Connectivity-based structural and functional parcellation of the human cortex using diffusion imaging and tractography

Abstract

The parcellation of the cortex via its anatomical properties has been an important research endeavor for over a century. To date, however, a universally accepted parcellation scheme for the human brain still remains elusive. In the current review, we explore the use of in vivo diffusion imaging and white matter tractography as a non-invasive method for the structural and functional parcellation of the human cerebral cortex, discussing the strengths and limitations of the current approaches. Cortical parcellation via white matter connectivity is based on the premise that, as connectional anatomy determines functional organization, it should be possible to segregate functionally-distinct cortical regions by identifying similarities and differences in connectivity profiles. Recent studies have provided initial evidence in support of the efficacy of this connectional parcellation methodology. Such investigations have identified distinct cortical subregions which correlate strongly with functional regions identified via fMRI and meta-analyses. Furthermore, a strong parallel between the cortical regions defined via tractographic and more traditional cytoarchitectonic parcellation methods has been observed. However, the degree of correspondence and relative functional importance of cytoarchitectonic- versus connectivity-derived parcellations still remains unclear. Diffusion tractography remains one of the only methods capable of visualizing the structural networks of the brain in vivo. As such, it is of vital importance to continue to improve the accuracy of the methodology and to extend its potential applications in the study of cognition in neurological health and disease.

Connectivity Profiles Reveal a Transition Subarea in the Parahippocampal Region That Integrates the Anterior Temporal–Posterior Medial Systems

“…Recently, methods based on connection-based parcellation (CBP) techniques have emerged as powerful tools for investigating the organization of the human brain (Cloutman and Lambon Ralph, 2012). Noninvasive CBP techniques have been used to define functionally distinct brain regions that are highly consistent with traditional cytoarchitectonic findings (Johansen-Berg et al, 2004;Beckmann et al, 2009;Zhang et al, 2014).…”

The influence of construction methodology on structural brain network measures: A review

“…The reports on brain parcellation seldom used the structural or functional connectivity information (Craddock et al, 2013), but nowadays it is thought that the ideal node is the brain region with a coherent pattern of anatomical or functional connections (Rubinov and Sporns, 2010;Amunts et al, 2014). Therefore, connectivity-based parcellations are considered to be the most promising approach, because they are based on brain functional and structural connectivity information (Cloutman and Lambon Ralph, 2012;de Reus and van den Heuvel, 2013). Especially, the CC200 atlas (Craddock et al, 2012) generated by dividing restingstate fMRI data into spatially coherent areas of homogeneous functional connectivity, might help to combine the structural and functional brain networks.…”

Transport for language south of the Sylvian fissure: The routes and history of the main tracts and stations in the ventral language network

“…This method can provide very similar results as gross dissection (Catani, Howard, Pajevic, & Jones, 2002) and is a more flexible technique. It allows both virtual dissections of white matter tracts as well as a method for parcellating the cortex according to tractographic profile of cortical voxels (Cloutman & Lambon Ralph, 2012). Since it is a computational technique, the data are not destroyed in the analytical process, meaning that it can be independently confirmed by other researchers.…”