Since human glia appeared to maintain the cell-autonomous size, complexity and domain architecture of human astrocytes in the mouse environment, we asked if human glial chimeric brains exhibited increased synaptic plasticity. To that end, Han and colleagues(Han et al. 2013) compared the threshold for inducing hippocampal long-term potentiation (LTP) in chimeric mice with that of littermate controls. We found that high frequency stimulation significantly potentiated the field EPSP slopes of neurons in the chimeric hippocampi, and indeed did so to a larger degree and for a substantially longer period, than in unengrafted littermate controls. Thus, human glial chimeras manifested substantially facilitated LTP (Figure 3). Importantly, such stable, long-lasting changes in synaptic function are thought to be involved in learning and memory, of which LTP is typically considered an in vitro surrogate. Since hippocampal LTP was enhanced in chimeric mice, we next asked whether the human glial chimeras might have cognitive advantages over their unengrafted or mouse GPC-allografted counterparts. We found that the human glial chimeras indeed performed better than control mice across a variety of learning tasks, that included auditory
