In a recent study, we recorded from both pyramidal and fast-spiking GABA interneurons in PFC cultures and examined how ethanol affects up-state activity in these neurons (Woodward and Pava, 2009). During dual patch-clamp recordings, neurons entered and exited the up-state simultaneously regardless of the type of neuron pairs recorded (pyramidal:pyramidal; interneuron:interneuron; pyramidal:interneuron). These findings are consistent with the idea of highly interconnected recurrent networks of excitatory and inhibitory neurons in the PFC. In FS GABAergic inteneurons, fast EPSPs could be observed during up-states whereas the up-state depolarization in pyramidal neurons was smooth and relatively constant as previously reported (McCormick et al., 2003; Seamans et al., 2003). However, individual EPSPs in pyramidal neurons were revealed by intracellular perfusion of the NMDA channel blocker MK801 supporting the suggestion from Seamans et al. (2003) that the slower kinetics of NMDA receptors bridge the fast transients gated by AMPA receptors. Intracellular MK801 had little effect on the up-state dynamics of FS neurons consistent with the reduced expression of NMDA receptors expression in this subpopulation of PFC interneurons (Wang and Gao, 2009). Despite these differences
