Non-maternal nest building behaviours in mice predict bilateral dorsal hippocampal lesion extent.

Lesions and pharmacological inactivation of the hippocampus have long been important tools for assessing the critical role of the hippocampus in learning and memory. Such studies often require a substantial investment of time and resources and, so, a tool for estimating lesion extent and screening animals prior to histological verification would be of considerable utility. Mice with bilateral hippocampal lesions have previously been observed to be deficient at nest building. Therefore, non-maternal nest construction was assessed as a predictor of the extent of hippocampal lesions. Mice with complete bilateral dorsal hippocampal lesions (comprising >50 % of the total volume of both hippocampi) exhibited severe deficits in nest building, failing to shred and/or gather nesting materials. In contrast, incomplete dorsal hippocampal lesions were not sufficient to cause impairments. Overall, among both male and female mice, nest construction score was highly positively correlated with the total volume of intact dorsal hippocampus. Importantly, reduced nesting behaviours could not be explained by gross motor deficits, which were evaluated by running performance on a non-motorized treadmill. Altogether, spontaneous nest building behaviour was confirmed to be a simple, cost-effective, and reliable predictor of bilateral dorsal hippocampal lesion extent in an otherwise healthy mouse strain.