Interrupt Cycle: Deterioration of Spatial Representation I, 2016
Testing Spatial Memory
A number tests for spatial memory have been devised to help determine how Alzheimer's disease impacts spatial memory and to test the effects of potential treatments. One of the most extensively used tests is the Morris Water Maze, which was originally developed to test spatial memory in rodents. In the test, subjects attempt to find a hidden platform in a circular arena, with visual cues placed around four edges to test for spatial memory. A computer generated version of the Morris Water Maze was developed to test humans [see figure below]. Firstly, in the learning trial, four pictures of well known landmarks are presented on the edges of a circular computer generated arena as cues. Participants are asked to locate a hidden platform within the arena as fast and accurately as possible. When participants pass over the platform, it becomes visible, after which they have 30 seconds to observe the relationship between themselves and the landmarks on the arena edges. The learning trials are repeated six times, and participants start from the same point on the border of the arena in each trial.
Computer Generated version of the Morris Water Maze. Four well known landmarks used as cues around the edges of the arena. [Top Left] The target platform inside the arena. [Top Right, Bottom Left] In the learning trials, participants try to reach the target platform. [Bottom Right] In the probe trial, the target platform was removed. The solid line represents the path of subjects who formed a cognitive map from the learning trials and the dotted line represents a control group.
After six learning trials, a probe trial following the same procedure is given in the same environment, except the target platform is removed. Participants are placed in the centre of the arena and given 30 seconds of search time to locate the area where the platform was, and to see if they could go directly to the target quadrant of the arena without going through non-target quadrants. Performance on this trial can be used to assess whether the participant has formed a cognitive map: those who formed the cognitive map should spend a greater proportion of their path in the target quadrant when searching for the target against normal controls [Figure D].
The 4 Mountains Test. The '4 Mountains' landscape is presented for 8 seconds and then removed. After a 2-second delay, this landscape is presented again from a rotated perspective, alongside three additional false landscapes as part of a delayed match-to-sample paradigm.
A second computer-generated test is the '4 Mountains' test. Participants are shown an image of a computer generated mountain landscape for 8 seconds. After a 2 second delay, 4 additional images appear. One image is a view of the same landscape from a rotated position, and the other three are 'dummy' control landscapes. The subject then attempts to correctly identify the original landscape. This test is particularly sensitive to detecting hippocampal damage and can also differentiate patients with Alzheimer's disease and those with non-AD dementias. Other tests include the Heading Orientation Test, The Money Road Map Test, and virtual reality tasks including a radial maze task.
Interrupt Cycle: Deterioration of Spatial Representation II, 2016
 SS. Jheng and MC. Pai, Cognitive map in patients with mild Alzheimer’s disease: A computer-generated arena study, Behavioural Brain Research 200 (2009) 42–47, p.42.
 R. Wood and D. Chan, The Hippocampus, Spatial Memory and Alzheimer’s Disease, Advances in Clinical Neuroscience and Rehabilitation, <http://www.acnr.co.uk/wp-content/uploads/2015/07/05-07_ACNRMJ15.pdf> [Accessed: 10/1/2016].