Assessing Spatial Memory Impairment in a Mouse Model of Traumatic Brain Injury Using a Radial Water Tread Maze
Summary
Here we present a protocol for a mouse-specific test of cognition that does not require swimming. This test can be used to successfully distinguish controlled cortical impact-induced traumatic brain injury mice from sham controls.
Abstract
Despite the recent increase in use of mouse models in scientific research, researchers continue to use cognitive tasks that were originally designed and validated for rat use. The Radial Water Tread (RWT) maze test of spatial memory (designed specifically for mice and requiring no swimming) has been shown previously to successfully distinguish between controlled cortical impact-induced TBI mice and sham controls. Here, a detailed protocol for this task is presented. The RWT maze capitalizes on the natural tendency of mice to avoid open areas in favor of hugging the sides of an apparatus (thigmotaxis). The walls of the maze are lined with nine escape holes placed above the floor of the apparatus, and mice are trained to use visual cues to locate the escape hole that leads out of the maze. The maze is filled with an inch of cold water, sufficient to motivate escape but not deep enough to require that the mouse swim. The acquisition period takes only four training days, with a test of memory retention on day five and a long-term memory test on day 12. The results reported here suggest that the RWT maze is a feasible alternative to rat-validated, swimming-based cognitive tests in the assessment of spatial memory deficits in mouse models of TBI.
Introduction
Memory impairments are among the most common symptoms reported by patients following traumatic brain injury (TBI)1,2. Accurate identification and assessment of analogous memory deficits in animal models of TBI, therefore, are essential to our understanding of this condition and its management. Here, we present a protocol to test spatial memory in a mouse model of TBI using a Radial Water Tread (RWT) maze. This apparatus was previously shown to assess cognitive deficits in mouse models of controlled cortical impact (CCI)-induced TBI3, and represents a potential alternative to rat-validated, swim-based tests of cognition.
The growing diversity and availability of transgenic mouse models has led to a recent increase in the use of mice over rats in scientific research4. Despite this shift, researchers continue to rely on behavioral and cognitive tasks that were originally designed and validated for rat use. The most common tests currently used to assess cognition in mice, the Morris Water Maze (MWM) and the Barnes circular maze, were specifically designed to capitalize on instinctual behaviors found in rats5,6. Considering the genetic, neuroethological, and cognitive differences that exist between these two species4, it is unsurprising that mice consistently underperform on these tasks7,8.
Species-dependent differences in testing ability are particularly concerning in swimming-based cognitive tests, such as the MWM. While both rats and mice are proficient swimmers, researchers have identified several mouse strains that perform remarkably poorly on swimming-based cognitive tasks9,10,11,12,13. Even in wild-type animals, rats generally outperform mice7,8. While this could be interpreted as a species-specific difference in spatial memory, analogous follow-up testing using a dry-land maze revealed no species-dependent differences in cognitive performance8. A number of factors unrelated to cognition could account for this finding, including species-dependent differences in either swimming ability or search strategy. Indeed, factor analysis of mouse-specific search strategies in the MWM show that noncognitive factors (in particular, thigomotaxis and passivity [i.e., floating]) may play a more significant role in MWM performance than spatial learning14.
Here, we demonstrate the use of a cognitive test designed to capitalize on the instinctual behavior of mice, and which does not require swimming, to measure spatial memory impairment in a mouse model of CCI-induced TBI. While the RWT maze (Figure 1A-B) was conceived as a novel hybrid of the MWM and Barnes circular maze, it was specifically designed to take advantage of thigmotactic behavior instinctual to mice15,16. The apparatus consists of a 32 inch diameter galvanized steel tub in which nine evenly spaced exit holes have been bored. The holes are centered 2-1/4 inches above the floor of the tub and are sized to fit commonly available 1-1/2 inch ABS DWV SPG x SJ trap adapters. Eight of the exits are capped from the outside and blinded to a depth of 1 inch with rubber stoppers. The ninth is connected by a 90° acrylonitrile butadiene styrene (ABS) elbow to an opaque plastic box from which the mouse can be easily removed after testing. Over the course of a brief acquisition period, the mouse is trained to use the unique visual cues lining the maze to locate this escape box. During testing, the maze is filled with an inch of cold water (12-14 °C), sufficiently aversive enough to promote escape, but not deep enough that the mouse is required to swim.
The RWT maze represents a low-cost, low-maintenance alternative to the MWM, and has been used successfully in aged and transgenic mice15,17,18,19, and CCI-induced mouse models of TBI3. The protocol outlined here represents a simple and effective method for measuring spatial memory impairment requiring no pre-injury training, and could be easily modified to suit the particular needs of a research laboratory.
Protocol
Representative Results
Discussion
The RWT maze protocol presented here successfully distinguishes between CCI-induced TBI mice and sham controls, and represents a feasible, mouse-centric, alternative to the MWM and Barnes circular maze. While the results reported here speak only to the use of the RWT maze in a TBI mouse model, this apparatus has been used successfully in aged and transgenic models where stress-induced noncompliance resulting from swim-based testing made using the MWM impractical15,17</…
Offenlegungen
The authors have nothing to disclose.
