Different roles for M1 and M2 receptors within perirhinal cortex in object recognition and discrimination.
Recognition and discrimination of objects and individuals are critical cognitive faculties in both humans and non-human animals, and cholinergic transmission has been shown to be essential for both of these functions. In the present study we focused on the role of M1 and M2 muscarinic receptors in perirhinal cortex (PRh)-dependent object recognition and discrimination. The selective M1 antagonists pirenzepine and the snake toxin MT-7, and a selective M2 antagonist, AF-DX 116, were infused directly into PRh. Pre-sample infusions of both pirenzepine and AF-DX 116 significantly impaired object recognition memory in a delay-dependent manner. However, pirenzepine and MT-7, but not AF-DX 116, impaired oddity discrimination performance in a perceptual difficulty-dependent manner. The findings indicate distinct functions for M1 and M2 receptors in object recognition and discrimination.
Department of Experimental Psychology, University of Cambridge, Downing St., Cambridge CB2 3EB, UK; MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK. Electronic address: susan.bartko.winters@gmail.com.
Susan J
SJ
Bartko
Department of Psychology and Collaborative Neuroscience Program, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Boyer D
BD
Winters
Department of Experimental Psychology, University of Cambridge, Downing St., Cambridge CB2 3EB, UK; MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK.
Lisa M
LM
Saksida
Department of Experimental Psychology, University of Cambridge, Downing St., Cambridge CB2 3EB, UK; MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK.
Timothy J
TJ
Bussey
D000818:Animals; D004192:Discrimination, Psychological / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D051381:Rats; D043643:Receptor, Muscarinic M1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D043585:Receptor, Muscarinic M2 / Q000037:antagonists & inhibitors / Q000502:physiology*; D021641:Recognition, Psychology / Q000187:drug effects / Q000502:physiology*; D013702:Temporal Lobe / Q000187:drug effects / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
D018727:Muscarinic Antagonists; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2
AF-DX 116; Medial temporal lobe; Muscarinic receptor; Muscarinic subtypes; Muscarinic toxin 7; Pirenzepine