Working memory, the ability to maintain information in mind even when that information is no longer perceptually available, is a fundamental cognitive ability. The mechanism allows us to efficiently apply prior knowledge to the processing of the current context; enabling complex decision-making and guiding attention towards the most relevant features of the environment. While the link between visual working memory (VWM) and attention is well studied, its direct relation to perceptual processing is relatively less clear. This project will leverage the known properties of the neural substrate that supports VWM, to investigate the interaction between what is held in mind and how the mind interprets visual stimuli. The project will identify the time course of this interaction, to understand how content maintained in VWM decays over time. Neural stimulation will then characterize the causal contribution, of cortical areas which support perception, to the maintenance of information in working memory. A better understanding of the mechanisms underlying VWM can inform the design of interactive displays (car dashboards and air traffic controls, for example), and can improve training for numerous professions (such as airport baggage screeners and radiologists).
Recent neurophysiological findings, showing that VWM recruits sensorimotor cortical areas, afford a unique opportunity to generate behavioral predictions about this complex and critical cognitive process. This proposal leverages the known neurophysiological properties of sensorimotor areas (such as tuning curves and retinotopy) to generate behavioral predictions about VWM maintenance. First, if the same circuits are utilized by VWM and perception, then each process should interfere with the other. Further, the strength of these effects should scale with the similarity between the maintained and current stimulus, dependent on known visual tuning properties (such as orientation, motion direction, and face spaces). Second, maintained information should decay over time, having less of an effect on perception and becoming more prone to interference, which challenges some models of VWM. Third, initiation and maintenance of VWM depends on dynamics between prefrontal and perceptual cortices. Transcranial magnetic stimulation will be used to investigate the causal interaction between prefrontal and perceptual areas. The proposed research will provide novel, causal, and fundamental insights into how the brain enables and constrains VWM.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
