Oxytocin and brain responses to infant crying

Studies indicate that mothers who abuse or neglect their infants show increased
physiological responses to sounds of infant crying. Increased physiological
responses to infant crying may involve brain mechanisms of emotion
amplification and dampening. Oxytocin appears to modulate the responsiveness
and balance of these brain mechanisms to stimuli such as baby crying. We aim at
gaining more insight in basic mechanisms that may be involved in child
maltreatment by studying effects of nasal oxytocin administration on brain
responses to infant crying sounds in healthy women.

The proposed study has two objectives. First, we will examine the neural
mechanisms of aversive responding to infant cries in healthy female subjects.
We will compare participants who showed high cardiovascular responses to infant
cries with participants who showed low cardiovascular responses, selected from
a larger group of subjects in which such responses have already been
determined. Second, the modulation of this neural mechanism by nasal
administration of oxytocin will be tested.

Out of a group of 400 participants already involved in an ongoing study, 20
participants will be selected who in previous testing showed the largest
cardiovascular (heart rate) responses to infant cries, and 20 participants who
showed the lowest cardiovascular responses to infant cries. From each group
half of the subjects will be randomly assigned to a condition in which they
will be administered placebo, the other half of the subjects will be assigned
to a condition in which they will be administered oxytocin. Assignment to
condition will be counterbalanced according to cardiovascular responses.

The subjects will take 6 puffs of nasal spray containing 4 IU/ puff of oxytocin
(Syntocinon, Novartis), or 6 puffs of a placebo-spray (NaCl solution).

At the beginning of the session the subject will take 6 puffs of nasal spray,
containing either oxytocin or a placebo. Intranasal oxytocin is widely
prescribed in lactating women and is well tolerated. High doses (> 60 IU) of
oxytocin nasal spray may in some cases lead to headache. Based on the single
doses of 24 IU (i.e. 6 puffs, each containing 4 IU of oxytocin) that will be
used in this study and the effects of oxytocin nasal spray in general, there
will be low risk for the participants in this study.
There are no known risks associated with participating in an fMRI study. This
is a noninvasive technique involving no catheterizations or introduction of
exogenous tracers. Numerous children and adults have undergone magnetic
resonance studies without apparent harmful consequences. Some people become
claustrophobic while inside the magnet and in these cases the study will be
terminated immediately at the subject's request. The only absolute
contraindications to MRI studies are the presence of intracranial or
intraocular metal, or a pacemaker. Relative contraindications include pregnancy
and claustrophobia. Subjects who may be pregnant, who may have metallic foreign
bodies in the eyes or head, or who have cardiac pacemakers will be excluded
because of potential contraindications of MRI in such subjects. Although there
is no direct benefit to the specific participants from this proposed research,
there are greater benefits to society from the potential knowledge gained from
this study for the targeted and effective prevention of child abuse and neglect
which has been shown to be present in 30 per 1000 Dutch children in 2005.