Biology subjects

Vandermosten, M.

Publications and source records attributed to Vandermosten, M..

12 recordsLinked to original sources

bioRxiv2025

Neural Phoneme Processing in Children with and without Dyslexia

This study investigates the neural dynamics of phoneme processing in 7-year-old children with and without dyslexia (25;9 [male]), using EEG recordings collected during continuous speech listening. By applying temporal generalization to phonetic descriptor decoding, we can disentangle whether potential phoneme processing deficits are due to the maintenance of phonemes in verbal short-term memory and/or inferred differences in phonetic processing speed, both of which are thought to be impaired in dyslexia. We investigated whether phonetic processing depends on the phonemes position or its lexical competition. Our results reveal two key findings that may help explain the challenges faced by children with dyslexia. First, these children exhibit reduced decoding accuracy for word-onset phonemes, suggesting disruptions in either predictive, word-level anticipatory mechanisms or in the intrinsic rhythmic processing aligned with word boundaries. Second, they exhibit increased decoding accuracy for non-onset phonemes with low lexical competition approximately 400 ms after phoneme onset. This pattern suggests that children with dyslexia retain linguistically less relevant sounds longer in verbal short-term memory and process them more slowly compared to their typical reading peers. Together, these findings suggest that dyslexia is characterized by altered phonetic encoding strategies, specifically inefficient prioritization of relevant phonological information. This work provides new insight into the neural mechanisms underlying phonological deficits and contributes to a deeper understanding of the cognitive basis of dyslexia. Significance statementDyslexia is associated with difficulties in phonological processing. Investigating EEG during continuous speech listening, we show that children with dyslexia exhibit weaker encoding of word-onset phonemes and prolonged processing of less informative phonemes. These altered encoding strategies suggest inefficient prioritization of linguistic information, offering new insight into the neural basis of dyslexia.

neuroscience↗

bioRxiv2024

The spatio-temporal dynamics of phoneme encoding in aging and aphasia

During successful language comprehension, speech sounds (phonemes) are encoded within a series of neural patterns that evolve over time. Here we tested whether these neural dynamics of speech encoding are altered for individuals with a language disorder. We recorded EEG responses from individuals with post-stroke aphasia and healthy age-matched controls (i.e., older adults) during 25 minutes of natural story listening. We estimated the duration of phonetic feature encoding, speed of evolution across neural populations, and the spatial location of encoding over EEG sensors. First, we establish that phonetic features are robustly encoded in EEG responses of healthy older adults. Second, when comparing individuals with aphasia to healthy controls, we find significantly decreased phonetic encoding in the aphasic group after shared initial processing pattern (0.08-0.25s after phoneme onset). Phonetic features were less strongly encoded over left-lateralized electrodes in the aphasia group compared to controls, with no difference in speed of neural pattern evolution. Finally, we observed that healthy controls, but not individuals with aphasia, encode phonetic features longer when uncertainty about word identity is high, indicating that this mechanism - encoding phonetic information until word identity is resolved - is crucial for successful comprehension. Together, our results suggest that aphasia may entail failure to maintain lower-order information long enough to recognize lexical items. Significance statementThis study reveals robust decoding of speech sound properties, so-called phonetic features, from EEG recordings in older adults, as well as decreased phonetic processing in individuals with a language disorder (aphasia) compared to healthy controls. This was most prominent over left-hemispheric electrodes. Additionally, we observed that healthy controls, but not individuals with aphasia, encode phonetic features longer when uncertainty about word identity is high, indicating that this mechanism - encoding phonetic information until word identity is resolved - is crucial for successful language processing. These insights deepen our understanding of disrupted mechanisms in a language disorder, and show how the integration between language processing levels works in the healthy aging, neurotypical brain.

neuroscience↗

bioRxiv2024

Neural substrates and behavioral relevance of speech envelope tracking: evidence from post-stroke aphasia

