This coming Monday, Xiongbo Wu , from Dynamics of memory formation group, will be presenting the talk:
Post-encoding reactivation binds episodic sequences in long-term memory
In episodic encoding, the unfolding experience is rapidly transformed into a memory representation that binds separate episodic elements into an integrated episodic form, so that it can be later recollected completely. Here, we examined whether this memory transformation takes place rapidly once the encoded episode is completed by means of neural reactivation. We asked participants to encode trial-unique combinations of face-object-scene picture triplets that were subsequently recalled in a test. We used representational similarity analysis of scalp electroencephalography (EEG) recordings during encoding and found evidence for memory reactivation of the just encoded episodic elements after encoding, i.e., at the offset following each triplet images presentation (i.e., at 500 ms at offset period onset). Neural patterns associated to item’s categories were obtained from a different set of images and applied on EEG signals to index the magnitude of discriminability across image categories during sequence encoding and at the offset period. We found that the degree of category discriminability decreased as a function of item order in the sequence, indicating the gradual integration of items’ category from the sequence during online encoding. However, we found much smaller degree of category discriminability at offset period presentation (i.e., at 500 ms at offset period onset) for sequences that would be later recollected compared to those that would be forgotten. Given the temporal overlap of the neural reactivation and the discriminability index analysis and the specificity of the effects in relation to memory performance, we conclude that episodic offset memory reactivation is a mechanism engaged to support integration of episodic elements in long term memory.
Location: Online (ZOOM). Click here to join the meeting