INVESTIGATION OF HIPPOCAMPAL NEURITE DENSITY AND DISPERSION AND THEIR RELATION TO MNEMONIC DISCRIMINATION IN PRESCHOOL-AGED CHILDREN

Abstract

Research has established links between mnemonic discrimination, sleep, and the hippocampus. Mnemonic discrimination is a cognitive ability that allows for the discrimination between two similar stimuli. This ability relies on pattern separation, a neurocomputational process in which similar representations are stored orthogonally within the hippocampus, a region critical for memory. Sleep strengthens memory traces via a process called consolidation, which relies on the hippocampus. Assessments of hippocampal microstructure (i.e., internal make-up) have become preferred over assessments of macrostructure (i.e., volume) because the hippocampus has a complex organizational structure, and metrics of microstructure are more precise and able to detect subtle changes in tissue integrity. However, previous studies have not yet explored how mnemonic discrimination, sleep, and the hippocampus relate, particularly in a developmental population when all three are still undergoing maturational changes. In the following thesis, the relation between mnemonic discrimination, sleep, and the hippocampus was investigated in a sample of 63 habitually napping preschool-aged children. We hypothesized that mnemonic discrimination performance would be worse following a nap, as napping may support gist memory but not precision memory, and that mnemonic discrimination ability would be significantly associated with hippocampal microstructure. A repeated measures ANOVA, linear regressions, and Bayesian probit regressions were conducted to test these hypotheses. Analyses revealed that relations between the variables did not reach significance. It may be that age contributes a substantial amount of variance to memory in early childhood, and that longitudinal methods may be more suitable for studying developmental populations as they investigate change with age as opposed to without it.