DOI: 10.1101/501122Dec 19, 2018Paper

Hippocampus activations reflect temporal contexts while medial prefrontal cortex activations reflect ordinal positions during sequence memory in humans

BioRxiv : the Preprint Server for Biology
Puck C ReedersAaron T Mattfeld


Sequence memory is a core function of the hippocampus (HC) and medial prefrontal cortex (mPFC), but their distinct contributions remain unclear. One possibility is that HC and mPFC represent sequences with temporal contexts and ordinal representations, respectively. To test the unique contributions of the HC and mPFC to sequence memory, we used fMRI while participants performed a sequence memory task suited to investigate underlying representations. After studying sequences, participants indicated whether items were in sequence (InSeq) or out of sequence (OutSeq). In our task, temporal context memory (TCM) predicts graded behavioral performance as a function of temporal contiguity. Thus, we predicted graded impairments across lag distance for items that skipped ahead in the sequence (Skips, e.g., ABD), and that short lags would take the biggest hit. Consistent with TCM, subjects found it difficult to identify OutSeq items that skipped ahead short distances compared to longer distances. We found that the right anterior HC tracked forward lag distance, providing evidence that HC supports sequence memory with temporal contexts. To test ordinal representations, we used items that were transferred from one sequence to another, but r...Continue Reading

Related Concepts

Hippocampus (Brain)
Molecular Sequence Database
Positioning Attribute
Nucleic Acid Sequencing
Chemical Probe
Medial Prefrontal Cortex

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