A bridge too far? Inference and extrapolation from model organisms in neuroscience

Like many other biological sciences, research in modern experimental neuroscience is heavily reliant on a range of model organisms, including but not limited to rats, mice, monkeys, birds, fish, and insects. The model organism approach is extremely well established in contemporary neuroscience as a means to investigate the nature of mind and brain. According to one recent estimate, studies involving nonhuman animals account for more than half of all the research undertaken (Manger et al. 2008). Even more strikingly, approximately 40% of all studies focus on just two model organisms that are quite evolutionarily distant from humans – the rat and the mouse (primarily the species Rattus norvegicus and Mus musculus) (Manger et al. 2008; Keifer and Summers 2016). Given that two central goals of neuroscience are arguably to: understand the distinctive structure and function of the human brain; and develop therapies for human brain diseases such as Alzheimer’s, Huntington’s, and amyotrophic lateral sclerosis, among others, a fundamental question naturally arises concerning what can be learned indirectly about humans by studying the brains and nervous systems of nonhuman animals.