NG2+/hNuclei+ cells (Figs. 1B, F, 2G). Stimulation of the medial perforant path (Colino and Malenka, 1993) consistently evoked a significantly steeper slope of field excitatory postsynaptic potentials (fEPSP) in the humanized chimeric mice than in either their uninjected littermates or mouse GPC allografted controls (n=3-40; F=3.15, by two-way ANOVA; p=0.044) (Fig. 4A). The allograft controls comprised a set of mice neonatally engrafted with murine GPCs derived from EGFP transgenic mice, otherwise using the same isolation and engraftment protocols as those using human GPCs. The steeper slope of the fEPSPs in the humanized chimeras compared to uninjected controls was still evident after normalization to the fiber volley amplitudes, a measure thought to reflect the number of stimulated axons (Fig. S3A). Thus, slices with human glia exhibited a significant enhancement in their basal level of excitatory synaptic transmission, over a wide range of stimulation intensities.
