The nature of the interactions between verbal working memory and long-term memory knowledge: a behavioral and neuroimaging investigation

The research conducted in this PhD Thesis aimed to determine the nature of the interactions between verbal working memory (WM) and long-term memory (LTM) knowledge by investigating the cognitive and neural aspects of the potential overlap between the two systems. This question was addressed through three experimental studies employing behavioral paradigms and advanced neuroimaging techniques, including the investigation of the impact of syntactic knowledge on verbal WM performance (Study 1), an fMRI investigation of the neural substrates associated with long-term semantic knowledge and maintenance of semantic information in verbal WM (Study 2), and an fMRI investigation of the language learning-related changes in the cortices that support verbal WM (Study 3). Our findings demonstrate at least partial overlap between verbal WM and long-term linguistic knowledge, characterized by dynamic and flexible interactions. Overall, these results support hybrid, partially emergent language-based models of WM, while emphasizing that although verbal WM and LTM knowledge interact, verbal WM performance extends beyond the simple activation of linguistic knowledge. Verbal WM interacts dynamically with other cognitive processes, and LTM knowledge rather intervenes in a flexible manner in verbal WM. This thesis highlights the importance of adopting an integrative approach that encompasses all language representations, takes into account potential interactions between verbal WM and episodic memory processes, and reflects the flexible and adaptive nature of long-term linguistic knowledge activation in verbal WM.