In collaboration with Simian Labs, MazeEngineers is proud to offer a virtual reality Radial Arm maze for researchers.
The Virtual RAM Mazes can use a combination of real-world elements and virtual elements. The virtual reality environment can be created as per the need of the experiment. In the Simian version, multiple environments can be configured.
The Radial Arm Maze (RAM) is a popular assay for studying spatial learning and memory in rodents. The maze was first used by Olton and Samuelson in 1976 to demonstrate the efficiency and memory of rodents in choosing an average of more than seven different arms in the first eight choices. The maze is based on the innate exploratory nature of the rodents and their ability to remember spatial locations, especially when rewarded. The Radial Arm Maze has been extensively used over the years in behavioral neuroscience research due to its effectiveness in measuring working and reference memory. The maze in comparison to other mazes puts minimal stress on the subjects.
The difficulty of the Radial Arm Maze task can be varied by simple modifications such as varying the number of arms. The 3D Radial Arm Maze is an adaptation of the conventional maze that removes the availability of safe spaces. This adaptation has flexible arms that allow different arm configurations. Unlike the traditional maze, the 3D RAM adds in the aversive component via the elevation and lack of walled arms. Another modification of the traditional RAM is the water Radial Arm Maze. This maze combines the advantages of the Morris Water Morris Maze and the RAM. The T-Maze and the Y-Maze are other similar mazes that also test spatial learning and memory.
The Radial Arm Maze serves as an ideal task for the assessment of learning and memory deficits and observation of brain function. The classical rodent’s radial arm maze task has been translated to humans using virtual radial arm mazes. The Virtual Radial Arm Maze has been used in studies relating to spatial learning and memory performances in individuals with neuropsychiatric illnesses. In their study of patients with Bulimia Nervosa using the virtual RAM, Cyr et al., 2016 observed that Bulimia Nervosa patients showed the abnormal functioning of the anterior hippocampus and frontostriatal regions. Another study evaluated the performance of Schizophrenics in a rewarded virtual Radial Arm Maze task. Spieker et al. (2016) tested Schizophrenic patients treated with antipsychotics on a desktop virtual RAM task. On comparison of maze performance with healthy controls, Schizophrenic participants were seen having decreased latencies to the rewards. The patients also made comparatively more working and reference errors.
The Virtual Radial Arm Task has also been used in understanding the role of gender and age in the navigational task performance. Levy et al. (2005) used a 12-arm virtual Radial Arm Maze to evaluate the spatial learning in men and women. Their investigation showed no difference in performance. The lack of difference was attributed to the superior object memory of women which, they believed, enabled them to associate the arms of the maze with specific extra-maze cues.
The Radial Arm Maze is also used in studying brain activity. In their investigation, Iglói et al. (2015) probed the role of the cerebellum in human spatial navigation. Another study by Demanuele et al. (2015) used a delayed win-shift virtual Radial Arm Maze task to investigate cognition and cognitive disturbances in humans. Investigation of brain activity in tasks such as the Radial Arm Maze allows understanding of how different parts of the brain operate and contribute to an individual’s learning and memory abilities.
Participants are informed of the experimental process beforehand. Participants comfortability with the technology used for the investigation is also noted, as this could be a potential influencer on the performance. Ancillary tests may also be part of the investigation.
The general procedure of the virtual Radial Arm Maze can involve the following tasks.
Along with these trials, probe trials are also included. Often matched control trials also accompany these tasks. Control trials are designed to isolate a process of interest in the task performance. These trials may have a slight variation in spatial cues or may eliminate spatial cues altogether. They can also restrict the area of exploration. Further, these tasks could also be designed to include false hints or cues to test memory and strategy. The overall task, however, remains the same as the matched trials.
Assessment of acquisition and usage of navigational strategies
Spriggs et al., 2018 designed a virtual analog 6-arm Radial Arm Maze called the Hex maze to distinguish between allocentric, egocentric-cue and egocentric-response strategies. The maze was also capable of indexing strategy aspects such as preference, acquisition, stability, and competence. The Hex maze consisted of a large circular arena (approx. 60m diameter) that was enclosed within a round room twice as large as the arena. The arms of the maze had low stone walls and tiled floor, and the ends of each arm had a floating whitish-grey sphere. Ends of the north and south arms (arbitrarily chosen) had large windows that allowed a view of mountain range and a large water body with an island, respectively. The east and west arms had narrower windows with the view of mountain range meeting the water body. Participants performed learning and probe trials, and other ancillary tests to allow assessment of navigational strategies used.
