The impact of lifestyle factors and development on relational memory

At a time when children in the U.S. and other developed nations are increasingly sedentary and often fail to meet dietary guidelines, the cognitive ramifications of these health choices continue to be elucidated. One brain structure impacted by fitness and nutrition is the hippocampus, and tasks that assess hippocampal function are ideally positioned for use in exercise and nutrition interventions, particularly early in life when these interventions may have the greatest benefit. While the hippocampus has historically been viewed as the heart of the episodic memory system and is known to support relational memory, a growing body of evidence has implicated the hippocampus in a wide range of cognitive domains, including mnemonic discrimination and creativity. The work presented in this dissertation investigates the development of hippocampaldependent cognition and the sensitivity of these varied aspects of hippocampal function to health factors, using a multidisciplinary approach that combines a broad array of physiological and cognitive metrics. Chapter one reviews the literature surrounding the hippocampal-dependent relational memory, its role in academic achievement, and the susceptibility of the hippocampus to the impact of physical activity, nutrition, and obesity and provides the framework within which the subsequent chapters operate. Chapter two investigates the relative contributions of aerobic fitness, body composition, and macular pigment optical density (MPOD) in predicting relational memory performance during childhood. Chapter three expands the investigation of hippocampal-dependent cognition beyond relational memory to include mnemonic discrimination and evaluates the associations between these distinct measures of hippocampal function and academic achievement. Chapter four continues to examine the relationship between the relational memory and mnemonic discrimination approaches to evaluating hippocampal function in adults and children, adding a developmental perspective to this body of work. Chapter five further extends the realm of hippocampal-dependent cognition to include creativity and investigates the relationship between diet and creativity performance during childhood. Taken together, this collection of experiments provides evidence that, like the structure of the hippocampus itself, the development of hippocampal-dependent cognition is not a uniform process, and the cognitive functions subserved by the hippocampus are differentially sensitive to the effects of aerobic fitness, nutrition, and obesity