Low-level neural auditory discrimination dysfunctions in specific language impairment—A review on mismatch negativity findings

Abstract In specific language impairment (SLI), there is a delay in the child’s oral language skills when compared with nonverbal cognitive abilities. The problems typically relate to phonological and morphological processing and word learning. This article reviews studies which have used mismatch negativity (MMN) in investigating low-level neural auditory dysfunctions in this disorder. With MMN, it is possible to tap the accuracy of neural sound discrimination and sensory memory functions. These studies have found smaller response amplitudes and longer latencies for speech and non-speech sound changes in children with SLI than in typically developing children, suggesting impaired and slow auditory discrimination in SLI. Furthermore, they suggest shortened sensory memory duration and vulnerability of the sensory memory to masking effects. Importantly, some studies reported associations between MMN parameters and language test measures. In addition, it was found that language intervention can influence the abnormal MMN in children with SLI, enhancing its amplitude. These results suggest that the MMN can shed light on the neural basis of various auditory and memory impairments in SLI, which are likely to influence speech perception.Abstract In specific language impairment (SLI), there is a delay in the child’s oral language skills when compared with nonverbal cognitive abilities. The problems typically relate to phonological and morphological processing and word learning. This article reviews studies which have used mismatch negativity (MMN) in investigating low-level neural auditory dysfunctions in this disorder. With MMN, it is possible to tap the accuracy of neural sound discrimination and sensory memory functions. These studies have found smaller response amplitudes and longer latencies for speech and non-speech sound changes in children with SLI than in typically developing children, suggesting impaired and slow auditory discrimination in SLI. Furthermore, they suggest shortened sensory memory duration and vulnerability of the sensory memory to masking effects. Importantly, some studies reported associations between MMN parameters and language test measures. In addition, it was found that language intervention can influence the abnormal MMN in children with SLI, enhancing its amplitude. These results suggest that the MMN can shed light on the neural basis of various auditory and memory impairments in SLI, which are likely to influence speech perception.Peer reviewe

Neural mechanisms underlying word- and phrase-level morphological parsing

How is morphological and morphosyntactic information processed during sentence reading? Are the neural mechanisms underlying word- and phrase-level combinatorial processing overlapping or distinct? Here, electroencephalography (EEG) and magnetoencephalography (MEG) responses were recorded simultaneously during silent reading of Finnish sentences. The experimental conditions included 1) well-formed grammatical sentences (correct condition), 2) sentences containing morphosyntactic violations (adjective–noun number agreement violations), 3) morphological violations (incorrect stem allomorph and inflectional suffix combination), and 4) combined violations, containing both morphosyntactic and morphological violations. Signal space and source modeling results showed that morphosyntactic violations elicited a left anterior negativity effect, generated particularly in the left inferior frontal area. Morphological violations elicited a widespread negativity, resembling the N400. The neural sources of this negativity were localized most prominently to the right temporal cortical networks. Furthermore, all violations elicited P600 effects with similar widespread bilateral fronto-temporal neural generators that did not differ between morphosyntactic and morphological conditions. Our findings suggest at least partially distinct subnetworks in the fronto-temporal cortices for morphological and morphosyntactic parsing during the earlier stages of processes (∼400 ms post stimulus onset) and shared neural generators for the later processing stages.Peer reviewe

Effect of language experience on selective auditory attention: An event-related potential study

Dual language experience has typically been shown to improve various executive control functions. We investigated with event-related brain potentials (ERPs) recorded from early (natively) bilingual speakers and control participants whether it also affects auditory selective attention. We delivered to our participants two tone streams, one to the left and one to the right ear. Both streams consisted of standard tones and two types of infrequent deviant tones which had either an enhanced duration or intensity. The participants were instructed to attend either to the right or left stream and to detect longer-duration deviants in the attended stream. The results showed that the early bilinguals did not outperform the controls in target detection accuracy or speed. However, the late portion of the attention-related ERP modulation (the negative difference, Nd) was larger over the left hemisphere in the early bilinguals than in the controls, suggesting that the maintenance of selective attention or further processing of selectively attended sounds is enhanced in the bilinguals. Moreover, the late reorienting negativity (RON) in response to intensity-deviant tones was larger in the bilinguals, suggesting more efficient disengagement of attention from distracting auditory events. Hence, our results demonstrate that brain responses associated with certain aspects of auditory attention are enhanced in the bilingual adults, indicating that early dual language exposure modulates the neuronal responsiveness of auditory modality.Peer reviewe

