Infant neurobehavioral development as a product of iterative, transactional engagement with their familial and social contexts Restricted; Files Only
Ford, Aiden (Spring 2024)
Published
Abstract
Early infancy, representing the first six postnatal months, is a period in which remarkable learning drives dynamic change in developing brain and behavior. Many of the neurobehavioral processes that define early infancy are experience-dependent, such that differences in learning, behavior, or neurodevelopment that originate in this period may accrue over time into measurable divergence in later infancy and childhood. Though the foundational significance of these neurobehavioral processes is well-recognized, few studies have directly investigated the neural systems associated with adaptive social learning in early infancy.
This dissertation presents three empirical studies that investigated how changes in behaviors central to social interactions between infants and their caregivers, which are an essential milieu for early learning, were related to infant neurodevelopment. Importantly, these studies grounded infant development within the transactional model (Sameroff and Chandler, 1975), which conceptualizes infants’ earliest postnatal experiences as defined by bidirectional, cumulative interaction with their familial and social environments. Application of the transactional model situates the neurobehavioral development of an infant within their broader social contexts, rather than solely within the infant themselves.
In Study 1 and Study 2, complimentary experimental designs were used to demonstrate that the maturation of primary sensorimotor cortices was associated with attention to the eyes of others, i.e., a behavior for adaptive social action evolutionarily conserved between human infants and infant non-human primates. Study 3 mapped change in infant-directed caregiver behavior as an inroad to understanding how infants may elicit different opportunities for learning from social interaction as they get older. The effects of developmental and environmental factors known to influence infant learning, specifically later autism diagnosis (in Study 3) and family social status (in Study 2 and Study 3), were also investigated. All three studies implemented longitudinal data collection and nonparametric curve-fitting methods to characterize the dynamics of these neurobehavioral processes as they unfold during early infancy.
Table of Contents
Table of Contents
List of Figures and Tables
Chapter 1: Framing infant neurobehavioral development within the transactional model.. 1
1.1 What are the key mechanisms of social learning in early infancy and how do they change through infant development?........ 3
1.1.1 Infants create opportunities for their own learning.................................................... 5
1.1.2 Developmental change in mechanisms of infant social learning............................... 7
1.1.3 Contributions from this dissertation........................................................................... 9
1.2 What are the developing brain systems associated with these described mechanisms of infant social learning? ........10
1.2.1 Theories of experience-dependent cortical maturation and specialization.............. 12
1.2.2 Integrating theoretical frameworks to predict the neural systems associated with preferential attention to the eyes.....15
1.2.3 Methodological advancements for the study of brain-behavior associations.......... 16
1.2.4 Contributions from this dissertation......................................................................... 18
1.3 How is this co-development of brain and behavior influenced by systematic differences in infant familial and social environments?......18
1.3.1 The effects of SES on infant engagement within early learning environments....... 20
1.3.2 The effects of SES on infant brain development...................................................... 22
1.3.3 The effects of SES on the co-development of brain and behavior during infancy.. 24
1.3.4 Contributions from this dissertation......................................................................... 26
1.4 How may accumulated changes to processes of transactional engagement affect continued neurobehavioral development and contribute to emergent disability?...................................................................................................................... 26
1.4.1 The Bucharest Early Intervention Project as an example of changes to early caregiving ........ 27
1.4.2 Premature birth as an example of changes to infant development and ability......... 29
1.4.3 The application of a transactional framework to neurobehavioral development in autism....... 30
1.4.4 Contributions from this dissertation......................................................................... 33
1.5 Chapter introduction................................................................................................................ 34
Chapter 2: Maturation of motor corticofugal tracts predicts preferential attention to the eyes of others in early infancy .....38
Acknowledgment of Reproduction............................................................................................... 39
2.1 Abstract................................................................................................................................... 39
2.2 Introduction............................................................................................................................. 40
2.3 Results..................................................................................................................................... 46
2.4 Discussion............................................................................................................................... 61
2.5 Methods................................................................................................................................... 68
2.5.1 Participants............................................................................................................... 68
2.5.2 Diffusion Weighted Imaging protocol..................................................................... 70
2.5.3 Eye-tracking protocol............................................................................................... 74
2.5.4 Statistical methods.................................................................................................... 77
2.6 Citation Diversity Statement................................................................................................... 80
2.7 Acknowledgements and Funding............................................................................................ 81
Chapter 3: Functional maturation in visual pathways predicts attention to the eyes in infant rhesus macaques: Effects of social status 82
Acknowledgment of Reproduction............................................................................................... 83
3.1 Abstract................................................................................................................................... 84
3.2 Introduction............................................................................................................................. 85
