Converging Meta-Analytic and Connectomic Evidence for Functional Subregions Within the Human Retrosplenial Region

Interest in the retrosplenial cortex (RSC) has surged in recent years, as this region has been implicated in a range of cognitive processes. Previously reported anatomical and functional definitions of the human RSC encompass a larger area than expected from underlying cytoarchitectonic profiles. Here, we used a large-scale, unbiased, and data-driven approach combining functional MRI meta-analysis and resting-state functional connectivity (rsFC) methods to test the nature of this heterogeneity. The automated toolset Neurosynth was used to conduct meta-analyses in order to (a) identify heterogeneous areas in the retrosplenial region (RS region) associated with one or more cognitive domains, and (b) contrast the activation profiles related to these domains. These analyses yielded several functional subregions across the RS region, highlighting differences between anterior RS regions associated with episodic memory and posterior RS regions in the parietal-occipital sulcus associated with scenes and navigation. These regions were subsequently used as seeds to conduct whole brain rsFC analyses using data from the Human Connectome Project. In support of the meta-analysis findings, rsFC revealed divergent connectivity profiles, with anterior regions demonstrating connectivity to the default mode network (DMN) and posterior regions demonstrating connectivity to visual regions. Anterior RS regions and the parietaloccipital sulcus connected to different subnetworks of the DMN. This convergent evidence supports the conclusion that the broad cortical RS region incorporating both anatomical and functional RSC consists of functionally heterogeneous subregions. This study combines two large databases to provide a novel methodological blueprint for understanding brain function in the RS region and beyond.