The neural causes of most complex behaviors are still not understood. It is thought that much of this is due to the fact that complex behavior depends on distributed neural control. Disruption in this causal web can produce effects that are difficult to trace back to their origin. Against this background, the finding that focal lesions of the ventromedial prefrontal cortex could lead to immoral and even criminal behavior has generated considerable interest. While a number of rare cases have now been described in which a focal lesion caused criminality, these are neither very consistent (the lesions occur in several different anatomical locations) nor at all reliable (only a small fraction of patients, for any lesion location, showed criminal behavior). To explain the effects of a lesion on criminal behavior, one needs to understand what it is that the lesion does to the rest of the brain. A network-level understanding of lesion effects is now provided by the new study of Darby and colleagues. In this study, all lesions were functionally connected to the same network of brain regions. This criminality-associated connectivity pattern was unique compared with lesions causing four other neuropsychiatric syndromes. The network includes regions involved in morality, value-based decision making, and theory of mind, but not regions involved in cognitive control or empathy. Finally, the results were replicated in a separate cohort of 23 cases in which a temporal relationship between brain lesions and criminal behavior was implied but not definitive. The results suggest that lesions in criminals occur in different brain locations but localize to a unique resting state network, providing insight into the neurobiology of criminal behavior.
Darby RR, Horn A, Cushman F and Fox MD: Lesion network localization of criminal behavior. Proc. Natl. Acad. Sci. USA [Epub ahead of print, Dec. 18, 2017; doi: 10.1073/pnas.1706587115.]