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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.
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Animals , Humans , Arm , Early Diagnosis , Head Movements , Immersion , Memory , Memory, Short-Term , Cognitive Dysfunction , Models, Animal , Spatial Learning , Spatial MemoryABSTRACT
Objective To investigate effects of isoflurane anesthesia of different time interval on acute injury of brain function in neonatal rats with consistent total time of isoflurane anesthesia. Methods Seven-day neonatal Sprague-Dawley (SD) rats were randomly divided into normal control group (breathe the air), continuous anesthesia group (a single 6-hour exposure to 1.5% isoflurane), and intermittent anesthesia 1 day and 3 days groups (three times of 2-hour exposure to anesthesia with an interval of 1 day or 3 days), 12 rats in each group. The ratio of male to female was 5:7. They underwent the test of learning and memory in the radial arm maze (RAM) 21 days after birth, twice a day for 4 days. The number of entry into wrong arms, number of repeated errors, number of total arm entries, and time for completing the task were recorded for evaluation of effect of neonatal isoflurane on cognitive behavior in rats. Results ① Compared with normal control group, the percentage of number of errors > 3 in anesthesia of 3-day interval group was significantly decreased (33.3% vs. 46.9%, P 0 and total arm entries > 8 were significantly increased (33.3% vs. 18.8%, 27.1% vs. 13.5%, both P 3 between continuous anesthesia group, interval anesthesia 1-day group and the normal control group (44.8%, 44.8% vs. 46.9%), the percentages of number of repeated mistake > 0 and total arm entries > 8 in above three groups were slightly increased as compared with those of normal control group (27.1%, 22.9% vs. 18.8%, 20.8%, 21.9% vs. 13.5%, all P > 0.05). No statistical differences in completing the task among normal control group, continuous anesthesia group, interval anesthesia 1 day and 3 days groups were found (minutes: 1.32±0.91, 1.54±1.05, 1.46±0.86, 1.38±0.79, all P > 0.05). ② It was found by gender analysis that the percentages number of repeated errors > 0 and total arm entries > 8 were significantly lower in female rats than those in the male rats only in normal control group (5.0% vs. 28.6%, P 0 in continuous anesthesia group, interval anesthesia 1 day and 3 days groups (25.0%, 25.0%, 30.0% vs. 5.0%, P 8 in interval anesthesia 1 day and 3 days groups were significantly higher than that of normal control group (22.5%, 25.0% vs. 5.0%, both P < 0.05). No significant difference about the RAM task in male rats of all the four groups was found. Conclusions Different time interval of neonatal isoflurane exposure may develop certain degree of acute brain injury in rats, characterized by cognitive function. Prolongation of the interval time significantly enhanced long-term memory in rats. Multiple neonatal exposures to isoflurane were associated with greater cognitive impairment than a single exposure. In addition, isoflurane can significantly increase cognitional functional disorder in the female, not in the male rats.
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Areca catechu Linn is one of the stimulant masticatory crude materials of Indian system of medicine. The present study was done to evaluate the effect of Areca catechu Linn extract on learning and memory in rats using radial arm maze. The extract used for study was of two different types of Areca catechu namely, wet and dried Areca catechu. Three groups of rats each consisting of seven animals were used for the purpose. Test groups were given 500mg/kg p.o of wet Areca catechu extract and dried Areca catechu extract respectively. It was observed that wet Areca catechu extract showed greater increase in spatial memory and learning in comparison to the control group of rats. Hence increase in spatial memory could be because of higher amount of arecoline present in wet Areca catechu extract.
ABSTRACT
Areca catechu Linn is one of the stimulant masticatory crude materials of Indian system of medicine. The present study was done to evaluate the effect of Areca catechu Linn extract on learning and memory in rats using radial arm maze. The extract used for study was of two different types of Areca catechu namely, wet and dried Areca catechu. Three groups of rats each consisting of seven animals were used for the purpose. Test groups were given 500mg/kg p.o of wet Areca catechu extract and dried Areca catechu extract respectively. It was observed that wet Areca catechu extract showed greater increase in spatial memory and learning in comparison to the control group of rats. Hence increase in spatial memory could be because of higher amount of arecoline present in wet Areca catechu extract.
ABSTRACT
The novel alternated dual task (ADT) arranged rats to learn Tmaze spontaneous alternation task and radial arm maze (RAM) task alternatively, and by doing ADT, rats could acquire the tasks more easily than non alternated dual task (NADT) group. Also retention capacity of ADT group was significantly more and ADT help to learn a complex task faster than learning it in isolation from other tasks. In the present study effect of methylphenidate (MPD), a mood elevator, known to enhance learning and memory, on ADT procedure is assessed. Also effect of ADT procedure and MPD on spatial learning and memory are compared. Different groups were assigned by administering MPD (intraperitoneal injection at a dose of 3 mg/kg body weight) during different phases of behavioural experiments, and control groups received saline injection. MPD administration increased both acquisition and retention capacities. The amelioration attained for retention of complex task by ADT procedure, could be achieved by NADT rats only by administration of MPD. The influence of ADT procedure on acquisition and retention of TM and RAM tasks were similar to the effects of MPD, especially for the RAM task. MPD at low dose is found to enhance the learning and memory capacity in rats, than deteriorating it, supporting the use of MPD as a drug to treat attention deficit hyperactive disorder. The recent reports suggesting the effect of MPD only on retention and not on acquisition could not be confirmed, as enhancement for both acquisition and retention was found in this study.
ABSTRACT
Allocentric spatial learning can be assessed using popular spontaneous alternation behaviour (SAB) tested with T-maze, and also using radial arm maze (RAM) tasks. But the SAB testing has been reported to have lack of validity as a measure of retention, especially when used as a measure of short term memory. A more complex dual alternated task was designed to clarify whether increasing novelty and alternation factors in a task will increase or decrease the short term and long term memory in rats. Rats were made to learn both T-maze spontaneous alternation task and RAM task alternatively. Another group of rats were made to learn both the task separately without any alternation. And control group of rats were assigned to learn only one type of task. It was found that the group of rats performing “alternated dual task” could acquire the tasks more easily than the control groups and non alternated dual task groups. This enhancement of acquisition was associated only with the complex task (RAM task) among the dual tasks. More over their retention (memory) ability was very significantly enhanced for both the tasks in dual tasks. It can be concluded that, the principle of “alternated dual task” can be made use when a complex task has to be acquired and learned faster by rats; as alternation with simple task enhances the ability of rats to learn and memorize a complex task more efficiently.