Cortico-Cortical, Cortico-Striatal, and Cortico-Thalamic White Matter Fiber Tracts Generated in the Macaque Brain via Dynamic Programming

Abstract

Probabilistic methods have the potential to generate multiple and complex white matter fiber tracts in diffusion tensor imaging (DTI). Here, a method based on dynamic programming (DP) is introduced to reconstruct fibers pathways whose complex anatomical structures cannot be resolved beyond the resolution of standard DTI data. DP is based on optimizing a sequentially additive cost function derived from a Gaussian diffusion model whose covariance is defined by the diffusion tensor. DP is used to determine the optimal path between initial and terminal nodes by efficiently searching over all paths, connecting the nodes, and choosing the path in which the total probability is maximized. An ex vivo high-resolution scan of a macaque hemi-brain is used to demonstrate the advantages and limitations of DP. DP can generate fiber bundles between distant cortical areas (superior longitudinal fasciculi, arcuate fasciculus, uncinate fasciculus, and fronto-occipital fasciculus), neighboring cortical areas (dorsal and ventral banks of the principal sulcus), as well as cortical projections to the hippocampal formation (cingulum bundle), neostriatum (motor cortical projections to the putamen), thalamus (subcortical bundle), and hippocampal formation projections to the mammillary bodies via the fornix. Validation is established either by comparison with in vivo intracellular transport of horseradish peroxidase in another macaque monkey or by comparison with atlases. DP is able to generate known pathways, including crossing and kissing tracts. Thus, DP has the potential to enhance neuroimaging studies of cortical connectivity.

Probabilistic maps of the white matter tracts with known associated functions on the neonatal brain atlas: Application to evaluate longitudinal developmental trajectories in term-born and preterm-born infants

“…These fibers connect the premotor and primary motor cortices, the thalamus and the primary somatosensory cortex, the medial geniculate body and the primary auditory cortex, and the primary visual and higher visual association cortices. These fiber trajectories were investigated in non-human primates using histology and neuroimaging approaches (Ratnanather et al, 2013; Schmahmann and Pandya, 2006) and compared to brain diffusion MRI results in humans (Berman et al, 2013; Oishi et al, 2011b). The fiber trajectories delineated in this study matched these findings, and we additionally proposed a three-dimensional trajectory between the primary and higher visual association cortices, which was not established previously.…”

“…The two major challenges were: to define cytoarchitectonically defined cortical areas that are usually invisible on conventional MRI or DTI; and to delineate fibers that course through the SWM. We applied the Jülich cytoarchitectonic atlas (Eickhoff, et al, 2005) to define cortical areas related to specific brain functions, and the Dynamic Programming (DP) method (Li et al, 2014; Ratnanather et al, 2013) to delineate the white matter pathways that course through the SWM. DP enables delineation of fibers within fiber-crossing areas using a probabilistic framework.…”

Revealing the Hippocampal Connectome through Super-Resolution 1150-Direction Diffusion MRI

“…One recent study presented dMRI tractography of the human Papez circuit in considerable detail 13 , demonstrating connections among hubs in the MTL, retrosplenial gyrus, hippocampus, mammillary bodies, and anterior thalamic nuclei. The mammillary bodies are connected to the hippocampus via the fornix 1,14 , and directly to the anterior thalamic nuclei via the mammillothalamic tracts 15 . The Wei, et al .…”

Regional subcortical shape analysis in premanifest Huntington's disease

“…To a considerable extent, these circuits reflect the functional organization of the cortex. A basic feature of basal ganglia circuitry organization is the topographic organization of corticostriate projections (Haber & Knutson, ; Haber, ; Kemp & Powell, ; Ratnanather et al, ). While there is some overlap of corticostriate projections (Selemon & Goldman‐Rakic, ; Yeterian & Pandya, ), the mapping of cortical functional domains onto striatal subregions is an important feature of striatal organization and preserved to some extent throughout the parallel cortico‐basal ganglionic–thalamocortical circuits.…”