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Neuron. 2014 Jul 2;83(1):189-201. doi: 10.1016/j.neuron.2014.05.018.

Hippocampal memory traces are differentially modulated by experience, time, and adult neurogenesis.

Author information

1
Department of Biological Sciences, New York State Psychiatric Institute, New York, NY 10032, USA; Department of Neuroscience and Psychiatry, New York State Psychiatric Institute, New York, NY 10032, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA.
2
Department of Neuroscience and Psychiatry, New York State Psychiatric Institute, New York, NY 10032, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA.
3
Department of Neuroscience and Psychiatry, New York State Psychiatric Institute, New York, NY 10032, USA; Department of Pharmacology, Columbia University, New York State Psychiatric Institute, New York, NY 10032, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA.
4
Department of Neuroscience and Psychiatry, New York State Psychiatric Institute, New York, NY 10032, USA.
5
Department of Biological Sciences, New York State Psychiatric Institute, New York, NY 10032, USA.
6
Department of Neuroscience and Psychiatry, New York State Psychiatric Institute, New York, NY 10032, USA; Department of Pharmacology, Columbia University, New York State Psychiatric Institute, New York, NY 10032, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA. Electronic address: rh95@columbia.edu.

Abstract

Memory traces are believed to be ensembles of cells used to store memories. To visualize memory traces, we created a transgenic line that allows for the comparison between cells activated during encoding and expression of a memory. Mice re-exposed to a fear-inducing context froze more and had a greater percentage of reactivated cells in the dentate gyrus (DG) and CA3 than mice exposed to a novel context. Over time, these differences disappeared, in keeping with the observation that memories become generalized. Optogenetically silencing DG or CA3 cells that were recruited during encoding of a fear-inducing context prevented expression of the corresponding memory. Mice with reduced neurogenesis displayed less contextual memory and less reactivation in CA3 but, surprisingly, normal reactivation in the DG. These studies suggest that distinct memory traces are located in the DG and in CA3 but that the strength of the memory is related to reactivation in CA3.

Comment in

PMID:
24991962
PMCID:
PMC4169172
DOI:
10.1016/j.neuron.2014.05.018
[Indexed for MEDLINE]
Free PMC Article

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