title: Role of Muscarinic Acetylcholine Receptors in Serial Feature-Positive Discrimination Task during Eyeblink Conditioning in Mice.
abstract: We investigated the role of muscarinic acetylcholine receptors (mAChRs) in eyeblink serial feature-positive discrimination learning in mice using the mAChR antagonist. A 2-s light cue was delivered 5 or 6 s before the presentation of a 350-ms tone paired with a 100-ms periorbital electrical shock (cued trial) but not before the tone-alone presentation (non-cued trial). Mice received 30 cued and 30 non-cued trials each day in a random order. We found that saline-injected control mice were successfully discriminating between cued and non-cued trials within a few days of conditioning. The mice responded more frequently to the tone in cued trials than in non-cued trials. Analysis of conditioned response (CR) dynamics revealed that the CR onset latency was shorter in cued trials than in non-cued trials, despite the CR peak amplitude not differing significantly between the two conditions. In contrast, scopolamine-injected mice developed an equal number of CRs with similar temporal patterns irrespective of the presence of the cue during the 7 days of conditioning, indicating in a failure to acquire conditional discrimination. In addition, the scopolamine administration to the control mice after they had successfully acquired discrimination did not impair the conditional discrimination and expression of pre-acquired CR. These results suggest that mAChRs may play a pivotal role in memory formation in the conditional brain state associated with the feature cue; however they are unlikely to be involved in the development of discrimination after conditional memory had formed in the serial feature-positive discrimination task during eyeblink conditioning.
authors.affiliation: Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan.
authors.forename: Md Ashrafur
authors.initials: MA
authors.lastname: Rahman
authors.affiliation: Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan.
authors.forename: Norifumi
authors.initials: N
authors.lastname: Tanaka
authors.affiliation: Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan.|Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Usui
authors.affiliation: Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan.|Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Kawahara
mesh_terms: D000818:Animals; D003215:Conditioning, Eyelid / Q000187:drug effects / Q000502:physiology*; D004193:Discrimination Learning / Q000187:drug effects / Q000502:physiology; D004576:Electromyography; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018727:Muscarinic Antagonists / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012601:Scopolamine / Q000494:pharmacology
chemical_list: D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D012601:Scopolamine
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