Neural Signatures of Storage Isolate Core Mechanisms of Working Memory

To successfully navigate through the world, we must be able to actively hold information in mind. From remembering your dual-factor authentication code to the name of someone you just met, working memory is a core component of everyday cognition, and individual differences in working memory have been associated with broad measures of intellectual function (e.g., IQ, scholastic achievement, and psychological well-being). This work investigates a recently identified neural signature that tracks the number of items in working memory, using it as a lens into the mechanisms underlying this critical process, and offers two major results. First, voluntary control over what gets stored in working memory is distinct from voluntarily directing attention towards specific regions of space. Even when observers direct spatial attention in the absence of external cues -- an act that requires sustained maintenance of information -- neural signatures of storage in working memory are not necessarily observed. This observation motivates a revision of standard definitions of working memory storage that focus only on information retention. Instead, I propose that WM storage is best defined as the item-based, capacity-limited storage system that drives the individual differences in intellectual ability described above. Second, WM storage mechanisms are applied across vastly different types of information and track behavioral capacity limits. This supports theories suggesting that WM storage relies on the abstract binding of items to a representation of the current event to enable selective maintenance and access to these items. I introduce an initial test of this theory, and close with a discussion of possible implementations of this theory in the brain. In summary, this work offers a framework for understanding the core components of working memory and the role they play in our ability to flexibly navigate everyday life.