Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

Persistence of parahippocampal representation in the absence of stimulus input enhances long-term encoding: a functional magnetic resonance imaging study of subsequent memory after a delayed match-to-sample task.

Recent theoretical models based on cellular processes in parahippocampal structures show that persistent neuronal spiking in the absence of stimulus input is important for encoding. The goal of this study was to examine in humans how sustained activity in the parahippocampal gyrus may underlie long-term encoding as well as active maintenance of novel information. The relationship between long-term encoding and active maintenance of novel information during brief memory delays was studied using functional magnetic resonance imaging (fMRI) in humans performing a delayed matching-to-sample (DMS) task and a post-scan subsequent recognition memory task of items encountered during DMS task performance. Multiple regression analyses revealed fMRI activity in parahippocampal structures associated with the active maintenance of trial-unique visual information during a brief memory delay. In addition to a role in active maintenance, we found that the subsequent memory for the sample stimuli as measured by the post-scan subsequent recognition memory task correlated with activity in the parahippocampal gyrus during the delay period. The results provide direct evidence that encoding mechanisms are engaged during brief memory delays when novel information is actively maintained. The relationship between active maintenance during the delay period and long-term subsequent memory is consistent with current theoretical models and experimental data that suggest that long-term encoding is enhanced by sustained parahippocampal activity.

Pubmed ID: 15590925


  • Schon K
  • Hasselmo ME
  • Lopresti ML
  • Tricarico MD
  • Stern CE


The Journal of neuroscience : the official journal of the Society for Neuroscience

Publication Data

December 8, 2004

Associated Grants

  • Agency: NIMH NIH HHS, Id: R01 MH61492
  • Agency: NINDS NIH HHS, Id: R01 NS41636

Mesh Terms

  • Adolescent
  • Adult
  • Cues
  • Female
  • Hippocampus
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Memory
  • Parahippocampal Gyrus
  • Photic Stimulation
  • Regression Analysis
  • Retention (Psychology)
  • Task Performance and Analysis
  • Temporal Lobe
  • Time Factors