Connectivity-based parcellation of the human frontal polar cortex

TL;DR

This study identifies two anatomical subregions in the human frontal pole, each linked to different brain networks related to self-related thought and attention.

Contribution

The paper introduces a connectivity-based parcellation of the frontal pole using diffusion tensor imaging and functional connectivity.

Findings

Three subregions were identified, but only two showed consistent spatial patterns across subjects.

The medial subregion connects to the default-mode network, while the lateral connects to the executive control network.

These findings support the idea of two major anatomical subregions in the frontal pole with distinct functional roles.

Abstract

The frontal pole corresponds to Brodmann area (BA) 10, the largest single architectonic area in the human frontal lobe. Generally, BA10 is thought to contain two or three subregions that subserve broad functions such as multitasking, social cognition, attention, and episodic memory. However, there is a substantial debate about the functional and structural heterogeneity of this large frontal region. Previous connectivity-based parcellation studies have identified two or three subregions in the human frontal pole. Here, we used diffusion tensor imaging to assess structural connectivity of BA10 in 35 healthy subjects and delineated subregions based on this connectivity. This allowed us to determine the correspondence of structurally based subregions with the scheme previously defined functionally. Three subregions could be defined in each subject. However, these three subregions were not spatially consistent between subjects. Therefore, we accepted a solution with two subregions that encompassed the lateral and medial frontal pole. We then examined resting-state functional connectivity of the two subregions and found significant differences between their connectivities. The medial cluster was connected to nodes of the default-mode network, which is implicated in internally focused, self-related thought, and social cognition. The lateral cluster was connected to nodes of the executive control network, associated with directed attention and working memory. These findings support the concept that there are two major anatomical subregions of the frontal pole related to differences in functional connectivity.

The online version of this article (doi:10.1007/s00429-014-0809-6) contains supplementary material, which is available to authorized users.

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