A resource for the detailed 3D mapping of white matter pathways in the marmoset brain

Abstract

While the fundamental importance of the white matter in supporting neuronal communication is well known, existing publications of primate brains do not feature a detailed description of its complex anatomy. The main barrier is that existing primate neuroimaging data have insufficient spatial resolution to resolve white matter pathways fully. Here, we present a resource that allows detailed descriptions of white matter structures and trajectories of fiber-pathways in the marmoset brain. The resource includes: (1) the highest resolution diffusion MRI (dMRI) data available to date, which reveal white matter features not previously described; (2) a comprehensive 3D white matter atlas depicting fiber-pathways that were either omitted or misidentified in previous atlases; and (3) comprehensive fiber-pathway maps of cortical connections combining dMRI tractography and neuronal tracing data. The resource, which can be downloaded from marmosetbrainmapping.org , will facilitate studies of brain connectivity and the development of tractography algorithms in the primate brain.

Histology-based average template of the marmoset cortex with probabilistic localization of cytoarchitectural areas

“…For example, registration of a structural MR image obtained from an individual to the present template can be used to direct tracer injections or electrode arrays to the coordinates most likely to belong to a specific area, or to assign levels of confidence to voxels revealed by functional imaging data. The feasibility of this approach is demonstrated by calculations of the transformations needed to register the present template to previously released high-resolution ex vivo MR images of the marmoset brain (Liu et al, 2020). This allowed us to correlate different structural features of various regions of the cortex, such as the T2* signal intensity and the Nissl image intensity, which, as the present study shows, is strongly correlated with neuronal density (Fig.…”

“…The approach adopted here may be useful in the context of the future development of average brain templates that incorporate information about the variability of areas in other species for which it may be impractical to ensure homogeneity of the sample in terms of age, sex and genetic background. Given the rapid development of open access digital resources for the marmoset brain Liu et al, 2020;Majka et al, 2020), and the availability of data on resting state functional connectivity (Hori et al, 2020), the present template may become an important contributor to studies that will lead to a new level of insight on the anatomical principles of organization of the primate brain.…”

“…To enable interoperability with other marmoset brain atlases, we registered the Nencki-Monash template to three other publicly available marmoset brain templates: the one based on the Paxinos et al (2012) atlas of the marmoset brain (Majka et al, 2016), the template developed by the Brain/MINDS consortium (Woodward et al, 2018) and the Marmoset Brain Mapping (MBM) 2.0 marmoset brain template (Liu et al, 2020). All these templates were released with cortical parcellations that follow the Paxinos et al (2012) convention, which makes it possible to augment the conventional intensity-based registration with the approach relying on label maps, analogously to the procedure demonstrated in Fig.…”

“…Finally, we address the interoperability between the NM template and other current digital atlases of the marmoset cortex: the Paxinos et al (2012) template converted into a three-dimensional image (Majka et al, 2016), the Brain/MINDS 3D marmoset brain atlas (Woodward et al, 2018) and the MBM 2.0 high-resolution MRI template (Liu et al, 2020). To enable the bidirectional traversal between different atlas spaces, three sets of affine and deformable spatial transformations were computed.…”

“…Utilizing the obtained spatial transformations, we have warped ultra-high resolution MR images of the MBM 2.0 atlas (Liu et al, 2020) into the space of the NM template. With these additional layers, the NM template provides an accurate multimodal view of the entire brain incorporating both cytoarchitecture and MR imaging modalities ( Figs.…”