This chapter demonstrates how evidence from the neurosciences can be combined with other forms of evidence to assess the morally relevant mental states and cognitive capacities of nonhuman animals. It discusses how neuroscience can be used to determine whether some nonhuman animals have the capacity for dissent in research contexts. The chapter suggests that neuroscience can complement, while never fully replacing, other forms of evidence that are marshaled for establishing the presence of mental capacities in nonhuman animal species. Earlier theorists arguing for reconsidering the moral standing of animals often highlighted a range of evidence, including behavioral similarities in reaction to pain, and physiological similarities to make the case that animals experience pain and distress. The chapter provides some reasons for thinking that the failure of anthropocentricism and human exceptionalism requires a reweighting of animal dissent in bioethical analyses of their use in research.