Anatomically, CHRM2 receptors are localized in cardiac muscle and serve to modulate potassium channels, which contribute to decreases in heart rate. A recent meta-analysis conducted on 45 independent effect sizes across 40 separate studies suggests that low resting heart rate is among the best-replicated biological correlates of antisocial behavior in children and adolescents (overall d = −0.44, p < .0001; see Ortiz & Raine, 2004). Moreover, researchers have posited a number of potential explanations for this link, including attempts to maintain normative levels of physiological arousal through acting out (Eysenck, 1997; Quay, 1965; Raine, 1997), and inadequate development of social consciousness given the inability to be conditioned to fear and punishment (Raine, 1993; Raine, 1997).