3.3 Materials and methods............................................................................................................. 88
3.3.1 Subjects and housing................................................................................................ 88
3.3.2. Social status............................................................................................................. 91
3.3.3 Resting-state functional Magnetic Resonance Imaging (rs-fMRI).......................... 92
3.3.4 Eye-tracking procedures........................................................................................... 94
3.3.5 Statistical analyses.................................................................................................... 96
3.4 Results..................................................................................................................................... 98
3.4.1 Functional connectivity in the visual object pathway.............................................. 98
3.4.2 Developmental change in attention to the eyes...................................................... 102
3.4.3 Effect of social status on trajectories of attention to eyes...................................... 103
3.4.4 Exploratory brain-behavior associations................................................................ 105
3.5 Conclusions........................................................................................................................... 108
3.5.1 Connectivity along the visual object pathway........................................................ 109
3.5.2 Social attention to the eyes of conspecifics............................................................ 112
3.5.3 Accelerated trajectories of eye-looking are predicted by functional connectivity between the visual areas and social rank 113
3.5.4 Advantages of nonparametric curve-fitting approaches......................................... 116
3.6 Limitations............................................................................................................................. 117
3.7 Citation Diversity Statement................................................................................................. 118
3.8 Acknowledgements and Funding.......................................................................................... 119
Chapter 4: Caregiver greeting to infants under 6 months already reflects emerging differences in those later diagnosed with autism 120
Acknowledgment of Reproduction............................................................................................. 121
4.1 Abstract................................................................................................................................. 122
4.2 Introduction........................................................................................................................... 123
4.3 Materials and methods........................................................................................................... 127
4.4 Results................................................................................................................................... 137
4.4.1 Effect of infant age on probability of caregiver greeting in neurotypical dyads... 137
4.4.2 Effect of infant diagnostic outcome (neurotypical versus autism) on probability of caregiver greeting........ 137
4.4.3 Effect of caregiver characteristics on probability of caregiver greeting................ 138
4.4.4 Identification of possible mediating variables from between-group differences in sociodemographic measures........140
4.4.5 Effect of household income on probability of caregiver greeting.......................... 141
4.5 Discussion............................................................................................................................. 143
4.5.1 Limitations.............................................................................................................. 147
4.5.2 Citation Diversity Statement.................................................................................. 148
4.6 Acknowledgements and Funding.......................................................................................... 148
Chapter 5: Summary, significance, and future directions..................................................... 149
5.1 Thesis contributions.............................................................................................................. 150
5.2 Summary of Chapter 1.......................................................................................................... 151
5.3 Summary of Study 1, Chapter 2............................................................................................ 152
5.4 Summary of Study 2, Chapter 3............................................................................................ 153
5.5 Summary of Study 3, Chapter 4............................................................................................ 154
5.6 General discussion................................................................................................................. 155
5.7 Future directions.................................................................................................................... 162
5.7.1 What’s next for the neural and behavioral systems associated with infant eye-looking?........162
5.7.2 A new method for mapping iterative, transactional infant-caregiver interaction . 164
5.8 In conclusion......................................................................................................................... 165
Appendix A: Methods to map the dynamics of infant-caregiver interaction...................... 167
A.1 The need to develop data-driven, scalable approaches to study interactive behavior.......... 168
A.2 The powerful combination of DeepLabCut and MotionMapper.......................................... 169
A.3 Aims and hypotheses of this research line........................................................................... 170
A.4 Data collection and preparation for analysis........................................................................ 171
A.5 Applying DeepLabCut and MotionMapper to recordings of infant-caregiver interactions. 172
A.6 Between-group differences in infant-caregiver interactive behavior................................... 174
Appendix B: Supplemental Information for Chapter 2: Maturation of motor corticofugal tracts predicts preferential attention to the eyes of others in early infancy.......................................................................................................... 178
Appendix C: Supplemental Information for Chapter 3: Functional maturation in visual pathways predicts attention to the eyes in infant rhesus macaques: Effects of social status................................................................................ 185
Appendix D: Supplemental Information for Chapter 4: Caregiver greeting to infants under 6 months already reflects emerging differences in those later diagnosed with autism........................................................................................ 194
References.................................................................................................................................. 208
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