ERBB4 and psychotic disorder: Based on the synaptic deficits previously reported in these animals,44 and the evidence that inhibitory interneuron deficits may underlie hippocampal hyperactivity in psychosis,2 we hypothesized that Erbb4 mouse mutants would show increases in CBF, glutamatergic metabolites and α1-3;5GABAAR density, as well as decreases in α5GABAAR and SV2A density, in the hippocampus compared to wild-type littermate controls.