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Nature. 2017 Mar 30;543(7647):670-675. doi: 10.1038/nature21682. Epub 2017 Mar 22.

Neural ensemble dynamics underlying a long-term associative memory.

Author information

1
James H. Clark Center for Biomedical Engineering &Sciences, Stanford University, Stanford, California, USA.
2
Howard Hughes Medical Institute, Stanford University, Stanford, California, USA.
3
CNC Program, Stanford University, Stanford, California, USA.
4
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
5
Pfizer Neuroscience Research, Cambridge, Massachusetts, USA.
6
University of Basel, Basel, Switzerland.

Abstract

The brain's ability to associate different stimuli is vital for long-term memory, but how neural ensembles encode associative memories is unknown. Here we studied how cell ensembles in the basal and lateral amygdala encode associations between conditioned and unconditioned stimuli (CS and US, respectively). Using a miniature fluorescence microscope, we tracked the Ca2+ dynamics of ensembles of amygdalar neurons during fear learning and extinction over 6 days in behaving mice. Fear conditioning induced both up- and down-regulation of individual cells' CS-evoked responses. This bi-directional plasticity mainly occurred after conditioning, and reshaped the neural ensemble representation of the CS to become more similar to the US representation. During extinction training with repetitive CS presentations, the CS representation became more distinctive without reverting to its original form. Throughout the experiments, the strength of the ensemble-encoded CS-US association predicted the level of behavioural conditioning in each mouse. These findings support a supervised learning model in which activation of the US representation guides the transformation of the CS representation.

PMID:
28329757
PMCID:
PMC5378308
DOI:
10.1038/nature21682
[Indexed for MEDLINE]
Free PMC Article

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