Facial speech processing in children with and without dyslexia

Dyslexia-Related Hearing Loss Occurs Mainly through the Abnormal Spontaneous Electrical Activity of Spiral Ganglion Neurons

Dyslexia is a reading and spelling disorder due to neurodevelopmental abnormalities and is occasionally found to be accompanied by hearing loss, but the reason for the associated deafness remains unclear. This study finds that knockout of the dyslexia susceptibility 1 candidate 1 gene (Dyx1c1^-/- ) in mice, the best gene for studying dyslexia, causes severe hearing loss, and thus it is a good model for studying the mechanism of dyslexia-related hearing loss (DRHL). This work finds that the Dyx1c1 gene is highly expressed in the mouse cochlea and that the spontaneous electrical activity of inner hair cells and type I spiral ganglion neurons is altered in the cochleae of Dyx1c1^-/- mice. In addition, primary ciliary dyskinesia-related phenotypes such as situs inversus and disrupted ciliary structure are seen in Dyx1c1^-/- mice. In conclusion, this study gives new insights into the mechanism of DRHL in detail and suggests that Dyx1c1 may serve as a potential target for the clinical diagnosis of DRHL.

Left visual field bias during face perception aligns with individual differences in reading skills and is absent in dyslexia

BACKGROUND

When looking at faces, we tend to attend more to the left visual field (corresponding to the right side of the person's face). This phenomenon is called the left visual field bias (LVF) and is presumed to reflect the brain's right-sided dominance for face processing. Whether alterations in hemispheric dominance are present in dyslexia, and are linked with individual differences in word reading development more generally, is still unclear, and no prior research has utilized gaze-based LVF bias to explore these topics.

AIMS

The aim of the study was to examine whether the LVF bias differs in dyslexia and to examine the association with word-reading skills assessed dimensionally.

SAMPLE

Forty-six 9-13 year-old children with dyslexia and community control children, matched on age and listening comprehension.

METHODS

Participants were presented with a recorded face on a screen while their gaze patterns were collected with an eye tracker. Fixations to the left versus the right side of the face stimuli were compared.

RESULTS

Results showed a clear LVF bias in community controls, while no such bias was seen in the dyslexic group. Moreover, the strength of the LVF bias was correlated with better word reading in the controls.

CONCLUSIONS

Our results suggest a link between weakened hemispheric dominance for face processing in dyslexia and in poor word reading, at least to the extent that the LVF bias actually mirrors underlying physiology. We discuss the implications of these novel findings, highlighting the need for future research to determine the specificity and developmental sources of LVF bias alterations.

Face Processing in School Children with Dyslexia: Neuropsychological and Eye-tracking Findings

Dyslexia is a neurodevelopmental difficulty affecting reading, but recent data in adults suggest that difficulties also extend to face processing. Here, we tested face processing in school children with and without dyslexia, using eye-tracking and neuropsychological tests. Children with dyslexia didn't differ significantly from controls in face gaze patterns, face memory, or face identification accuracy. However, they were slower and more heterogeneous, with larger within-group variance than controls. Increased gaze patterns toward the eyes were associated with better face memory in controls. We discuss the possible role of experiential factors in prior research linking dyslexia and face processing differences.