Neural tracking of the low-frequency temporal envelope of speech has emerged as a prominent tool to investigate the neural mechanisms of natural speech processing in the brain. However, there is ongoing debate regarding the functional role of neural envelope tracking. In this context, our study aims to offer a novel perspective by investigating the critical brain areas and behavioral skills required for neural envelope tracking in aphasia, a language disorder characterized by impaired neural envelope tracking. We analyzed an EEG dataset of 39 individuals with post-stroke aphasia suffering a left-hemispheric stroke who listened to natural speech. Our analysis involved lesion mapping, where left lesioned brain voxels served as binary features to predict neural envelope tracking measures. We also examined the behavioral correlates of receptive language, naming, and auditory processing (via rise time discrimination task) skills. The lesion mapping analysis revealed that lesions in language areas, such as the middle temporal gyrus, supramarginal gyrus and angular gyrus, were associated with poorer neural envelope tracking. Additionally, neural tracking was related to auditory processing skills and language (receptive and naming) skills. However, the effects on language skills were less robust, possibly due to ceiling effects in the language scores. Our [fi]ndings highlight the importance of central brain areas implicated in language understanding, extending beyond the primary auditory cortex, and emphasize the role of intact auditory processing and language abilities in effectively processing the temporal envelope of speech. Collectively, these [fi]ndings underscore the signi[fi]cance of neural envelope tracking beyond mere audibility and acoustic processes. Signi[fi]cance statementWhile some studies have proposed that neural envelope tracking primarily relates to audibility and acoustic speech processes, others have suggested its involvement in actual speech and language comprehension. By investigating the critical brain areas and behavioral skills essential in aphasia, we argue for a broader signi[fi]cance of neural envelope tracking in language processing. Furthermore, our [fi]ndings highlight a speci[fi]city among individuals with aphasia, indicating its correlation with lesions in temporal brain regions associated with receptive language functions. This addresses the signi[fi]cant heterogeneity in lesion characteristics present among individuals with aphasia and suggests the potential of neural tracking as an EEG-based tool for speci[fi]cally assessing receptive language abilities in this population.

neuroscience↗

bioRxiv2024

Individualized functional localization of the language and multiple demand network in chronic post-stroke aphasia

Recent research found a distinct dissociation between brain regions supporting domain-general cognitive processes and regions supporting core language functions. The question of whether individuals with post-stroke aphasia (IWA) exhibit a comparable dissociation remains debated, particularly as previous studies overlooked individual variability in functional network organization and aphasia heterogeneity. To address this gap, we employed an individualized functional localization approach to test the involvement of the domain-general multiple demand (MD) network during language processing in chronic aphasia. We collected functional MRI data in 15 IWA and 13 age-matched controls. Participants performed a spatial working memory task, triggering MD network activation, as well as a listening and reading task, triggering language network activation. We compared both groups individualized activation patterns and investigated the link with aphasia severity. Involvement of the MD network during language processing was examined by investigating language task activity within subject-specific regions that are active during the MD task. The language and MD network each generalized well across different task modalities, but exhibited robust spatial dissociation from each other in both groups. Moreover, there was no evidence of MD network activation during language processing in either group. Additionally, the language network showed weaker activation in IWA compared to controls in left-hemispheric brain regions, with higher activation values in the left correlating with improved language performance in IWA. In conclusion, our findings suggest that the MD network does not contribute to passive, receptive language functions in chronic aphasia or healthy older adults. Instead, our results align with previous research proposing that normalized left-hemispheric language activity supports language performance in chronic aphasia.

neuroscience↗

bioRxiv2023

EEG reveals brain network alterations in chronic aphasia during natural speech listening.

Aphasia is a common consequence of a stroke which affects language processing. In search of an objective biomarker for aphasia, we used EEG to investigate how functional network patterns in the cortex are affected in persons with post-stroke chronic aphasia (PWA) compared to healthy controls (HC) while they are listening to a story. EEG was recorded from 22 HC and 27 PWA while they listened to a 25-min-long story. Functional connectivity between scalp regions was measured with the weighted phase lag index. The Network- Based Statistics toolbox was used to detect altered network patterns and to investigate correlations with behavioural tests within the aphasia group. Differences in network geometry were assessed by means of graph theory and a targeted node-attack approach. Group-classification accuracy was obtained with a support vector machine classifier. PWA showed stronger inter-hemispheric connectivity compared to HC in the theta-band (4.5-7 Hz), whilst a weaker subnetwork emerged in the low-gamma band (30.5-49 Hz). Two subnetworks correlated with semantic fluency in PWA respectively in delta- (1-4 Hz) and low-gamma-bands. In the theta-band network, graph alterations in PWA emerged at both local and global level, whilst only local changes were found in the low-gamma-band network. As assessed with the targeted node-attack, PWA exhibit a more scale-free network compared to HC. Network metrics effectively discriminated PWA and HC (AUC = 83%). Overall, we showed for that EEG-network metrics are effective biomarkers to assess natural speech processing in chronic aphasia. We hypothesize that the detected alterations reflect compensatory mechanisms associated with recovery.

