How will further efforts bring us closer to understanding the role of inhibition in cortical function? New methodological approaches offer an unprecedented ability to precisely determine the functional properties of distinct inhibitory circuits. A variety of genetic tools are now available to perturb neuronal activity with exquisite spatial and temporal precision (Fenno et al., 2011; Kim et al., 2009; Magnus et al., 2011; Rogan and Roth, 2011; Tan et al., 2006). However, a critical factor in using these genetic tools to dissect circuit function is the capacity to target them to particular types of neurons using cell-specific promoters. Thankfully, the abundance of studies characterizing biochemical and genetic phenotypes of cortical inhibitory neurons makes this possible. For example, these characterizations have established the foundations for designing a variety of currently available mouse lines in which Cre recombinase can be used to target genetic tools to discrete subtypes of interneurons, such as parvalbumin-expressing basket cells or somatostatin-expressing Martinotti cells (Taniguchi et al., 2011).
