Functional connectivity to a right hemisphere language center in prematurely born adolescents

Abstract

Prematurely born children are at increased risk for language deficits at school age and beyond, but the neurobiological basis of these findings remains poorly understood. Thirty-one PT adolescents (600-1250g birth weight) and 36 T controls were evaluated using an fMRI passive language task and neurodevelopmental assessments including: the Wechsler Intelligence Scale for Children-III (WISC-III), the Peabody Picture Vocabulary Test-Revised (PPVT-R), the Comprehensive Test of Phonological Processing (CTOPP) and the Test of Word Reading Efficiency (TOWRE) at 16years of age. Neural activity was assessed for language processing and the data were evaluated for connectivity and correlations to cognitive outcomes. PT subjects scored significantly lower on all components of the WISC-III (p<0.05) compared to term subjects, but there was no significant difference in PPVT-R scores between the groups. Functional connectivity (fcMRI) between Wernicke's area (left BA 22) and the right supramarginal gyrus (BA 40) was increased in preterm subjects relative to term controls (p=0.03), and the strength of this connection was inversely related to performance on both the PPVT-R (R(2)=0.553, p=0.002), and the verbal comprehension index (R(2)=0.439, p=0.019). Preterm adolescents engage a dorsal right hemisphere region for language at age 16years. Those with the greatest cognitive deficits demonstrate increasing reliance on this alternate pathway.

Figure 1

Anatomic ROIs where connectivity to left Wernicke’s area (red) was assessed. Left and right BA 40 are shown in blue, and the ROI in right BA 44/45 is green.

Figure 2

Scatterplots depict connectivity-cognitive relationships in the preterm subjects. The strength of connection between Wernicke’s area and the ROI in right BA40 was inversely related to scores on the PPVT-R (top plot, y = 137–388*x), the VCI (middle plot, y = 122–264*x) and the vocabulary score of the WISC-III (bottom plot, y = 16–68*x).