neuroscience↗

bioRxiv2023

Exploring neural tracking of acoustic and linguistic speech representations in individuals with post-stroke aphasia

Aphasia is a communication disorder that affects processing of language at different levels (e.g., acoustic, phonological, semantic). Recording brain activity via EEG while people listen to a continuous story allows to analyze brain responses to acoustic and linguistic properties of speech. When the neural activity aligns with these speech properties, it is referred to as neural tracking. Even though measuring neural tracking of speech may present an interesting approach to studying aphasia in an ecologically valid way, it has not yet been investigated in individuals with stroke-induced aphasia. Here, we explored processing of acoustic and linguistic speech representations in individuals with aphasia in the chronic phase after stroke and age-matched healthy controls. We found decreased neural tracking of acoustic speech representations (envelope and envelope onsets) in individuals with aphasia. In addition, word surprisal displayed decreased amplitudes in individuals with aphasia around 195 ms over frontal electrodes, although this effect was not corrected for multiple comparisons. These results show that there is potential to capture language processing impairments in individuals with aphasia by measuring neural tracking of continuous speech. However, more research is needed to validate these results. Nonetheless, this exploratory study shows that neural tracking of naturalistic, continuous speech presents a powerful approach to studying aphasia. Key pointsO_LIIndividuals with aphasia display decreased encoding of acoustic speech properties (envelope and its onsets) in comparison to healthy controls. C_LIO_LINeural responses to word surprisal reveal decreased amplitudes in individuals with aphasia around 195 ms processing time (not corrected for multiple comparisons). C_LIO_LINeural tracking of natural speech can be used to study speech processing impairments in aphasia. C_LI

neuroscience↗

bioRxiv2022

Tuning in on auditory details is difficult: Individuals with aphasia show impaired acoustic and phonemic processing

Acoustic and phonemic processing are understudied in aphasia, a language disorder that can affect different levels and modalities of language processing. For successful speech comprehension, processing of the speech envelope is necessary, which relates to amplitude changes over time (e.g., the rise times). Moreover, to identify speech sounds (i.e., phonemes), efficient processing of spectro-temporal changes as reflected in formant transitions is essential. Given the lack of aphasia studies on these aspects, we tested rise time processing and phoneme identification in 29 individuals with post-stroke aphasia and 23 healthy age-matched controls. We found significantly lower performance in the aphasia group than in the control group on both tasks, even when controlling for individual differences in hearing levels and cognitive functioning. Further, by conducting an individual deviance analysis, we found a low-level acoustic or phonemic processing impairment in 76% of individuals with aphasia. Additionally, we investigated whether this impairment would propagate to higher-level language processing and found that rise time processing predicts phonological processing performance in individuals with aphasia. These findings show that it is important to develop diagnostic and treatment tools that target low-level language processing mechanisms.

