Hong-Yan Bi

The visual magnocellular pathway in Chinese-speaking children with developmental dyslexia

Previous research into the cognitive processes involved in reading Chinese and developmental dyslexia in Chinese, revealed that the single most important factor appears to be orthographic processing skills rather than phonological skills. Also some studies have indicated that even in alphabetic languages some dyslexic individuals reveal deficits in orthographic processing skills, which are linked to a deficit in the visual magnocellular pathway. The current study therefore employed a visual psychophysical experiment together with visual and auditory event-related potential (ERP) experiments eliciting mismatch negativity (MMN) to investigate the link between visual magnocellular functional abnormalities and developmental dyslexia in Chinese. The performance levels of Chinese children with developmental dyslexia (DD) from the behavioural and electrophysiological experiments were compared to those of the chronological age-matched (CA) children and those of the reading level matched (RL) younger children. Both the behavioural and electrophysiological results suggest that the orthographic processing skills were compromised in the Chinese developmental dyslexics, which in turn is linked to a deficit in the visual magnocellular system.

The visual magnocellular-dorsal dysfunction in Chinese children with developmental dyslexia impedes Chinese character recognition

The visual magnocellular-dorsal (M-D) deficit theory of developmental dyslexia (DD) is still highly debated. Many researchers have made great efforts to investigate the relationship between M-D dysfunction and reading disability. Given that visual analysis plays an important role in Chinese reading, the present study tried to examine how the M-D dysfunction affected Chinese character recognition in Chinese children with DD. Sixteen DD children with M-D deficit, fifteen DD children with normal M-D function and twenty-seven age-matched typically developing children participated in this study. A global/local decision task was adopted, in which we manipulated the spatial frequency of target characters to separate an M-D condition from an unfiltered condition. Results of reaction times and error rates showed that in the M-D condition both M-D normal dyslexics and controls exhibited a significant global precedence effect, with faster responses and lower error rates in global decision than in local decision. In contrast, this global advantage was absent for the M-D impaired dyslexics. Accordingly, we propose that the M-D impairment present in some but not all dyslexics might influence global recognition of Chinese characters in this subgroup of children with DD, which might be implicated in their difficulties in learning to read.

Developmental Changes in the Role of Different Metalinguistic Awareness Skills in Chinese Reading Acquisition from Preschool to Third Grade

The present study investigated the relationship between Chinese reading skills and metalinguistic awareness skills such as phonological, morphological, and orthographic awareness for 101 Preschool, 94 Grade-1, 98 Grade-2, and 98 Grade-3 children from two primary schools in Mainland China. The aim of the study was to examine how each of these metalinguistic awareness skills would exert their influence on the success of reading in Chinese with age. The results showed that all three metalinguistic awareness skills significantly predicted reading success. It further revealed that orthographic awareness played a dominant role in the early stages of reading acquisition, and its influence decreased with age, while the opposite was true for the contribution of morphological awareness. The results were in stark contrast with studies in English, where phonological awareness is typically shown as the single most potent metalinguistic awareness factor in literacy acquisition. In order to account for the current data, a three-stage model of reading acquisition in Chinese is discussed.

Orthographic neighborhood size effect in Chinese character naming: Orthographic and phonological activations

The present study examined the effects of orthographic neighborhood (N) size on the cognitive processes underlying Chinese character reading. Previous research has shown increasing N size facilitates word naming and recognition performance in alphabetic languages. Experiment 1 revealed that a large N size was associated with a general inhibition of processes underlying character reading, in contrast to previous findings with alphabetic languages. This inhibitory effect was influenced by regularity and consistency. Experiment 2 sought to assess the effects of higher-frequency neighbors on character naming performance. The results revealed that higher-frequency neighbors with different pronunciation to the target interfered with the phonological retrieval of targets. We propose that this type of interference may have caused the N size effect observed in Experiment 1. The results of Experiment 3 revealed that a large N size facilitated target naming in the absence of higher-frequency neighbors. The current results shed light on the processes underlying character naming, and we propose possible cognitive mechanisms of the N size effect on Chinese character naming.

The visual magnocellular deficit in Chinese-speaking children with developmental dyslexia

Many alphabetic studies have evidenced that individuals with developmental dyslexia (DD) have deficits in visual magnocellular (M) pathway. However, there are few studies to investigate the M function of Chinese DD. Chinese is a logographic language, and Chinese characters are complicated in structure. Visual skills and orthographic processing abilities are particularly important for efficient reading in Chinese as compared to alphabetic languages. Therefore, it is necessary to investigate the visual M function of Chinese DD and whether the M function was associated with orthographic skills. In the present study, 26 dyslexic children (mean age: 10.03 years) and 27 age-matched normal children (mean age: 10.37 years) took part in a coherent motion (CM) detection task and an orthographic awareness test. The results showed that dyslexic children had a significantly higher threshold than age-matched children in CM detection task. Meanwhile, children with DD responded more slowly in orthographic awareness test, although the group difference was marginally significant. The results suggested that Chinese dyslexics had deficits both in visual M pathway processing and orthographic processing. In order to investigate the relationship between M function and orthographic skills, we made a correlation analysis between CM threshold and orthographic awareness by merging performance of dyslexic children and age-matched children. The results revealed that CM thresholds were positively correlated with reaction times in orthographic awareness test, suggesting that better M function was related to better orthographic processing skills.

