and attention focusing, and is thought to signal that a completed perceptual representation has been formed (Potts, 2004; Wijers et al., 1997). The more anterior fronto-central N2 is frequently interpreted as an index of response inhibition (Falkenstein, 2006; 1999) and/or conflict monitoring (Donkers and van Boxtel, 2004; Nieuwenhuis et al., 2003; van Veen and Carter, 2002a; 2002b) mediated by the anterior cingulate cortex (ACC) and other prefrontal regions (Bekker et al., 2005; Jonkman et al., 2007; Mathalon et al., 2003; van Veen and Carter, 2002a; van Veen and Carter, 2002b). Watson and colleagues (2009) have recently examined the effects of ketamine and thiopental on N2 amplitude, showing that drugs that affect glutamate and GABA neurotransmission reduce N2 amplitude, indexing a disruption of ACC activity required for the detection and processing of infrequent target stimuli. It is possible that alcohol has comparable effects but, given the novelty of our observation, replication of our observation should precede additional study of mechanisms involved.
