System-Specific Patterns of Thalamocortical Connectivity in Early Brain Development as Revealed by Structural and Functional MRI

Abstract

The normal development of thalamocortical connections plays a critical role in shaping brain connectivity in the prenatal and postnatal periods. Recent studies using advanced magnetic resonance imaging (MRI) techniques in neonates and infants have shown that abnormal thalamocortical connectivity is associated with adverse neurodevelopmental outcomes. However, all these studies have focused on a single neuroimaging modality, overlooking the dynamic relationship between structure and function at this early stage. Here, we study the relationship between structural and functional thalamocortical connectivity patterns derived from healthy full-term infants scanned with diffusion-weighted MRI and resting-state functional MRI within the first weeks of life (mean gestational age = 39.3 ± 1.2 weeks; age at scan = 24.2 ± 7.9 days). Our results show that while there is, in general, good spatial agreement between both MRI modalities, there are regional variations that are system-specific: regions involving primary-sensory cortices exhibit greater structural/functional overlap, whereas higher-order association areas such as temporal and posterior parietal cortices show divergence in spatial patterns of each modality. This variability illustrates the complementarity of both modalities and highlights the importance of multimodal approaches.

Trial registration: ClinicalTrials.gov NCT02058225.

Figures

Figure 1.

Anatomical images of a single subject and its corresponding segmentations in native space. (a) Original T1-weighed MRI, (b) brain extracted MRI, (c) automatically generated anatomical masks: CSF (blue), WM (red), GM (yellow), and thalamic and cortical labels used for (d) functional connectivity and (e) probabilistic tractography analysis. (f) Pial cortical surface showing cortical regions used for connectivity analysis (following FreeSurfer standard color lookup table).

Figure 2.

Functional (a) and structural (b) connectivity maps obtained in a group of 20 healthy neonates. Spatial overlap (c) between modalities shows different degrees of spatial agreement.

Figure 3.

Thalamic parcellations. (a) Cortical surface showing the 7 cortical regions used in the connectivity analysis. Functional (b) and structural (c) thalamic parcellations were color-coded based on the FreeSurfer standard color lookup table.

Figure 4.

Number of cortical regions with significant thalamocortical connectivity derived from the functional (top) and structural (bottom) connectivity analysis.