Children at risk for dyslexia show deficient left-hemispheric memory representations for new spoken word forms

Impaired Cortical Tracking of Speech in Children with Developmental Language Disorder

In developmental language disorder (DLD), learning to comprehend and express oneself with spoken language is impaired, but the reason for this remains unknown. Using millisecond-scale magnetoencephalography recordings combined with machine learning models, we investigated whether the possible neural basis of this disruption lies in poor cortical tracking of speech. The stimuli were common spoken Finnish words (e.g., dog, car, hammer) and sounds with corresponding meanings (e.g., dog bark, car engine, hammering). In both children with DLD (10 boys and 7 girls) and typically developing (TD) control children (14 boys and 3 girls), aged 10-15 years, the cortical activation to spoken words was best modeled as time-locked to the unfolding speech input at ∼100 ms latency between sound and cortical activation. Amplitude envelope (amplitude changes) and spectrogram (detailed time-varying spectral content) of the spoken words, but not other sounds, were very successfully decoded based on time-locked brain responses in bilateral temporal areas; based on the cortical responses, the models could tell at ∼75-85% accuracy which of the two sounds had been presented to the participant. However, the cortical representation of the amplitude envelope information was poorer in children with DLD compared with TD children at longer latencies (at ∼200-300 ms lag). We interpret this effect as reflecting poorer retention of acoustic-phonetic information in short-term memory. This impaired tracking could potentially affect the processing and learning of words as well as continuous speech. The present results offer an explanation for the problems in language comprehension and acquisition in DLD.

Atypical characteristic changes of surface morphology and structural covariance network in developmental dyslexia

BACKGROUND

Developmental dyslexia (DD) is a neurodevelopmental disorder that is characterized by difficulties with all aspects of information acquisition in the written word, including slow and inaccurate word recognition. The neural basis behind DD has not been fully elucidated.

METHOD

The study included 22 typically developing (TD) children, 16 children with isolated spelling disorder (SpD), and 20 children with DD. The cortical thickness, folding index, and mean curvature of Broca's area, including the triangular part of the left inferior frontal gyrus (IFGtriang) and the opercular part of the left inferior frontal gyrus, were assessed to explore the differences of surface morphology among the TD, SpD, and DD groups. Furthermore, the structural covariance network (SCN) of the triangular part of the left inferior frontal gyrus was analyzed to explore the changes of structural connectivity in the SpD and DD groups.

RESULTS

The DD group showed higher curvature and cortical folding of the left IFGtriang than the TD group and SpD group. In addition, compared with the TD group and the SpD group, the structural connectivity between the left IFGtriang and the left middle-frontal gyrus and the right mid-orbital frontal gyrus was increased in the DD group, and the structural connectivity between the left IFGtriang and the right precuneus and anterior cingulate was decreased in the DD group.

CONCLUSION

DD had atypical structural connectivity in brain regions related to visual attention, memory and which might impact the information input and integration needed for reading and spelling.

Psychophysiological evaluation of the Smartick method in children with reading and mathematical difficulties

Introduction

Assistive technologies for learning are aimed at promoting academic skills, such as reading and mathematics. These technologies mainly embrace mobile and web apps addressed to children with learning difficulties. Nevertheless, most applications lack pedagogical foundation. Additionally, the task of selecting suitable technology for educational purposes becomes challenging. Hence, this protocol posits the psychophysiological assessment of an online method for learning (OML) named Smartick. This platform comprises reading and math activities for learning training. In this protocol, individual monitoring of each child is proposed to determine the progress in learning caused by Smartick.

Methods and analysis

One hundred and twelve children aged between 8 and 12 who present reading or math difficulty after a rigorous psychometric evaluation will be recruited. The study comprises four sessions. In sessions 1 and 2, collective and individual psychometric evaluations will be performed, respectively. Reading and mathematical proficiency will be assessed, as well as attentional levels and intellectual quotient. Subsequently, each child will be semi-randomly assigned to either the experimental or control groups. Afterward, a first EEG will be collected for all children in session 3. Then, experimental groups will use Smartick for 3 months, in addition to their traditional learning method. In contrast, control groups will only continue with their traditional learning method. Finally, session 4 will consist of performing a second psychometric evaluation and another EEG, so that psychophysiological parameters can be encountered that indicate learning improvements due to the OML, regardless of the traditional learning method at hand.

Discussion

Currently, few studies have validated learning improvement due to assistive technologies for learning. However, this proposal presents a psychophysiological evaluation addressed to children with reading or math difficulties who will be trained with an OML.

Brain responses during auditory word recognition vary with reading ability in Chinese school-age children

While the close relationship between the brain system for speech processing and reading development is well-documented in alphabetic languages, whether and how such a link exists in children in a language without systematic grapheme-phoneme correspondence has not been directly investigated. In the present study, we measured Chinese children's brain activation during an auditory lexical decision task with functional magnetic resonance imaging. The results showed that brain areas distributed across the temporal and frontal lobes activated during spoken word recognition. In addition, the left occipitotemporal cortex (OTC) was recruited, especially under the real word condition, thus confirming the involvement of this orthographic-related area in spoken language processing in Chinese children. Importantly, activation of the left temporoparietal cortex (TPC) in response to words and pseudowords was positively correlated with children's reading ability, thus supporting the salient role phonological processing plays in Chinese reading in the developing brain. Furthermore, children with higher reading scores also increasingly recruited the left anterior OTC to make decisions on the lexical status of pseudowords, indicating that higher-skill children tend to search abstract lexical representations more deeply than lower-skill children in deciding whether spoken syllables are real. In contrast, the precuneus was more related to trial-by-trial reaction time in lower-skill children, suggesting that effort-related neural systems differ among pupils with varying reading abilities. Taken together, these findings suggest a strong link between the neural correlates of speech processing and reading ability in Chinese children, thus supporting a universal basis underlying reading development across languages.

The rise and fall of rapid occipito-temporal sensitivity to letters: Transient specialization through elementary school

Letters, foundational units of alphabetic writing systems, are quintessential to human culture. The ability to read, indispensable to perform in today’s society, necessitates a reorganization of visual cortex for fast letter recognition, but the developmental course of this process has not yet been characterized. Here, we show the emergence of visual sensitivity to letters across five electroencephalography measurements from kindergarten and throughout elementary school and relate this development to emerging reading skills. We examined the visual N1, the electrophysiological correlate of ventral occipito-temporal cortex activation in 65 children at varying familial risk for dyslexia. N1 letter sensitivity emerged in first grade, when letter sound knowledge gains were most pronounced and decayed shortly after when letter knowledge is consolidated, showing an inverted U-shaped development. This trajectory can be interpreted within an interactive framework that underscores the influence of top-down predictions. While the N1 amplitudes to letters correlated with letter sound knowledge at the beginning of learning, no association between the early N1 letter response and later reading skills was found. In summary, the current findings provide an important reference point for our neuroscientific understanding of learning trajectories and the process of visual specialization during skill learning.