Neuroimaging findings suggest that these apparent interactions between age and gender arise due to age-related gender differences in brain maturational processes. Although pubertal development occurs earlier in females, the rates of certain neuromaturational processes during adolescence (notably dendritic pruning, myelination, and increases in corpus callosum size) appear to occur faster in males (De Bellis et al., 2001). Because P300 amplitude may be influenced by both sex steroids (Gould et al., 1990; Woolley et al., 1996) and the volumes of certain brain regions, including the corpus callosum (Alexander and Polich, 1995; Hoffman and Polich, 1999), comparatively early pubertal development in females, alongside comparatively faster rate of neuromaturational processes in males, may explain the noted interactions between age and gender in P300 amplitude. This hypothesis, however, can only be tested within a longitudinal design that spans the period from late childhood to early adulthood.
