition, the spectrally rotated counterparts of the vowels were presented. Findings show N1 repetition-attenuation in the face of acoustic and perceptual category variability, but no impact of the degree of variability on the degree of N1 attenuation. Speech stimuli resulted in less attenuation than the acoustically matched non-speech stimuli, which is in line with previous findings. It remains unclear if the attenuation of the N1 wave is reduced as a result of stimuli being perceived as belonging to perceptual categories or as a result of some other characteristic of speech.

Computer-assisted reading intervention for children with hearing impairment using cochlear implants: Effects on auditory event-related potentials and mismatch negativity.

OBJECTIVES: The primary aim was to find out whether a computer-assisted reading intervention program with a phonic approach can affect event-related (ERPs) and mismatch negativity (MMN) in hearing impaired (HI) children using cochlear implants (CIs). METHODS: This study involved a test group of 15 HI children with CIs and a control group of 14 normal hearing (NH) children. The children were 4 years and 10 months to 8 years and 1 month old. ERPs were recorded immediately before and after 4 weeks of training with a computer-assisted reading intervention, GraphoGame. A multi-feature paradigm, Optimum-1, was used, i.e. a standard stimulus alternated with five different deviants: gap intensity, pitch, location and duration. MMN was calculated from the mean amplitude ERP of each deviant minus the standard stimulus response in a specific time interval, 80 - 224 ms. Repeated measures ANOVA was used for the statistical analysis. RESULTS: The results did not show any significant changes with the computerassisted training in the ERPs and MMNs among the HI children with CIs. The presence of both MMN and a positive mismatch response (pMMR), which might reflect an immaturity, complicates interpreting the results in this age group. Individually, there was a mix of MMNs and pMMRs among all participants, pre and post training, and the change of each deviant after intervention was not predictable. CONCLUSIONS: There are no significant changes in ERP or MMN after intervention, however lack of significances must be interpreted with caution. Besides the presence of both MMNs and pMMRs, only modest changes are to be expected on an individual basis and small samples hinder making statistical conclusions regarding the training's effects. The study contributes to some more descriptive pieces of ERPs and MMNs among the HI children with CIs. The issues of MMN and pMMR are highlighted.

A randomized controlled trial to examine the effect of two teaching methods on preschool children's language and communication, executive functions, socioemotional comprehension, and early math skills.

BACKGROUND: During the preschool years, children's development of skills like language and communication, executive functions, and socioemotional comprehension undergo dramatic development. Still, our knowledge of how these skills are enhanced is limited. The preschool contexts constitute a well-suited arena for investigating these skills and hold the potential for giving children an equal opportunity preparing for the school years to come. The present study compared two pedagogical methods in the Swedish preschool context as to their effect on language and communication, executive functions, socioemotional comprehension, and early math. The study targeted children in the age span four-to-six-year-old, with an additional focus on these children's backgrounds in terms of socioeconomic status, age, gender, number of languages, time spent at preschool, and preschool start. An additional goal of the study was to add to prior research by aiming at disentangling the relationship between the investigated variables. METHOD: The study constitutes a randomized controlled trial including 18 preschools and 29 preschool units, with a total of 431 children, and 98 teachers. The interventions lasted for 6 weeks, preceded by pre-testing and followed by post-testing of the children. Randomization was conducted on the level of preschool unit, to either of the two interventions or to control. The interventions consisted of a socioemotional and material learning paradigm (SEMLA) and a digitally implemented attention and math training paradigm (DIL). The preschools were further evaluated with ECERS-3. The main analysis was a series of univariate mixed regression models, where the nested structure of individuals, preschool units and preschools were modeled using random variables. RESULTS: The result of the intervention shows that neither of the two intervention paradigms had measurable effects on the targeted skills. However, there were results as to the follow-up questions, such as executive functions predicting all other variables (language and communication, socioemotional comprehension, and math). Background variables were related to each other in patterns congruent with earlier findings, such as socioeconomic status predicting outcome measures across the board. The results are discussed in relation to intervention fidelity, length of intervention, preschool quality, and the impact of background variables on children's developmental trajectories and life prospects.

Computer-assisted reading intervention for children with sensorineural hearing loss using hearing aids: Effects on auditory event-related potentials and mismatch negativity.

