Our new preprint on constructive memory for temporal relations and generalization is now on bioRxiv.
In this experiment, participants learned the times of events forming different sequences. Participants had to construct event times relative to a hidden clock based on infrequent cues and their feeling of passing time. In our preprint, we describe how participants’ memory was shaped by the hidden clock rather than the order of events or true elapsing time. This was also mirrored in hippocampal activation patterns, which reflected temporal distances between the events of a sequence. Crucially, the hippocampus also generalized temporal relations across sequences – events that occurred at similar times, but in different sequences, became more similar than those separated by larger temporal distances. We also observed that general knowledge about the sequences explained remembered event times: The times of events occurring at the same position in other sequences predicted errors in participants’ memory for the time of a specific event. This shows that general knowledge not only provides a scaffold for specific memories, but can also bias memory.
There is much more in the preprint, for example a dissociation between how memory specificity and generalization shape event memories in the entorhinal cortex and hippocampus. You can find the preprint on bioRxiv or directly download the PDF. If you really want to dive into the details, you can find extensive documentation of the analysis code and results on my project page on GitHub.
JLS Bellmund, L Deuker, ND Montjn, CF Doeller (2021). Structuring time: The hippocampus constructs sequence memories that generalize temporal relations across experiences. bioRxiv. doi:
The hippocampal-entorhinal region supports memory for episodic details, such as temporal relations of sequential events, and mnemonic constructions combining experiences for inferential reasoning. However, it is unclear whether hippocampal event representations reflect temporal relations derived from mnemonic constructions, event order, or elapsing time, and whether they generalize temporal relations across similar sequences. Here, participants mnemonically constructed times of events from multiple sequences using infrequent cues and their experience of passing time. After learning, event representations in the anterior hippocampus reflected sequence relations based on constructed times. These event representations generalized across sequences, revealing distinct representational formats for events from the same or different sequences. Structural knowledge about time patterns, abstracted from different sequences, biased the construction of specific event times. These findings demonstrate that the hippocampus reconciles representations of specific relations with the generalization across different episodes, consistent with memory-based constructions combining episodic details and general knowledge to simulate scenarios.