Katherine S. Young

Postnatal depression and its effects on child development: a review of evidence from low- and middle-income countries

INTRODUCTION OR BACKGROUND It is well established that postnatal depression (PND) is prevalent in high-income countries and is associated with negative personal, family and child developmental outcomes. SOURCES OF DATA Here, studies on the prevalence of maternal PND in low- and middle-income countries are reviewed and a geographical prevalence map is presented. The impact of PND upon child outcomes is also reviewed. AREAS OF AGREEMENT The available evidence suggests that rates of PND are substantial, and in many regions, are higher than those reported for high-income countries. An association between PND and adverse child developmental outcomes was identified in many of the countries examined. AREAS OF CONTROVERSY Significant heterogeneity in prevalence rates and impact on child outcomes across studies means that the true extent of the disease burden is still unclear. AREAS TIMELY FOR DEVELOPING RESEARCH Nonetheless, there is a compelling case for the implementation of interventions to reduce the impact of PND on the quality of the mother-infant relationship and improve child outcomes.

The Motivational Salience of Infant Faces Is Similar for Men and Women

Infant facial features are thought to be powerful elicitors of caregiving behaviour. It has been widely assumed that men and women respond in different ways to those features, such as a large forehead and eyes and round protruding cheeks, colloquially described as ‘cute’. We investigated experimentally potential differences using measures of both conscious appraisal (‘liking’) and behavioural responsivity (‘wanting’) to real world infant and adult faces in 71 non-parents. Overall, women gave significantly higher ‘liking’ ratings for infant faces (but not adult faces) compared to men. However, this difference was not seen in the ‘wanting’ task, where we measured the willingness of men and women to key-press to increase or decrease viewing duration of an infant face. Further analysis of sensitivity to cuteness, categorising infants by degree of infantile features, revealed that both men and women showed a graded significant increase in both positive attractiveness ratings and viewing times to the ‘cutest’ infants. We suggest that infant faces may have similar motivational salience to men and women, despite gender idiosyncrasies in their conscious appraisal.

The functional neuroanatomy of the evolving parent-infant relationship.

Infant survival and the development of secure and cooperative relationships are central to the future of the species. In humans, this relies heavily on the evolving early parent-infant social and affective relationship. While much is known about the behavioural and psychological components of this relationship, relatively little is known about the underlying functional neuroanatomy. Affective and social neuroscience has helped to describe the main adult brain networks involved, but has so far engaged very little with developmental findings. In this review, we seek to highlight future avenues for research by providing a coherent framework for describing the parent-infant relationship over the first 18 months. We provide an outline of the evolving nature of the relationship, starting with basic orienting and recognition processes, and culminating in the infants attainment of higher socio-emotional and cognitive capacities. Key social and affective interactions, such as communication, cooperative play and the establishment of specific attachments propel the development of the parent-infant relationship. We summarise our current knowledge of the developing infant brain in terms of structure and function, and how these relate to the emergent abilities necessary for the formation of a secure and cooperative relationship with parents or other caregivers. Important roles have been found for brain regions including the orbitofrontal, cingulate, and insular cortices in parent-infant interactions, but it has become clear that much more information is needed about the developmental time course and connectivity of these regions.

Understanding the human parental brain: A critical role of the orbitofrontal cortex

The bond between a parent and an infant often appears to form effortlessly and intuitively, and this relationship is fundamental to infant survival and development. Parenting is considered to depend on specific brain networks that are largely conserved across species and in place even before parenthood. Efforts to understand the neural basis of parenting in humans have focused on the overlapping networks implicated in reward and social cognition, within which the orbitofrontal cortex (OFC) is considered to be a crucial hub. This review examines emerging evidence that the OFC may be engaged in several phases of parent–infant interactions, from early, privileged orienting to infant cues, to ongoing monitoring of interactions and subsequent learning. Specifically, we review evidence suggesting that the OFC rapidly responds to a range of infant communicative cues, such as faces and voices, supporting their efficient processing. Crucially, this early orienting response may be fundamental in supporting adults to respond rapidly and appropriately to infant needs. We suggest a number of avenues for future research, including investigating neural activity in disrupted parenting, exploring multimodal cues, and consideration of neuroendocrine involvement in responsivity to infant cues. An increased understanding of the brain basis of caregiving will provide insight into our greatest challenge: parenting our young.

Minor structural abnormalities in the infant face disrupt neural processing: a unique window into early caregiving responses.

