Task-Based fMRI Reveals Neural Mechanisms of Speech Production and Perception in Preschoolers

• In Event: Breaking Barriers to Better Understand Early Cognitive Development: Novel Task-Based fMRI Paradigms in Young Children

Abstract

Speech production and perception skills continue to develop through the preschool years and are sensitive to delays and disorders during this time. These skills involve integration of motor and auditory function, as well as development of mental representations of speech sounds. However, the neural bases of these mechanisms in young children are not well-understood. We recruited 23 preschoolers, aged 4:0-5:11 to participate in a functional magnetic resonance imaging (fMRI) study involving two tasks. First, to examine speech production, they completed a syllable repetition task (SRT, Shriberg et al., 2009), which involves repetition of phonetically simple phonemes (/b, d, m, n, ɑ/) in syllable series. Items increase in length from 2-4 syllables (e.g. /bɑdɑ/ to /bɑmɑdɑnɑ/); 18 items total. In the “repeat” condition, children hear the syllable sequence and immediately repeat it. In the “listen” condition, children passively listen to the same syllable sequences. All items are presented in both conditions, counter-balanced across 6-items blocks. A sparse acquisition approach allows children to hear the auditory stimulus and for their overt repetition response to be recorded without scanner noise. Six seconds of MRI silence for presentation of the auditory stimulus, and spoken response if appropriate, is followed by 6 seconds of fMRI acquisition. This task is presented twice. Second, children completed a word-picture matching task. Simple color drawings of common objects were presented, and one second later, children hear a one-syllable word/pseudoword that either matches or does not match the picture, due to a mismatch in the word’s initial sound (e.g. boat for coat). Children respond with a button-press within 3 seconds, only when the word matches the picture (40/120 of trials). FMRI data collection for both tasks used a multi-echo technique (TR=1200ms, TE=14ms, 32ms, 50ms). 23 preschoolers completed the SRT task, but 6 were excluded due to technical problems with task timing/poor task compliance. 18 completed the word-picture matching task and 5 were excluded due to task performance below 70% accuracy. FMRI data were analyzed using standard pipelines in FSL (Jenkinson et al., 2012) for motion correction and spatial normalization. Multi-echo data were modeled using T2* estimation. Group results were thresholded at p<.01 (uncorrected). The SRT showed increases in activation for speech production>listening in left superior temporal gyrus and insula, left fusiform gyrus, left precentral gyrus, bilateral anterior cingulate cortex, right inferior temporal gyrus, and right angular gyrus. The speech perception task, when comparing matching items to non-matching items, showed activation in left precentral and postcentral gyrus, right middle frontal gyrus, anterior and posterior cingulate cortex, and regions of right parietal cortex. These results reflect, depending on task, engagement of regions involved in auditory and motor/somatosensory function, executive function, and memory. Further analyses will examine effects of task performance on activation as well as functional connectivity. In addition, we will discuss methodological challenges associated with task-based fMRI in preschoolers, particularly for overt speech and auditory verbal materials. An understanding of these patterns of activation in typically-developing children provides a foundation for further investigation into developmental processes and disorders that affect speech.

Authors

• Jennifer Vannest, University of Cincinnati
  Presenting Author

• Thomas C. Maloney, University of Cincinnati

• Julia Hoyda, University of Cincinnati

• Darren S. Kadis, University of Cincinnati

• Erin R. Sizemore, Mount St. Joseph University

• Jonathan Preston, Syracuse University

• Suzanne Boyce, University of Cincinnati