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This article is part of the supplement: Twentieth Annual Computational Neuroscience Meeting: CNS*2011

Open Access Poster presentation

Role of neuromodulators in regulating Hippocampal encoding and retrieval in anxiety disorders

Ali Hummos12*, Charles Franklin2 and Satish Nair2

Author Affiliations

1 Department of Psychiatry, University of Missouri, Columbia, MO 65212, USA

2 Department of Electrical Engineering, University of Missouri, Columbia, MO 65212, USA

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BMC Neuroscience 2011, 12(Suppl 1):P232  doi:10.1186/1471-2202-12-S1-P232

The electronic version of this article is the complete one and can be found online at:

Published:18 July 2011

© 2011 Hummos et al; licensee BioMed Central Ltd.

This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Poster presentation

The hippocampus has a critical role in processing context during the acquisition and retrieval of memories. The contextual-dependence of Pavlovian fear extinction is closely associated with the hippocampus [1]. The contextually modulated retrieval of fear extinction leads to limited benefits from exposure therapy for anxiety disorders [1]. We recast extinction learning processing in the hippocampus in terms of a memory task that is dependent on pattern separation and completion machinery in the hippocampus. We developed a spiking neuron model of the Entorhinal cortex, dentate gyrus, and CA3 of the hippocampus. We simulate Acetylcholine and Dopamine effects on regulating pattern separation and completion processes in the hippocampus. Our preliminary results indicate that fear extinction processing can be explained in terms of the encoding and retrieval mechanisms in the hippocampus and accordingly, can be manipulated by neuromodulators. We show that, in our model, manipulating levels of neuromodulators during extinction training can decrease the contextual-dependence of the extinction memory. We conclude that Dopamine is another important modulator of pattern separation and completion in the hippocampus, and that understanding of these neuromodulators will allow targeting specific memories in the hippocampus.


  1. Bouton ME: Context, ambiguity and unlearning: sources of relapse after behavioral extinction.

    Biol Psychiatry 2002, 2:976-986. Publisher Full Text OpenURL