A diffusion tensor brain template for Rhesus Macaques

Abstract

Diffusion tensor imaging (DTI) is a powerful and noninvasive imaging method for characterizing tissue microstructure and white matter organization in the brain. While it has been applied extensively in research studies of the human brain, DTI studies of non-human primates have been performed only recently. The growing application of DTI in rhesus monkey studies would significantly benefit from a standardized framework to compare findings across different studies. A very common strategy for image analysis is to spatially normalize (co-register) the individual scans to a representative template space. This paper presents the development of a DTI brain template, UWRMAC-DTI271, for adolescent Rhesus Macaque (Macaca mulatta) monkeys. The template was generated from 271 rhesus monkeys, collected as part of a unique brain imaging genetics study. It is the largest number of animals ever used to generate a computational brain template, which enables the generation of a template that has high image quality and accounts for variability in the species. The quality of the template is further ensured with the use of DTI-TK, a well-tested and high-performance DTI spatial normalization method in human studies. We demonstrated its efficacy in monkey studies for the first time by comparing it to other commonly used scalar-methods for DTI normalization. It is anticipated that this template will play an important role in facilitating cross-site voxelwise DTI analyses in rhesus macaques. Such analyses are crucial in investigating the role of white matter structure in brain function, development, and other psychopathological disorders for which there are well-validated non-human primate models.

A diffusion tensor MRI atlas of the postmortem rhesus macaque brain

“…Brain atlases have become important tools for studying normal neuroanatomy and for localizing neuropathology that is the basis of disease states. Many different brain atlases have been generated for the rhesus macaque including those based on conventional histology (Paxinos et al, 2009; Saleem and Logothetis, 2012), anterograde/retrograde neuronal tracer studies (Schmahmann and Pandya, 2009), and magnetic resonance imaging (MRI) (Adluru et al, 2012; Dubach and Bowden, 2009; Frey et al, 2011; McLaren et al, 2009; Rohlfing et al, 2012; Saleem and Logothetis, 2012; Zakszewski et al, 2014). Although it is generally of lower resolution than other brain atlasing methods, MRI has several important advantages: 1) it is three-dimensional (3D) and volumetrically accurate; 2) it can provide multiple different image contrasts from the same tissue; and, 3) it allows probabilistic atlases to be generated from multiple subjects through non-linear image registration techniques.…”

“…Several MRI and even DTI-based atlases of the rhesus macaque brain exist, but they are often limited by low contrast and/or low spatial resolution (Adluru et al, 2012; Frey et al, 2011; McLaren et al, 2009; Saleem and Logothetis, 2012; Wisco et al, 2008b; Zakszewski et al, 2014). Image resolution is particularly important because the macaque brain is 10–15 fold smaller volumetrically than the human brain (Herculano-Houzel, 2009), so image voxels must be 10–15 fold smaller to have comparable structural resolution.…”

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

“…Though no direct comparisons with other methods were made, it is worth noting that Figure 2 given the FOF-Frontal and FOF-PO ROIs, FACT with a threshold of 0.1 generated a bundle that was more inferior to the true FOF going through the middle longitudinal fasciculus and Extreme Capsule (see Figs. 14-2 and 15-1 in Schmahmann and Pandya, 2006) similar to those generated by deterministic approaches (Adluru et al, 2012;Hofer and Frahm, 2008). This led to the inference of a macaque homologue of the human inferior FOF that does not exist (Catani et al, 2007;Schmahmann and Pandya, 2007).…”

“…Unlike DP, FACT was unable to deal with kissing and crossing fibers seen with HAR (Wedeen et al, 2008(Wedeen et al, , 2012. Adluru et al (2012) also used a deterministic approach to track several bundles with an FA threshold of 0.1-0.15 in a template of 0.5 mm 3 resolution generated as a population average from 271 macaques from a 3T scanner. DP has several limitations.…”

Combined Effects of Primary and Tertiary Blast on Rat Brain: Characterization of a Model of Blast-induced Mild Traumatic Brain Injury

“…For unbiased quantification of DTI measures using anatomically based ROIs, DTI volumes from all subjects were first registered to a common space using an iterative, tensor-based registration routine implemented in DTI-TK 54 . Rigid-body, affine, and diffeomorphic (piecewise affine) methods were used in succession to progressively improve registration accuracy, as this approach has been shown to be superior to other routines 55 . The final image resolution was 120 3 120 3 500 mm…”