Marijke A. K. A Braeken

Detecting violations of temporal regularities in waking and sleeping two-month-old infants

Correctly processing rapid sequences of sounds is essential for developmental milestones, such as language acquisition. We investigated the sensitivity of two-month-old infants to violations of a temporal regularity, by recording event-related brain potentials (ERPs) in an auditory oddball paradigm from 36 waking and 40 sleeping infants. Standard tones were presented at a regular 300 ms inter-stimulus interval (ISI). One deviant, otherwise identical to the standard, was preceded by a 100 ms ISI. Two other deviants, presented with the standard ISI, differed from the standard in their spectral makeup. We found significant differences between ERP responses elicited by the standard and each of the deviant sounds. The results suggest that the ability to extract both temporal and spectral regularities from a sound sequence is already functional within the first few months of life. The scalp distribution of all three deviant-stimulus responses was influenced by the infants state of alertness.

Pregnant mothers with resolved anxiety disorders and their offspring have reduced heart rate variability: implications for the health of children.

Objective Active anxiety disorders have lasting detrimental effects on pregnant mothers and their offspring but it is unknown if historical, non-active, maternal anxiety disorders have similar effects. Anxiety-related conditions, such as reduced autonomic cardiac control, indicated by reduced heart rate variability (HRV) could persist despite disorder resolution, with long-term health implications for mothers and children. The objective in this study is to test the hypotheses that pregnant mothers with a history of, but not current anxiety and their children have low HRV, predicting anxiety-like offspring temperaments. Methods The participants in this case-control study consist of 56 women during their first trimester and their offspring (15 male, 29 female). Women had a history of an anxiety disorder (n=22) or no psychopathology (n=34) determined using the Mini-International Neuropsychiatric Interview. The main outcome measures were indices of autonomic cardiac control including root mean square of successive differences (RMSSD) and high frequency (HF) variability. Children’s fearfulness was also assessed using the Laboratory Temperament Assessment Battery (Lab-TAB)-Locomotor Version. Results HRV was lower in women and children in the past anxiety group compared to controls. HRV measures for mothers and children were positively correlated in the anxiety group only. In all children, low HRV measures at 2-4 months were associated with a higher chance of fearful behavior at 9-10 months. Conclusions Pregnant women with previous but not current anxiety and their children have low HRV. Children with low HRV tend to show more fearfulness. These findings have implications for identifying children at risk of anxiety disorders and point to possible underlying mechanisms of child psychopathology.

Multimodal processing of emotional information in 9-month-old infants II: Prenatal exposure to maternal anxiety

The ability to read emotional expressions from human face and voice is an important skill in our day-to-day interactions with others. How this ability develops may be influenced by atypical experiences early in life. Here, we investigated multimodal processing of fearful and happy face/voice pairs in 9-month-olds prenatally exposed to maternal anxiety, using event-related potentials (ERPs). Infants were presented with emotional vocalisations (happy/fearful) preceded by emotional facial expressions (happy/fearful). The results revealed larger P350 amplitudes in response to fearful vocalisations when infants had been exposed to higher levels of anxiety, regardless of the type of visual prime, which may indicate increased attention to fearful vocalisations. A trend for a positive association between P150 amplitudes and maternal anxiety scores during pregnancy may suggest these infants are more easily aroused by and extract features more thoroughly from fearful vocalisations as well. These findings are compatible with the hypothesis that prenatal exposure to maternal anxiety is related to more extensive processing of fear-related stimuli.

Multimodal processing of emotional information in 9-month-old infants I: emotional faces and voices

Making sense of emotions manifesting in human voice is an important social skill which is influenced by emotions in other modalities, such as that of the corresponding face. Although processing emotional information from voices and faces simultaneously has been studied in adults, little is known about the neural mechanisms underlying the development of this ability in infancy. Here we investigated multimodal processing of fearful and happy face/voice pairs using event-related potential (ERP) measures in a group of 84 9-month-olds. Infants were presented with emotional vocalisations (fearful/happy) preceded by the same or a different facial expression (fearful/happy). The ERP data revealed that the processing of emotional information appearing in human voice was modulated by the emotional expression appearing on the corresponding face: Infants responded with larger auditory ERPs after fearful compared to happy facial primes. This finding suggests that infants dedicate more processing capacities to potentially threatening than to non-threatening stimuli.

Differences between human auditory event-related potentials (AERPs) measured at 2 and 4 months after birth

Infant auditory event-related potentials (AERPs) show a series of marked changes during the first year of life. These AERP changes indicate important advances in early development. The current study examined AERP differences between 2- and 4-month-old infants. An auditory oddball paradigm was delivered to infants with a frequent repetitive tone and three rare auditory events. The three rare events included a shorter than the regular inter-stimulus interval (ISI-deviant), white noise segments, and environmental sounds. The results suggest that the N250 infantile AERP component emerges during this period in response to white noise but not to environmental sounds, possibly indicating a developmental step towards separating acoustic deviance from contextual novelty. The scalp distribution of the AERP response to both the white noise and the environmental sounds shifted towards frontal areas and AERP peak latencies were overall lower in infants at 4 than at 2 months of age. These observations indicate improvements in the speed of sound processing and maturation of the frontal attentional network in infants during this period.