Psychiatry - August 2008 - (Page 31)

Lorberbaum and colleagues predicted that baby cries would selectively activate thalamus, cingulate, medial, and orbitofrontal cortex of parents. They first exposed mothers, who were less than 3.5 years postpartum, to blocks of 30 seconds of a standard baby cry versus white noise stimuli.23 In this small (n=4) study, they found increased activity in anterior cingulate and right medial prefrontal cortex. In the follow-up study,24 brain activity in breastfeeding first-time mothers (n=10) 4 to 8 weeks postpartum was measured while listening to standard baby cry compared with intensity and pattern matched white noise. In this more methodologically stringent study, with respect to subject selection and stimulus, all of the hypothesized regions as well as midbrain, hypothalamus, striatum, and septal regions—known to be important for rodent maternal behavior— were selectively more active in response to baby cry.10,11 It is interesting to consider whether parental neural responses to baby sounds would be different for mothers and fathers, whether parents are first-time or veteran, or at different times in the postpartum as the parent-infant relationship develops.26 Hypothesizing that gender and experience would affect the neural responses to baby cry and laughter, Seifritz and colleagues27 studied four groups: mothers and fathers of children under three years of age and nonparent men and women, with 10 subjects in each group. Using an event-related design, which measured localized brain responses to brief six-second events, it was found that over the entire sample, crying and laughing baby stimuli produced more activity in Heshyl’s gyrus (auditory cortex). Further, it was reported that women have a decrease in activity to both baby cry and laughter in the anterior cingulate to these brief signals, which was not present in men. This is contrary to other studies,23,24,26 which may mean that six-second stimuli have a different meaning to new parents compared to 30-second blocks. Finally, looking at parental status, Seifritz and colleagues27 reported that nonparents activated right amygdala with baby-laugh stimuli but parents did not; while with baby-cry stimuli, nonparents activated right amygdala but parents did not. These data represent the first steps into the study of gender and experiencedependant aspects of parental brain circuitry. With the transforming experience of having a baby and the tendency for parents to be highly preoccupied in the immediate postpartum,5,28,29 Swain and colleagues26 hypothesized that parental responses to baby cries might produce activations in certain brain regions that might change over the first several weeks postpartum. These regions may include the thalamus-cortical-basal ganglia circuits akin to those seen in humans relating to ritualistic behaviors, such as with obsessivecompulsive disorder,28,30 in addition to emotional alarm centers, including amygdala and insula. Using own baby-cry stimuli compared with other baby cry, Swain and colleagues26 reported regions of relative activation in a group of first-time mothers (n=9) at 2 to 4 weeks postpartum, which included midbrain, basal ganglia, cingulate, amygdala, and insula. Preliminary analysis of the parenting interview data showed that mothers were significantly more preoccupied than fathers, which may be reflected in the relative lack of activation for fathers in amygdala and basal ganglia.6 It is especially interesting that in the group of primiparous mothers, given the same stimuli at 3 to 4 months postpartum, amygdala and insular activations were not observed; instead, medial prefrontal cortical and hypothalamic activations31 were seen, perhaps reflecting a change in regional brain responses as the parent-infant relationship develops. It would be interesting to see how measures of parenting behaviors and parent-infant interaction might be reflected in these changing brain activations as parent-infant attachment develops. In a pilot study, Swain and colleagues32 found correlations between own versus other baby-cry brain activity, and measures of parental preoccupation in 14 first-time mothers at 2 to 4 weeks postpartum were in medial frontal cortex, basal ganglia, and hippocampus.32 This kind of correlation analysis promises to reveal parenting circuits that are important in responding to baby cry proportional to specific dimensions of the relationship. BABY VISUALS AND THE PARENT BRAIN In addition to baby-cry stimuli, several groups are using baby visual stimuli.26,33–35 Building on their neuroimaging of romantic love,36 which showed areas of activation in the insula, anterior cingulate, and basal ganglia when adults are shown pictures of romantic partners versus control pictures, they are more recently studying parental love. Hypothesizing that reward and emotion circuits, which are important for aspects of romantic love, might also be involved in maternal love, Bartels and Zeki33 exposed parents to photographs of own, familiar, and unfamiliar children (9 months to 6 years of age) to study parental brain circuits. They reported relative activations in anterior cingulate, insula, basal ganglia (striatum), and midbrain (periaqueductal gray). These regions may mediate the emotionally rewarding aspects of maternal behavior. Bartels and Zeki33 also reported decreases in activity in areas important for negative emotions, avoidance behavior, and social assessment. They suggest a push-pull mechanism for maternal behavior in which child stimuli activate [AUGUST] Psychiatry 2008 31

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Psychiatry - August 2008 Editor’s Message Editorial Advisory Board Contents Borderline Personality Disorder: Are Proliferative Symptoms Characteristic? Short-acting versus Long-acting Medications for the Treatment of ADHD Baby Stimuli and the Parent Brain: Functional Neuroimaging of the Neural Substrates of Parent-Infant Attachment These Boots Are Made for Stalking: Characteristics of Female Stalkers Managing Attention Deficit Hyperactivity Disorder in the Emergency Department Obstructive Sleep Apnea, Hypoxia, and Metabolic Syndrome in Psychiatric and Nonpsychiatric Settings Improving the Quality of Life in Patients with Alzheimer’s Disease The Process of Getting New Drugs to Market Journal Watch Classified Advertising Information for Authors

Psychiatry - August 2008

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