Examining the Development of Hippocampal-Dependent Cognition in Young Children: Neuroimaging and Behavioral Approaches

The current dissertation examined neurological and behavioral approaches to studying the development of large-scale spatial cognition and its underlying neurobiology in young children. Study one reviewed the literature on the development of the neurobiology of spatial navigation and reorientation, including the hippocampus and the parahippocampal, parietal, and prefrontal cortices, and discussed how researchers can overcome the challenges of studying these brain-behavior relations in young children. One solution, I propose, is to employ a hippocampal-dependent form of associative learning known as Pavlovian Trace Eyeblink Conditioning (EBC) to assess hippocampal functioning indirectly and safely in pediatric populations. For the following two empirical studies, children between the ages of four and six years completed three structural magnetic resonance imaging scans (MRI), a hippocampal-dependent eyeblink conditioning paradigm, a spatial reorientation test, a left-right assessment, the Boehm-3 Preschool Test of Basic Concepts, and two control tasks, the Children’s Mental Transformation Task (CMTT) and the NIH Toolbox Pattern Comparison Processing vii Speed (PCPS) Test. Study two (N=31) examined the validity of using a child-friendly, hippocampal-dependent measure of associative learning (i.e., trace EBC) as a proxy for hippocampal function and efficiency. Results revealed that individual differences in greater neurite density of the bilateral hippocampus, but not the cerebellum, predicted later, and thus more efficient, timing of learned associations between auditory and tactile stimuli. Study three (N=39) investigated the role of spatial language on children’s spatial reorientation strategies and outcomes. Findings showed that, independent of age, children who could comprehend relative locations such as left and right, as opposed to general relational concepts, were better at encoding the geometry of a room to recall the location of a hidden object after being disoriented. Implications, limitations, and suggestions for future studies with young children are discussed