Publication Round Up

A cognitive map for value-guided choice in ventromedial prefrontal cortex

Presented by Sebastijan Veselic 

Abstract: The prefrontal cortex (PFC) is crucial for economic decision-making. However, how PFC value representations facilitate flexible decisions remains unknown. We reframe economic decision-making as a navigation process through a cognitive map of choice values. We found rhesus macaques represented choices as navigation trajectories in a value space using a grid-like code. This occurred in ventromedial PFC (vmPFC) local field potential theta frequency across two datasets. vmPFC neurons deployed the same grid-like code, and encoded chosen value. However, both signals depended on theta phase: occurring on theta troughs but on separate theta cycles. Finally, we found sharp-wave ripples – a key signature of planning and flexible behaviour – in vmPFC. Thus, vmPFC utilises cognitive map-based computations to organise and compare values, suggesting an alternative architecture for economic choice in PFC.

Neural Dynamics of Reselecting Visual and Motor Contents in Working Memory after External Interference

Presented by Sage Boettcher 

Abstract: In everyday tasks, we must often shift our focus away from internal representations held in working memory to engage with perceptual events in the external world. Here, we investigated how our internal focus is reestablished following an interrupting task by tracking the reselection of visual representations and their associated action plans in working memory. Specifically, we asked whether reselection occurs for both visual and motor memory attributes and when this reselection occurs. We developed a visual-motor working-memory task in which participants were retrospectively cued to select one of two memory items before being interrupted by a perceptual discrimination task. To determine what information was reselected, the memory items had distinct visual and motor attributes. To determine when internal representations were reselected, the interrupting task was presented at one of three distinct time points following the retro-cue. We employed electroencephalography time–frequency analyses to track the initial selection and later reselection of visual and motor representations, as operationalized through modulations of posterior alpha (8–12 Hz) activity relative to the memorized item location (visual) and of central beta (13–30 Hz) activity relative to the required response hand (motor). Our results show that internal visual and motor contents were concurrently reselected immediately after completing the interrupting task, rather than only when internal information was required for memory-guided behavior. Thus, following interruption, we swiftly resume our internal focus in working memory through the simultaneous reselection of memorized visual representations and their associated action plans, thereby restoring internal contents to a ready-to-use state.