Dopamine modulates memory consolidation of discrimination learning in the auditory cortex

Authors

  • Horst Schicknick,

    1. Special Lab Molecular Biological Techniques, Leibniz Institute for Neurobiology, Brenneckestrasse 6, D-39118 Magdeburg, Germany
    2. DZNE, German Center for Neurodegenerative Diseases, Magdeburg, Germany
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  • Nicole Reichenbach,

    1. Special Lab Molecular Biological Techniques, Leibniz Institute for Neurobiology, Brenneckestrasse 6, D-39118 Magdeburg, Germany
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  • Karl-Heinz Smalla,

    1. Special Lab Molecular Biological Techniques, Leibniz Institute for Neurobiology, Brenneckestrasse 6, D-39118 Magdeburg, Germany
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  • Henning Scheich,

    1. DZNE, German Center for Neurodegenerative Diseases, Magdeburg, Germany
    2. Department for Auditory Learning and Speech, Leibniz Institute for Neurobiology, Magdeburg, Germany
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  • Eckart D. Gundelfinger,

    1. Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
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  • Wolfgang Tischmeyer

    1. Special Lab Molecular Biological Techniques, Leibniz Institute for Neurobiology, Brenneckestrasse 6, D-39118 Magdeburg, Germany
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W. Tischmeyer, as above.
E-mail: tischmeyer@lin-magdeburg.de

Abstract

In Mongolian gerbils, the auditory cortex is critical for discriminating rising vs. falling frequency-modulated tones. Based on our previous studies, we hypothesized that dopaminergic inputs to the auditory cortex during and shortly after acquisition of the discrimination strategy control long-term memory formation. To test this hypothesis, we studied frequency-modulated tone discrimination learning of gerbils in a shuttle box GO/NO-GO procedure following differential treatments. (i) Pre-exposure of gerbils to the frequency-modulated tones at 1 day before the first discrimination training session severely impaired the accuracy of the discrimination acquired in that session during the initial trials of a second training session, performed 1 day later. (ii) Local injection of the D1/D5 dopamine receptor antagonist SCH-23390 into the auditory cortex after task acquisition caused a discrimination deficit of similar extent and time course as with pre-exposure. This effect was dependent on the dose and time point of injection. (iii) Injection of the D1/D5 dopamine receptor agonist SKF-38393 into the auditory cortex after retraining caused a further discrimination improvement at the beginning of subsequent sessions. All three treatments, which supposedly interfered with dopamine signalling during conditioning and/or retraining, had a substantial impact on the dynamics of the discrimination performance particularly at the beginning of subsequent training sessions. These findings suggest that auditory-cortical dopamine activity after acquisition of a discrimination of complex sounds and after retrieval of weak frequency-modulated tone discrimination memory further improves memory consolidation, i.e. the correct association of two sounds with their respective GO/NO-GO meaning, in support of future memory recall.

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