Loss-of-function or overexpression of Homer genes in rodents revealed roles for these proteins in neuropsychological disorders, ranging from impairment of memory and motivation-based learning tasks to compulsive behavior and addiction to drugs and alcohol [7,22,23,24] and clinical studies implicated Homer dysfunction in the pathogenesis of depression, schizophrenia and addiction [25,26,27]. The gene discussed is HOMER1; the disease is major depressive disorder.