Electroencephalographic and morphometric abnormalities in psychopath offenders

How reliable are amygdala findings in psychopathy? A systematic review of MRI studies

The amygdala is a key component in predominant neural circuitry models of psychopathy. Yet, after two decades of neuroimaging research on psychopathy, the reproducibility of amygdala findings is questionable. We systematically reviewed MRI studies (81 of adults, 53 of juveniles) to determine the consistency of amygdala findings across studies, as well as within specific types of experimental tasks, community versus forensic populations, and the lowest- versus highest-powered studies. Three primary findings emerged. First, the majority of studies found null relationships between psychopathy and amygdala structure and function, even in the context of theoretically relevant tasks. Second, findings of reduced amygdala activity were more common in studies with low compared to high statistical power. Third, the majority of peak coordinates of reduced amygdala activity did not fall primarily within the anatomical bounds of the amygdala. Collectively, these findings demonstrate significant gaps in the empirical support for the theorized role of the amygdala in psychopathy and indicate the need for novel research perspectives and approaches in this field.

Rational capacity and criminal responsibility in the USA

The United States Supreme Court recently found that an insanity defense based upon moral incapacity was not constitutionally required. This decision allows states with a moral incapacity insanity defense, i.e., most states, to abolish their insanity defense. Unfortunately, the Court's opinion was based upon conflated concepts without considering irrationality, traditionally and universally the indispensable core element of insanity standards. This present perspective review attempts to clarify and disambiguate the critical concepts of instrumental and rational capacities as applied to insanity standards. With a proper understanding and application of these distinctly different capacities, insanity standards that at least incorporate rationality should in the future meet the Court's touchstone for determining constitutionally required due process.