Evidence for cerebellar dysfunction in Chinese children with developmental dyslexia: an fMRI study.

Numerous studies reported that developmental dyslexia in alphabetic languages was associated with a wide range of sensorimotor deficits, including balance, motor skill and time estimation, explained by skill automatization deficit hypothesis. Neural correlates of skill automatization deficit point to cerebellar dysfunction. Recently, a behavioral study revealed an implicit motor learning deficit in Chinese children with developmental dyslexia in their left hands, indicating left cerebellar dysfunction. Using functional magnetic resonance imaging (fMRI), our study examined the brain activation during implicit motor learning in 9 Chinese dyslexic and 12 age-matched children. Dyslexic children showed abnormal activations in the left cerebellum, left middle/medial temporal lobe and right thalamus compared with age-matched children during implicit motor learning. These findings provide evidence of cerebellar abnormality in Chinese dyslexic people. Furthermore, dysfunction of the left cerebellum in Chinese dyslexia is inconsistent with the right cerebellum abnormalities that were reported by studies on alphabetic-language dyslexia, suggesting that neurobiological abnormalities of impaired reading are probably language specific.

Neural correlates of the orthographic neighborhood size effect in Chinese

Word recognition research with alphabetical scripts has revealed a facilitatory neighborhood size effect, whereby naming of words with more orthographic neighbors is faster than that of words with fewer neighbors. Preliminary behavioral evidence in Chinese revealed both facilitatory and inhibitory neighborhood size effects, depending on whether there are higher‐frequency neighbors (HFNs) than the target. This functional magnetic resonance imaging study examined the neural substrates of the neighborhood size effect with silent naming. Neighborhood size and the HFN factor were factorially manipulated. Behavioral results replicated previous findings showing that larger neighborhood size facilitated naming in the absence of HFNs, but inhibited naming in their presence. Imaging results identified greater activation in the left middle frontal gyrus for small than larger neighborhood size, and bilateral inferior frontal activations for the with‐HFN condition as compared with the without‐HFN condition. Critically, there was an interaction in the right middle occipital gyrus showing greater activation for large than for small neighborhood size in the absence of HFNs but no neighborhood size effect in their presence. The results support a proposal that, in addition to a facilitatory contribution from orthographic activation of neighborhoods, naming is also affected by whether there are higher‐frequency neighbors, particularly in scripts with deep orthography, where orthographically similar words can be pronounced very differently.

The Characteristics of Chinese Orthographic Neighborhood Size Effect for Developing Readers

Orthographic neighborhood size (N size) effect in Chinese character naming has been studied in adults. In the present study, we aimed to explore the developmental characteristics of Chinese N size effect. One hundred and seventeen students (40 from the 3rd grade with mean age of 9 years; 40 from the 5th grade with mean age of 11 years; 37 from the 7th grade with mean age of 13 years) were recruited in the study. A naming task of Chinese characters was adopted to elucidate N-size- effect development. Reaction times and error rates were recorded. Results showed that children in the 3rd grade named characters from large neighborhoods faster than named those from small neighborhoods, revealing a facilitatory N size effect; the 5th graders showed null N size effect; while the 7th graders showed an inhibitory N size effect, with longer reaction times for the characters from large neighborhoods than for those from small neighborhoods. The change from facilitation to inhibition of neighborhood size effect across grades suggested the transition from broadly tuned to finely tuned lexical representation in reading development, and the possible inhibition from higher frequency neighbors for higher graders.

The effect of magnocellular-based visual-motor intervention on Chinese children with developmental dyslexia.

Magnocellular (M) deficit theory points out that the core deficit of developmental dyslexia (DD) is the impairment in M pathway, which has been evidenced in many previous studies. Based on the M deficit, some researchers found that visual intervention focusing on M deficit improved dyslexics’ M function as well as reading abilities. However, the number and reliability of these training studies were limited. Therefore, the present study conducted an M-based visual-motor intervention on Chinese children with DD to investigate the relationship between M deficit and Chinese DD. Intervention programs included coherent motion detection, visual search, visual tracking, and juggling, which were related to M function. The results showed that M function and phonological awareness of training dyslexic group were improved to a normal level as age-matched normal children after intervention, while non-training dyslexics did not. It supported M deficit theory, and suggested M deficit might be the core deficit of Chinese DD.

Anomalous Cerebellar Anatomy in Chinese Children with Dyslexia

The cerebellar deficit hypothesis for developmental dyslexia claims that cerebellar dysfunction causes the failures in the acquisition of visuomotor skills and automatic reading and writing skills. In people with dyslexia in the alphabetic languages, the abnormal activation and structure of the right or bilateral cerebellar lobes have been identified. Using a typical implicit motor learning task, however, one neuroimaging study demonstrated the left cerebellar dysfunction in Chinese children with dyslexia. In the present study, using voxel-based morphometry, we found decreased gray matter volume in the left cerebellum in Chinese children with dyslexia relative to age-matched controls. The positive correlation between reading performance and regional gray matter volume suggests that the abnormal structure in the left cerebellum is responsible for reading disability in Chinese children with dyslexia.