Schema representations in distinct brain networks support narrative memory during encoding and retrieval.

Schematic prior knowledge can scaffold the construction of event memories during perception and also provide structured cues to guide memory search during retrieval. We measured the activation of story-specific and schematic representations using fMRI while participants were presented with 16 stories and then recalled each of the narratives, and related these activations to memory for specific story details. We predicted that schema representations in medial prefrontal cortex (mPFC) would be correlated with successful recall of story details. In keeping with this prediction, an anterior mPFC region showed a significant correlation between activation of schema representations at encoding and subsequent behavioral recall performance; however, this mPFC region was not implicated in schema representation during retrieval. More generally, our analyses revealed largely distinct brain networks at encoding and retrieval in which schema activation was related to successful recall. These results provide new insight into when and where event knowledge can support narrative memory.

Our day-to-day experiences are incredibly complex, so how does the brain remember them? Cognitive scientists have shown that memories rely on knowledge of common events that we have experienced before. Think about going to a restaurant: you arrive, you find a table, you order food, and then you eat. This kind of predictable sequence is called a schema. When humans make memories, our brains use schemas like these as scaffolding. They take a basic pattern constructed from past experience and fill it in with the specific details of an event. When memories are recalled, our brains use schemas as step-by-step guides to remember the events in the right order. Most research so far on how the brain uses schemas for memory has involved showing participants pictures or words and then testing their memory by asking 'true or false' questions. This revealed that a brain area called the medial prefrontal cortex plays an important role in creating and retrieving memories for items related to a schema. But, studies have not yet assessed exactly how the brain uses schemas to understand and remember a long, realistic event that unfolds over several minutes. To answer this question, Masís-Obando et al. scanned people's brains while they watched or listened to clips of two familiar experiences: eating at a restaurant or catching a flight at an airport. Then, the participants were scanned while they tried to retell each story in their own words. The volunteers were graded based on how many details they recalled. The scans showed that when volunteers' medial prefrontal cortex kept track of the schema throughout the whole time that an event was happening, they were more likely to score well on the memory test. But it wasn't necessary for medial prefrontal cortex to hold the schema in mind when remembering the story. Instead, a different set of brain regions maintained schema information during successful remembering. This study reveals new information about how memories and schemas work that could help explain why people develop problems making or recalling memories in diseases such as Alzheimer's. The findings could also be used to help people make experiences or stories more memorable.

Context-dependent memory effects in two immersive virtual reality environments: On Mars and underwater.

The context-dependent memory effect, in which memory for an item is better when the retrieval context matches the original learning context, has proved to be difficult to reproduce in a laboratory setting. In an effort to identify a set of features that generate a robust context-dependent memory effect, we developed a paradigm in virtual reality using two semantically distinct virtual contexts: underwater and Mars environments, each with a separate body of knowledge (schema) associated with it. We show that items are better recalled when retrieved in the same context as the study context; we also show that the size of the effect is larger for items deemed context-relevant at encoding, suggesting that context-dependent memory effects may depend on items being integrated into an active schema.