In collaboration with Simian Labs, MazeEngineers is proud to offer a virtual reality Morris Water maze for researchers.
The virtual reality environment can be created as per the need of the experiment. In the Simian version multiple environments can be configured.
The Morris Water Maze (MWM) is a widely used behavioral task developed by Richard G. Morris in the year 1981 as a response to the Radial Arm Maze (RAM). As opposed to the Radial Arm Maze, the Morris Water Maze doesn’t provide the subject with a choice point. Further, the task utilizes the fear of drowning to motivate the subject to learn the location of the escape platform quickly. The navigational task is effective in the assessment of spatial learning, and over the course of years has seen modifications and adaptations such as the Water T-Maze, the Water Y-Maze, and the Water RAM.
The Morris Water Maze has been used for various investigations including endocrine abnormalities, strokes, Alzheimer’s disease, other neurodegenerative diseases, and their effects on learning and memory (Brandeis et al., 1989). The task is also able to differentiate between spatial and non-spatial learning by using visible and hidden platforms. The different possible variations in protocols such as Discrimination learning protocol, Cued learning protocol and Latent learning protocol (Vorhees and Williams 2006) allow measuring the different specificity of spatial learning and memory.
With the advancements in technology and methodology, the virtual applications of the Morris Water Maze are rapidly evolving. The virtualization of the Morris Water Maze task can be homologous to the rodent MWM, depicting the environment like a pool, or can be analogous in nature, wherein the concept of the MWM is applied in an environment such as a room. The underlying principle of Morris Water Maze is that spatial learning is not dependent on local auditory, visual or olfactory cues (Morris, 1981). The task suggests that the subjects can navigate themselves to the goal platform by utilizing the distal cues.
The virtual environments of the Morris Water Maze task are developed based on the requirements of the investigations. These environments can be analogous or homologous to the traditional Morris Water Maze. Analogous environments usually present a more ethological approach such as presenting a room as in the experiments carried out by Daga et al., 2017 and Livingstone and Skelton (2007). These environments are modeled on the principle of the Morris Water Maze, that is, navigation of space is possible based on distal cues. These environments use objects or markings (such as a green cone or a circular spot on the floor) as an analogy for the Morris Water Maze’s escape platforms. On the other hand, homologous environments use the same design concept as the physical rodent Morris Water Maze. The environment is a pool (Cornwell et al., 2008) that has distal cues present on the walls surrounding the pool.
The earliest use of a virtual Morris Water Maze in humans was by Astur et al. (1998). In their study, they assessed the difference in performance of male and female participants. The study involved using a 3D computer simulation of the Morris Water Maze that the participants had to navigate using a joystick to find the escape platform. Similar to the rodent MWM, the participants were assessed in a water pool that had hidden/visible escape platform, the position of which was kept constant throughout the sessions. Their study was able to conclude that males, in fact, performed significantly better than the female participants in this navigation task.
The virtual Morris Water Maze was also used by Rahman and Koerting (2008) in evaluating if sexual orientation of the participants contributed to the performance in the spatial memory task. Based on the data, they were able to conclude that no significant difference in performance could be observed between homosexuals and heterosexuals. However, the difference between the sexes could be seen.
Another area explored using the virtual Morris Water Maze is neuropsychiatric disorders’ effect on spatial task performance. In early 2010, Folley and coworkers evaluated the performance of schizophrenic patients in the virtual Morris Water Maze that was presented to them as a pool within a room. Subjects that met the criteria were then evaluated using a fMRI task. From the data analysis, it was concluded that the inefficiency of the schizophrenic patients in allocentric learning and memory could be related to the inability to recruit appropriate task-dependent neural circuits. Another study involved evaluating the performance of depressed individuals in the virtual MWM task (Cornwell et al., 2010). During the task whole-head, magnetoencephalography (MEG) recordings were also performed. The results showed that the depressed individuals performed significantly worse than the controls.
The virtual environments of the Morris Water Maze task can either have multiple cues or a single fixed cue such as the fixed chair in the center of the room in the experiments carried out by Daga et al. (2017). The two types of cue variation allow assessment of allocentric- and egocentric- reference based navigations.
Advanced technologies allow the creation of rich and immersive environments such as the one created by Schoenfeld et al., 2014. For their virtual adaptation of the Morris Water Maze task, Schoenfeld et al. created an island on which the participants had to find a treasure box. Off-shore elements included a yacht, wind turbine, bridge and water tower. These elements served as distal cues for their task. Simple environments such as the one used by Kolarik et al., 2018 are also just as effective. Kolarik’s et al., 2018 environment was a simple 8 x 8 m virtual room that had unique paintings placed unevenly spaced on each of the four walls.
