![]() ![]() ![]() Similarly, neuropsychology studies in humans ( 6) and lesion experiments in nonhuman primates ( 11) and rodents ( 12) often find temporally graded retrograde amnesia following hippocampal damage recently acquired memories are lost, while remote or more distant memories are spared. On one hand, clinicians have long noted a pattern by which temporally distant memories are the best retained and the first recovered following insults such as brain injury ( 9, 10). Over the last several decades, a debate has arisen regarding the nature of hippocampal–neocortical interaction during the retrieval of recent, as compared to remote, events. These findings support predictions of the standard model of consolidation and demonstrate the potential benefits of overt recall in neuroimaging experiments. Task-based connectivity between posterior hippocampal regions and others associated with mental scene construction also exhibited a temporal gradient, with greater connectivity accompanying the recall of recent events. Consistent with predictions of the standard model, recall-related hippocampal activity differed from a non-autobiographical control task only for recent, and not remote, events. Posterior hippocampal regions exhibited temporally graded activity patterns (recent events > remote events), as did several regions of frontal and parietal cortex. Details associated with each memory were identified and modeled in the fMRI time-series data using a variant of the Autobiographical Interview procedure, and activity associated with the recall of recent and remote memories was then compared. Forty participants retrieved recent and remote memories, describing each for approximately 2 min. Here, we capitalized on advances in fMRI denoising to employ overtly spoken recall. Lesion evidence remains inconclusive, and the inferences one can draw from functional MRI (fMRI) have been limited by reliance on covert (silent) recall, which obscures dynamic, moment-to-moment content of retrieved memories. The standard model of consolidation predicts a time-limited role for the hippocampus, but the competing multiple trace/trace transformation theories posit indefinite involvement. The necessity of the human hippocampus for remote autobiographical recall remains fiercely debated. ![]()
0 Comments
Leave a Reply. |