Semantic training facilitates the acquisition of novel morphemes : MEG evidence

Learning to recognize morphemic boundaries is essential for fluent language use. In languages with rich morphology, the question of morphological learning is particularly relevant. Some neurocognitive models propose that morphologically complex words are parsed and their constituents are stored as separate units in lexical memory. Neural mechanisms underlying the acquisition of such novel morphological units, however, remain largely unexplored. Here, we trained 19 native Finnish-speaking participants with novel derivational suffixes through a word-picture association task. Following this short training session, we used magnetoencephalography to record the participants’ brain responses to trained and untrained suffixes combined with new real and pseudoword stems in a 22-minute passive listening task. Existing Finnish suffixes served as controls. We compared the responses measured early and late (first/last 5 minutes) during passive exposure to investigate the online build-up of novel suffix representations. In the left frontal and temporal cortices, source activation for real suffixes was significantly higher than for both trained and untrained novel suffixes in the 60-80 ms, 120-140 ms and 220-260 ms time-windows (around ERF peaks) following the suffix onset, suggesting the activation of pre-existing long-term memory traces. However, we also found increased source amplitudes for the trained as opposed to the untrained suffixes already early in exposure. Although such a brief exposure may not be sufficient for the integration of novel morphological units into lexical memory, our findings suggest that a short semantic training of novel affixes facilitates morphological decomposition and speeds up suffix memory trace formation in the left fronto-temporal language networks.Peer reviewe

Acquisition of L2 morphology by adult language learners

Learning a new language requires the acquisition of morphological units that enable the fluent use of words in different grammatical contexts. While accumulating research has elucidated the neural processing of native morphology, much less is known about how second-language (L2) learners acquire and process morphology in their L2. To address this question, we presented native speakers as well as beginning and advanced learners of Finnish with spoken (1) derived words, (2) inflected words, (3) novel derivations (novel combinations of existing stem + suffix), and (4) pseudo-suffixed words (existing stem + pseudo-suffix) in a passive listening EEG experiment. An early (60 msec after suffix deviation point) positive ERP response showed no difference between inflections and derivations, suggesting similar early parsing of these complex words. At 130 msec, derivations elicited a lexical ERP pattern of full-form memory-trace activation, present in the L2 beginners and advanced speakers to different degrees, implying a shift from lexical processing to more dual parsing and lexical activation of the complex forms with increasing proficiency. Pseudo-suffixed words produced a syntactic pattern in a later, 170 240 msec time-window, exhibiting enhanced ERPs compared to well-formed inflections, indicating second-pass syntactic parsing. Overall, the L2 learners demonstrated a gradual effect of proficiency towards L1-like responses. Advanced L2 learners seem to have developed memory traces for derivations and their neurolinguistic system is capable of early automatic parsing. This suggests that advanced learners have already developed sensitivity to morphological information, while such knowledge is weak in beginners. Discrepancies in ERP dynamics and topographies indicate partially differing recruitment of the language network in L1 and L2. In beginners, response differences between existing and novel morphology were scarce, implying that representations for complex forms are not yet well-established. The results suggest successful development of brain mechanisms for automatic processing of L2 morphology, capable of gradually attaining L1-like functionality with increasing proficiency. (C) 2019 The Authors. Published by Elsevier Ltd.Peer reviewe

Brain activity during shadowing of audiovisual cocktail party speech, contributions of auditory-motor integration and selective attention

Selective listening to cocktail-party speech involves a network of auditory and inferior frontal cortical regions. However, cognitive and motor cortical regions are differentially activated depending on whether the task emphasizes semantic or phonological aspects of speech. Here we tested whether processing of cocktail-party speech differs when participants perform a shadowing (immediate speech repetition) task compared to an attentive listening task in the presence of irrelevant speech. Participants viewed audiovisual dialogues with concurrent distracting speech during functional imaging. Participants either attentively listened to the dialogue, overtly repeated (i.e., shadowed) attended speech, or performed visual or speech motor control tasks where they did not attend to speech and responses were not related to the speech input. Dialogues were presented with good or poor auditory and visual quality. As a novel result, we show that attentive processing of speech activated the same network of sensory and frontal regions during listening and shadowing. However, in the superior temporal gyrus (STG), peak activations during shadowing were posterior to those during listening, suggesting that an anterior-posterior distinction is present for motor vs. perceptual processing of speech already at the level of the auditory cortex. We also found that activations along the dorsal auditory processing stream were specifically associated with the shadowing task. These activations are likely to be due to complex interactions between perceptual, attention dependent speech processing and motor speech generation that matches the heard speech. Our results suggest that interactions between perceptual and motor processing of speech relies on a distributed network of temporal and motor regions rather than any specific anatomical landmark as suggested by some previous studies.Peer reviewe

Quick reorganization of memory traces for morphologically complex words in young children

