The Neural Correlates of Updating and Gating in Procedural Working Memory

Goal-directed behavior relies on maintaining relevant goals in working memory (WM) and updating them when required. Computational modeling, behavioral, and neuroimaging work has previously identified the processes and brain regions involved in selecting, updating, and maintaining declarative information, such as letters and pictures. However, the neural substrates that underlie the analogous processes that operate on procedural information, namely, task goals, are currently unknown. Forty-three participants were therefore scanned with fMRI while performing a procedural version of the reference-back paradigm that allowed for the decomposition of WM updating processes into gate-opening, gate-closing, task switching, and task cue conflict components. Significant behavioral costs were observed for each of these components, with interactions indicating facilitation between gate-opening and task switching, and a modulation of cue conflict by gate state. In neural terms, opening the gate to procedural WM was associated with activity in medial pFC, posterior parietal cortex (PPC), the basal ganglia (BG), thalamus, and midbrain, but only when the task set needed to be updated. Closing the gate to procedural WM was associated with frontoparietal and BG activity specifically in conditions where conflicting task cues had to be ignored. Task switching was associated with activity in the medial pFC/ACC, PPC, and BG, whereas cue conflict was associated with PPC and BG activity during gate closing but was abolished when the gate was already closed. These results are discussed in relation to declarative WM and to gating models of WM.

Automated summary

Goal-directed behavior relies on maintaining and updating relevant goals in working memory. This study aimed to uncover the neural processes involved in procedural information (task goals) and found that opening the gate to procedural working memory involved activity in medial pFC, PPC, BG, thalamus, and midbrain, while closing the gate involved frontoparietal and BG activity. Task switching was associated with medial pFC/ACC, PPC, and BG activity, and cue conflict was associated with PPC and BG activity during gate closing. These findings contribute to our understanding of working memory and its gating mechanisms.