Mouse. Mus musculus strain:C57BL/6J

To facilitate the rapid dissection of gene function, both in normal and disease-related brain processes, we need the ability to precisely and efficiently manipulate the genome of neurons in vivo. The CRISPR-associated endonuclease Cas9 from Streptococcus pyogenes (SpCas9) has been shown to mediate genome cleavage of individual and multiple genes in replicating eukaryotic cells, resulting in frame-shifting insertion/deletion (indel) mutations and subsequent protein depletion. Here, we combined SpCas9 with adeno-associated viral (AAV) delivery to manipulate gene function in the adult mouse brain in vivo. We characterized Cas9-mediated genome perturbation with biochemical, genetic, electrophysiological, and behavioral readouts in postmitotic neurons, demonstrating the potential of Cas9 to facilitate reverse genetic studies of gene function in the brain.