neuroscience↗

bioRxiv2022

Beyond Linear Neural Envelope Tracking: A Mutual Information Approach

The human brain tracks the temporal envelope of speech, which contains essential cues for speech understanding. Linear models are the most common tool to study neural envelope tracking. However, information on how speech is processed can be lost since nonlinear relations are precluded. As an alternative, mutual information (MI) analysis can detect both linear and nonlinear relations. Yet, several different approaches to calculating MI are applied without consensus on which approach to use. Furthermore, the added value of nonlinear techniques remains a subject of debate in the field. To resolve this, we applied linear and MI analyses to electroencephalography (EEG) data of participants listening to continuous speech. Comparing the different MI approaches, we conclude that results are most reliable and robust using the Gaussian copula approach, which first transforms the data to standard Gaussians. With this approach, the MI analysis is a valid technique for studying neural envelope tracking. Like linear models, it allows spatial and temporal interpretations of speech processing, peak latency analyses, and applications to multiple EEG channels combined. Finally, we demonstrate that the MI analysis can detect nonlinear components on the single-subject level, beyond the limits of linear models. We conclude that the MI analysis is a more informative tool for studying neural envelope tracking. Significance statementIn the present study, we addressed key methodological considerations for MI applications. Traditional MI methodologies require the estimation of a probability distribution at first. We show that this step can introduce a bias in the results and, consequently, severely impact interpretations. As an alternative, we propose using the parametric Gaussian copula method, which we demonstrated to be robust against biases. Second, using the parametric MI analysis, we show that there is nonlinear variance in the EEG data that the envelope of speech can explain at the single-subject level, proving its added value to neural envelope tracking. We conclude that the MI analysis is a statistically more powerful tool for studying neural envelope tracking than linear models. In addition, it retains spatial and temporal characteristics of speech processing which are lost when using more complex deep neural networks.

neuroscience↗

bioRxiv2022

Linguistic speech processing decreases with advancing age

BackgroundOlder adults process speech differently, but it is not yet clear how aging affects different levels of processing natural, continuous speech, both in terms of bottom-up acoustic analysis and top-down generation of linguistic-based predictions. We studied natural speech processing across the adult lifespan via electroencephalography (EEG) measurements of neural tracking. GoalsOur goals are to analyze the unique contribution of linguistic speech processing across the adult lifespan using natural speech, while controlling for the influence of acoustic processing. In particular, we focus on changes in spatial and temporal activation patterns in response to natural speech across the lifespan. Methods52 normal-hearing adults between 17 and 82 years of age listened to a naturally spoken story while the EEG signal was recorded. We investigated the effect of age on acoustic and linguistic processing of speech. Because age correlated with hearing capacity and measures of cognition, we investigated whether the observed age effect is mediated by these factors. Furthermore, we investigated whether there is an effect of age on hemisphere lateralization and on spatiotemporal patterns of the neural responses. ResultsOur EEG results showed that linguistic speech processing declines with advancing age. More-over, as age increased, the neural response latency to certain aspects of linguistic speech processing increased. Also acoustic neural tracking (NT) decreased with increasing age but in contrast to linguistic processing, older subjects showed shorter latencies for early acoustic responses to speech. No evidence was found for hemispheric lateralization in neither younger nor older adults during linguistic speech processing. Most of the observed aging effects on acoustic and linguistic processing were not explained by age-related decline in hearing capacity or cognition. However, our results suggest that the effect of decreasing linguistic neural tracking with advancing age at word-level is likely more due to an age-related decline in cognition than a robust effect of age. ConclusionSpatial and temporal characteristics of the neural responses to continuous speech change across the adult lifespan for both acoustic and linguistic speech processing. These changes may be traces of structural and/or functional change that occurs with advancing age. HighlightsO_LIWith increasing age, linguistic neural tracking of continuous speech decreases. C_LIO_LIWith increasing age, the processing speed of linguistic aspects of speech slows down. C_LIO_LIAging-related changes in word-level linguistic processing are affected by cognition. C_LIO_LIWith advancing age, tracking of speech acoustics decreases in the right hemisphere. C_LIO_LIOlder adults displayed earlier neural responses to speech acoustics. C_LI

neuroscience↗

bioRxiv2021

Ahead of Maturation: Enhanced Speech Envelope Training Boosts Rise Time Discrimination in Pre-Readers at Cognitive Risk for Dyslexia

