Skip to main content
. 2014 Oct 15;31(20):1677–1688. doi: 10.1089/neu.2013.3252

FIG. 5.

FIG. 5.

Ccr2−/− mice demonstrate improved spatial memory and learning following traumatic brain injury (TBI). The Morris water maze was used to assess cognitive function eight weeks following TBI (n=12/group). Animals were trained to locate a cued platform for 2 d (A–D, left column), and a hidden platform for 3 d (A–D, right column). Cued platform graphs show statistical results for the effect of TBI. Hidden platform graphs show statistical results for the effect of TBI and post-hoc analyses, and when a genotype effect achieved significance in a repeated measure analyses of variance with post-hoc analyses. Mean±standard error of the mean is shown. (A) TBI prolonged the time (latency) to reach the platform (***p<0.001). For the hidden platform trials, the Ccr2−/− TBI group performed better than the wild-type TBI group by finding the hidden platform quicker (post hoc test, *p<0.05). (B) Swim velocity for all animal groups were statistically identical. (C) TBI increased the animals' total distance from the platform during the trials (***p<0.001). For the hidden platform trials, the Ccr2−/− TBI group performed better than the wild-type TBI group by being closer to the hidden platform at all times (post hoc test, *p<0.05). (D) TBI induced thigmotaxic behavior as shown by increased time spent near the perimeter during the platform search (***p<0.001). For the hidden platform trials, the Ccr2−/− TBI group showed decreased thigmotaxic behavior, compared with the wild-type TBI group, as indicated by reduced time spent near the perimeter (post hoc test, †p=0.05), indicating that Ccr2−/− mice had improved spatial learning and more productive search strategies post-TBI, compared with wild-type mice. (E) Ccr2−/− mice had improved memory retention as assessed during a probe trial of the Morris water maze. The percent of time spent searching in each quadrant of the pool is shown. Sham groups and the Ccr2−/− TBI group preferentially searched in the target quadrant, while the wild-type TBI group failed this test (most stringent student's t-test result: wild-type sham, ***p<0.001;, Ccr2−/− sham, *p<0.05; wild-type TBI, p>0.05; Ccr2−/− TBI, **p<0.01). (F) TBI impaired memory retention as assessed by the animals' crossing frequency over the area of the target platform during a probe trial (***p<0.0001). Ccr2−/− TBI mice crossed the target platform area more frequently, compared with wild-type TBI mice (post hoc test, *p<0.05). (G) TBI delayed the first encounter to the target platform position during the probe trial (***p<0.0001). Ccr2−/− TBI mice came across the target platform location much sooner than wild-type TBI mice (post hoc test, *p<0.05).