Human “Time Cells” Encode, Process Flow of Time

Neurons in the hippocampus store information on the timing of experiences in addition to their content, helping to mediate sequential memory recall, a new study shows.

Written byAnne N. Connor

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The paper
L. Reddy et al., “Human hippocampal neurons track moments in a sequence of events,” J Neurosci, doi:10.1523/jneurosci.3157-20.2021, 2021.

Neurons in the hippocampus of many species are known for encoding the “who, what, and where” of memories. Researchers had previously learned that some hippocampal neurons in mice also index memories sequentially, capturing the “when” as well. But whether this was the case in humans remained unknown until Leila Reddy had the opportunity to monitor neural activity in the hippocampus of epilepsy patients who already had electrodes implanted in this deep region of the brain.

Reddy, a neurobiologist at the National Center for Scientific Research’s Brain and Cognition Research Center in France, and her colleagues asked those patients to memorize a sequence of pictures before replaying and randomly pausing the sequence and asking them which image would come next. Hippocampal neurons fired when participants saw each image ...

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Meet the Author

Anne N. Connor
Anne N. Connor is a solutions-based science writer and editor based in Vermont. Her primary beats are climate change, the environment, and health. She has been writing about science for about fifteen years and earned her master’s degree in science writing from Johns Hopkins University. Read more about her work here: https://annenconnor.com. Find her on Twitter: @AnneENConnor.
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