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158 EFFECTS OF EARLY MALTREATMENT AND STRESSdopamine in the mPFC and is the primary form of dopamine clearance in the mPFC(Matsumoto et al., 2003). COMT is highly expressed in the mPFC (Matsumotoet al., 2003), and COMT knockout mice show increases in mPFC dopamine concentrations(Gogos et al., 1998). COMT levels are significantly increased in themPFC in adult offspring of High compared with Low LG-ABN mothers (Zhanget al., 2005), a difference that may contribute to the different cortical dopamineresponse to stress. However, this effect alone cannot explain the difference in stressinducedmPFC dopamine levels because the alteration in COMT expression unlikethat for the dopamine stress response is apparent in both hemispheres.Environmental Regulation of Maternal BehaviorThe argument presented here is that environmental influences shape the developmentof defensive responses in early life, and that these environmental effects aremediated by variations in parental investment. If parental care is to serve as themediator for the effects of environmental adversity on development, then theremust be a predictable relation between the quality of the environment and parentalcare. There is considerable evidence for a relationship between environmentaladversity and parental care in humans (Fleming, 1999; Repetti et al., 2002). Suchstudies are, of course, correlational. Perhaps the most compelling evidence for adirect effect of environmental adversity on parent-infant interactions emerges fromthe studies of Rosenblum, Coplan, and colleagues with nonhuman primates(Coplan et al., 1996, 1998; Rosenblum & Andrews, 1994). Bonnet macaquemother-infant dyads were maintained under one of three foraging conditions: LowForaging Demand (LFD), in which food was readily available, High ForagingDemand (HFD), in which ample food was available but required long periods ofsearching, and Variable Foraging Demand (VFD), a mixture of the two conditionson a schedule that did not allow for predictability. At the time that theseconditions were imposed, there were no differences in the nature of motherinfantinteractions. However, following a number of months of these conditions,there were highly significant differences in mother-infant interactions. The VFDcondition was clearly the most disruptive. Mother-infant conflict increased in theVFD condition. Infants of mothers housed under these conditions were significantlymore timid and fearful. These infants showed signs of depression commonlyobserved in maternally separated macaque infants. Remarkably these reactionsare apparent even when the infants are in contact with their mothers. As adolescents,the infants reared in the VFD conditions are more fearful, submissive, andshowed less social play behavior.More recent studies demonstrate the effects of these conditions on the developmentof neural systems that mediate behavioral and endocrine response to stress.As adults, monkeys reared under VFD conditions showed increased CSF levelsof CRF (Coplan et al., 1996, 1998). Increased central CRF drive would suggestaltered noradrenergic and serotonergic responses to stress, and this is exactly what