“…Maternal separation alters the HPA axis, with reports of either hypersensitivity marked by elevated basal and stress-induced blood corticosterone measured later in life (Higley et al, 1991;Plotsky and Meaney, 1993;Vazquez et al, 2005a) or hyposensitivity marked by lower basal and stress-induced blood corticosterone levels (Greisen et al, 2005;Kim et al, 2005;Roman et al, 2006); however, these latter studies assayed blood after testing animals in different behavioral tasks such as the elevated plus maze. Despite these discrepant findings, prolonged maternal separation blunts the negative feedback of glucocorticoids on the HPA axis (Ladd et al, 2004) and produces a constellation of behavioral changes reflecting increased anxiety and depressive symptoms Faturi et al, 2010). Even more subtle early life stress, such as being reared by a mother who engages in low levels of licking and grooming her offspring, engenders hypersensitivity and slower negative feedback of the HPA axis (Liu et al, 1997), thus attesting to the long-lasting influence of early life mother-infant interactions.…”