A less literal form of lateral inhibition that does not require a two dimensional spatial mapping of stimulus features still applies to cortical tuning: namely, that synaptic excitation to a preferred stimulus roughly shapes the tuning of a cell’s spike output and that tuning is further sharpened by robust synaptic inhibition in response to non-preferred stimuli (Priebe and Ferster, 2008). This notion, however, has been challenged by intracellular recording studies in several cortical regions showing that in individual neurons the stimuli that generate the strongest excitation (preferred stimuli) can be the same as those generating the strongest inhibition (Fig. 2A, 3B) (Anderson et al., 2000; Liu et al., 2011; Marino et al., 2005; Martinez et al., 2002; Tan et al., 2004; Tan et al., 2011; Wehr and Zador, 2003; Wilent and Contreras, 2005; Wu et al., 2008; Zhang et al., 2003), but see (Monier et al., 2003). Furthermore, as the stimulus gradually changes away from the preferred feature, both excitation and inhibition decrease. In other words the tuning curves for excitation and for inhibition show considerable overlap.
