Poster Session E, Monday, March 25, 2:30 – 4:30 pm, Pacific Concourse
Time course of encoding and delayed recognition in human memory
Domile Tautvydaite1, Alexandra Adam-Darque1, Aurélie L. Manuel1, Armin Schnider1; 1Laboratory of Cognitive Neurorehabilitation, University Hospital of Geneva and University of Geneva, Switzerland
The medial-temporal lobe (MTL) is crucial for encoding novel information, but may also be involved in memory retrieval and recognition (Nadel & Moscovitch, Curr Opin Neurobiol 1997). The time course of these processes is unknown. Recent evoked potential studies suggested that MTL-mediated encoding may be an early process, occurring 200-300 ms after stimulus presentation (James et al., Hippocampus 2009; Thézé et al, Hippocampus 2017). In the present study, we juxtaposed encoding and recognition in a single continuous recognition paradigm (CRT) with meaningful designs. 20 healthy subjects performed a CRT containing New stimuli (New trials), thought to induce encoding, which were then repeated up to 4 consecutive times (RepX trials), a procedure thought to produce an over-familiarity with the stimulus. These stimuli later reappeared after 9 to 15 intervening items, thus requiring recognition (LateRep trials). Waveform ERP analyses yielded a strong frontal positivity in response to New stimuli at 320-435 ms in comparison to RepX and LateRep trials, suggesting that encoding occurs in this early period. LateRep trials, in comparison to New stimuli and RepX trials, induced a strong posterior positivity at 435-500 ms, indicating that recognition occurs in this late period. These results suggest that encoding of novel stimuli is initiated before recognition of previously encountered material. The results complement earlier studies indicating rapid limbic influences on memory processing, not only for encoding, but also for orbitofrontal reality filtering (Thézé et al. Front Behav Neurosci 2017).
Topic Area: LONG-TERM MEMORY: Episodic