Improving Tools for the Analysis of Brain Based Measures of Infant Information Processing

While current methodological approaches to data-acquisition and -analysis used in ERP-studies have shown to be appropriate for adult populations, their applicability with infant populations is debatable. Many researchers agree that they are, in fact, unsuitable for infants. However, due to a lack of alternatives, traditional ways of data-collection and -analysis originally designed for adults are still used with developmental and clinical populations. The four studies reported in the current thesis propose novel approaches to methodological issues involved in infant ERP-studies. Limiting the number of artefact-free trials included in the average, Study 1 shows that fewer trials from earlier stages of a test-session can convey meaningful information and provide new insights into infant cognition. Additionally, it is shown that large amounts of usable data are often discarded in a traditional data-analysis. Study 2 aimed to provide a general overview on attrition in infant ERP-studies – which often seems to be accepted as a given among developmental psychologists – and to find underlying causes for attrition which may be based on study-design features that are common to all studies. The majority of investigated features did not impact attrition. Therefore, further factors outside the scope of the current consideration are responsible for an increase in attrition. Studies 3 and 4 built on the findings of the first two. Presenting infants with eight experimental conditions, Study 3 illustrates a novel approach to study-design which both yielded more data from individual participants and decreased attrition. Finally, using the data-analysis outlined in Study 1 on the data collected for Study 3, Study 4 both substantiates the claims made in Study 1 and provides further, previously unanticipated insights into infant cognition. These findings illustrate that more infant-suitable strategies for study-design and data-analysis are possible and that they can enhance our knowledge about infant cognitive processes

Impact of maternal depressive symptoms on the development of infant temperament: Cascading effects during the first year of life

Maternal depression is associated with a range of child development outcomes, including difficult temperament. This longitudinal study investigated whether depressive symptoms (DS) that mothers experience after childbirth predict infant negative affect (NA), as well as potential effects of infant NA on maternal DS, across the first year of life. In the study (N = 63), questionnaires (the Beck Depression Inventory Second Edition, and the Infant Behavior Questionnaire–Revised Very Short Form) were administered at 2 weeks, 4, 6, and 9 months after birth. Using path analysis, we tested five different models that could explain the relationship between maternal DS and infant NA. The best‐fitting model showed that the days immediately following childbirth represent an important time for the development of infant temperament as maternal mood significantly predicts infant NA for at least 4 months after birth. This does not constitute a single sensitive period; a new predictive effect emerges around 4 months of age, suggesting cascading influences of maternal DS across the first 6 months of life. These results suggest a need for support, should a mother experience DS, not only immediately after birth, but also throughout the early stages of parenting

Theta- and alpha-band EEG activity in response to eye gaze cues in early infancy

In order to elucidate the development of how infants use eye gaze as a referential cue, we investigated theta and alpha oscillations in response to object-directed and object-averted eye gaze in infants aged 2, 4, 5, and 9 months. At 2 months of age, no difference between conditions was found. In 4- and 9-month-olds, alpha-band activity desynchronized more in response to faces looking at objects compared to faces looking away from objects. Theta activity in 5-month-old infants differed between conditions with more theta synchronization for object-averted eye gaze. Whereas alpha desynchronization might reflect mechanisms of early social object learning, theta is proposed to imply activity in the executive attention network. The interplay between alpha and theta activity represents developmental changes in both kinds of processes during early infancy

How do bodies become special? Electrophysiological evidence for the emergence of body-related cortical processing in the first 14 months of life

There is general consensus that the representation of the human face becomes functionally specialized within the first few months of an infant's life. The literature is divided, however, on the question whether the specialized representation of the remainder of the human body form follows a similarly rapid trajectory or emerges more slowly and in line with domain-general learning mechanisms. Our study investigates visual event-related potentials (ERPs) in adults (P1 and N170) and infants (P1, N290, P400, and Nc) of 3 age groups (3.5, 10, and 14 months) to compare the emergence of face- and body-structural encoding. Our findings show that visual ERPs were absent (P1, N290, P400) or smaller (Nc) for bodies than for faces at 3.5 months. At older ages, P400 was smaller (10 months) and peaked later (14 months) for bodies than for faces. Effects of stimulus orientation were not reliably found until 14 months, where they were more broadly distributed for faces than for bodies. Inverted faces, but not bodies, produced an adult-like pattern for P400 at 14 months, emphasizing the role of P400 as the precursor of the adult N170. Importantly, our findings argue that structural encoding of the human body form emerges later in infancy and is qualitatively different from the structural encoding for faces. This is commensurate with infant motor development and the experience of viewing complete body shapes later than faces

Maternal depressive symptoms and infant temperament in the first year of life predict child behavior at 36 months of age

In a longitudinal study, mothers (N = 50) self-reported on their depressive symptoms (DS) and their child’s behavior during the first year and at 36 months postpartum. Maternal DS during infancy were associated with child conduct problems (CP), suggesting a long-term association between maternal mental health and the development of child behavior. Infant temperament was also associated with child behavior so that negative affect predicted child CP, while infant surgency was associated with later hyperactivity-inattention. This study contributes to the literature by jointly assessing the role of maternal DS and infant temperament and showing that these are independent predictors of childhood behavior

How do bodies become special? Electrophysiological evidence for the emergence of body-related cortical processing in the first 14 months of life.