Formation of neural mechanisms for morphosyntactic processing in young children is still poorly understood. Here, we addressed neural processing and rapid online acquisition of familiar and unfamiliar combinations of morphemes. Three different types of morphologically complex words - derived, inflected, and novel (pseudostem + real suffix) - were presented in a passive listening setting to 16 typically developing 3-4-year old children (as part of a longitudinal Helsinki SLI follow-up study). The mismatch negativity (MMN) component of event-related potentials (ERP), an established index of long-term linguistic memory traces in the brain, was analysed separately for the initial and final periods of the exposure to these items. We found MMN response enhancement for the inflected words towards the end of the recording session, whereas no response change was observed for the derived or novel complex forms. This enhancement indicates rapid build-up of a new memory trace for the combination of real morphemes, suggesting a capacity for online formation of whole-form lexicalized representations as one of the morphological mechanisms in the developing brain. Furthermore, this enhancement increased with age, suggesting the development of automatic morphological processing circuits in the age range of 3-4 years.Peer reviewe

Development of a Method to Compensate for Signal Quality Variations in Repeated Auditory Event-Related Potential Recordings

Reliable measurements are mandatory in clinically relevant auditory event-related potential (AERP)-based tools and applications. The comparability of the results gets worse as a result of variations in the remaining measurement error. A potential method is studied that allows optimization of the length of the recording session according to the concurrent quality of the recorded data. In this way, the sufficiency of the trials can be better guaranteed, which enables control of the remaining measurement error. The suggested method is based on monitoring the signal-to-noise ratio (SNR) and remaining measurement error which are compared to predefined threshold values. The SNR test is well defined, but the criterion for the measurement error test still requires further empirical testing in practice. According to the results, the reproducibility of average AERPs in repeated experiments is improved in comparison to a case where the number of recorded trials is constant. The test-retest reliability is not significantly changed on average but the between-subject variation in the value is reduced by 33–35%. The optimization of the number of trials also prevents excessive recordings which might be of practical interest especially in the clinical context. The efficiency of the method may be further increased by implementing online tools that improve data consistency

Evaluating bicyclists’ risk perception using video clips: Comparison of frequent and infrequent city cyclists

Abstract Hazard and risk perception has been studied extensively among car drivers, and their link to crash involvement is established. Bicyclists, in particular, are vulnerable road users. Better understanding of their risk and hazard perception could help to improve their traffic safety. In this study, we investigated the risk perception of bicyclists in a city environment. Two groups of bicyclists were compared: 19 frequent and 19 infrequent bicyclists. Participants were shown video clips taken with a camera attached to the handlebar of a bicycle, and they were asked to continuously indicate with a slider how much caution the situation needed. The frequent cyclists had more frequent rises in the caution estimate, which suggest that they anticipated or detected more hazards than infrequent cyclists. This is in line with the classical hazard perception results, which link the car driving experience to faster and more accurate hazard perception. The overall level or caution was not directly related to the rise event rate or bicycling frequency. Those cyclists who reported typically cycling faster than others showed elevated overall level of caution on sidewalks compared with others, but there was no difference on bike paths.Hazard and risk perception has been studied extensively among car drivers, and their link to crash involvement is established. Bicyclists, in particular, are vulnerable road users. Better understanding of their risk and hazard perception could help to improve their traffic safety. In this study, we investigated the risk perception of bicyclists in a city environment. Two groups of bicyclists were compared: 19 frequent and 19 infrequent bicyclists. Participants were shown video clips taken with a camera attached to the handlebar of a bicycle, and they were asked to continuously indicate with a slider how much caution the situation needed. The frequent cyclists had more frequent rises in the caution estimate, which suggest that they anticipated or detected more hazards than infrequent cyclists. This is in line with the classical hazard perception results, which link the car driving experience to faster and more accurate hazard perception. The overall level or caution was not directly related to the rise event rate or bicycling frequency. Those cyclists who reported typically cycling faster than others showed elevated overall level of caution on sidewalks compared with others, but there was no difference on bike paths. (C) 2015 Elsevier Ltd. All rights reserved.Peer reviewe

Electrophysiological Indicators of the Age-Related Deterioration in the Sensitivity to Auditory Duration Deviance

The present study investigates age-related changes in duration discrimination in millisecond time domain. We tested young (N = 20, mean age = 24.5, SD = 2.97) and elderly (N = 20, mean age = 65.2, SD = 2.94) subjects using the mismatch negativity (MMN) paradigm. White-noise bursts of two different durations (50 and 10 ms) were presented in two oddball blocks. In one block (Increment Condition), the repetitive sequence of 10 ms standards was interspersed by occasional 50 ms deviants. In the Decrement Condition, the roles of the two stimuli were reversed. We analyzed the P1-N1 complex, MMN and P3a and found the effect of age for all these components. Moreover, the impact of stimulus presentation condition (increment/decrement) was observed for MMN and P3a. Our results confirmed the previous evidence for deteriorated duration discrimination in elderly people. Additionally, we found that this effect may be influenced by procedural factors.Peer reviewe