Infant faces elicit early, specific activity in the orbitofrontal cortex (OFC), a key cortical region for reward and affective processing. A test of the causal relationship between infant facial configuration and OFC activity is provided by naturally occurring disruptions to the face structure. One such disruption is cleft lip, a small change to one facial feature, shown to disrupt parenting. Using magnetoencephalography, we investigated neural responses to infant faces with cleft lip compared with typical infant and adult faces. We found activity in the right OFC at 140 ms in response to typical infant faces but diminished activity to infant faces with cleft lip or adult faces. Activity in the right fusiform face area was of similar magnitude for typical adult and infant faces but was significantly lower for infant faces with cleft lip. This is the first evidence that a minor change to the infant face can disrupt neural activity potentially implicated in caregiving.

Listening to infant distress vocalizations enhances effortful motor performance

There are few sounds that carry as much biological clout as the cries of a distressed infant. Consider a crying infant on a plane: the sound is as unpleasant as it is difficult to ignore, even amongst a host of other environmental noises. A distressed infant’s cry, characterized by high and variable pitch, elicits autonomic arousal in the listener as measured by heart rate, blood pressure, skin conductance [for review, see (1,2)] or hand grip force (3). The physiological arousal seen in response to infant cries may reflect a ‘high-alert’ state which prepares an adult to react rapidly to the infant’s distress (4). We examined whether the reported physiological change in response to infant cries translates into measurable differences in adults’ ability to move in a concerted and accurate manner. To this end, we played a series of infant cries and other sounds to a group of adults and measured subsequent performance on an effortful motor speed and dexterity task, in the form of a miniature version of the classic arcade game, ‘Whack-a-mole’. This game is brief but engaging and requires participants to press down on a target button (indicated by a light), with a predetermined amount of force, in order to score points. Within the same individuals, we compared performance on this task after listening to infant distress vocalizations, adult distress vocalizations and nondistressed, but high-pitched bird vocalizations. An individual’s overall score on the task reflected their success in pressing target buttons quickly enough and with sufficient force. An additional, subtle measure of change in performance was obtained in the form of effort exerted by participants, by measuring the pressure applied to target buttons during the game. Similar measures such as hand-grip force in humans (5) or lever pressing in animal models have been taken as an index of behavioural activation or motivation to act (6). Forty adults (20 men), ranging in age from 19 to 59 years took part (M = 26.5, SD = 8.2). Three participants were parents, but none had young children. All participants had normal hearing and normal vision or vision corrected to normal. The task, a small-scale version of ‘Whack-a-mole’ (Fig. 1A, ‘Whack it’, USB version), requires participants to press one of nine buttons, whose location varies randomly across the game. As the game progresses, the speed of change in location of the target button increases. The game was mounted on top of electronic scales (Salter 1036 BKDR), which were used to gauge the amount of effort participants exerted to push the buttons by measuring peak weight (in grams; minimum, maximum and average weights were recorded by videotaping the scales for the duration of the experiment). The amount of effort participants needed to apply to a target button in order to score was measured on the scales as approximately 350 g. After playing three 30 sec practice rounds, each participant listened to 4.5 min of one of the sound categories and then immediately replayed the game for 60 sec. This was repeated for each of the sound categories, with the order in which participants heard each sound category counterbalanced across participants. Each sound category consisted of 15 sounds, clipped to 1500 msec, free from background noise and matched to have linear rise and fall times of 150 msec and comparable average root mean square intensity. The sounds were presented at 70 dBFS above each participant’s absolute hearing threshold using Sony In-Ear earphones (MDR-EX77LP). The three categories of sound Acta Paediatrica ISSN 0803–5253

MEG Can Map Short and Long-Term Changes in Brain Activity following Deep Brain Stimulation for Chronic Pain

