Registration-free analysis of diffusion MRI tractography data across subjects through the human lifespan.

Diffusion MRI tractography produces massive sets of streamlines that need to be clustered into anatomically meaningful white-matter bundles. Conventional clustering techniques group streamlines based on their proximity in Euclidean space. We have developed AnatomiCuts, an unsupervised method for clustering tractography streamlines based on their neighboring anatomical structures, rather than their coordinates in Euclidean space. In this work, we show that the anatomical similarity metric used in AnatomiCuts can be extended to find corresponding clusters across subjects and across hemispheres, without inter-subject or inter-hemispheric registration. Our proposed approach enables group-wise tract cluster analysis, as well as studies of hemispheric asymmetry. We evaluate our approach on data from the pilot MGH-Harvard-USC Lifespan Human Connectome project, showing improved correspondence in tract clusters across 184 subjects aged 8-90. Our method shows up to 38% improvement in the overlap of corresponding clusters when comparing subjects with large age differences. The techniques presented here do not require registration to a template and can thus be applied to populations with large inter-subject variability, e.g., due to brain development, aging, or neurological disorders.

Charting the expansion of strategic exploratory behavior during adolescence.

Although models of exploratory decision making implicate a suite of strategies that guide the pursuit of information, the developmental emergence of these strategies remains poorly understood. This study takes an interdisciplinary perspective, merging computational decision making and developmental approaches to characterize age-related shifts in exploratory strategy from adolescence to young adulthood. Participants were 149 12-28-year-olds who completed a computational explore-exploit paradigm that manipulated reward value, information value, and decision horizon (i.e., the utility that information holds for future choices). Strategic directed exploration, defined as information seeking selective for long time horizons, emerged during adolescence and maintained its level through early adulthood. This age difference was partially driven by adolescents valuing immediate reward over new information. Strategic random exploration, defined as stochastic choice behavior selective for long time horizons, was invoked at comparable levels over the age range, and predicted individual differences in attitudes toward risk taking in daily life within the adolescent portion of the sample. Collectively, these findings reveal an expansion of the diversity of strategic exploration over development, implicate distinct mechanisms for directed and random exploratory strategies, and suggest novel mechanisms for adolescent-typical shifts in decision making. (PsycINFO Database Record

What develops during emotional development? A component process approach to identifying sources of psychopathology risk in adolescence.

Adolescence is a phase of the lifespan associated with widespread changes in emotional behavior thought to reflect both changing environments and stressors, and psychological and neurobiological development. However, emotions themselves are complex phenomena that are composed of multiple subprocesses. In this paper, we argue that examining emotional development from a process-level perspective facilitates important insights into the mechanisms that underlie adolescents' shifting emotions and intensified risk for psychopathology. Contrasting the developmental progressions for the antecedents to emotion, physiological reactivity to emotion, emotional regulation capacity, and motivation to experience particular affective states reveals complex trajectories that intersect in a unique way during adolescence. We consider the implications of these intersecting trajectories for negative outcomes such as psychopathology, as well as positive outcomes for adolescent social bonds.

La adolescencia es una fase de la vida que se asocia con cambios generalizados en la conducta emotional, lo que se piensa refleja tanto cambios ambientales y de estresores, como desarrollo psicológico y neurobiológico. Sin embargo, las emocíones en sí mismas son fenómenos complejos que están compuestos por múltiples subprocesos. En este artículo se postula que el examen del desarrollo emocional desde una perspectiva a nivel de procesos facilita importantes conocimientos acerca de los mecanismos que subyacen a las emocíones cambiantes de los adolescentes y al aumento del riesgo de psicopatología. En contraste con el progreso del desarrollo, los antecedentes de la emoción, la reactividad fisiológica a la emoción, la capacidad de regulación emocíonal y la motivacíon para experimentar determinados estados afectivos revelan complejas trayectorias que se intersectan de manera singular durante la adolescencia. Se consideran las implicancias de estas intersecciones, tanto en términos de consecuencias negativas como la psicopatología, así como de resultados positives para los vínculos sociales de los adolescentes.

L'adolescence est un moment de la vie associé à des changements amples du comportement émotionnel, supposés refléter des modifications de l'environnement et des facteurs de stress ainsi que le développement psychologique et neurobiologique. Les émotions elles-mêmes sont cependant des phénomènes complexes composés de sous-processus multiples. Dans cet article, nous pensons que l'examen du développement émotionnel par niveau du processus permet d'avoir une meilleure idée des mécanismes sous-tendant les changements d'émotion des adolescents et intensifiant le risque d'apparition d'une psychopathologie. Opposer les progressions du développement pour les antécédents émotionnels, la réactivité physiologique à l'émotion, la capacité de régulation émotionnelle et la motivation à expérimenter des états affectifs particuliers révèle des trajectoires complexes qui se croisent de façon unique à l'adolescence. Nous analysons les implications de ces trajectoires croisées pour des résultats négatifs comme une psychopathologie, ainsi que pour des résultats positifs comme les liens sociaux à l'adolescence.