of white matter, particularly in circuits that link the striatum and limbic regions with the frontal lobe (19,20,22). In contrast, although declines in cortical gray matter as well as cortical thickness are also observed, these changes are maximal early in adolescence with much more subtle changes thereafter. Thus, we hypothesized that if alcohol functions as a neurotoxin when ingested in small to moderate quantities during middle-to-later adolescence, its effects might be more readily observed in relation to indices of white matter extent and organization versus gray matter volumes or cortical thickness, because developmental changes in the latter tissue types have largely stabilized prior to use onset.