OBJECTIVES: The primary aim was to investigate whether computer-assisted reading intervention somehow can affect event-related potentials (ERP) and mismatch negativity (MMN) in hearing impaired (HI) children with hearing aids (HAs) and normal hearing (NH) children. METHODS: The study included 15 HI children with sensorineural hearing loss (SNHL) using bilateral HAs and 14 NH children as a reference group; all children between the ages of 5 and 8. A multi-feature MMN-paradigm, Optimum-1, with a standard stimulus alternating with 5 different deviants was used. ERPs were recorded pre and post intervention, i.e. one month of repeatedly computer-assisted training (GraphoGame). MMN was calculated from the average ERP of each deviant minus standard. Data were based on samples within a specific time interval, 80-224 ms, and repeated measures ANOVA was used to analyze possible interactions. RESULTS: There was a significant difference between groups before training, though, the mean obligatory responses or MMN was not statistically significantly different before versus after training, neither among the NH nor the HI children. Further, the HI children did generally achieve lower levels in GraphoGame compared to the NH children. Altogether, our findings indicate differences between the groups and that training may affect the neurophysiological processing in the brain, gaining the HI children. Both MMN and positive mismatch response (pMMR) were seen among both the HA and NH children, irrespective to deviant type. Individually, changes of the MMN and pMMR after training seem unpredictable. CONCLUSION: There are statistically significant differences in both the obligatory responses in ERP and the MMNs between the NH and HI groups before the computer-assisted training. Though, these differences disappear after the intervention. This suggests possible training effects regarding the central auditory processing among the HI children.

A protocol for a three-arm cluster randomized controlled superiority trial investigating the effects of two pedagogical methodologies in Swedish preschool settings on language and communication, executive functions, auditive selective attention, socioemotional skills and early maths skills.

BACKGROUND: During the preschool years, children develop abilities and skills in areas crucial for later success in life. These abilities include language, executive functions, attention, and socioemotional skills. The pedagogical methods used in preschools hold the potential to enhance these abilities, but our knowledge of which pedagogical practices aid which abilities, and for which children, is limited. The aim of this paper is to describe an intervention study designed to evaluate and compare two pedagogical methodologies in terms of their effect on the above-mentioned skills in Swedish preschool children. METHOD: The study is a randomized control trial (RCT) where two pedagogical methodologies were tested to evaluate how they enhanced children's language, executive functions and attention, socioemotional skills, and early maths skills during an intensive 6-week intervention. Eighteen preschools including 28 units and 432 children were enrolled in a municipality close to Stockholm, Sweden. The children were between 4;0 and 6;0 years old and each preschool unit was randomly assigned to either of the interventions or to the control group. Background information on all children was collected via questionnaires completed by parents and preschools. Pre- and post-intervention testing consisted of a test battery including tests on language, executive functions, selective auditive attention, socioemotional skills and early maths skills. The interventions consisted of 6 weeks of intensive practice of either a socioemotional and material learning paradigm (SEMLA), for which group-based activities and interactional structures were the main focus, or an individual, digitally implemented attention and math training paradigm, which also included a set of self-regulation practices (DIL). All preschools were evaluated with the ECERS-3. DISCUSSION: If this intervention study shows evidence of a difference between group-based learning paradigms and individual training of specific skills in terms of enhancing children's abilities in fundamental areas like language, executive functions and attention, socioemotional skills and early math, this will have big impact on the preschool agenda in the future. The potential for different pedagogical methodologies to have different impacts on children of different ages and with different backgrounds invites a wider discussion within the field of how to develop a preschool curriculum suited for all children.

Using a multi-feature paradigm to measure mismatch responses to minimal sound contrasts in children with cochlear implants and hearing aids.

Our aim was to explore whether a multi-feature paradigm (Optimum-1) for eliciting mismatch negativity (MMN) would objectively capture difficulties in perceiving small sound contrasts in children with hearing impairment (HI) listening through their hearing aids (HAs) and/or cochlear implants (CIs). Children aged 5-7 years with HAs, CIs and children with normal hearing (NH) were tested in a free-field setting using a multi-feature paradigm with deviations in pitch, intensity, gap, duration, and location. There were significant mismatch responses across all subjects that were positive (p-MMR) for the gap and pitch deviants (F(1,43) = 5.17, p = 0.028 and F(1,43) = 6.56, p = 0.014, respectively) and negative (MMN) for the duration deviant (F(1,43) = 4.74, p = 0.035). Only the intensity deviant showed a significant group interaction with MMN in the HA group and p-MMR in the CI group (F(2,43) = 3.40, p = 0.043). The p-MMR correlated negatively with age, with the strongest correlation in the NH subjects. In the CI group, the late discriminative negativity (LDN) was replaced by a late positivity with a significant group interaction for the location deviant. Children with severe HI can be assessed through their hearing device with a fast multi-feature paradigm. For further studies a multi-feature paradigm including more complex speech sounds may better capture variation in auditory processing in these children.

Semantic Processing in Deaf and Hard-of-Hearing Children: Large N400 Mismatch Effects in Brain Responses, Despite Poor Semantic Ability.

Difficulties in auditory and phonological processing affect semantic processing in speech comprehension for deaf and hard-of-hearing (DHH) children. However, little is known about brain responses related to semantic processing in this group. We investigated event-related potentials (ERPs) in DHH children with cochlear implants (CIs) and/or hearing aids (HAs), and in normally hearing controls (NH). We used a semantic priming task with spoken word primes followed by picture targets. In both DHH children and controls, cortical response differences between matching and mismatching targets revealed a typical N400 effect associated with semantic processing. Children with CI had the largest mismatch response despite poor semantic abilities overall; Children with CI also had the largest ERP differentiation between mismatch types, with small effects in within-category mismatch trials (target from same category as prime) and large effects in between-category mismatch trials (where target is from a different category than prime), compared to matching trials. Children with NH and HA had similar responses to both mismatch types. While the large and differentiated ERP responses in the CI group were unexpected and should be interpreted with caution, the results could reflect less precision in semantic processing among children with CI, or a stronger reliance on predictive processing.

