Abstract
How do we rapidly process incoming streams of information in working memory, a cognitive mechanism central to human behavior? Dominant views of working memory focus on the prefrontal cortex (PFC), but human hippocampal recordings provide a neurophysiological signature distinct from the PFC. Are these regions independent, or do they interact in the service of working memory? We addressed this core issue in behavior by recording directly from frontotemporal sites in humans performing a visuospatial working memory task that operationalizes the types of identity and spatiotemporal information we encounter every day. Theta band oscillations drove bidirectional interactions between the PFC and medial temporal lobe (MTL; including the hippocampus). MTL theta oscillations directed the PFC preferentially during the processing of spatiotemporal information, while PFC theta oscillations directed the MTL for all types of information being processed in working memory. These findings reveal an MTL theta mechanism for processing space and time and a domain-general PFC theta mechanism, providing evidence that rapid, dynamic MTL–PFC interactions underlie working memory for everyday experiences.
Highlights
The ability to hold and manipulate features of information in working memory provides the neurobiological infrastructure for our cognitive experiences
How do we rapidly process incoming streams of information in working memory? Dominant views of working memory focus on the prefrontal cortex (PFC), but other data suggest a role for the medial temporal lobe (MTL)
To delineate whether these brain regions interact during working memory, we recorded directly from PFC and MTL sites in humans performing a task that tests working memory for the types of “what,” “where,” and “when” information encountered every day
Summary
The ability to hold and manipulate features of information in working memory provides the neurobiological infrastructure for our cognitive experiences. Recent proposals suggest that the MTL is critical to working memory for spatiotemporal context, as it is for long-term memory [8,9,10]. These findings raise the question of how the MTL and PFC interact during working memory or, rather, whether the MTL and PFC contribute independently to working memory. Our findings provide evidence for bidirectional MTL–PFC communication in humans (see [11,12,13] for evidence from animal physiology) and suggest that dynamic MTL–PFC interactions underlie working memory for everyday experiences
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