From relatively obscure beginnings, oxytocin has emerged as a major biological marker of social and affiliative behavior in humans, with numerous randomized placebo-controlled trials of intranasal oxytocin demonstrating its effects in altering perception, emotion, and interpersonal functioning (as reviewed in Striepens et al., 2011
). Although oxytocin was originally thought to have universal effects on prosocial behavior, it is now evident that its effects are moderated by contextual factors and individual characteristics (Bartz et al., 2011b
). Surprisingly few studies, however, have examined factors which moderate the effect of oxytocin in mothers themselves, despite the primary role of oxytocin in maternal caregiving (Galbally et al., 2011
). This study examined the relationship between oxytocin response and a variety of state and trait measures in first-time mothers. We have demonstrated that maternal oxytocin response is significantly associated with adult temperament factors, including measures of orienting sensitivity and, most significantly, effortful control. No associations were found with other trait or state measures examined.
In the ATQ, “effortful control” refers to one’s propensity to focus on executing plans, performing tasks and maintaining focus and attention (Rothbart et al., 2000
). Although these characteristics may still be important in maternal caregiving, this factor scale was inversely associated with oxytocin response in first-time mothers. Other studies have shown that baseline oxytocin levels in mothers are positively correlated with mother–infant synchrony, but not with intrusiveness (i.e. maternal behavior that disregards infant cues or seeks to control infant behavior) (Atzil et al., 2011
). In non-mother populations, intranasally administered oxytocin results in greater emotional empathy (Hurlemann et al., 2010
), generosity (Zak et al., 2007
), social cooperation (De Dreu et al., 2010
), trust (Kosfeld et al., 2005
) and positive communication during conflict (Ditzen et al., 2009
). In our study, the negative correlation between Effortful Control and maternal oxytocin response appears to have been driven by the tendency to plan, schedule and act upon specific tasks, as measured by the Activation Control subscale, rather than to inhibit impulses (Inhibitory Control subscale) or focus one’s attention (Attentional Control subscale) ( and ). This suggests that new mothers who are more cognitively focused on task performance and executing plans may be less responsive to their infants’ affective cues.
In contrast, “orienting sensitivity” refers to one’s responsiveness to sensory cues, moods and emotions. During the stages of pregnancy, childbirth and breastfeeding, new mothers gradually learn to relinquish control of their external environment, while attending more to internal sensory cues from their own body (such as during labor and delivery), and then from their new infant (such as during breastfeeding). Maternal oxytocin response during interactive mother–infant play appears to be positively associated with this important capacity. Other studies have demonstrated that oxytocin, compared with placebo, enhances perception and processing of positive social cues (Unkelbach et al., 2008
), emotion recognition (Marsh et al., 2010
) and sensitivity to biological (but not non-biological) motion (Keri and Benedek, 2009
), although none of these studies specifically targeted mothers. However, as noted above, baseline oxytocin measures have been positively correlated with positive parent engagement (Feldman et al., 2011
), and maternal bonding behaviors, such as affectionate touch and infant-directed gaze and vocalization (Feldman et al., 2007
). Likewise, intranasally administered oxytocin results in an increase in fathers’ responsive behavior toward their children (Naber et al., 2010
In sum, mothers who showed an increased oxytocin response when interacting with their infant rated themselves as being more sensitive of moods, emotions and physical sensations, but less compulsive, schedule driven and task oriented.
Nevertheless, oxytocin is only one of several neuroendocrine systems – such as vasopressin, dopamine and prolactin – which may contribute to adaptive parenting behaviors (Swain et al., 2007
). Dopamine, for example, is a key neurotransmitter known to play an important role in maternal caregiving responses, as implicated in both human fMRI studies (Lorberbaum et al., 2002
; Strathearn et al., 2008
) and non-human animal models (Champagne et al., 2004
; Gammie et al., 2008
). In the brain, dopamine plays a role in reward signaling and reinforcement learning, and oxytocin appears to interact with the mesocorticolimbic dopamine system to reinforce maternal caregiving in response to infant cues (Shahrokh et al., 2010
; Strathearn, 2011
; Strathearn et al., 2009
). We have previously proposed that dopamine may be related to more “cognitive”, taskoriented aspects of parenting, such as decision-making and planning (similar to those characteristics measured by the Effortful Control factor scale). One model of adult attachment proposes that secure attachment is based on an integration of both affective (intensity-based) and cognitive (temporally-ordered) information processing in the brain (Crittenden and Landini, 2011
; Strathearn, 2007
). Optimal maternal caregiving responses may involve both
sensitive attunement to infant cues, via oxytocin-mediated mechanisms, and decision making and planning to meet the temporal needs of a family, as mediated by the nigrostriatal dopaminergic system (Strathearn, 2011
). Additional study is required to examine whether Effortful Control is positively associated with dopaminergic functioning in the brain.
One limitation of this research is that all of the state and trait measures were self-reported, and thus susceptible to reporting bias. Correlations and statistical associations do not necessarily represent causality, and the directionality of effects in this study is unknown. For example, although the ATQ, as a measure of temperament, is assumed to be stable across time with a genetic underpinning (Rothbart et al., 2000
), it is possible that lifetime patterns of oxytocin stimulation and reactivity may influence the development of these temperament characteristics, as seen in rodent models (Champagne and Meaney, 2001
). Although we considered oxytocin levels during the initial mother–infant separation to be “baseline,” it is possible that the change in oxytocin was due to the mother–infant separation rather than interaction.
Future studies should determine whether differences in adult temperament are associated with differences in maternal caregiving behavior. For example, is Effortful Control inversely associated with maternal sensitivity, and can temperament measures predict who will be more or less likely to respond to intranasally administered oxytocin, as a treatment for deficits in social functioning or maternal caregiving? The potential role of intranasal oxytocin in the treatment of disorders such as maternal neglect, post-partum depression and maternal addiction is currently being explored (Strathearn, 2011
; Strathearn and Mayes, 2010
; Striepens et al., 2011