An ECoG Study On Working Memory With ’Double Delay Double Response’Paradigm

Term’working memory’refers to a brain system that temporarily stores and manipulates information for a following action. This system is essential for sequential complicated cog-nitive tasks. A well accepted theoretical model of working memory is a multi-component working memory model proposed by Baddeley. With profound research on working mem-ory, neural substrates of the components of the model have been gradually revealed. How-ever, a common single-delay paradigm applied in working memory experiments may not be able to unambiguously dissociate working-memory-related maintenance from response or-ganization in a sole delay interval. Volle et al.1have developed a’double delay double re-sponse’paradigm, which separates these two processes into two delay intervals respectively. In our current research, we improved their paradigm and conducted an ECoG (Electrocorti-cogram) study on maintenance and response organization in working memory.Four patients with medically resistive epilepsy participated in this study while undergo-ing invasive monitoring for epilepsy surgery. Subjects retained information of the stimulus during delay I, but during delay II, they were instructed to organize different responses ac-cording to one of three distinct instructions presented to them. By analyzing Event-Related Potentials (ERP) and Event-Related Spectral Perturbation (ERSP), we observed slow ERP components and found Event-Related Synchronization/De-synchronization (ERS/ERD) in various bands. Working-memory-related slow positive waves were located in prefrontal cortex while slow negative waves in other frontal areas. In the ERSP analysis, we found working-memory-related ERD in both alpha (8-12Hz) and beta (20-36Hz) bands, and ERS in gamma band (60-100Hz).With fine temporal and spatial resolution and high signal quality of ECoG recording method, we took advantage of the improved double-delay-double-response paradigm to in-vestigate maintenance and response organization in working memory. Findings in this study revealed neural correlates of maintenance and response organization related to working mem- ory, and facilitate further research in this field.