The existing mazes are mainly used to study the learning and memory of animals. However, there is still a lack of corresponding maze and method in the aspect of the observation and test of aquatic animal robots. For this purpose, the authors have developed a three-dimensional water maze combined with bilayer multi-channel which equips with stratified lines and tick marks. This device is a rectangular structure composed of one square bottom and four rectangular side walls, and the channels of every side wall are composed of one upper channel and two lower channels. The center of the upper channels is in the vertical center line of every side wall, and the two uper channels of adjacent side walls are at 90° degrees with each other, and the two lower channels of adjacent side walls are at 45° degrees with each other. There are stratified lines and tick marks on the side wall to test the spatial location and movement trajectories of aquatic animals. The carp robot was put into the water maze for the underwater experimental detection. The success rates of left and right steering at 135, 90 and 45 degrees as well as forward motion of the carp robots (n = 10) were over 60%. This study showed that the device could be used to observe and test the motion of the carp robot.
ObjectiveTo investigate the effect of sex on learning and memory ability of newborn mice with hypoxic-ischemic brain injury.MethodsFifty C57BL/6 mice aged 10 days were divided into hypoxia-ischemia group and sham group according to the random number table method, and there were 28 in the hypoxic-ischemic group and 22 in the sham group with half female and half male respectively. In the ischemia-hypoxia group, the left common carotid artery was ligated and then the mice were placed in 34℃ hypoxia chambers with 8% oxygen and 92% nitrogen mixture for 45 minutes. In the sham group, only the skin of the left neck was cut and sutured. After 2 months, Y maze test and Morris water maze test were used to evaluate the learning and memory ability of mice.ResultsThe success rate of the hypoxic-ischemic group was 71.4% (20/28), and that of the sham group was 100.0% (22/22), a total of 42 mice were enrolled in the experiment. In Y maze test, there were differences in entries and total distance of new arms between the two groups (entries: F=16.068, P<0.001; total distance: F=8.532, P=0.007); compared between different groups in the same gender, the entries and total distance of new arms in the hypoxic-ischemic group were lower than those in the sham group with statistically significant differences (entries in males: P=0.001, entries in females: P=0.012; total distance in males: P=0.010, total distance in females: P=0.046). Compared between males and females in the same group, the entries and total distance of new arms of females were higher than those of males in the hypoxic-ischemic group, with statistically significant differences (P=0.039, 0.043). In Morris water maze test, the escape latency of positioning navigation in the hypoxic-ischemic group was higher than that in the sham group, and males showed more obviously poor performance (P<0.001); in the experiment of space exploration, differences were found in the duration of stay and the target quadrant entries between the two groups (duration of stay: F=8.297, P<0.001; entries: F=4.042, P=0.014), and there were statistically significant differences in the same gender males and females in the hypoxic-ischemic group and the sham group (duration of stay in males: P=0.003, duration of stay in females: P=0.038; entries in males: P=0.006, entries in females: P=0.041). Compared between males and females in the same group, the duration of stay and the target quadrant entries of females were higher than those of males in the hypoxic-ischemic group, with statistically significant differences (duration of stay: P=0.018; entries: P=0.032).ConclusionsThe learning and memory ability of newborn mice may be slightly impaired after hypoxic ischemic brain injury. There is significant difference in the effect on learning and memory ability between different genders, and the effect on males is higher than that on females.