Developmental psychobiology
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We developed a novel animal model of early life experiences in which rat pups are trained during postnatal days (PND) 10-13 in a T-maze with maternal contact as a reward (RER group) or its denial (DER group) as a mildly aversive event. Both groups of animals learn the T-maze, albeit the RER do so more efficiently. Training results in activation of the basal ganglia in the RER and of the hippocampus and prefrontal cortex in the DER. ⋯ Furthermore, DER animals have a hypofunctioning serotonergic system and express depressive-like behavior and increased aggression. However, they have increased hippocampal glucocorticoid receptors, indicative of efficient hypothalamic-pituitary-adrenal axis function, and an adaptive pattern of stress-induced corticosterone response. The DER experience with its relatively negative emotional valence results in a complex behavioral phenotype, which cannot be considered simply as adaptive or maladaptive.
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Knowledge of normal development of brain-behavior relations plays an important role in understanding how the plasticity of the nervous system can be used to promote recovery of function following brain damage. Aspects of the other articles in this issue are used in justification of the value of such developmental knowledge. Also, the development of amblyopia and its remediation in adulthood is discussed as a model for developing other techniques for ensuring recovery of function after stroke. Although the articles in this issue establish an excellent context for improving actual recovery of function (rather than compensation for deficits), much still needs to be discovered about how we can use developmental knowledge, along with knowledge of the plasticity of the nervous system, to improve remediation techniques.
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Epigenetics commonly refers to the developmental process by which cellular traits are established and inherited without a change in DNA sequence. These mechanisms of cellular memory also orchestrate gene expression in the adult brain and recent evidence suggests that the "epigenome" represents a critical interface between environmental signals, activation, repression and maintenance of genomic responses, and persistent behavior. We here review the current state of knowledge regarding the contribution of the epigenome toward the development of psychiatric disorders.
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The magnitude and duration of the hormonal stress response change dramatically throughout an organism's lifespan. Although much is known about the factors that modulate stress reactivity during adulthood and how neonatal development and aging influence stress responsiveness, we know relatively little about how stress reactivity changes during the juvenile to adult transition. ⋯ A growing body of literature indicates that pubertal organisms react differentially, both physiologically and behaviorally, to a stressor compared to adults. The purpose of this review, therefore, is to discuss the recent findings regarding the pubertal maturation of stress reactivity, while also highlighting future research directions that will aid in our understanding of stress and adolescent mental health and development.
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Adult cognitive neuroscience employs a wide variety of techniques to investigate a broad range of behavioral and cognitive functions. One prominent area of study is that of executive control, complemented by a smaller but growing literature exploring the developmental cognitive neuroscience of executive control. To date this approach has often compared children with specific developmental disorders, such as ADHD and ASD, with typically developing controls. ⋯ Some very elegant investigations illustrate how seemingly common processes in adulthood present as separable in childhood, on the basis of their distinctive developmental trajectories. These demonstrations have implications not only for an understanding of changing behavior from infancy through childhood and adolescence into adulthood, but, moreover, for our grasp of the adult end-state per se. We contend that, if used appropriately, developmental cognitive neuroscience could enable us to construct a more mechanistic account of executive control.