Noninvasive Functional and Structural Connectivity Mapping of the Human Thalamocortical System

TLDR

Understanding brain physiology requires linking structural connectivity to functional activity, and the thalamocortical system—well‑documented anatomically—provides an ideal model for such studies. We mapped the human thalamocortical system with functional and diffusion‑weighted MRI, validating the results against histology and primate connectivity data. The imaging data largely agree with histology, supporting a direct anatomical connectivity model, yet notable discrepancies between structural and functional maps indicate additional complexity and distinct contributions of each modality.

Abstract

Relating structural connectivity with functional activity is fundamentally important to understanding the brain's physiology. The thalamocortical system serves as a good model system for exploring structure/function relationships because of its well-documented anatomical connectivity. Here we performed functional and structural magnetic resonance mapping of the human thalamocortical system using intrinsic brain activity and diffusion-weighted imaging. The accuracy of these imaging techniques is tested by comparison with human histology registered to common anatomical space and connectional anatomy derived from nonhuman primates. In general, there is good overall concordance among structural, functional, and histological results which suggests that a simple model of direct anatomical connectivity between the cerebral cortex and the thalamus is capable of explaining much of the observed correlations in neuronal activity. However, important differences between structural and functional mapping results are also manifest which suggests a more complex interpretation and emphasizes the unique contributions from structural and functional mapping.