Segmental and suprasegmental properties in nonword repetition--an explorative study of the associations with nonword decoding in children with normal hearing and children with bilateral cochlear implants.

This study explored nonword repetition (NWR) and nonword decoding in normal-hearing (NH) children and in children with bilateral cochlear implants (CI). Participants were 11 children, with CI, 5:0-7:11 years (M = 6.5 years), and 11 NH children, individually age-matched to the children with CI. This study fills an important gap in research, since it thoroughly describes detailed aspects of NWR and nonword decoding and their possible associations. All children were assessed after having practiced with a computer-assisted reading intervention with a phonics approach during four weeks. Results showed that NH children outperformed children with CI on the majority of aspects of NWR. The analysis of syllable number in NWR revealed that children with CI made more syllable omissions than did the NH children, and predominantly in prestressed positions. In addition, the consonant cluster analysis in NWR showed significantly more consonant omissions and substitutions in children with CI suggesting that reaching fine-grained levels of phonological processing was particularly difficult for these children. No significant difference was found for nonword-decoding accuracy between the groups, as measured by whole words correct and phonemes correct, but differences were observed regarding error patterns. In children with CI phoneme, deletions occurred significantly more often than in children with NH. The correlation analysis revealed that the ability to repeat consonant clusters in NWR had the strongest associations to nonword decoding in both groups. The absence of as frequent significant associations between NWR and nonword decoding in children with CI compared to children with NH suggest that these children partly use other decoding strategies to compensate for less precise phonological knowledge, for example, lexicalizations in nonword decoding, specifically, making a real word of a nonword.

Computer-assisted reading intervention with a phonics approach for children using cochlear implants or hearing aids.

The present study examined computer-assisted reading intervention with a phonics approach for deaf and hard of hearing (DHH) children in Sweden using cochlear implants or hearing aids, or a combination of both. The study included 48 children, 5, 6 and 7 years of age. Sixteen children with normal hearing (NH) served as a reference group. The first purpose of the study was to compare NH and DHH children's reading ability at pre and post-intervention. The second purpose was to investigate effects of the intervention. Cognitive and demographic factors were analyzed in relation to reading improvement. Results showed no statistically significant difference for reading ability at the group level, although NH children showed overall higher reading scores at both test points. Age comparisons revealed a statistically significant higher reading ability in the NH 7-year-olds compared to the DHH 7-year-olds. The intervention proved successful for word decoding accuracy, passage comprehension and as a reduction of nonword decoding errors in both NH and DHH children. Reading improvement was associated with complex working memory and phonological processing skills in NH children. Correspondent associations were observed with visual working memory and letter knowledge in the DHH children. Age was the only demographic factor that was significantly correlated with reading improvement. The results suggest that DHH children's beginning reading may be influenced by visual strategies that might explain the reading delay in the older children.

Computer-assisted training of phoneme-grapheme correspondence for children who are deaf and hard of hearing: effects on phonological processing skills.

OBJECTIVE: Examine deaf and hard of hearing (DHH) children's phonological processing skills in relation to a reference group of children with normal hearing (NH) at two baselines pre intervention. Study the effects of computer-assisted phoneme-grapheme correspondence training in the children. Specifically analyze possible effects on DHH children's phonological processing skills. METHODS: The study included 48 children who participated in a computer-assisted intervention study, which focuses on phoneme-grapheme correspondence. Children were 5, 6, and 7 years of age. There were 32 DHH children using cochlear implants (CI) or hearing aids (HA), or both in combination, and 16 children with NH. The study had a quasi-experimental design with three test occasions separated in time by four weeks; baseline 1 and 2 pre intervention, and 3 post intervention. Children performed tasks measuring lexical access, phonological processing, and letter knowledge. All children were asked to practice ten minutes per day at home supported by their parents. RESULTS: NH children outperformed DHH children on the majority of tasks. All children improved their accuracy in phoneme-grapheme correspondence and output phonology as a function of the computer-assisted intervention. For the whole group of children, and specifically for children with CI, a lower initial phonological composite score was associated with a larger phonological change between baseline 2 and post intervention. Finally, 18 DHH children, whereof 11 children with CI, showed specific intervention effects on their phonological processing skills, and strong effect sizes for their improved accuracy of phoneme-grapheme correspondence. CONCLUSION: For some DHH children phonological processing skills are boosted relatively more by phoneme-grapheme correspondence training. This reflects the reciprocal relationship between phonological change and exposure to and manipulations of letters.