VIP and epilepsy: Several studies have previously shown that a specific subpopulation of CINs, the fast-spiking PVALB-positive CINs, play a central role in epilepsy (Cammarota et al., 2013; Sessolo et al., 2015); nevertheless, our present data and other studies have also shown that alterations in the SST-positive, CALB2-, and VIP-positive populations of CINs may also contribute to epileptic activity (Cobos et al., 2005).