Acknowledgements
This research was supported by the Institute for Translational Health Sciences pilot project grant opportunity (UL1TR000423), the University of Washington Center on Human Development and Disability, and the University of Washington Animal Behavior Core and Brain Imaging Core. We would like to acknowledge Dr. Warren Ladiges for his role in the development and dissemination of the original Radial Water Tread maze design and protocol presented here. We also thank Toby Cole for his assistance with this project.
Materials
| 35 Gal. Hot Dipped Steel Round Tub | Home Depot | Internet #206638142 | Needed: 1 |
| 1-1/2 in. ABS DWV SPG x SJ Trap Adapter | Home Depot | Internet #100344703, Store SKU #188956 | Needed: 9 |
| 1-3/4 in. x 1-7/16 in. Black Rubber Stopper | Home Depot | Internet #100114974 Store SKU #755844 | Needed: 8 |
| 1-1/2 in. ABS DWV 90 Degree Hub x Hub Elbow | Home Depot | Internet #100346663 Store SKU #188603 | Needed: 1 |
| HDX 10 Gal. Storage Tote |
Home Depot | Internet #202523587 Store SKU #258804 Store SO SKU #258804 | Needed: 1 |
| Impact One Stereotaxic Impactor for CCI | Leica Biosystems | 39463920 | Needed: 1 |
| Vernier Stereotaxic w/ Manual Fine Drive Stereotaxic Instrument for Small Animals | Leica Biosystems | 39463001 | Needed: 1 |
Referenzen
- Levin, H. Neurobehavioral outcome of closed head injury: Implications for clinical trials. J. Neurotrauma. 12 (4), 601-610 (1995).
- Schretlen, D., Shapiro, A. A quantitative review of the effects of traumatic brain injury on cognitive functioning. Int Rev Psychiatry. 15 (4), 341-349 (2003).
- Cline, M. M., et al. Novel application of a radial water tread maze can distinguish cognitive deficits in mice with traumatic brain injury. Brain Res. 1657, 140-147 (2017).
- Ellenbroek, B., Youn, J. Rodent models in neuroscience research: Is it a rat race?. Dis. Model. Mech. 9 (10), 1079-1087 (2016).
- Morris, R. Developments of a water-maze procedure for studying spatial learning in the rat. J. Neurosci Methods. 11 (1), 47-60 (1984).
- Barnes, C. Memory deficits associated with senescence: A neurophysiological and behavioral study in the rat. J. Comp. Physiol. Psych. 93 (1), 74-104 (1979).
- Frick, K., Stillner, E., Berger-Sweeney, J. Mice are not little rats: Species differences in a one-day water maze task. Neuroreport. 11 (16), 3461-3465 (2000).
- Whishaw, I., Tomie, J. Of Mice and Mazes: Similarities Between Mice and Rats on Dry Land But Not Water Mazes. Physiol Behav. 60 (5), 1191-1197 (1995).
- Francis, D., Zaharia, M., Shanks, N., Anisman, H. Stress-induced disturbances in Morris water-maze performance: Interstrain variability. Physiol Behav. 58 (1), 57-65 (1995).
- Wahlsten, D., Rustay, N., Metten, P., Crabbe, J. In search of a better mouse test. Trends Neurosci. 26 (3), 132-136 (2003).
- Crawley, , et al. Behavioral phenotypes of inbred mouse strains: implications and recommendations for molecular studies. Psychopharmacology. (Berl). 132 (2), 107-124 (1997).
- Wahlsten, D., et al. Different data from different labs: lessons from studies of gene-environment interaction. J. Neurobiol. 54 (1), 283-311 (2002).
- Rogers, D. C., et al. Use of SHIRPA and discriminant analysis to characterise marked differences in the behavioural phenotype of six inbred mouse strains. Behav Brain Res. 105 (2), 207-217 (1999).
- Wolfer, D. P., Stagljar-Bozicevic, M., Errington, M. L., Lipp, H. Spatial Memory and Learning in Transgenic Mice: Fact or Artifact?. Physiology. 13 (3), 118-123 (1998).
- Koopmans, G., Blokland, A., Vannieuwenhuijzen, P., Prickaerts, J. Assessment of spatial learning abilities of mice in a new circular maze. Physiol Behav. 79 (4-5), 683-693 (2003).
- Deacon, R., Rawlins, N. Learning impairments of hippocampal-lesioned mice in a paddling pool. Behav Neurosci. 116 (3), 472-478 (2002).
- Pettan-Brewer, C., et al. A novel radial water tread maze tracks age-related cognitive decline in mice. Pathobiol Aging Age Relat Dis. 3, 1-4 (2013).
- Wiley, J., Pettan-Brewer, C., Ladiges, W. Phenylbutyric acid reduces amyloid plaques and rescues cognitive behavior in AD transgenic mice. Aging Cell. 10 (3), 418-428 (2011).
- Enns, L., et al. Disruption of Protein Kinase A in Mice Enhances Healthy Aging. PLoS ONE. 4 (6), (2009).
- Ivonen, H., Nurminen, L., Harri, M., Tanila, H., Puolivali, J. Hypothermia in mice tested in Morris water maze. Behav Brain Res. 141 (2), 207-213 (2003).
- Shultz, S. R., et al. Granulocyte-macrophage colony-stimulating factor is neuroprotective in experimental traumatic brain injury. J Neurotrauma. 31 (10), 976-983 (2014).
