Visualizing Myeloarchitecture In Vivo with Magnetic Resonance Imaging in Common Marmosets (Callithrix jacchus)

This Chapter details the visualization of myeloarchitecture in vivo in small New World monkeys (common marmosets – Callithrix jacchus) using magnetic resonance imaging (MRI). The features of myeloarchitecture in marmosets are well described from traditional histology studies; here we use very high resolution MRI (160 μm isotropic) to visualize these features in living animals. Following processing, our images show the complete pattern of myelin content over the marmoset cortex, revealing the size, location, and spatial relationship between regions including the primary auditory, somatosensory, and visual regions, and visually-associated areas including the middle temporal and dorsomedial regions. For morphological studies, the surface areas of regions can be computed for individual animals, which in this Chapter reveals the large proportion of the marmoset cortex dedicated to vision. Finally, digital flattening of the surface further reveals fine details in the myeloarchitecture.