title: Dopamine modulates memory consolidation of discrimination learning in the auditory cortex.
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.
authors.affiliation: Special Lab Molecular Biological Techniques, Leibniz Institute for Neurobiology, Brenneckestrasse 6, D-39118 Magdeburg, Germany.
authors.forename: Horst
authors.initials: H
authors.lastname: Schicknick
authors.forename: Nicole
authors.initials: N
authors.lastname: Reichenbach
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Smalla
authors.forename: Henning
authors.initials: H
authors.lastname: Scheich
authors.forename: Eckart D
authors.initials: ED
authors.lastname: Gundelfinger
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Tischmeyer
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000161:Acoustic Stimulation / Q000379:methods*; D000818:Animals; D001303:Auditory Cortex / Q000187:drug effects / Q000502:physiology*; D001552:Benzazepines / Q000494:pharmacology; D004193:Discrimination Learning / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005849:Gerbillinae; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*
chemical_list: D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; C534628:SCH 23390; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D004298:Dopamine