We previously reported that some genes associated with major mental illnesses, such as DISC1 and G72, showed low sequence conservation between rodents and humans (Bord et al, SFN abstract, 2004), suggesting a possible limitation in using rodent tissues to address molecular mechanisms in the pathophysiology of mental conditions. To overcome this potential limitation, we have explored the use of primate derived primary brain cultures. We established primary brain cultures that contain neurons, astrocytes, and microglial cells from cryopreserved fetal cerebral cortex of cynomolgus monkeys (Macaca fascicularis) (Negishi et al, J Neurosci Methods, 2003). The study has faithfully followed the Guidelines for Animal Experimentation, The University of Tokyo. Here we report optimized conditions of gene transfection (expression constructs, RNAi constructs) that lead to preferential transfection to neurons or astrocytes. Application of this technique to studies of DISC1 and G72 is now shedding light on the molecular m...