Figure 4.

Evaluation of motor coordination and spatial navigation of mice through the Morris water maze (MWM). The analysis package divided the searching area into four quadrants, one of which contains the escape platform (red circle) (A). The process of finding the escape platform from the starting point was tracked in the mice (pink) for 1 min (A). Mice were trained with the visible platform at post-operative day (POD) 8 (not depicted) and hidden platform for 4 consecutive days (POD 10–13) and no platform in the probe trial at POD 14 (B). Longer values of escape latency to find the hidden platform indicate an inadequate acquisition of spatial memory and navigation, which showed differences between groups at the last two training days (χ² = 6.54, p < 0.05 and χ² = 10.52, p < 0.01, Kruskal–Wallis test). Non-GVS mice had a longer escape latency (33.5 s on the third day and 20.9 s on the fourth day of hidden platform trials) than those of the GVS group (27.67 s, Z = −2.07, p < 0.05 on the third day and 17.39 s, Z = −2.73, p < 0.01 on the fourth day) and the control group (26.47 s, Z = −2.19, p < 0.05 on the third day and 11.25 s, Z = −2.61, p < 0.01 on the fourth day) (Mann–Whitney U-test) (C). During the probe trial at POD 14, there was a significant decrease in the percentage of time spent in the target quadrant in the non-GVS mice [28.5% (26.2–30.6%)] compared to the control group [35.2% (34.0–37.3%), Z = −2.61, p < 0.01, Mann–Whitney U-test] (D). GVS intervention substantially enhanced recovery of this deficit [33.7% (30.9–36.5%), Z = −2.73, p < 0.01, Mann–Whitney U-test], and they were no different from the control group (D). *Significantly different between two groups; ^#Significantly different between three groups; *^{, #}p < 0.05; **^{, ##}p < 0.01. Values of significant difference were calculated by using the Kruskal–Wallis test for between groups and the Mann–Whitney U-tests for pairwise comparisons. Reproduced from Nguyen et al. (25).