Eliminating the use of non-human primates in certain fields (see P. Bateson and C. I. Ragan Nature 514, 567; 2014) has no bearing on their utility in neuropsychiatry and neurology.

The use of these animals, including genetically modified marmosets, is in our view essential for fundamental research into mental-health disorders. Similarities in the structure of higher-order cortical brain regions — which are dysregulated in disorders such as depression and schizophrenia — enable the most accurate and relevant mapping of the primate brain's functional organization.

A prominent example is the mapping of neural pathways in the rhesus monkey, which led to the discovery that deep brain stimulation can be an effective treatment for Parkinson's disease (see go.nature.com/28spre).

The US National Institute of Mental Health has recognized that such fundamental research should be applied to the understanding and treatment of neuropsychiatric disorders (Research Domain Criteria; see go.nature.com/or4keu), to identify discrete psychological deficits associated with specific neural pathways.