“…Their research has linked these undefined aspects of maternal behavior to behavioral and neurological alterations in offspring development as well as to enduring, epigenetic changes in gene expression (e.g., Champagne, 2008;Champagne, Diorio, Sharma, & Meaney, 2001;Francis, Champagne, & Meaney, 2000;Liu, Diorio, Day, Francis, & Meaney, 2000;Liu et al, 1997;Meaney, 2010;Meaney & Szyf, 2005). In other studies of age-dependent odor learning in rats, stroking a pup's body with a soft brush is used to ''mimic'' maternal licking; this stimulation can lead to preferential approach toward a conditioned odor (Moriceau & Sullivan, 2005;Roth & Sullivan, 2006;Sullivan & Hall, 1988;Sullivan & Wilson, 1994;Woo & Leon, 1987). Such conditioned approach behavior is often interpreted as representing approach to the mother, reinforced by a simulation of maternal licking/grooming (e.g., Moriceau & Sullivan, 2005;Pedersen et al, 1982;Sullivan & Hall, 1988).…”