Poster Slam Session D, Wednesday, August 21, 2019, 5:00 - 5:15 pm, Finlandia Hall, Emily Myers
Neural correlates of learning novel word forms in children with developmental language disorder
Saloni Krishnan1, Harriet J. Smith1, Hannah Willis1, Kate E. Watkins1;1Department of Experimental Psychology, University of Oxford
Background: Developmental language disorder (DLD; previously known as specific language impairment) is characterised by unexplained difficulties in learning one’s native language, and affects at least 7% of children. We have argued that children with DLD have particular trouble with tasks that involve implicit learning of sequence structure, such as learning novel word forms. We hypothesised that dysfunction in corticostriatal systems is associated with these learning difficulties in DLD. Yet, to date, no previous fMRI work has directly tested this idea. In adults, learning to articulate novel word forms elicits changes in BOLD activity within frontostriatal systems, with decreases in activity in left premotor cortex, inferior frontal gyrus and putamen as pseudowords are repeated. Here, we explore the neural correlates of learning novel word forms in children with DLD and in typically developing children. Methods: 19 children with DLD (14 males) and 54 typically developing controls (19 males), aged between 10-15 years, were scanned at 3T while overtly repeating pseudowords (2- and 4-syllables). Sixteen words were heard and repeated only once; another sixteen were heard and repeated four times (each stimulus repetition occurred at 30s intervals, and never consecutively). Echo-planar images of the whole head were acquired during task performance (60 axial slices, voxel size 2.4mm3, TR=0.8s, TE=30ms, 600 volumes). For whole-brain group analyses, age and nonverbal IQ were entered as covariates with the general linear model (thresholded at Z>3.1, cluster corrected p<0.05). We used ROIs of the caudate nucleus and the putamen to probe changes within striatal nuclei. Results When repeating pseudowords, both groups activated regions associated with speech production, namely the left inferior frontal gyrus, the premotor cortex, superior temporal gyrus, supplementary motor cortex, and cerebellum bilaterally, as well as the caudate nucleus, putamen, thalamus and parahippocampal gyrus bilaterally. Repetitions of pseudowords resulted in linear decreases in activity in the superior temporal gyrus bilaterally and at a slightly lowered threshold, in the left inferior frontal gyrus, premotor cortex, and putamen, and the right caudate nucleus. ROI analysis showed that children with DLD had significantly reduced learning related decreases in activity compared with controls in the caudate nucleus bilaterally and in the right putamen. Conclusions The neural correlates of learning novel word forms in children mirrors the pattern seen in adults. A subset of regions, including the left inferior frontal gyrus and the dorsal striatum, showed decreases in activity with repeated stimulus presentation, consistent with the idea that learned word forms are represented more efficiently in these areas. In children with DLD, we find that activity in the dorsal striatum did not decrease to the same extent as seen in typically developing children. These results support our hypothesis that the frontostriatal system is dysfunctional in DLD, and the importance of corticostriatal interactions in speech and language learning.
Themes: Disorders: Developmental, Language Production
Method: Functional Imaging
Poster D11