NRG1 and psychiatric disorder: Neuregulin 1-ErbB receptor signaling appears to play a critical role in the ontogeny of psychiatric disorders and this hypothesis has been supported by the identification of altered expression levels and/or function of NRG1, ErbB3, and ErbB4 in patients with schizophrenia (Corfas et al., 2004; Silberberg et al., 2006).