Mental development is associated with cortical connectivity of the ventral and nonspecific thalamus of preterm newborns

The thalamus is a key hub for regulating cortical connectivity. Dysmaturation of thalamocortical networks that accompany white matter injury have been hypothesized as neuroanatomical correlate of late life neurocognitive impairment following preterm birth. Our objective was to find a link between thalamocortical connectivity measures at term equivalent age and two year neurodevelopmental outcome in preterm infants. Diffusion tensor MRI of 58 infants (postmenstrual age at birth, mean (SD), 29.71 (1.47) weeks) was used to trace connections between the cortex and thalami. We found strong correlation between mental developmental index and two complementary measures of thalamocortical networks: connectivity strength projected to a cortical skeleton and pathway length emerging from thalamic voxels (partial correlation, R=0.552 and R=0.535, respectively, threshold-free cluster enhancement, corrected p-value<0.05), while psychomotor development was not associated with thalamocortical connectivity. Post hoc stepwise linear regression analysis revealed that parental socioeconomic scale, postmenstrual age and the duration of mechanical ventilation at the intensive care unit contribute to the variability of outcome. Our findings independently validated previous observations in preterm infants, providing additional evidence injury or dysmaturation of tracts emerging from ventral specific and various non-specific thalamus projecting to late-maturing cortical regions are predictive of mental, but not psychomotor developmental outcomes.