正常人兩大腦半球間結構與功能關聯性之研究

Abstract

人腦是一個在結構與功能上整合的複雜系統，為了探究其結構連結與功能連結之間的關係，本研究以連結左右大腦半球的胼胝體為研究目標，採用嚴謹分析方法探討其結構連結與功能連結之間的關聯性，以及其關聯性在額葉、頂葉、枕葉和聶葉之特徵。本研究徵招二十位右撇子的正常人，於3T的核磁共振掃描系統中取得一組高解析度結構影像、一組功能性影像以及一組擴散性影像。任意兩點之結構連結性定義為連接該兩點之纖維束總數除以胼胝體總纖維束。任意兩點之功能連結性定義為該兩點之時間序列的偏相關系數。該結構連結與功能連結之間的關聯性定義為兩者之間的相關系數。 本研究顯示出在胼胝體其結構連結與功能連結之間的關聯性為輕度至中度。此外，該關聯性在同倫連結與異倫連結之間有顯著性的不同，此結果意謂胼胝體之結構幾何對於該關聯性有貢獻。輕度至中度的結構功能關聯性意謂著兩半腦間之功能連結的現象為大腦白質結構整合之結果，不僅只透過胼胝體，該結構功能關聯性比我們預期更為複雜。 本研究以嚴謹分析方法探究大腦最簡單的結構─胼胝體，我們的結果與過去各種分析方法及技術得到的結果一致，驗證大腦的結構連結與功能連結僅中度相關，而非高度相關。

The aim of this study is to well-knit approach to better understand the structure-function relationships in healthy human brains using the simplest system as a model to investigate the relationships between interhemispheric structural connectivity and functional connectivity and the characteristics among different lobes in the brain. To understand the structure-function relationships in human brain, this study focuses on the corpus callosum, the simplest system in human brain. We recruited 20 young healthy right-handed adults in this study. Scanning was performed on a 3T MRI system, consisting of structural, functional, and diffusion MRI. Structural connectivity was defined as the number of connected tracts terminating between two regions divided by the total number of corpus callosal tracts and functional connectivity was defined as the partial correlation coefficient of time courses between two distinct regions. Structure-function relationships were computed by correlating functional connectivity with structural connectivity. We found weak to moderate structure-function correlations in the corpus callosum. In addition, homotopic and heterotopic connections showed distinct strengths of structure-function correlations. These results indicate the topology of the corpus callosum is associated with structure-function relationships. Moreover, functional connectivity can be explained by structural connectivity to some degree, such that interhemispheric functional connectivity may involve contributions from other physical connections in addition to the corpus callosum and hormone effect. In this study, we use the simplest system corpus callosum to confirm that instead of strong degree of structure-function relationship, the structural connectivity is moderately correlated with the functional connectivity, which is the consistent result across a wide variety of methods.