There is general consensus that the representation of the human face becomes functionally specialized within the first few months of an infant’s life. The literature is divided, however, on the question whether the specialized representation of the remainder of the human body form follows a similarly rapid trajectory or emerges more slowly and in line with domain-general learning mechanisms. Our study investigates visual event-related potentials (ERPs) in adults (P1 and N170) and infants (P1, N290, P400, and Nc) of 3 age groups (3.5, 10, and 14 months) to compare the emergence of face- and body-structural encoding. Our findings show that visual ERPs were absent (P1, N290, P400) or smaller (Nc) for bodies than for faces at 3.5 months. At older ages, P400 was smaller (10 months) and peaked later (14 months) for bodies than for faces. Effects of stimulus orientation were not reliably found until 14 months, where they were more broadly distributed for faces than for bodies. Inverted faces, but not bodies, produced an adult-like pattern for P400 at 14 months, emphasizing the role of P400 as the precursor of the adult N170. Importantly, our findings argue that structural encoding of the human body form emerges later in infancy and is qualitatively different from the structural encoding for faces. This is commensurate with infant motor development and the experience of viewing complete body shapes later than faces

Recruitment of Language-, Emotion- and Speech-Timing Associated Brain Regions for Expressing Emotional Prosody: Investigation of Functional Neuroanatomy with fMRI

We aimed to progress understanding of prosodic emotion expression by establishing brain regions active when expressing specific emotions, those activated irrespective of the target emotion, and those whose activation intensity varied depending on individual performance. BOLD contrast data were acquired whilst participants spoke non-sense words in happy, angry or neutral tones, or performed jaw-movements. Emotion-specific analyses demonstrated that when expressing angry prosody, activated brain regions included the inferior frontal and superior temporal gyri, the insula, and the basal ganglia. When expressing happy prosody, the activated brain regions also included the superior temporal gyrus, insula, and basal ganglia, with additional activation in the anterior cingulate. Conjunction analysis confirmed that the superior temporal gyrus and basal ganglia were activated regardless of the specific emotion concerned. Nevertheless, disjunctive comparisons between the expression of angry and happy prosody established that anterior cingulate activity was significantly higher for angry prosody than for happy prosody production. Degree of inferior frontal gyrus activity correlated with the ability to express the target emotion through prosody. We conclude that expressing prosodic emotions (vs. neutral intonation) requires generic brain regions involved in comprehending numerous aspects of language, emotion-related processes such as experiencing emotions, and in the time-critical integration of speech information

Infant ERP amplitudes change over the course of an experimental session:implications for cognitive processes and methodology

Event-related Potentials (ERP) studies are a widely used methodology to investigate the early cognitive development in infants of all age ranges. We examined changes in amplitude contribution in a set of previously published data (see [4]) in relation to the Negative component as a function of number of trials contributing to each individual average and with time as a co-variate to that contribution. With only seven trials contributing to each individual's average the Nc for the object-directed condition was significantly more negative than the one for the averted-gaze condition, which is the opposite of the effect reported in Hoehl et al. [4]. The analysis including time as a co-variate revealed that the effect did not alter according to the amount of time taken during the experiment to collect each trial, suggesting that data of the quality needed to contribute to the ERP is itself a measure of time varying components of the experimental session. We conclude that infants initially allocate more attentional resources to object-directed gaze. This suggests that the temporal dynamics of infant ERP violates assumptions present in adult ERP, and that differences between conditions in relatively few trials inform us of cognitive capacities during infancy. (C) 2010 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved

A meta-analysis investigating factors underlying attrition rates in infant ERP studies

In this meta-analysis, we examined interrelationships between characteristics of infant event-related potential (ERP) studies and their attrition rates. One-hundred and forty-nine published studies provided information on 314 experimental groups of which 181 provided data on attrition. A random effects meta-analysis revealed a high average attrition rate of 49.2%. Additionally, we used meta-regression for 178 groups with attrition data to analyze which variables best explained attrition variance. Our main findings were that the nature of the stimuli-visual, auditory, or combined as well as if stimuli were animated-influenced exclusion rates from the final analysis and that infant age did not alter attrition rates