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Hippocampal sequence-encoding driven by a cortical multi-item working memory buffer

2004; Elsevier BV; Volume: 28; Issue: 2 Linguagem: Inglês

10.1016/j.tins.2004.12.001

1878-108X

Ole Jensen, John Lisman,

Neural dynamics and brain function

Encoding and recall of memory sequences is an important process. Memory encoding is thought to occur by long-term potentiation (LTP) in the hippocampus; however, it remains unclear how LTP, which has a time window for induction of ∼100 ms, could encode the linkage between sequential items that arrive with a temporal separation >100 ms. Here, we argue that LTP can underlie the learning of such memory sequences, provided the input to the hippocampus is from a cortical multi-item working memory buffer in which theta and gamma oscillations have an important role. In such a buffer, memory items that occurred seconds apart are represented with a temporal separation of 20–30 ms, thereby bringing them within the LTP window. The physiological and behavioral evidence for such a buffer will be reviewed. Encoding and recall of memory sequences is an important process. Memory encoding is thought to occur by long-term potentiation (LTP) in the hippocampus; however, it remains unclear how LTP, which has a time window for induction of ∼100 ms, could encode the linkage between sequential items that arrive with a temporal separation >100 ms. Here, we argue that LTP can underlie the learning of such memory sequences, provided the input to the hippocampus is from a cortical multi-item working memory buffer in which theta and gamma oscillations have an important role. In such a buffer, memory items that occurred seconds apart are represented with a temporal separation of 20–30 ms, thereby bringing them within the LTP window. The physiological and behavioral evidence for such a buffer will be reviewed.