81 % of mice display a preference for either the left or the right paw; In rats, 84 % of animals display a preference for either the left or the right paw; brain asymmetries are a basic characteristic of the rodent brain

Paw preferences in mice and rats: Meta-analysis. Martina Manns et al. Neuroscience & Biobehavioral Reviews, May 15 2021. https://doi.org/10.1016/j.neubiorev.2021.05.011

Highlights

• In mice, 81 % of animals display a preference for either the left or the right paw.

• In rats, 84 % of animals display a preference for either the left or the right paw.

• Rodents display individual- but not population-level lateralization for limb use.

• Brain asymmetries are a basic characteristic of the rodent brain.

Abstract: Mice and rats are among the most common animal model species in both basic and clinical neuroscience. Despite their ubiquity as model species, many clinically relevant brain-behaviour relationships in rodents are not well understood. In particular, data on hemispheric asymmetries, an important organizational principle in the vertebrate brain, are conflicting as existing studies are often statistically underpowered due to small sample sizes. Paw preference is one of the most frequently investigated forms of hemispheric asymmetries on the behavioural level. Here, we used meta-analysis to statistically integrated findings on paw preferences in rats and mice. For both species, results indicate significant hemispheric asymmetries on the individual level. In mice, 81 % of animals showed a preference for either the left or the right paw, while 84 % of rats show this preference. However, contrary to what has been reported in humans, population level asymmetries were not observed. These results are particularly significant as they point out that paying attention to potential individual hemispheric differences is important in both basic and clinical neuroscience.

Keywords: Animal modelClinical neuroscienceHandednessHemispheric asymmetriesLateralityRodentsTranslational neuroscience