To better assess the scope of performance enhancement in the human glial chimeras, we next assessed their performance in the Barnes maze, another hippocampal-dependent learning task. In this spatial learning task mice learn the location of a hole that leads to an escape/drop box. By just the second day of serial daily testing, the human glial chimeras made fewer errors and displayed a significantly shorter latency in finding the drop box, compared to their littermate controls (n=6, 7.4 ± 0.1 months; F=13.4 by two-way repeated measures ANOVA, p=0.004) (Fig. 6C). These differences persisted throughout the four-trial testing period (n=6, 7.4 ± 0.1 months; F=11.4, p=0.007). With additional training, the unengrafted control mice were capable of completing the task, indicating that they could master the task if given sufficient training (Fig. S5F).
