The availability of human glial chimeric mice allow us to now assess the natural history, network contributions, and pathophysiology of human glia in vivo, in the context of the normal adult brain (Goldman and Windrem 2009; Windrem et al. 2008). This model lends itself to the study of a number of questions never before approachable, for want of an appropriate in vivo model of human glial function. First, we have only begun to consider the species-specific influences of human glia upon neural network function. Astrocytes clearly play a central role in synaptic efficiency and plasticity in mammals, and human astrocytes, with their greater fiber complexity than that of infraprimate mammals, coordinate the excitability of many more synapses within their individual geographic domains (Oberheim et al. 2006; Oberheim et al. 2009) (Araque et al. 1999; Kang et al. 1998). Hominid evolution has thus been attended by progressive astrocytic complexity, which may in turn have contributed to the increased rate and efficiency of information processing in the primate brain. As such, do the unique capabilities of the human brain thereby reflect the
