Hippocampal theta codes for distances in semantic and temporal spaces
Abstract
The medial temporal lobe (MTL) plays a role in both spatial navigation and memory, but how these 2 cognitive processes are linked remains unclear. In particular, theta oscillations (4 to 8 Hz) appear prominently in the hippocampus in rodents and humans as they move through spatial environments, but there is mixed evidence as to whether this signal also emerges while animals search memory for previously acquired information. Using electrodes implanted in human neurosurgical patients, we showed that hippocampal theta oscillations reflect representational distances between word items in memory. This suggests there is a fundamental theta-based mechanism that supports the creation and retrieval of "cognitive maps" in the MTL, for explicitly nonspatial information.
- Publication:
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Proceedings of the National Academy of Science
- Pub Date:
- November 2019
- DOI:
- 10.1073/pnas.1906729116
- Bibcode:
- 2019PNAS..11624343S