Dyslexia has frequently been related to atypical auditory temporal processing and speech perception. Results of studies emphasizing speech onset cues and reinforcing the temporal structure of the speech envelope, i.e. envelope enhancement, demonstrated reduced speech perception deficits in individuals with dyslexia. The use of this strategy as an auditory intervention might thus reduce some of the deficits related to dyslexia. Importantly, interventions are most effective when they are provided during kindergarten and first grade. Hence, we provided a tablet-based 12-week preventive auditory and phonics-based intervention to pre-readers at cognitive risk for dyslexia and investigated the effect on auditory temporal processing with a rise time discrimination task. Ninety-one pre-readers at cognitive risk for dyslexia (aged 5-6) were assigned to two groups receiving a phonics-based intervention and playing a story listening game either with (n = 31) or without (n = 31) envelope enhancement or a third group playing control games and listening to non-enhanced stories (n = 29). Rise time discrimination was measured directly before, directly after and one year after the intervention. While the groups listening to non-enhanced stories mainly improved after the intervention during first grade, the group listening to enhanced stories improved during the intervention in kindergarten and subsequently remained stable during first grade. Hence, an envelope enhancement intervention improves auditory processing skills important for the development of phonological skills. This occurred before the onset of reading instruction, preceding the maturational improvement of these skills, hence giving at risk children a head start when learning to read. Research highlightsO_LIThe first investigation of speech envelope enhancement as a potential preventive intervention strategy in pre-readers at cognitive risk for dyslexia C_LIO_LISpeech envelope enhancement increases the rise time sensitivity of children at cognitive risk for dyslexia C_LIO_LIRise time discrimination can be enhanced before formal reading instruction, a crucial period in development C_LI

neuroscience↗

bioRxiv2020

The influence of intergenerational transfer of white matter tracts on early reading development

Parents have large genetic and environmental influences on their childrens cognition, behavior, and brain. Previous studies have indicated intergenerational transfer of the behavior of reading. Despite a close coupling between brain and behavior however, the intergenerational transfer of reading-related structural brain networks have not been investigated. Therefore, we investigated its parent-child associations for the first time. We examined how white matter tracts i.e., Arcuate Fasciculus (AF) and Inferior Fronto-Occipital Fasciculus (IFOF), are associated with childrens early reading development from Kindergarten to Grade 3 in 33 families. First, we observed in our sample of children -who all had typical reading skills despite half of them having an increased risk for dyslexia- that fractional anisotropy in bilateral IFOF and right AF correlated with reading development. Second, parent-child correlations were observed for bilateral IFOF but not for AF. Finally, we demonstrated that the relation between childrens IFOF and reading development was largely explained by parental IFOF. The findings preliminarily suggest that white matter organization in IFOF represents a pre-existing protective factor in children at risk, as it is mainly determined by biological parental factors. Large-scale intergenerational, multi-level and longitudinal studies are needed to understand the dynamic interrelations between brain, environment and behavior.

neuroscience↗

bioRxiv2020

Advanced paternal age effect on offspring's reading ability: The mediating role of thalamic maturation

The importance of (inherited) genetic impact in reading development is well-established. De novo mutation is another important contributor that is recently gathering interest as a major liability of neurodevelopmental disorders, but has been neglected in reading research to date. Paternal age at childbirth (PatAGE) is known as the most prominent risk factor for de novo mutation, which has been repeatedly shown by molecular genetic studies. As one of the first efforts, we performed a preliminary investigation of the relationship between PatAGE, offsprings reading, and brain structure in a longitudinal neuroimaging study following 51 children from kindergarten through third grade. The results showed that greater PatAGE was associated significantly with worse reading, explaining an additional 9.5% of the variations after controlling for a number of confounds--including familial factors and cognitive-linguistic reading precursors. Moreover, this effect was mediated by volumetric maturation of the left posterior thalamus from ages 5 to 8. Complementary analyses indicated the PatAGE-related thalamic region was most likely located in the pulvinar nuclei and related to the dorsal attention network by using brain atlases, public datasets, and offsprings diffusion imaging data. Altogether, these findings provide novel insights into neurocognitive mechanisms underlying the PatAGE effect on reading acquisition during its earliest phase and suggest promising areas of future research. HighlightsO_LIPaternal age at childbirth (PatAGE) is negatively correlated with offsprings reading abilities. C_LIO_LIPatAGE is related to volumetric maturation of the left posterior thalamus. C_LIO_LIThalamic development mediates the PatAGE effect on reading. C_LIO_LIThe PatAGE-related thalamic area is more likely to connect with the dorsal attention network. C_LI

neuroscience↗