Quantitative evaluation of orofacial motor function in mice: The pasta gnawing test, a voluntary and stress-free behavior test

BACKGROUND Evaluation of motor deficits in rodents is mostly restricted to limb motor tests that are often high stressors for the animals. NEW METHOD To test rodents for orofacial motor impairments in a stress-free environment, we established the pasta gnawing test by measuring the biting noise of mice that eat a piece of spaghetti. Two parameters were evaluated, the biting speed and the biting peaks per biting episode. To evaluate the power of this test compared to commonly used limb motor and muscle strength tests, three mouse models of Parkinson's disease, amyotrophic lateral sclerosis and Niemann-Pick disease were tested in the pasta gnawing test, RotaRod and wire suspension test. RESULTS Our results show that the pasta gnawing test reliably displays orofacial motor deficits. COMPARISON WITH EXISTING METHODS The test is especially useful as additional motor test in early onset disease models, since it shows first deficits later than the RotaRod or wire suspension test. The test depends on a voluntary eating behavior of the animal with only a short-time food deprivation and should thus be stress-free. CONCLUSIONS The pasta gnawing test represents a valuable tool to analyze orofacial motor deficits in different early onset disease models.