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Updated: Dec 3, 2025
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Published on: August 2, 2017
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Time cells in the human hippocampus and entorhinal cortex support episodic memory
Gray Umbach1, Pranish Kantak1, Joshua Jacobs2
1Department of Neurological Surgery, University of Texas Southwestern, Dallas, TX 75390.
Summary
Scientists found "time cells" in the human brain that help organize episodic memories. These brain cells predict the order of recalled information, revealing a key mechanism for memory formation.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Memory Research
Background:
- Episodic memory relies on organizing temporal information.
- Rodent studies suggest hippocampal "time cells" encode temporal sequences.
- A cellular basis for temporal coding in human memory remains largely unknown.
Purpose of the Study:
- To identify and characterize "time cells" in the human brain.
- To investigate the role of neuronal activity in encoding temporal aspects of episodic memory.
- To explore complementary neural mechanisms, like ramping activity, for temporal information representation.
Main Methods:
- Intracranial microelectrode recordings from 27 epilepsy patients.
- Analysis of neuronal activity during an episodic memory task.
- Correlation of neural firing patterns with memory recall timing.
Main Results:
- Identification of human time cells in the hippocampus.
- Time cell activity significantly predicted the temporal order of retrieved memory items.
- Evidence of ramping cell activity, a distinct temporal coding mechanism, was also observed.
Conclusions:
- Human time cells provide a cellular mechanism for representing temporal information in episodic memory.
- Ramping activity offers a complementary neural code for temporal sequencing.
- These findings advance our understanding of the neural basis of human memory.
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