Best practices in neurotoxicology research must account for spontaneous brain malformations in rodent models.

Spontaneous neocortical and cerebellar heterotopia are present in rat and mouse strains commonly used in neurotoxicology research. These malformations reflect neuronal migration defects during neocortical and cerebellar development that are inherent in these strains, yet the influence of these heterotopia are not considered in the design and interpretation of neurotoxicology research. In this review, we describe anatomical, behavioral, and physiological studies relevant to spontaneous neocortical and cerebellar heterotopia in rats and mice. This work will inform researchers in possible design and assessment approaches to account for these malformations which will likely be present in both control and exposure-treated groups.