Why marmosets?

Over the past several years the common marmoset (Callithrix jacchus) has ascended from an established, albeit niche, model species in neuroscience to one with broad appeal that stands to expand and reshape the scientific landscape. Despite years of pioneering research involving marmosets (Dias et al., 1996; Roberts and Wallis, 2000; Bourne et al., 2002; Bendor and Wang, 2005; Wang et al., 2005; Solomon and Rosa, 2014), it was not until Sasaki et al. (2009) used marmosets to demonstrate the first germ-line transmission of exogenous genetic information in a nonhuman primate that this New World monkey entered the broader collective awareness of the neuroscientific community. The raw excitement was fueled, at least in part, by a confluence of events. While modern molecular techniques were revolutionizing the study of neural circuits in mice, there was reasonable expectations that the same methods could, in principle, be similarly effective at explicating questions of primate brain function. However, efforts to apply these molecular techniques to the rhesus monkey, the most commonly used primate model, had proven significantly less effective than in rodents (Geritis and Vanduffel, 2013; O’Shea et al., 2017). The marmoset offered the hope of bridging these technologies and their significant advantages to elucidate the intricacies of the primate brain. Prospects for developing cutting-edge technologies to deliver exogenous genes to primates with a marmoset model remain considerable (Kaiser and Feng, 2015; Jennings et al., 2016; Okano et al., 2016a,b), particularly as these efforts are quickly beginning to bear fruit (Sasaki et al., 2009; Sadakane et al., 2015; Watakabe et al., 2015; MacDougall et al., 2016; Park et al., 2016; Santisakultarm et al., 2016; Sato et al., 2016). This line of work, however, is no longer the principle force driving the species’ continued growth across the field. There is a maturing appreciation of this Neotropical primate’s distinctive behavioral characteristics and the potential to leverage these qualities to expand the types of questions being asked at the neurobiological level (Saito, 2015; Miller et al., 2016). The principal goal of this Special Issue is to both highlight the current state of work developing and implementing modern molecular technologies for marmosets and to underscore the significance of several areas of ongoing research where this New World primate offers exciting opportunities to advance the frontiers of primate neuroscience. Certainly this collection of manuscripts is not exhaustive, there are many other areas of research for which marmosets can serve as a valuable animal model.