Cortical GABAergic interneurons are a heterogeneous bunch (reviewed in (Ascoli et al., 2008; Freund and Buzsaki, 1996; Kawaguchi and Kondo, 2002; Kawaguchi and Kubota, 1998; Klausberger and Somogyi, 2008; Markram et al., 2004; Monyer and Markram, 2004; Mott and Dingledine, 2003; Somogyi and Klausberger, 2005; Somogyi et al., 1998). One of the most striking features of this group of neurons is their morphological diversity, in particular with regard to their axonal arborization and, as a consequence, their postsynaptic targets. In fact, distinct classes of GABAergic interneurons inhibit particular compartments of principal neurons; "basket" cells, that target the somatic and perisomatic compartment, "chandelier" cells, that selectively inhibit the axon initial segment, or "Martinotti" cells, that preferentially target the apical dendritic tuft are just a few classic examples of this compartmentalization of inhibition. Morphological differences are however not the only properties that contribute to the diversity of cortical inhibitory neurons. Interneurons can be also subdivided based on intrinsic electrophysiological properties, synaptic characteristics, and protein expression patterns. Probably because of the many dimensions that can be used to describe an interneuron, no consensus
