Magnetic Resonance Imaging of Marmoset Monkeys

Abstract

The use of the common marmoset monkey (Callithrix jacchus) for neuroscientific research has grown markedly in the last decade. Magnetic resonance imaging (MRI) has played a significant role in establishing the extent of comparability of marmoset brain architecture with the human brain and brains of other preclinical species (eg, macaques and rodents). As a non-invasive technique, MRI allows for the flexible acquisition of the same sequences across different species in vivo, including imaging of whole-brain functional topologies not possible with more invasive techniques. Being one of the smallest New World primates, the marmoset may be an ideal nonhuman primate species to study with MRI. As primates, marmosets have an elaborated frontal cortex with features analogous to the human brain, while also having a small enough body size to fit into powerful small-bore MRI systems typically employed for rodent imaging; these systems offer superior signal strength and resolution. Further, marmosets have a rich behavioral repertoire uniquely paired with a lissencephalic cortex (like rodents). This smooth cortical surface lends itself well to MRI and also other invasive methodologies. With the advent of transgenic modification techniques, marmosets have gained significant traction as a powerful complement to canonical mammalian modelling species. Marmosets are poised to make major contributions to preclinical investigations of the pathophysiology of human brain disorders as well as more basic mechanistic explorations of the brain. The goal of this article is to provide an overview of the practical aspects of implementing MRI and fMRI in marmosets (both under anesthesia and fully awake) and discuss the development of resources recently made available for marmoset imaging.

Effects of Anesthesia on Cerebral Blood Flow and Functional Connectivity of Nonhuman Primates

“…Compared to isoflurane, sevoflurane does not have a pungent smell and is not irritating to the respiratory tract. Therefore, sevoflurane can be an alternative for mask induction with an induction chamber and maintenance of New World primates (such as marmosets) [ 118 ]. Previous PET studies of adult rhesus monkeys suggested sevoflurane exposure has minimal effect on cognitive function [ 119 ], and the suppression effects of sevoflurane on the BOLD signal and intrinsic neural activity of the human brain were seen [ 120 ].…”

Development of a non-invasive novel individual marmoset holder for evaluation by awake functional magnetic resonance brain imaging

“…One possible reason for not using fMRI in marmosets is that it is necessary to have a wide-bore MRI scanner for small animals to replicate currently published methods. In small animal MRI, the bore size in marmosets ranges from 15 to 30 cm without a gradient coil (Schaeffer et al, 2020a). An MRI with a small bore has advantages such as lower costs and a higher potential to equip high gradients than an MRI with a wide bore.…”

“…Small-bore MRI is also sufficient if the animals are under anesthesia. However, introducing a marmoset holder for fMRI is challenging to apply to small-bore MRI scanners (Schaeffer et al, 2020a). Therefore, if the development of a marmoset holder for small-bore MRI scanners were possible, the opportunities to conduct fMRI in marmosets would expand.…”

The Common Marmoset—Biomedical Research Animal Model Applications and Common Spontaneous Diseases

“…Over the past two decades, marmosets have been more frequently used in preclinical, toxicology, and safety assessment of drugs. 4-30…”