Summary: New research shows that people can intentionally remove specific details from working memory by reducing the activity of the very brain circuits that encoded them. In the reported experiment, volunteers were instructed to forget one of two items they had been holding in mind, after which their memory for the remaining relevant items was tested.
Electroencephalogram (EEG) recordings revealed that deliberately discarding information is linked with decreased excitability in perceptual circuits that represent the unwanted content. These results clarify a neural mechanism for active forgetting and help explain how people manage intrusive thoughts, persistent rumination, or distressing recollections.
Key facts:
- Active forgetting: People can intentionally suppress specific memory traces through targeted neural processes.
- Circuit deactivation: EEG evidence indicates that forgetting corresponds with a down-modulation of perceptual circuits tuned to the discarded item.
- Mental health relevance: Understanding this mechanism may illuminate strategies the brain uses to control intrusive thoughts, rumination, and hallucination-like experiences.
Source: SfN
Deliberately removing information can help preserve the memories that matter.
Prior work has often emphasized passive forgetting—simply withdrawing attention from a memory—but there are cases where actively removing a memory’s specific content is advantageous. The new study examines how the brain implements this active removal process, focusing on whether top-down control reduces the sensitivity of sensory circuits that represent the to-be-forgotten information.
This capacity for intentional removal may be particularly useful when certain memory details are harmful or disruptive—for instance, when people need to counteract rumination, intrusive negative thoughts, or hallucinations. The study provides neural evidence for an active process that clears irrelevant content from working memory, which could support better cognitive control and emotional regulation.
In the Journal of Neuroscience paper, researchers Jiangang Shan and Bradley Postle (University of Wisconsin–Madison) used an established working-memory paradigm to compare active removal with passive forgetting. The experiment enrolled nearly 30 participants who completed a task designed to reveal how and when memory content is eliminated.
During each trial, participants first encoded two items. In some trials they were instructed to actively remove one of those items from memory; in other trials they were encouraged to let the item become irrelevant without deliberate removal. After this instruction, participants encoded a third item and were later tested on their memory for the relevant initial item and the final item.
Behavioral analyses showed that active removal produced a measurable reduction in the familiarity or accessibility of the discarded item, compared with passive removal. In other words, intentionally removing an item made it less likely to influence later memory judgments, consistent with an effective forgetting process.
About the neural findings
To investigate neural mechanisms, the team recorded EEG signals throughout the task. They assessed two phases linked to active removal: the triggering phase, when the instruction to remove was given, and the consequence phase, when the brain’s response to later probes was measured.
Analyses revealed a stronger anterior-to-posterior traveling wave at the time the removal was triggered for active versus passive trials, suggesting top-down control signals propagate from frontal to sensory regions. As a consequence of active removal, the brain’s response to an irrelevant “ping” probe was reduced over perceptual circuits that had encoded the discarded item. This reduced evoked response, measured with event-related potentials (ERPs), indicates decreased excitability of those sensory channels.
Taken together, the EEG and behavioral results support a “hijacked adaptation” model: top-down control diminishes the gain of perceptual circuits tuned to the to-be-removed information, rendering those channels less sensitive and thereby reducing the memory’s persistence.
Abstract
EEG Correlates of Active Removal from Working Memory
Removing no-longer-relevant visual information from working memory is critical because of WM’s strict capacity limits. Using an established “ABC-retrocuing” task, previous work showed removal can occur passively—by withdrawing attention from an irrelevant memory item (IMI)—or actively, through a deliberate removal process (Shan and Postle, 2022). In the present study, EEG recordings examined whether active removal involves a top-down reduction in the gain of perceptual circuits tuned to the IMI. Behaviorally, active removal led to a decline in familiarity centered on the IMI compared with passive removal. Neurally, active removal was linked to a stronger anterior-to-posterior traveling wave at trigger time and to a reduced ERP response to a task-irrelevant “ping,” consistent with decreased excitability in perceptual circuits representing the IMI.
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Image: The image is credited to Neuroscience News
Original Research: Closed access. “EEG Correlates of Active Removal from Working Memory” by Jiangang Shan et al. Journal of Neuroscience