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Language Network Structure and Vocabulary Size of Toddlers Born Preterm

Poster C64 in Poster Session C, Friday, October 7, 10:15 am - 12:00 pm EDT, Millennium Hall

Kelly A. Vaughn¹, Hana Taha¹, Johanna Bick², Susan H. Landry¹, Dana M. DeMaster¹; ¹University of Texas Health Science Center at Houston, ²University of Houston

Preterm birth has been associated with risk for long-term language impairment, which may be explained by an interruption of typical in-utero language network development. Research with infants demonstrates that the brain’s language networks, including the bilateral inferior frontal gyrus (IFG) and superior temporal gyrus (STG), are altered in infants born preterm compared to full-term. The current set of analyses focused on toddlerhood, a key period of early language development, to investigate the relationship between gray matter volume in the language network, prematurity, and vocabulary size. These results are part of a larger study focused on toddler brain and cognitive development following preterm birth. The first analysis focused on parent-reported vocabulary size from toddlers born very or extremely preterm (n =16; adjusted age M =20.40 months; SD = 5.19 months; gestational weeks at birth: M = 26.13; SD = 2.42), including English monolinguals (n = 8), Spanish monolinguals (n = 2), and Spanish-English bilinguals (n =6). Parents completed the MacArthur-Bates Communicative Development Inventory Short Form in English and/or Spanish and composite scores were calculated for bilingual children. Results indicated that, on average, the preterm toddlers understood 59.50 words (SD = 26.20) and produced 20.44 words (SD = 5.80). Based on their term-corrected ages and genders, these vocabulary sizes reflect scores in the bottom 25th percentile, with large variability (SD = 29 percentile points). Next, we compared gray matter volume in the language network from a subset of the preterm toddlers with MRI data (n = 9) to an age-matched sample of toddlers born full-term (n = 8). We processed their T1- and T2-weighted images using the Infant Brain Extraction and Analysis Toolbox (iBEAT V2.0 Cloud), resulting in segmented gray and white matter. We then applied an age-appropriate atlas and extracted gray matter volume from the bilateral IFG (pars opercularis and pars triangularis) and the bilateral STG. Results indicated that, when controlling for total gray matter volume, preterm toddlers had smaller bilateral IFGs only in the pars triangularis region (left: t = 3.13, p = 0.007, Cohen’s d = 1.75; right: t = 4.61, p < 0.001, Cohen’s d = 2.59). Similar results were observed in the left STG (t = 3.00, p = 0.01, Cohen’s d = 3.00). Finally, we examined the relationship between vocabulary size and gray matter volume in the bilateral IFG and STG within the preterm sample. Results indicated that receptive vocabulary size was related to gray matter volume only in the left STG, while controlling for total gray matter volume and gestational age at birth (b -1.14, partial r = -0.96, p =0 0.02). These results reveal language delays and reduced gray matter volume in the left STG and bilateral pars triangularis for preterm toddlers, and highlight the left STG as a region that may explain some of their language delays. Future research is needed to understand how these relationships unfold across the first few years of life and whether high-quality language environments support early brain development for children born preterm.

Topic Areas: Development, Disorders: Developmental