Poster A80, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Neural similarity patterns across repeated memory encoding are further influenced by the modality in which stimuli are presented
Carolin Sievers1, Fraser W. Smith1, Louis Renoult1; 1University of East Anglia, UK
The present experiment used functional magnetic resonance imaging to investigate representational similarity patterns across repeated stimulus encoding with stimuli being presented in different modalities. Twenty adult participants performed a categorization task during the encoding phase, followed by an unexpected recognition-source memory task. During encoding, each stimulus was presented four times in one of three modalities: 1) repeatedly as a picture, 2) repeatedly as a word, 3) alternately as a picture or a word. We hypothesized subsequent correct source memory judgements to be associated with higher neural pattern similarity at encoding compared to incorrect source memory judgements. Furthermore, we predicted that pattern similarity would be influenced by the modality the stimulus was presented in. In line with these hypotheses, cortical neural similarity was generally found to be higher for correct compared to incorrect source memory judgements. Moreover, effects of modality on similarity patterns differed across regions of interest. Visuo-perceptual regions, such as superior occipital and fusiform gyri, were associated with higher similarity for the picture (1) than word (2) modality. Regions previously linked to multi-modal feature integration, e.g., angular gyrus, tended to show higher similarity for the alternating picture and word (3) modality. These results suggest subsequent source memory effects on cortical similarity patterns to be relatively global, while differences in similarity patterns relating to modality are more region-specific. Moreover, regions such as the angular gyrus appear to rely on greater pattern similarity in a cross-modal compared to a unimodal condition despite perceptual dissimilarities of stimuli across multiple encoding.
Topic Area: LONG-TERM MEMORY: Episodic