Schedule of Events | Symposia

Transcranial Direct Current Stimulation interferes with access and consolidation of weak episodic memories

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

Shawn Hiew¹ (shawn.hiew@unibe.ch), Konstantinos Ioannis Zervas¹, Katharina Henke¹; ¹University of Bern

The ability to recall past events depends upon the strength and content of the memory traces which are determined as they are being formed, and which continue to be modifiable throughout the path of the memory trace until it is ultimately forgotten. In the present study, we perturbed different key processes of episodic memory, namely encoding, re-encoding, reconsolidation and retrieval, in order to uncover the key contributors to forgetting. 120 healthy young subjects received transcranial direct current stimulation (tDCS) targeting the right medial temporal lobe (MTL) during an episodic memory task. Participants form 96 face-object associations, which later, when presented with face cues, they retrieve indicating the category of the associated object (natural or man-made). They either receive real or sham tDCS, at one of three time points: encoding, early retrieval (30 mins), and late retrieval (24 hrs). A final retrieval – without brain stimulation - took place one week following encoding. TDCS applied at early retrieval enhanced the subjective memory quality reflected by enhanced clarity of scene retrieval and confidence of object category judgements. Compared to sham, anodal tDCS at early retrieval worsened the accuracy of object category judgements at all retrieval time points. TDCS applied at encoding and late retrieval had no effect on memory performance. Hence, tDCS may have interfered with the restabilization of memory traces as they are retrieved for the first time. Our findings suggest that memories are most vulnerable to interference during initial re-encoding and reconsolidation before their overnight consolidation.

Topic Area: LONG-TERM MEMORY: Episodic