Although target P3 is a well-established endophenotype, it is not a unitary phenomenon and comprises multiple overlapping subprocesses. Evidence shows that it is primarily the outcome of frontocentral theta activity (attentional, memory aspects) and centroparietal delta activity (decision-making and response aspects) during oddball tasks. It has been suggested that decomposing target P3 into its simpler more specific time-frequency event-related oscillation (ERO) measures may provide more nuanced understanding of the neural endophenotypes that index genetic risk (Bachman & Bernat, 2018). Accordingly, EROs within the theta frequency band (4–7.5 Hz; 200–400 ms) during oddball tasks are mediated by fronto-limbic sources linked with earlier cognitive processes, such as conscious awareness, recognition memory, episodic retrieval, and frontal inhibitory control (Pandey et al., 2016). Previous work suggests that low-target/oddball theta power is observed in high-risk adolescent offspring of AUD individuals and shares genetic variance with problematic alcohol and substance use (Rangaswamy et al., 2007). Recent work has also shown that low FT prospectively predicts the development of adolescent alcohol misuse (Harper et al., 2021). Thus, both P3 amplitude and FT are important neural endophenotypes that have been linked to alcohol use problems.
