Antisocial men appear to have reduced gray matter in the prefrontal cortex (Raine, Lencz, Bihrle, LaCasse, & Colletti, 2000), and it is unclear when this difference first manifests. Adolescence is a crucial period when the prefrontal cortex is thought to mature through the processes of targeted cell body loss, synaptic pruning, and increased axonal myelination of pathways connecting it to other brain structures (Lewis, 1997; Sowell et al., 2001; Spear, 2000). Normatively larger visual P300 might be seen at early ages because more neurons are recruited in the stimulus processing involved in the updating of memory, stimulus categorization, or inhibition of inappropriate responses required to perform a task like the one used in the present study. Fewer neurons may be required with increasing maturity because of greater refinement and efficiency of the cortical areas activated (e.g., Durston et al., 2006; Tamm, Menon, & Reiss, 2002). If P300 amplitude reflects genetic influences on the development of frontally influenced cognitive processes, a more restrictive limit on the degrees of freedom available for neuronal and synaptic pruning in vulnerable children could limit the
