Despite Nrg1 TM HET mice showing increased susceptibility to the effects of cannabinoids and methamphetamine on schizophrenia-relevant behaviours (e.g. locomotion, social behaviours, sensorimotor gating), behaviours relevant to substance use problems have not been examined in these mice (e.g. drug reward and self-administration, extinction and reinstatement, locomotor sensitization). The gene discussed is NRG1; the disease is schizophrenia.