Participants are informed of the experimental process beforehand. Participants comfortability with the technology used for the investigation is also noted, as this could also be a potential influencer on the performance. Ancillary tests may also be part of the investigation. The start location is usually randomized during consecutive trials.
The general procedure of the virtual Morris Water Maze task usually involves four tasks in the following order.
Evaluation of the impact of glaucomatous visual field loss on wayfinding behavior
Participants with glaucomatous were evaluated in two virtual environments modeled after the Morris Water Maze. Both the environments were identical 20 x 20 x 3 m rooms that the patients had to navigate. The first room consisted of multiple visual cues (such as painted wall, chair, plant) and the second room consisted of a centrally placed chair maintained in a fixed position. The first room was designed to test allocentric reference frame and cognitive mapping, while the second room tested egocentric reference frame-based navigation. The participants had to navigate to a green cone (target). Trials were conducted where the target was visible and hidden. In comparison to the average 24.2 sec spent by healthy controls, glaucoma patients spent an average of 35 sec in room one. However, no significant performance difference was observed in the single cue room (fixed chair) (Daga et al., 2017).
Evaluation of cognitive deficits following Traumatic brain injury
Livingstone and Skelton (2007) investigated the pattern of preserved and impaired cognitive mechanism among Traumatic Brain Injury (TBI) survivors using a virtual task modeled after the Morris Water Maze. The virtual arena was presented to the participants via a desktop computer. The virtual environment was designed as a large room that consisted of a large round arena that had walls at a height that prevented the participants from leaving it while allowing an unobstructed view of the distal cues. Large windows surrounded the large room and provided a panoramic view of realistic mountains and water bodies. The task was performed as 4 trials in the following order: exploration, visible, invisible, and probe. The environment was adapted to each trial. Participants had to navigate to a green spot (target) that was, depending on the trial, invisible or visible. The results of the task suggested that the navigational deficits in TBI survivors were due to their inability to form, remember or use cognitive maps. This was evident from the significant latency and distance in comparison to the controls in the invisible platform trial.
Evaluation of spatial learning deficits in Parkinson’s disease
In the first of its kind study in Parkinson’s disease, Schneider et al., 2017 evaluated the performance of Parkinson patients with mild cognitive impairment (MCI) in a virtual Morris Water Maze task. The performances were compared to PD patients without cognitive impairments and healthy controls. The task performance showed that controls performed significantly better than both the PD groups regarding latency to locate the target and heading error. However, no significant performance difference was observed between unimpaired and MCI Parkinson’s disease patients.
Investigation of the effect of acute stress on MWM performance
Participants were exposed to acute psychological stress using the Paced Auditory Serial Addition Task (PASAT) before subjecting them to a modified virtual Morris Water Maze task. The virtual MWM was composed of a 75 x 75 m room having a height of 16.5 m. Two opposing walls had large windows that showed distal landscape features (mountains and water body respectively). The other two opposing walls had 3 smaller windows each that showed hills sloping to the water. The virtual room housed a 42 m circular arena with 1 m boundary high wall. Aligned along cardinal and intercardinal axes were 8 proximal navigational cues perched on the arena walls. The navigational goal was a small, circular green platform that measured 1/6th the arena diameter. Data results showed that stress affected the navigational strategy used and that participants with acute stress used allocentric navigation more often than the egocentric approach. (van Gerven et al., 2016)
Investigation of the effect of medial temporal lobe lesions on spatial precision
Amnestic patients were evaluated in an analog virtual Morris Water Maze task. The participants were required to find the 0.4 x 0.4 m square on the room floor. The virtual environment was an 8 x 8 m room that consisted of 4 unique paintings that were spaced unevenly on each wall. These paintings served as visual cues for the task. Kolarik et al., 2018 assessed the precision of trajectories using sliding windows at parametrically greater distances from the target that were all centered on the target location. This was done to overcome the shortcomings of traditional quadrant analysis approach. From the data analysis, it was revealed that amnestic patients showed significant impairments in the smallest precision windows in comparison to the controls.
The Morris Water Maze is a navigational task that evaluates spatial learning and memory of the participants when they are provided with distal cues. Some investigations may make use of cues that allow both allocentric and egocentric learning. To record behavioral measures, the test area is often divided into quadrants. However, some investigations may also base the behavioral measure’s data on the proximity to the target.
The following data and behavioral measures can be recorded during the virtual Morris Water Maze task.
Based on the requirements of the investigation, neuroactivity may also be recorded using fMRI scans or whole-head magnetoencephalography. 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 Morris Water Maze task allows translation of rodent model into a viable human model. The virtual environment allows setting up both homologous and analogous test areas that are easy to manipulate and adapt. The Morris Water Maze task is an effective and reliable method of measuring hippocampal-dependent spatial memory and learning. In comparison to other batteries such as the Radial Arm Maze, the Morris Water Maze is rather straightforward and simple to administer. Further, the task is not as time-consuming as other behavioral assays.
