The human hippocampus is sensitive to the durations of events and intervals within a sequence

Abstract

Temporal details are an important facet of our memories for events. Consistent with this, it has been demonstrated that the hippocampus, a key structure in learning and memory, is sensitive to the temporal aspects of event sequences, including temporal order, context, recency and distance. One unexplored issue is whether the hippocampus also responds to the temporal duration characteristics of an event sequence, for example, how long each event lasted for or how much time elapsed between events. To address this, we used a temporal match–mismatch detection paradigm across two functional neuroimaging studies to explore whether the human hippocampus is sensitive to the durations of events and intervals that comprise a sequence lasting on the order of seconds. On each trial participants were shown a series of four scenes during an encoding and a test phase, and had to determine whether the durations of the intervals or events were altered. We observed hippocampal sensitivity to temporal durations within event sequences. Activity was significantly greater when participants detected repeating, in comparison to novel, durations. Moreover, greater functional connectivity was observed between hippocampus and brain regions previously implicated in second and millisecond timing when durations were novel, suggesting that the hippocampus may receive duration information from these areas for use within a mnemonic context rather than generate an independent timing signal. Our novel findings suggest that the hippocampus may integrate temporal duration information when binding event sequences.