Barnes maze

The Barnes maze

The Barnes maze is a tool used in psychological laboratory experiments to measure spatial learning and memory. The test was first developed by Dr. Carol Barnes in 1979. ^[1]The test subjects are usually rodents such as mice or lab rats, which either serve as a control or may have some genetic variable or deficiency present in them which will cause them to react differently to the maze. This noninvasive task is useful for evaluating novel chemical entities for their effects on cognition as well as identifying cognitive deficits in transgenic strains of rodents that model for disease such as Alzheimer's disease^[2].

Contents   [hide]  1 Set-up 2 Performance 3 Comparison to other mazes 4 See also 5 References

[edit]Set-up

The Barnes maze consists of a circular surface with up to 20 circular holes around its circumference. Visual cues, such as colored shapes or patterns, are placed around the table in plain sight of the animal. The table surface is brightly lit by overhead lighting. Under one of the holes is an "escape box" which can be reached by the rodent through the corresponding hole on the table top. The model is based on rodents' aversion of open spaces, which motivates the test subject to seek shelter in the escape box. A normal rodent will learn to find the escape box within four to five trials and will head directly toward the escape box without attempting to escape via incorrect holes. Various parameters are measured including latency to escape, path length, number of errors, and velocity.

[edit]Performance

Performance is typically measured by number of errors the rodent makes, i.e. the number of times it pokes its nose into a hole that does not contain the escape box. The rate of decline in the number of errors per trial can be calculated to represent a learning curve. Other performance values can also be measured, such as path length to the escape box, with a shorter path indicating fewer errors. Additionally, the strategy used by each rodent can be scored as random (randomly checking each hole), systematic (checking each hole in a pattern) or spatial (direct movement to the hole with the drop box).

Due to the spatial nature of the Barnes Maze, damage to the hippocampus leads to deficits in performance of the task.^[3] An experiment done on Degu, a specific rodent species, showed that there can be gender differences in performance on the Barnes Maze. During the task training where encoding would occur, females used more frequently a spatial strategy, while males preferably applied either serial, random or opposite strategies. The differences between male and females encoding period but not during the storage, indicating that acquisition and consolidation are differently influenced by gender in the Degu species.^[4]

[edit]Comparison to other mazes

The Barnes Maze is similar to the Morris water navigation task and to the Radial arm maze task, but does not utilize a strong aversive stimuli (stress induced by swimming such as in the Morris Water Maze) or deprivation (food or water deprivation such as in the Radial Arm Maze) is being used as reinforcement. Behavioral tasks involving high levels of stress can influence the animal's performance ^[5] on the task, making the Barnes Maze ideal for eliminating stress-induced confounds. However, due to the lack of a strong aversive stimuli, some rodents may lack motivation to complete the task. Once acclimated to the maze, subjects may prefer to explore instead of complete the task. Using different parameters to analyze the data is important for avoiding this issue. Latency, path length to escape box, and number of errors to the first nose poke at the escape hole have been used as measures previously ^[6]. Another drawback to the Barnes Maze is that when testing multiple animals, scent cues left on the maze by the previous animal could alter the performance of subsequent subjects.

[edit]See also

• Morris water navigation task
• Oasis maze

[edit]References

1. ^ Barnes, CA (1979). "Memory deficits associated with senescence: a neurophysiological and behavioral study in the rat." J Comp Physiol Psychol. 1979 Feb;93(1):74-104.
2. ^ Reiserer, RS., Harrison, FE., Syverud, DC., McDonald, MP. Impaired spatial learning in the APPSwe + PSEN1DeltaE9 bigenic mouse model of Alzheimer’s disease. Genes Brain Behav. 6:54-65 (2007).
3. ^ Fox, GB., Fan, L., LeVasseur, RA., Faden, AI. Effect of traumatic brain injury on mouse spatial and nonspatial learning in the Barnes circular maze. J Neurotrauma. 15:1037-1046 (1998).
4. ^ Popovic, N, Madrid, J.A, Rol, M.A, Caballero-Bleda, M, Popvic M. (2010) "Barnes maze performance of Octodon degus is gender dependent". Behavioural Brain Research. Volume:212(2)
5. ^ Holscher C. Stress impairs performance in spatial water maze learning tasks. Behav Brain Res. 100:225-235 (1999).
6. ^ Harrison, FE., Reiserer, RS., Tomarken, AJ., McDonald, MP. Spatial and nonspatial escape strategies in the Barnes maze. Learn Mem. 13:809-819 (2006).