Spectral characteristics of visual working memory in the monkey frontoparietal network

Abstract

Working memory is a crucial cognitive function enabling executive control. It has been studied using Baddeley's multicomponent model which comprises a visuospatial sketchpad, phonological loop, and a central executive. Recent work extends this approach by considering working memory's emergence over large-scale cognitive networks. They are best studied in non-human primates using simultaneous recordings from electrodes distributed throughout the brain. Signals obtained from active networks can be characterized according to spectral features. Here, we aggregate spectral characteristics of the frontoparietal network supporting visual working memory in non-human primates. Low, mid, and high frequency bands were found to support different kinds of working memory tasks in different roles and in slightly different ranges. A low frequency network in both frontal and parietal regions supported spatial and nonspatial tasks. It may sustain attention and target stimuli. Mid band activity fulfilled a variety of roles across spatial, non-spatial and visuospatial working memory tasks. It may filter out competing stimuli, preserving working memory content over time. High band activity within frontal and parietal regions supported spatial, non-spatial and visuospatial working memory tasks. It may transport working memory information within each region. Taken together, these findings constitute a new spectral model of visual working memory in the monkey. It supports the central executive as controller over frontal and parietal neural processes. However, inter-band coordination procedures and the effects of their malfunction are unknown. Future work on the model could help develop a more mechanistic understanding of visual working memory.