Muscarinic cholinergic receptors and odor discrimination and learning in mice.

Abstract

Event Abstract Back to Event Muscarinic cholinergic receptors and odor discrimination and learning in mice. Ricardo C. Araneda1*, Robert K. Maurer1 and Wilson Chan1 1 University of Maryland, Biology, United States The olfactory system enables the proper execution of behaviors that are critical for survival of mammals and the olfactory bulb (OB) is the site where initial odor information processing occurs. Reciprocal and lateral inhibition mediated by dendrodendritic synapses between mitral (MCs) and granule cells (GCs) is an important mechanism in OB processing and modulation of these synapses by the cholinergic system is important for odor discrimination and olfactory learning. Acetylcholine modulates several brain functions including learning and attention through the activation of two different receptor subtypes, nicotinic and muscarinic receptors (mAChR). Previous studies from our lab have shown that activation of the M1-mAChR subtype increases the excitability of GCs, which enhances the inhibitory input onto MCs, suggesting an important role for M1-mAChRs in olfactory behavior (Smith and Araneda, 2009). Here, we examine the behavioral consequences of disrupting cholinergic function in mice lacking specific mAChRs subtypes. To evaluate olfactory function we utilized two testing paradigms, the habituation-dishabituation (H-D) and the hidden-cookie tests, which rely on short and long-term memory, respectively. Using the H-D test we find that unlike the wild-type, mice lacking the M1 mAChR subtype fail to discriminate odor molecules differing by one single carbon. Moreover, wild-type and M1 k.o. mice cannot discriminate between pairs of enantiomers of carvone. However, the M1 k.o. mice can learn to discriminate these odors when they are associated with a reward in the hidden-cookie test albeit with a slower learning curve than wild type. Visual discrimination, response to aversive odors and response to complex social odors was not affected in the M1 k.o. mice, indicating that disruption of these receptors does not impair general sensory function. These results further support the involvement of M1 mAchRs in olfactory discrimination, a sensory property emerging from the concerted activity of neuronal circuitry in the OB. Our results suggest that activation of these receptors is necessary for the short term odor memory. Acknowledgements NIDCD Grant DC RO1-DC-009817 to R.C. Araneda and HHMI Undergraduate Research Fellowship to R. K. Maurer References Smith, R.S. and Araneda, RC (2010). "Cholinergic modulation of neuronal excitability in the accessory olfactory bulb." J. Neurophys. 104(6): 2963-74. Keywords: Acetylcholine, dendrodendritc synapses, granule cell, Neuromodulation, Olfactory Bulb Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for Participant Symposium) Topic: Sensory: Olfaction and Taste Citation: Araneda RC, Maurer RK and Chan W (2012). Muscarinic cholinergic receptors and odor discrimination and learning in mice.. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00369 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 May 2012; Published Online: 07 Jul 2012. * Correspondence: Dr. Ricardo C Araneda, University of Maryland, Biology, College Park, MD, 20742, United States, raraneda@umd.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Ricardo C Araneda Robert K Maurer Wilson Chan Google Ricardo C Araneda Robert K Maurer Wilson Chan Google Scholar Ricardo C Araneda Robert K Maurer Wilson Chan PubMed Ricardo C Araneda Robert K Maurer Wilson Chan Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.