Investigation of manganese (Mn) as a neurodevelopmental toxicant
Bauer et al. (2017) investigated the sex-specific susceptibility of children (aged 10 to 14) to manganese-related neurobehavioral abilities. Estimation of prenatal and early postnatal Mn exposure was done using participants naturally shed deciduous teeth. A virtual Radial Arm Maze task was administered using a laptop and joystick to evaluate visuospatial learning, working memory and reference memory. The 3D virtual environment consisted of a Radial Arm Maze that was placed in an asymmetrical room that had plenty of visual cues such as doors, windows, and other landmarks. The arms of the maze, each had a well of which only four of the eight were baited with a reward. Result analysis showed that females were more prone to visuospatial decrements leading from prenatal Mn overexposure. Prenatal Mn exposure in females resulted in worse scores in task performance for both high and low concentrations.
Evaluation of spatial learning in participants with Bulimia Nervosa
Cyr et al., 2016 used a virtual Radial Arm Maze to evaluate the spatial learning abilities of participants with Bulimia Nervosa. The virtual RAM had 8-arms surrounded by landscape elements that served as spatial cues. The participants navigated the maze using a joystick and were provided with reward stimuli hidden in the arm ends. The task utilized reward-based spatial learning paradigm and consisted of learning and control conditions to assess the learning abilities. The task results and MRI scan data revealed that, although behavioral performance did not differ between healthy controls and the bulimic participants, abnormal functioning in the hippocampus and frontostriatal regions was observed in the latter group. The bulimic participants showed activation of the right anterior hippocampus when they received unexpected rewards (control condition), and deactivation of the left superior frontal gyrus and right anterior hippocampus during learning condition trial.
Investigation of spatial navigation performance of individuals with mild cognitive impairments
Migo et al. (2016) evaluated participants with amnestic mild cognitive impairments using spatial navigation task in conjunction with fMRI. Participants aged between 61 and 80 years performed the task in an analog virtual Radial Arm Maze that used platforms instead of arms. The maze was constructed in a virtual open green arena that had plenty of landmarks (visual cues) such as cottage, car, wind turbine, bus. To avoid simple egocentric strategies, participants were only allowed to select a platform if it was yellow. Task difficulty was managed by changing the number of platforms the participants could choose to 4 or 6. Task performance between the aMCI group and control group was comparable. However, fMRI data revealed that aMCI patients showed increased activity in the right dorsolateral prefrontal cortex, which plausibly was in compensation of reduced bilateral activity in the hippocampus, retrosplenial cortex, and left dorsolateral prefrontal cortex.
Evaluation of spatial memory deficits in Schizophrenic patients
In a virtual Radial Arm Maze, Spieker et al., 2016 evaluated the learning and memory impairments of schizophrenic patients. The virtual maze was placed in the center of a virtual room. The room consisted of visual cues such as chairs, bookshelf, and textured walls. The room was roofed with lighting arrangements. The Radial Arm Maze had 8-arms extending from a central platform. The ends of each arm were equipped with wells of which four were baited. Schizophrenic patients took longer to complete the trials and traveled more distance when compared to healthy controls. They also made more working and reference memory errors.
Examination of cerebellar contribution to human spatial navigation
Iglói et al., 2015 used functional magnetic resonance imaging to observe brain activity while participants performed spatial navigation task in a virtual 5-arm Radial Arm Maze. The maze design consisted of a central pentagonal ring, as opposed to a platform, and had five arms radiating out from its angles. The virtual environment flaunted natural scenery that provided spatial cues to the participants. Participants performed trials that were interleaved with probe trials. Participants also performed control trials wherein they were limited to a certain part of the maze and were forced to choose without any environmental cues. Brain activity analysis was performed for activation before the first-choice point of the trials to enable strategy-based analysis.
Segregation of cognitive task stages multivariate fMRI BOLD time series.
Demanuele et al., 2015 used the performance in a virtual 12-arm Radial Arm Maze to study human cognition and its disturbances. By utilizing fMRI blood oxygenation level dependent (BOLD) time series, they distinguished different cognitive stages (encoding/retrieval, choice, reward and delay stages) in a win-shift task. The virtual maze consisted of a park that had 12 pathways radiating from a central area. The maze was surrounded by 5 landmarks (houses, church, tree, telephone booth, and tractor) and the participants used them as visual cues to find the hidden gold coins.
