The role of contextual similarity on brain activity patterns for associated events

Abstract

Our everyday lives are characterized by repeated contexts, such as returning to work in the same office every day. Although the physical office may be identical, other features vary--e.g., time of day, light conditions, one's internal state--leading to differing degrees of similarity, even among putatively identical contexts. Alternatively, contexts can change abruptly, such as leaving the office to go home for dinner. Despite the prevalence of various levels of contextual overlap in everyday life, prior experimental work has largely ignored their influence on related experiences. To address this gap, we took a novel approach in which participants viewed real-world audiovisual stimuli (commercials [events], TV shows [contexts]) while undergoing functional magnetic resonance imaging scans (fMRI) to examine whether the degree of contextual overlap influenced brain activity patterns for related events. Representational similarity analyses revealed sensitivity to global context--greater similarity for commercials seen within the same versus different show--in ventromedial prefrontal cortex, posterior medial cortex, perirhinal cortex, and parahippocampal cortex. Additionally, parahippocampal cortex was uniquely sensitive to local context--greater similarity for commercials seen in the same versus different episode of the same show--and showed reduced activity to repetition of event-specific information, suggesting representation of event-level conceptual information. Thus, even with no explicit demand to retrieve contextual associations, event representations changed based on the degree of contextual similarity, suggesting that contextual information is an inherent part of how experiences are represented.