| Functional connectivity analyses are recent advances in functional magnetic resonance imaging (fMRI) methodology that model the neural circuitry underlying cognitive performance. One technique, within-condition interregional covariance analysis (WICA), assesses the covariance of distinct brain regions across time to model cortical and subcortical networks mediating a given task. For this dissertation, WICA was used to model the neural network regulating sequential finger movements in humans. Additionally, WICA evaluated changes to this network during effortful (explicit) and effortless (implicit) learning of a serial reaction time task (SRTT) motor sequence. Finally, these functional connectivity models for motor performance were compared across age groups to test competing theories for age-related cognitive decline.;Fifty undergraduate participants were recruited for a behavioral pilot study that compared the effectiveness of three motor learning paradigms. Control charts were adapted for statistical analyses of behavioral responses that revealed relatively consistent rates of implicit learning across individuals despite considerable intersubject variability for explicit motor learning rates. These findings suggest that implicit motor learning is an invariant process subject to supplementation by explicit strategy.;Eighteen young adults (<35 years old) and nine senior adults (60-75 years old) underwent fMRI scanning while implicitly and explicitly learning a motor sequence. Novel behavior-driven connectivity approaches were contrasted against traditional general linear model approaches to define regions of interest (ROI) mediating motor performance and learning. Both approaches gave analogous results. Connectivity models were then developed for each learning condition (random, implicit, and explicit) and age group (young and senior).;The functional connectivity models of brain activity did not differ between learning conditions for either age group. These null findings may stem from modeling insensitivities to dynamic processes. However, senior adult brains demonstrated significant decreases in functional connectivity compared to young adults during performance of random trials. Increased noise in senior brains was refuted as a possible explanation for the decreasing interregional correlations with age. Furthermore, the decreases in functional connectivity were not constrained to any single brain region, thus supporting aging models that propose distributed cognitive decline. These novel connectivity methods stand to supplement existing psychological models of behavior with physiological models of underlying neural circuitry. |
