| Summary: | Research has demonstrated that the human brain undergoes significant change in both structure and function during adolescence, but little is known about the role of puberty in this developmental process. The aim of this thesis is to investigate the relationship between puberty and brain development during adolescence. The first two chapters of this thesis summarise the current understanding of the behavioural and brain changes associated with both adolescence and puberty, and review the methods employed to assess puberty in research. Chapters 3 and 4 focus on the relationship between puberty and changes in brain structure. In Chapter 3, the influence of puberty on subcortical structural development is investigated in a large longitudinal MRI dataset, using a mixed effects modelling analysis method. Chapter 4 investigates the relationship between pubertal status, as measured by physical pubertal stage and levels of salivary sex steroid hormones, and white matter structural development in a cross-sectional sample of 12-16 year old boys, using diffusion tensor imaging. In Chapters 5-7, functional brain changes with puberty are explored. Chapters 5 and 6 focus on social emotion processing, where social emotions (e.g. embarrassment) are defined as emotions that require an awareness of other people’s mental states, while basic emotions (e.g. fear) are those which do not. In Chapter 5, the neural correlates of social and basic emotion processing are investigated in relation to pubertal status. In Chapter 6, the fMRI data are reanalysed using psycho-physiological interaction (PPI) analysis to investigate puberty-related changes in functional connectivity during the same task. Chapter 7 explores, in males, how developmental changes in brain function when performing a risk-taking task are related to puberty, independently of chronological age. Finally, in Chapter 8, the results of the empirical studies are summarised and the findings and implications of the thesis are discussed.
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