Longitudinal changes in cortical responses to letter-speech sound stimuli in 8 – 11 year-old children

in npj Science of Learning (2022)

While children are able to name letters fairly quickly, the automatisation of letter-speech sound mappings continues over the first years of reading development. In the current longitudinal fMRI study, we ... [more ▼]

While children are able to name letters fairly quickly, the automatisation of letter-speech sound mappings continues over the first years of reading development. In the current longitudinal fMRI study, we explored developmental changes in cortical responses to letters and speech sounds across 3 yearly measurements in a sample of 18 8–11 year old children. We employed a text-based recalibration paradigm in which combined exposure to text and ambiguous speech sounds shifts participants’ later perception of the ambiguous sounds towards the text. Our results showed that activity of the left superior temporal and lateral inferior precentral gyri followed a non-linear developmental pattern across the measurement sessions. This pattern is reminiscent of previously reported inverted-u-shape developmental trajectories in children’s visual cortical responses to text. Our findings suggest that the processing of letters and speech sounds involves non-linear changes in the brain’s spoken language network possibly related to progressive automatisation of reading skills. [less ▲]

Reading-induced shifts in speech perception in dyslexic and typically reading children

in Frontiers in Psychology (2019), 221(10),

One of the proposed mechanisms underlying reading difficulties observed indevelopmental dyslexia is impaired mapping of visual to auditory speechrepresentations. We investigate these mappings in 20 ... [more ▼]

One of the proposed mechanisms underlying reading difficulties observed indevelopmental dyslexia is impaired mapping of visual to auditory speechrepresentations. We investigate these mappings in 20 typically reading and 20 childrenwith dyslexia aged 8–10 years using text-based recalibration. In this paradigm, thepairing of visual text and ambiguous speech sounds shifts (recalibrates) the participant’sperception of the ambiguous speech in subsequent auditory-only post-test trials.Recent research in adults demonstrated this text-induced perceptual shift in typical,but not in dyslexic readers. Our current results instead show significant text-inducedrecalibration in both typically reading children and children with dyslexia. The strengthof this effect was significantly linked to the strength of perceptual adaptation effects inchildren with dyslexia but not typically reading children. Furthermore, additional analysesin a sample of typically reading children of various reading levels revealed a significant linkbetween recalibration and phoneme categorization. Taken together, our study highlightsthe importance of considering dynamic developmental changes in reading, letter-speechsound coupling and speech perception when investigating group differences betweentypical and dyslexic readers. [less ▲]