ERBB4 and schizophrenia: Here we report that ErbB4 null mutant mice exhibit an imbalance of extracellular DA levels relative to controls, with increased levels in the dorsal striatum but reduced levels in the prefrontal cortex (PFC), hippocampus, and nucleus accumbens (NAc); a similar striatal and cortical DA imbalance has been reported in subjects with schizophrenia.