Deep brain stimulation (DBS) has been shown to be clinically effective for some forms of treatment-resistant chronic pain, but the precise mechanisms of action are not well understood. Here, we present an analysis of magnetoencephalography (MEG) data from a patient with whole-body chronic pain, in order to investigate changes in neural activity induced by DBS for pain relief over both short- and long-term. This patient is one of the few cases treated using DBS of the anterior cingulate cortex (ACC). We demonstrate that a novel method, null-beamforming, can be used to localise accurately brain activity despite the artefacts caused by the presence of DBS electrodes and stimulus pulses. The accuracy of our source localisation was verified by correlating the predicted DBS electrode positions with their actual positions. Using this beamforming method, we examined changes in whole-brain activity comparing pain relief achieved with deep brain stimulation (DBS ON) and compared with pain experienced with no stimulation (DBS OFF). We found significant changes in activity in pain-related regions including the pre-supplementary motor area, brainstem (periaqueductal gray) and dissociable parts of caudal and rostral ACC. In particular, when the patient reported experiencing pain, there was increased activity in different regions of ACC compared to when he experienced pain relief. We were also able to demonstrate long-term functional brain changes as a result of continuous DBS over one year, leading to specific changes in the activity in dissociable regions of caudal and rostral ACC. These results broaden our understanding of the underlying mechanisms of DBS in the human brain.

Interpreting infant vocal distress: the ameliorative effect of musical training in depression.

An infants cry is one of the most emotionally salient sounds in our environment. Depression is known to disrupt a mothers ability to respond to her infant, but it is not well-understood why such difficulties arise. One reason might be that depression disrupts the perceptual abilities necessary to interpret infants affective cues. Given that musicians are known to have enhanced auditory perception, we assessed whether depression and previous musical training can impact on the ability to interpret distress in infant cries, as manipulated by changes in pitch. Depressed participants with musical training demonstrated better discriminative acuity of distress in infant cry bursts compared to those without. Non-depressed participants, with and without musical training, had levels comparable to musicians with depression. We suggest that previous musical training may act as a protective factor that maintains auditory perceptual abilities in the context of depression. These findings have potential implications for the development of novel training interventions to maintain sensitivity to infant vocal cues in individuals with postnatal depression.

Motion and emotion: depression reduces psychomotor performance and alters affective movements in caregiving interactions.

Background: Impaired social functioning is a well-established feature of depression. Evidence to date suggests that disrupted processing of emotional cues may constitute part of this impairment. Beyond processing of emotional cues, fluent social interactions require that people physically move in synchronized, contingent ways. Disruptions to physical movements are a diagnostic feature of depression (psychomotor disturbance) but have not previously been assessed in the context of social functioning. Here we investigated the impact of psychomotor disturbance in depression on physical responsive behavior in both an experimental and observational setting. Methods: In Experiment 1, we examined motor disturbance in depression in response to salient emotional sounds, using a laboratory-based effortful motor task. In Experiment 2, we explored whether psychomotor disturbance was apparent in real-life social interactions. Using mother-infant interactions as a model affective social situation, we compared physical behaviors of mothers with and without postnatal depression (PND). Results: We found impairments in precise, controlled psychomotor performance in adults with depression relative to healthy adults (Experiment 1). Despite this disruption, all adults showed enhanced performance following exposure to highly salient emotional cues (infant cries). Examining real-life interactions, we found differences in physical movements, namely reduced affective touching, in mothers with PND responding to their infants, compared to healthy mothers (Experiment 2). Conclusions: Together, these findings suggest that psychomotor disturbance may be an important feature of depression that can impair social functioning. Future work investigating whether improvements in physical movement in depression could have a positive impact on social interactions would be of much interest.

Introducing the Oxford Vocal (OxVoc) Sounds database: a validated set of non-acted affective sounds from human infants, adults, and domestic animals

Sound moves us. Nowhere is this more apparent than in our responses to genuine emotional vocalizations, be they heartfelt distress cries or raucous laughter. Here, we present perceptual ratings and a description of a freely available, large database of natural affective vocal sounds from human infants, adults and domestic animals, the Oxford Vocal (OxVoc) Sounds database. This database consists of 173 non-verbal sounds expressing a range of happy, sad, and neutral emotional states. Ratings are presented for the sounds on a range of dimensions from a number of independent participant samples. Perceptions related to valence, including distress, vocalizer mood, and listener mood are presented in Study 1. Perceptions of the arousal of the sound, listener motivation to respond and valence (positive, negative) are presented in Study 2. Perceptions of the emotional content of the stimuli in both Study 1 and 2 were consistent with the predefined categories (e.g., laugh stimuli perceived as positive). While the adult vocalizations received more extreme valence ratings, rated motivation to respond to the sounds was highest for the infant sounds. The major advantages of this database are the inclusion of vocalizations from naturalistic situations, which represent genuine expressions of emotion, and the inclusion of vocalizations from animals and infants, providing comparison stimuli for use in cross-species and developmental studies. The associated website provides a detailed description of the physical properties of each sound stimulus along with cross-category descriptions.