From suppression to awareness: temporoparietal junction dynamics support attentional reorientation during memory control

Background

Memory control enables the retrieval of relevant information while suppressing unwanted memories, and is supported by executive control processes. Failure of memory control is common in healthy cognition but can become disruptive in PTSD and depression, when memories suddenly intrude into awareness. However, little is known about how suppressed memories transition into awareness over time. To address this, we leveraged the temporal precision of neural activity as it unfolds during voluntary memory retrieval. We hypothesized that transitions of memory into awareness rely on time-specific activity in the temporoparietal junction, reflecting its role in attentional reorientation and in coordinating fronto-parietal executive function and memory processes.

Methods

We employed a modified version of the Think/No-Think paradigm to examine electrophysiological dynamics as a thought was brought into awareness. Thirty-three healthy participants learned cue-target word pairs and completed suppression (No-Think) or suppression-to-retrieval (No-Think to Think) trials. When the cue word was presented in red, participants were instructed to think only about the cue word while suppressing the target word; a color change to green signaled the need to actively retrieve the target. At the end of each trial, participants reported whether the target item came to mind. EEG was recorded and analyzed using cluster-based permutation testing to identify ERP differences across regions of interest between No-Think and Think trials.

Results

ERP analyses revealed significant (p < 0.05) differences between suppression and retrieval trials across regions linked to memory control. Fronto-central regions showed an early effect (120 ms onwards) during retrieval, followed by sustained bilateral frontal activity that was positive during suppression (≈400-800 ms), which is consistent with ongoing control engagement and task-switching demands. Parietal regions exhibited stronger early- and late-positive amplitudes during retrieval (≈200-3200 ms), particularly over left and central sites, consistent with its role in recollection processes. Critically, the temporoparietal junction activity showed dynamic shifts during retrieval, with early negative deflections (120 ms onwards) followed by polarity changes over the left temporoparietal junction (710 ms onwards), whereas it remained relatively stable during continuous suppression.

Conclusions

We found distinct temporal coordination between the temporoparietal junction, which supports attentional reorientation, and fronto-central regions commonly involved in memory-control systems as thoughts transition into awareness. This aligns with the idea that the temporoparietal junction guides flexible behavior in collaboration with the dorsolateral prefrontal cortex (DLPFC) during cognitive transitions. Our results suggest that the temporoparietal junction is a dynamic contributor to memory control. This supports its role in contextual updating and the flexible reallocation of attention during the shift from suppression to retrieval. This framework integrates memory control, encompassing suppression and retrieval, with broader cognitive control dynamics involved in attentional orientation. A key next step is to examine whether similar temporal dynamics underlie involuntary transitions into awareness, such as intrusive thoughts.

References

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