Beyond the Status Quo: A Role for Beta Oscillations in Endogenous Content (Re-) Activation

Abstract

Among the rhythms of the brain, oscillations in the beta frequency range (approx. 13–30 Hz) have been considered the most enigmatic. Traditionally associated with sensorimotor functions, beta oscillations have recently become more broadly implicated in top-down processing, long-range communication, and preservation of the current brain state. Here, we extend and refine these views based on accumulating new findings of content-specific beta synchronization during endogenous information processing in working memory and decision-making. We characterize such content-specific beta activity as short-lived, flexible network dynamics supporting the endogenous (re-)activation of cortical representations. Specifically, we suggest that beta-mediated ensemble formation within and between cortical areas may awake, rather than merely preserve, an endogenous cognitive set in the service of current task demands. This proposal accommodates key aspects of content-specific beta modulations in monkeys and humans, integrates with timely computational models, and outlines a functional role for beta that fits its transient temporal characteristics.

Significance Statement Brain oscillations at frequencies of 13–30 Hz (the “beta” rhythm) are traditionally associated with sensory and motor processing, but are increasingly implicated in various cognitive functions, such as working memory and decision-making. Here, we review new evidence that beta activity in these domains can be content-specific, that is, it can reflect the very information that is currently being processed. Going beyond previous accounts that link beta to maintenance of the current brain state, our review highlights the dynamic, often short-lived nature of beta modulations during endogenous information processing. We integrate these findings in a dynamic network view where beta synchronization supports the internally driven (re-)activation of neuronal ensembles to represent currently task-relevant contents.