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Proc Natl Acad Sci U S A. 2016 Sep 13;113(37):E5501-10. doi: 10.1073/pnas.1606951113. Epub 2016 Aug 29.

Dopaminergic inputs in the dentate gyrus direct the choice of memory encoding.

Author information

1
Department of Physiology, School of Basic Medicine, Huazhong University of Science and Technology, Wuhan 430030, China;
2
Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037;
3
Data-Driven and Neural Computing Department, Sandia National Laboratories, Albuquerque, NM 87185;
4
Shenzhen Key Laboratory of Neuropsychiatric Modulation, Chinese Academy of Sciences Center for Excellence in Brain Science, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China;
5
Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037; gage@salk.edu ymu@hust.edu.cn.
6
Department of Physiology, School of Basic Medicine, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China gage@salk.edu ymu@hust.edu.cn.

Abstract

Rewarding experiences are often well remembered, and such memory formation is known to be dependent on dopamine modulation of the neural substrates engaged in learning and memory; however, it is unknown how and where in the brain dopamine signals bias episodic memory toward preceding rather than subsequent events. Here we found that photostimulation of channelrhodopsin-2-expressing dopaminergic fibers in the dentate gyrus induced a long-term depression of cortical inputs, diminished theta oscillations, and impaired subsequent contextual learning. Computational modeling based on this dopamine modulation indicated an asymmetric association of events occurring before and after reward in memory tasks. In subsequent behavioral experiments, preexposure to a natural reward suppressed hippocampus-dependent memory formation, with an effective time window consistent with the duration of dopamine-induced changes of dentate activity. Overall, our results suggest a mechanism by which dopamine enables the hippocampus to encode memory with reduced interference from subsequent experience.

KEYWORDS:

channelrhodopsin-2; dopamine; temporal difference learning; theta oscillation

PMID:
27573822
PMCID:
PMC5027420
DOI:
10.1073/pnas.1606951113
[Indexed for MEDLINE]
Free PMC Article

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