A left cerebellar pathway mediates language in prematurely-born young adults

Abstract

Preterm (PT) subjects are at risk for developmental delay, and task-based studies suggest that developmental disorders may be due to alterations in neural connectivity. Since emerging data imply the importance of right cerebellar function for language acquisition in typical development, we hypothesized that PT subjects would have alternate areas of cerebellar connectivity, and that these areas would be responsible for differences in cognitive outcomes between PT subjects and term controls at age 20 years. Nineteen PT and 19 term control young adults were prospectively studied using resting-state functional MRI (fMRI) to create voxel-based contrast maps reflecting the functional connectivity of each tissue element in the grey matter through analysis of the intrinsic connectivity contrast degree (ICC-d). Left cerebellar ICC-d differences between subjects identified a region of interest that was used for subsequent seed-based connectivity analyses. Subjects underwent standardized language testing, and correlations with cognitive outcomes were assessed. There were no differences in gender, hand preference, maternal education, age at study, or Peabody Picture Vocabulary Test (PPVT) scores. Functional connectivity (FcMRI) demonstrated increased tissue connectivity in the biventer, simple and quadrangular lobules of the L cerebellum (p<0.05) in PTs compared to term controls; seed-based analyses from these regions demonstrated alterations in connectivity from L cerebellum to both R and L inferior frontal gyri (IFG) in PTs compared to term controls. For PTs but not term controls, there were significant positive correlations between these connections and PPVT scores (R IFG: r=0.555, p=0.01; L IFG: r=0.454, p=0.05), as well as Verbal Comprehension Index (VCI) scores (R IFG: r=0.472, p=0.04). These data suggest the presence of a left cerebellar language circuit in PT subjects at young adulthood. These findings may represent either a delay in maturation or the engagement of alternative neural pathways for language in the developing PT brain.

Copyright © 2012 Elsevier Inc. All rights reserved.

Figures

Figure 1

Cerebellar region showing group differences (preterm – term) in local tissue connectivity as measured by the network measure degree (p

Figure 2

Map showing group differences (preterm – term, p

Figure 3

Plot illustrating the relationship between PPVT score and cerebellar-to-left IFG connectivity for preterms (a) and for term controls (b), and cerebellar-to-right IFG connectivity for preterm subjects (c) and term controls (d). Both the L cerebellar to L IFG (panel a) and L cerebellar to R IFG (panel c) connections are significantly positively correlated with the PPVT scores for the preterm subjects (r = 0.454, p = 0.05 and r = 0.555, p = 0.01, respectively). In contrast, there was a trend negative correlation for the L cerebellar to L IFG connection for PPVT score (panel b: r = −0.441, p = 0.06) for the term controls. There was no correlation between the L cerebellar to R IFG connection and PPVT score for the term subject group (panel d: r = −0.159, p = 0.52). The solid lines represent the regression lines; the dashed lines are the 95% confidence limits of the mean.