The Radial Arm Maze allows multiple choices. The difficulty of the task can be varied by varying the number of arms or the number of cues. The Radial Arm Maze is usually used in the understanding of spatial memory and learning and can involve different protocols such as the win-shift task or the win-stay task. Virtual rewards and punishments can also be combined with physical rewards and punishments to enhance the motivation of the participants.
The behavioral data measures can include the following,
Based on the requirements of the investigation fMRI data may also be recorded. Other measures (relevant to the investigation) may include assessment of stress, anxiety and heart rate levels, among others. Ancillary questionnaires may also be used to further refine the data and the understanding of the task performance.
The Virtual Radial Arm Maze challenges the participant’s place learning skills, allowing assessment of their capacity to discriminate, remember and process the information as they explore the maze. As opposed to the Morris Water Maze, the RAM has fixed paths that the participant can traverse. Further, the task doesn’t use an aversive motivation that can be induced by tasks such as a virtual elevated T-Maze. The Radial Arm Maze can be easily adapted and modified to limit the use of certain strategies by the participants. Using inter-trial delays can also aid in the investigation of the memory capabilities of the participants. The absence of significant stressors and familiarization with the maze before testing allows for better observations of working and reference memory of the participants.
Since the virtual Radial Arm Maze design can vary across different investigation, the cohesiveness of the results may not be the same. Factors such as participants comfortability with the technology and the virtual environment could impact performance results. The mental and emotional status of the participants could also impact the performance in the task. Performance in the task may also be influenced by the age, gender and other aspects of the participants. In comparison to other behavioral tasks, the Radial Arm Maze may be more time-consuming.
Bauer JA, Claus Henn B, Austin C, Zoni S, Fedrighi C, Cagna G, Placidi D, White RF, Yang Q, Coull BA, Smith D, Lucchini RG, Wright RO, Arora M (2017). Manganese in teeth and neurobehavior: Sex-specific windows of susceptibility. Environ Int. 108:299-308. doi: 10.1016/j.envint.2017.08.013.
Cyr M, Wang Z, Tau GZ, Zhao G, Friedl E, Stefan M, Terranova K, Marsh R (2016). Reward-Based Spatial Learning in Teens With Bulimia Nervosa. J Am Acad Child Adolesc Psychiatry. 55(11):962-971.e3. doi: 10.1016/j.jaac.2016.07.778.
Demanuele C, Bähner F, Plichta MM, Kirsch P, Tost H, Meyer-Lindenberg A, Durstewitz D (2015). A statistical approach for segregating cognitive task stages from multivariate fMRI BOLD time series. Front Hum Neurosci. 9:537. doi: 10.3389/fnhum.2015.00537.
Iglói K, Doeller CF, Paradis AL, Benchenane K, Berthoz A, Burgess N, Rondi-Reig L (2015). Interaction Between Hippocampus and Cerebellum Crus I in Sequence-Based but not Place-Based Navigation. Cereb Cortex. 25(11):4146-54. doi: 10.1093/cercor/bhu132.
Levy LJ, Astur RS, Frick KM (2005). Men and women differ in object memory but not performance of a virtual radial maze. Behav Neurosci.119(4):853-62.
Migo EM, O’Daly O, Mitterschiffthaler M, Antonova E, Dawson GR, Dourish CT, Craig KJ, Simmons A, Wilcock GK, McCulloch E, Jackson SH, Kopelman MD, Williams SC, Morris RG (2016). Investigating virtual reality navigation in amnestic mild cognitive impairment using fMRI. Neuropsychol Dev Cogn B Aging Neuropsychol Cogn. 23(2):196-217. doi: 10.1080/13825585.2015.1073218.
Olton, D.S., Samuelson, R.J. (1976) Remembrance of places passed: Spatial memory in rats. J. Exper. Psych. Animal Behav. Processes 2, 97-116
Raiesdana S (2018). Modeling the interaction of navigational systems in a reward-based virtual navigation task. J Integr Neurosci.;17(1):45-67. doi: 10.3233/JIN-170036.
Spieker EA, Astur RS, West JT, Griego JA, Rowland LM (2012). Spatial memory deficits in a virtual reality eight-arm radial maze in schizophrenia. Schizophr Res.135(1-3):84-9. doi: 10.1016/j.schres.2011.11.014.
Spriggs MJ, Kirk IJ, Skelton RW (2018). Hex Maze: A new virtual maze able to track acquisition and usage of three navigation strategies. Behav Brain Res. 339:195-206. doi: 10.1016/j.bbr.2017.11.041.
