Janice Chen, PhD, Psychology, Princeton University
Title: Reinstatement of Neural Patterns During Narrative Recall
Ebbinghaus Empire Series 2014-2015
VIDEO RECORDING OF TALK
Abstract: When we perceive the external world, we encode part of that experience into memory. During subsequent recall, states of the brain supporting the initial perception of that experience are reinstated. Reinstatement can be measured by comparing the spatial patterns of neural activity during encoding against those observed during recall; this method illuminates what regions in the brain are involved in representation of both the encoded and recalled material. Previous studies have relied on simple stimuli and multiple encoding exposures to amplify effects. In this study, we present robust encoding-recall neural pattern similarity in a highly naturalistic task: watching a movie and freely recalling the plot. Seventeen subjects watched a 50-minute movie (BBC’s “Sherlock”), and then verbally recounted the movie, all while their brain activity was recorded using fMRI. No cues or other experimenter input were provided during recall – subjects described the movie in their own words. Recall sessions lasted 15-20 minutes on average. Neural data from the movie scans were divided into scene segments, data from the recall scans were divided into matching segments, and voxel pattern similarity was calculated between encoding/recall scene pairs. A searchlight analysis revealed a network of regions in which encoding/recall similarity was statistically significant, including posterior medial cortex, lateral prefrontal and medial prefrontal cortex, posterior parahippocampal gyrus, and angular gyrus. This network corresponded closely to regions that were functionally correlated with retrosplenial cortex (the “default network”); the same network exhibits sensitivity to information over long timescales and is known to be connected to medial temporal lobe structures. Our results reveal a widespread network of regions that support representations of complex episodic memory during encoding that are reinstated during spoken recall.
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