ERBB4 and attention deficit-hyperactivity disorder: Since ADHD and mania animal models have overlapped behavioral phenotypes (Beyer and Freund, 2017; Itohara et al., 2015), we treated ErbB4-deficient mice with methylphenidate (MHP), a clinical ADHD medication which alleviates hyperactivity of ADHD animal models but aggravates hyperactivity of mania models (D'Andrea et al., 2015; Souza et al., 2016; Sumitomo et al., 2018).