Understanding the role of inhibition in cortical function has been a challenge, mainly due to the lack of sufficiently specific tools. The general pharmacological block of inhibition in cortical structures invariably leads to epileptiform activity and thus precludes an accurate assessment of which cortical properties (tuning, receptive field size, etc.) are affected by the absence of inhibition. Thus, many of the reported roles of inhibition rely on correlative evidence substantiated by a great deal of computational models. Despite the relative paucity of functional analysis, however, there has been an explosion in the number of studies reporting on the properties and mechanisms of cortical inhibition. Morphological, physiological, pharmacological, biochemical and genetic properties of cortical inhibitory neurons, the circuits they are embedded in, and the properties of synapses they form are being worked out with unprecedented detail (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). We are thus facing a
