Marble Burying Test
The marble burying test (MBT) is a test used to assess anxiety and compulsive behaviour in mice and rats. The test is applied to investigate the effects of pharmacological, genetic, and behavioral manipulations. It has also been suggested as a test of neophobia because rodents often bury novel objects.
The test uses rodents’ burying behaviour, which with burrowing, and digging form part of the normal behavioral repertoire of rodents, in both the wild and the laboratory for searching for food, burying both noxious and harmless objects, and building adequate shelters. The behaviour is expressed in both non-anxiogenic (e.g., nesting, hoarding, foraging) and anxiogenic situations (e.g., burying of noxious objects, confronting predators) (Wolmarans et al., 2016).
The test refers to the displacement of bedding material using the snout and forepaws in an effort to cover an object, because rodents have been reported to use this behaviour in response to aversive stimuli including shock prods, air puffs, noxious food, scorpions and non-aversive objects, such as food pellets and glass marbles (Thomas et al., 2009).
However, outcomes of MBT studies are often contradictory and inconsistent, as shown by variable responses to a range of pharmacological interventions reported, and the variations in methodology (deBrouwer et al., 2019). Thomas et al. (2009) provided evidence that marble burying is genetically regulated, not correlated with anxiety, and not stimulated by novelty. It is a repetitive behavior that persists with little change across multiple exposures. Thus, taken together, these findings question the test reliability, validity and translational usefulness.
Marbles are sometimes used as enrichment for rodents. However, their benefit is questionable if their presence triggers digging behaviour when there is no substrate (e.g. in a metabolic cage), or insufficient or inappropriate substrate to bury them entirely.
References
deBrouwer G., Fick A., Harvey B.H. & Wolmarans D. (2019): A critical inquiry into marble-burying as a preclinical screening paradigm of relevance for anxiety and obsessive–compulsive disorder: Mapping the way forward. Cognitive, Affective & Behavioral Neuroscience, 19:1-39. https://doi.org/10.3758/s13415-018-00653-4
Thomas A., Burant A., Bui N., Graham D., Yuva-Paylor L.A. & Paylor R. (2009): Marble burying reflects a repetitive and perseverative behavior more than novelty-induced anxiety. Psychopharmacology, 204:361-373. https://doi.org/10.1007/s00213-009-1466-y
Wolmarans D., Stein D.J. & Harvey B.H. (2016): Of mice and marbles: Novel perspectives on burying behavior as a screening test for psychiatric illness. Cognitive, Affective & Behavioral Neuroscience, 16:551–560. https://doi.org/10.3758/s13415-016-0413-8
Text supplied by: Sylvie Cloutier, Ph.D., scientist, Ottawa, Canada
