Changes in connectivity profiles define functionally distinct regions in human medial frontal cortex

doi:10.1073/pnas.0403743101

Changes in connectivity profiles define functionally distinct regions in human medial frontal cortex

^*Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom; ^§University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom; ^¶Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom; ^∥Department of Engineering Science, Medical Vision Laboratory, University of Oxford, Oxford OX1 3PJ, United Kingdom; and ^**Department of Mathematics, Univesity of Strathclyde, Glasgow G1 1HX, Scotland, United Kingdom

Edited by Marcus E. Raichle, Washington University School of Medicine, St. Louis, MO, and approved July 30, 2004 (received for review May 27, 2004)

Abstract

A fundamental issue in neuroscience is the relation between structure and function. However, gross landmarks do not correspond well to microstructural borders and cytoarchitecture cannot be visualized in a living brain used for functional studies. Here, we used diffusion-weighted and functional MRI to test structure-function relations directly. Distinct neocortical regions were defined as volumes having similar connectivity profiles and borders identified where connectivity changed. Without using prior information, we found an abrupt profile change where the border between supplementary motor area (SMA) and pre-SMA is expected. Consistent with this anatomical assignment, putative SMA and pre-SMA connected to motor and prefrontal regions, respectively. Excellent spatial correlations were found between volumes defined by using connectivity alone and volumes activated during tasks designed to involve SMA or pre-SMA selectively. This finding demonstrates a strong relationship between structure and function in medial frontal cortex and offers a strategy for testing such correspondences elsewhere in the brain.

Footnotes

↵ ‡ To whom correspondence should be addressed. E-mail: heidi{at}fmrib.ox.ac.uk.
↵ † H.J.-B. and T.E.J.B. contributed equally to this work.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: SMA, supplementary motor area; fMRI, functional MRI; BOLD, blood oxygenation level-dependent; DWI, diffusion-weighted imaging; MNI, Montreal Neurological Institute.