The hippocampus (HP) is a horseshoe shaped sheet of neurons located on the floor of each lateral ventricle within the temporal lobes and adjacent to the amygdala. As part of the limbic system, it is intimately involved in motivation and emotion, and it also plays a central role in the formation of memories (Burgess et al 2002). The HP consists of the complex interfolded layers of the dentate gyrus and cornus ammonis, which are continuous with the subiculum, which, in turn, merges with the parahipocampal gyrus. The anatomy of the HP is closely associated with subcortical structures that contribute to the hypothalamic-pituitary-adrenal axis (Kjelstrup et al 2002). A recent study also demonstrated that encoding of emotional memories depends on the HP in conjunction with the amygdala as well as their interaction with each other (Richardson et al 2004). Although the idea that the HP may play a role in brain mechanisms underlying anxiety is not new (McNaughton and Gray 2000; Deacon et al 2002), there is now mounting evidence that the ventral HP plays an important role in a brain