The Morris Water Maze task is easily able to differentiate between spatial and non-spatial learning via the visible and hidden target/platform protocols. The task can easily evaluate memory and learning performances of participants with different diseases, injuries, and neuropsychiatric disorders.
As opposed to the Radial Arm Maze and other commonly used mazes, the Morris Water Maze isn’t truly a labyrinth. The apparatus is a navigational task in an open area. Traditional Morris Water Maze uses the fear of drowning as the primary motivation, which cannot be mimicked in a virtual environment. The Morris Water Maze could also take up more time in the event the participants are not aware of the task requirements. Clueless wandering may result in wastage of valuable time and incorrect data. Performance in the task may be influenced by the age, gender and other aspects of the participants. Participants comfortability with the technology and the virtual environment is also an important factor. The mental and emotional status of the participants could also impact the performance in the task.
Astur RS, Ortiz ML, Sutherland RJ (1998). A characterization of performance by men and women in a virtual Morris water task: a large and reliable sex difference. Behav Brain Res. 93(1-2):185-90.
Brandeis, R., Brandys, Y., & Yehuda, S. (1989) The use of the Morris Water Maze in the study of memory and learning. Int. J. Neurosci. 48, 29-69
Cornwell BR, Johnson LL, Holroyd T, Carver FW, Grillon C (2008). Human hippocampal and parahippocampal theta during goal-directed spatial navigation predicts performance on a virtual Morris water maze. J Neurosci. 28(23):5983-90. doi: 10.1523/JNEUROSCI.5001-07.2008.
Cornwell BR, Salvadore G, Colon-Rosario V, Latov DR, Holroyd T, Carver FW, Coppola R, Manji HK, Zarate CA Jr, Grillon C (2010). Abnormal hippocampal functioning and impaired spatial navigation in depressed individuals: evidence from whole-head magnetoencephalography. Am J Psychiatry.167(7):836-44. doi: 10.1176/appi.ajp.2009.09050614.
Daga FB, Macagno E, Stevenson C, Elhosseiny A, Diniz-Filho A, Boer ER, Schulze J, Medeiros FA (2017). Wayfinding and Glaucoma: A Virtual Reality Experiment. Invest Ophthalmol Vis Sci. 2017 Jul 1;58(9):3343-3349. doi: 10.1167/iovs.17-21849.
Folley BS, Astur R, Jagannathan K, Calhoun VD, Pearlson GD (2010). Anomalous neural circuit function in schizophrenia during a virtual Morris water task. Neuroimage. 49(4):3373-84. doi: 10.1016/j.neuroimage.2009.11.034.
Kolarik BS, Baer T, Shahlaie K, Yonelinas AP, Ekstrom AD (2018). Close but no cigar: Spatial precision deficits following medial temporal lobe lesions provide novel insight into theoretical models of navigation and memory. Hippocampus. 28(1):31-41. doi: 10.1002/hipo.22801.
Livingstone SA, Skelton RW (2007). Virtual environment navigation tasks and the assessment of cognitive deficits in individuals with brain injury. Behav Brain Res. 185(1):21-31.
Morris, R.G.M. Spatial localization does not require the presence of local cues. (1981) Learn. Motiv. 12, 239-260
Rahman Q, Koerting J (2008). Sexual orientation-related differences in allocentric spatial memory tasks. Hippocampus. 18(1):55-63.
Schneider CB, Linse K, Schönfeld R, Brown S, Koch R, Reichmann H, Leplow B, Storch A (2017). Spatial learning deficits in Parkinson’s disease with and without mild cognitive impairment. Parkinsonism Relat Disord. 36:83-88. doi: 10.1016/j.parkreldis.2016.12.020.
Schoenfeld R, Foreman N, Leplow B (2014). Ageing and spatial reversal learning in humans: findings from a virtual water maze. Behav Brain Res. 270:47-55. doi: 10.1016/j.bbr.2014.04.036.
van Gerven DJH, Ferguson T, Skelton RW (2016). Acute stress switches spatial navigation strategy from egocentric to allocentric in a virtual Morris water maze. Neurobiol Learn Mem. 132:29-39. doi: 10.1016/j.nlm.2016.05.003
Vorhees CV, Williams MT. (2006) Morris water maze: procedures for assessing spatial and related forms of learning and memory. Nat Protoc. 1(2):848-58.
Vuong AM, Braun JM, Yolton K, Xie C, Webster GM, Sjödin A, Dietrich KN, Lanphear BP, Chen A (2017). Prenatal and postnatal polybrominated diphenyl ether exposure and visual spatial abilities in children. Environ Res. 153:83-92. doi: 10.1016/j.envres.2016.11.020
