The hippocampus is vulnerable to the effects of ethanol, particularly during adolescence (Medina et al., 2007b; Nagel et al., 2005). Running dorsally to the hippocampus are the fornix and stria terminalis, both compact limbic projections terminating at hippocampal and amygdala regions, respectively (Wakana et al., 2004). Since these fibers are tightly packed together, it is difficult to ascertain whether the decreased FA observed in this area indicates altered white matter integrity to the fibers making up the fornix, terminal stria, or both. As adolescents with alcohol use disorders have demonstrated impairments in learning and memory (Tapert et al., 2002), diminished FA in the fibers extending to the hippocampus may suggest changes in structural connectedness leading to functional aberrations in teenage drinkers. Multimodal neuroimaging studies will help solidify the nature of white matter connectivity between these regions (e.g., frontal lobe, thalamus, pons, cerebellum, insula, hippocampus, and amygdala), and elucidate the influence of heavy drinking on these networks.
