Spatial Learning and Memory Using a Radial Arm Maze with a Head-Mounted Display

OBJECTIVE: A radial arm maze (RAM) is an essential tool for assessing spatial learning and memory. Although this tool is widely used to study deficits in spatial memory in animal models, it has several restrictions that prevent its adaptation to human research and training. Therefore, we developed a head-mounted-display RAM (HMD-RAM) program for humans and verified its validity by comparing it to the results obtained by previous RAM studies. We also compared the HMD and a flat monitor as experimental devices. METHODS: Forty participants were recruited for the current study (Study 1: 20 participants with the HMD device; Study 2: 20 participants with the flat monitor). They navigated a virtual room as a first-person viewer and used environmental landmarks to remember their spatial position and orientation. The main dependent measures were working memory error, reference memory error, detection time, travel distance, and participant’s head movements. To validate the program, participants also conducted neuropsychological assessments and self-reported measures. RESULTS: The results for HMD-RAM tasks were consistent with the results of previous research conducted on animals, and the HMD elicited a higher sense of presence, immersion, and simulator sickness than the flat monitor. According to post-experiment questions on navigation strategy, creating landmarks was important when people were discovering locations in their environment, and an HMD was beneficial for better navigation strategy. CONCLUSION: These results suggest that the HMD-RAM is valuable for estimating spatial learning and memory in humans and may be a useful tool for early diagnosis of deficits in spatial learning and memory, including amnestic mild cognitive impairment and Alzheimer’s disease.

Effects of isoflurane on spatial reference memory and changes of Caspase-3 expression and apoptosis in brain of aged mice / 中华行为医学与脑科学杂志

Objective To investigate the effect of isoflurane on the spatial learning and memory in aged mice,and whether this is associated with the changes of Caspase-3 expression and apoptosis in brain.Methods Twenty-four CO57BL/6 aged mice(16 months)were randomly divided into isoflurane treatment group(Iso Group,n=12) and sham control group (Con Group,n=12).Mice in Iso group were exposed to 1% isoflurane in carrying gas of 30% oxygen,balance nitrogen in a warmed,humidified chamber for4 h per day for2 days.For Con group,animals were treated at the same condition with only carrying gas.After anesthetic exposures,behavioral testing was performed using the Morris water maze(MWM),and then changes of Caspase-3 expression and apoptosis in hippocampus CAI,dentate gyrus(DG) and cortex(CX) in brain were determined by using immunofluorecence staining and TUNEL staining.Results In hidden-platform training of MWM,the mean escape latency to platform showed no significant difference between the two groups (F=0.007,P=1.235),but the mice in Iso group showed obviously impaired retention of memory by spending more percentage of time swimming in the probe quadrant as compared to the control animals in the probe test((34.5±5.0)%vs(45.1±4.9)%.P<0.01).There was no significant difference in average swimming speed during the MWM testing trials between the two groups (F=1.537,P=0.241).A few Caspase-3 and apoptosis positive cells were found in hippocampus Cal,DG and CX regious,while no difference was found in the density of positive cells between the two groups(P>0.05).Conclusion 1% isoflurane repeatedly exposure significantly impaires the spatial reference memory in aged mouses,however does not significantly change the expression of easpase-3 and apoptosis in brain.