Functional magnetic resonance connectivity studies in infants born preterm: suggestions of proximate and long-lasting changes in language organization

Abstract

Sophisticated neuroimaging strategies demonstrate alterations in functional connectivity at school age, adolescence, and young adulthood in individuals born preterm. Recent data suggest these alterations are present in the postnatal period prior to term-equivalent age in neonates born preterm. Likewise, functional organization increases across development, but the influence of preterm birth on this fundamental infrastructure is immediate and unchanging. This article briefly reviews the current methods of measuring functional connectivity throughout development in those born preterm, and the association of functional connectivity with language disorders. Taken together, these data suggest that the effects of preterm birth on the functional organization of language in the developing brain are both proximate and long-lasting.

Figure 1:

Overview of functional connectivity. (a) Functional connectivity is defined as the correlation between blood oxygen level dependent time course for any two regions or voxels in the brain. A higher correlation between time course implies higher functional connectivity between the regions. Common methods for functional connectivity include seed, matrix, and voxel-wise connectivity. (b) Seed connectivity involves identifying key regions or seeds and assessing connectivity between these seeds and all other voxels in the brain. This analysis is the most common. (c) Matrix connectivity involves parcellating the brain in ~100 to 400 distinct regions and assessing connectivity between each of these regions. These connectivity matrices typically use graph theory. (d) Voxel-wise connectivity involves assessing connectivity for every voxel in the brain to every other voxel in the brain and summarizing these correlations with a summary statistic. This method is highly data driven as no a priori region needs to be specified (unlike seed and matrix connectivity). However, any information about a specific connection is lost.