Schedule of Events | Symposia

Inducing Amnesia via Suppressing Default Network Activity through Focused External Perceptual Attention

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Akul Satish¹, Justin Hulbert², Michael Anderson¹; ¹MRC Cognition and Brain Sciences Unit, University of Cambridge, UK, ²Program in Neuroscience, Bates College, USA

A new theory proposes that functionally suppressing hippocampal activity induces amnesia in healthy adults. Amnesia has been observed for events presented or reactivated around times when participants were cued to suppress retrieval of unrelated memories—which downregulates the hippocampus, a central region in the posterior-medial episodic memory network. The hippocampus is also part of the default network, itself known to be downregulated during challenging perceptual tasks. Given this overlap, we tested whether focused external perceptual attention could similarly induce an amnesic shadow. Specifically, we predicted that memories that were encoded or reactivated between challenging perceptual tasks would be relatively more vulnerable to forgetting. In the first experiment, we found greater forgetting of object-scene pairs encoded between difficult visual discrimination trials (independently associated with default-network suppression) than those encoded between easier discrimination trials (independently associated with default-network activation). In the second experiment, participants encoded object-scene pairs before we examined the impact of simply reactivating already encoded memories in between easy or difficult perceptual discrimination tasks. We found greater forgetting of unpleasant scenes that were reactivated between difficult perceptual tasks compared to baseline scenes that were not reactivated at all. Crucially, this forgetting persisted even when scene memory was tested via independent cues that were not presented during the perceptual tasks, indicating degradation of the memory trace itself. Together, these findings indicate that memories encoded or reactivated around periods of intense perceptual focus are more likely to be forgotten, providing evidence for a novel mechanism of forgetting: mnemonic process inhibition via default-network modulation.

Topic Area: LONG-TERM MEMORY: Episodic