The Fronto-Parietal network and beyond : a study of the spatiotemporal patterns underlying visual working memory
Dotson, Nicholas Monroe.
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Working memory, an integral component of higher cognitive functions, involves the short-term retention and utilization of behaviorally relevant information when that information is no longer available in the environment. Tragically, individuals suffering from traumatic brain injuries, psychiatric disorders, and other neurological disorders often exhibit working memory deficits. The study of working memory may thus provide insight into the mechanisms underlying cognitive functions and the potential to alleviate major health problems. In order to understand cognitive processes, like working memory, several pieces of information must be considered: the cortical and sub-cortical areas involved, the manner in which these areas integrate, or share information, and the underlying dynamics of these integrative processes. These pieces form a hierarchical structure of investigation, from the individual areas to global principles of coordination. The objective of this study is to elucidate the relevant spatiotemporal patterns of oscillatory synchronization underlying visual working memory in the fronto-parietal network and across the brain. Relevant patterns for consideration are those that encode stimulus information, are modulated by the task, and those with distinct anatomical variations. The results of the studies presented in Chapters 2-4 provide extensive evidence that oscillatory synchronization is a mechanism for distributed integration. We show that the patterns of coherent activity 1) encode working memory items, 2) are indicative of the task period, 3) provide the potential for multiple functional networks, defined by the relative phase and, 4) are highly dynamic, with large fluctuations in magnitude and relative phase. Future studies will be necessary to further investigate the role of oscillatory synchronization. Efforts to perturb oscillatory activity in order to illustrate its utility, rather than simply correlating its activity with stimulus and task components, will be crucial. Finally, understanding the spatiotemporal activity patterns underlying working memory may ultimately allow for the identification of aberrant patterns, such as those brought on by disease, and allow for these patterns to be meaningfully interacted with - via neuroprosthetic devices.