Thalamocortical Connectivity Predicts Cognition in Children Born Preterm

Abstract

Thalamocortical connections are: essential for brain function, established early in development, and significantly impaired following preterm birth. Impaired cognitive abilities in preterm infants may be related to disruptions in thalamocortical connectivity. The aim of this study was to test the hypothesis: thalamocortical connectivity in the preterm brain at term-equivalent is correlated with cognitive performance in early childhood. We examined 57 infants who were born <35 weeks gestational age (GA) and had no evidence of focal abnormality on magnetic resonance imaging (MRI). Infants underwent diffusion MRI at term and cognitive performance at 2 years was assessed using the Bayley III scales of Infant and Toddler development. Cognitive scores at 2 years were correlated with structural connectivity between the thalamus and extensive cortical regions at term. Mean thalamocortical connectivity across the whole cortex explained 11% of the variance in cognitive scores at 2 years. The inclusion of GA at birth and parental socioeconomic group in the model explained 30% of the variance in subsequent cognitive performance. Identifying impairments in thalamocortical connectivity as early as term equivalent can help identify those infants at risk of subsequent cognitive delay and may be useful to assess efficacy of potential treatments at an early age.

Keywords: brain; cognition; diffusion magnetic resonance imaging; infant; preterm.

Figure 1.

Thalamocortical connectivity and cognition. (A) Regions where thalamocortical connectivity at term equivalent age was correlated to cognition at 2 years, P < 0.05 adjusted for GA at birth, PMA at scan, and parental socioeconomic group, are shown in yellow. (B) Surface renderings showing the t-statistic of each significant voxel in A. (C) Full model fit (top) and semi-partial correlation plots (bottom) showing the relationship between cognitive score at 2 years, parental socioeconomic status and mean connectivity. Socioeconomic score and mean connectivity are adjusted for each other and GA at birth.

Figure 2.

Gray matter mean diffusivity and cognition. (A) Regions where cortical diffusivity was correlated to cognition at 2 years, P < 0.01 adjusted for GA at birth, PMA at scan and parental socioeconomic group, are shown in red. (B) surface rendering of the t-statistic of each significant voxel in A. (C) correlation between mean cortical diffusivity and thalamic diffusivity, corrected for GA at birth and age at scan. (D) Semi-partial correlation plots showing the relationships between cognitive score, parental socioeconomic status (of note a higher SES denotes a lower socioeconomic group), mean thalamocortical connectivity and mean thalamic diffusivity.