Decomposing P300 to identify its genetic basis

In this commentary, I explore reasons why it has been difficult to associate P300 amplitude with a gene or a single nucleotide polymorphism (SNP). I suggest we decompose P300 into the factors that contribute to it to get better traction on its genetic basis. Specifically, I note that we can improve the measurement of P300 to remove state-dependent contributions by including more than one measurement occasion; we can identify and extract the neural components contributing to P300 amplitude by estimating EEG power in specific bands of the P300; we can adjust P300 for single-trial variability; we can extract single-trial variability; and we can refine the tasks to isolate the separate psychological processes that P300 reflects. In the end, each of these factors that contribute to the conglomerate P300 may be a separate endophenotype mapping onto a separate SNP or gene.