Transformation of continuous experience into discrete memories

 Our daily experience is continuous, yet when we reminisce about the past, we tend to remember it as being composed of distinct events. How does this transpire? By using increasingly-naturalistic stimuli, I explore the question of when an event is encoded to memory as a cohesive unit, focusing on the encoding-activity in the hippocampus. First, using short film clips as memoranda, we find that hippocampal activity is time-locked to the offset of the event, potentially reflecting the encoding of a bound representation to long-term memory. Notably, when distinct clips were presented in immediate succession, the hippocampus responded at the offset of each event, suggesting hippocampal activity is triggered the occurrence of event boundaries (transition between events). However, while brief film clips mimic several aspects of real-life, they are still discrete events. To determine whether event boundaries drive hippocampal activity in an ongoing experience, we analysed brain activity of participants viewing naturalistic films and found that the hippocampus responded both reliably and specifically to shifts between scenes. Taken together, these results suggest that during encoding of a continuous experience, event boundaries drive hippocampal processing, potentially supporting the transformation of the continuous stream of information into distinct episodic representations.