We show that our light-off behaviour system can monitor changes in PPI performances in genetically manipulated Drosophila. We were able to detect PPI phenotypes by decreasing or increasing the expression of two Drosophila orthologues of human schizophrenia susceptibility genes (Dysbindin [32–35] and Nmdar1 [27, 28, 30, 31]). The gene discussed is GRIN1; the disease is schizophrenia.