A wide range of proposals has been put forward in order to account for the cognitive and functional significance of the P3. These include the influential Context Updating account (Donchin, 1981 and Donchin and Coles, 1988; see also Polich, 1985 and Polich, 2007), according to which the P3 reflects memory adaptions following critical events. Another prominent account (Verleger, 1988 and Verleger et al., 2005) assigns a more tactical role to the P3 by proposing that it marks the linkage between critical events and reactions (henceforth: the Linking account of the P3). In a more strongly

biologically-grounded approach, Nieuwenhuis, Aston-Jones and Cohen (2005) associate the P3 with the norepinephrine (NE) neuromodulator system Afatinib ic50 and systemic NE release from the brainstem nucleus Locus Coeruleus (LC), which facilitates general cortical state transitions and thus supports cognitive

reorientation (like response execution or inhibition). All approaches agree that the P3 follows highly salient events such as novel and unexpected events, highly task-relevant expected events, and self-relevant stimuli. In contrast to the Context Updating theory, however, the Linking and LC/NE accounts stress that, if a task requires overt behaviour and elicits a P3, there is a tight temporal coupling between the P3 and the DAPT mouse response. The P3 is therefore often investigated following stimuli to which subjects respond Resveratrol directly. While overt responses are not a necessary precondition for P3 elicitation, if overt responses do occur, they are typically aligned with the P3. Specifically,

a frontal instance of the P3-family peaks slightly before the response, while the P3b typically peaks just at, or rapidly following it (Delorme et al., 2007a, Makeig et al., 1999 and Makeig et al., 2004). However, the P3 is not a motor component. A P3 is found in response inhibition trials (Falkenstein, Hoormann, & Hohnsbein, 1999). Furthermore, direct comparisons between overt and covert tasks have demonstrated that the P3 is also observable in passive (task-free) paradigms (e.g. in response to incorrect sequence endings), with P3 amplitudes typically (but not always) smaller than in the presence of an active task (see Lang & Kotchoubey, 2002, and the references cited therein). In one study, a silent counting task even increased P3 amplitude (Salisbury, Rutherford, Shenton, & McCarley, 2001). One reliable exception to the tight coupling between response timing and P3 latency is found when response selection is rendered complicated, for example by introducing incompatible stimulus–response mappings or complex motor actions (Verleger, 1997). Stressing speed over accuracy (Kutas, McCarthy, & Donchin, 1977) also dissociates RT and P3.