title: What are the elements of motivation for acquisition of conditioned taste aversion?
abstract: The pond snail Lymnaea stagnalis is capable of being classically conditioned to avoid food and to consolidate this aversion into a long-term memory (LTM). Previous studies have shown that the length of food deprivation is important for both the acquisition of taste aversion and its consolidation into LTM, which is referred to as conditioned taste aversion (CTA). Here we tested the hypothesis that the hemolymph glucose concentration is an important factor in the learning and memory of CTA. One-day food deprivation resulted in the best learning and memory, whereas more prolonged food deprivation had diminishing effects. Five-day food deprivation resulted in snails incapable of learning or remembering. During this food deprivation period, the hemolymph glucose concentration decreased. If snails were fed for 2days following the 5-day food deprivation, their glucose levels increased significantly and they exhibited both learning and memory, but neither learning nor memory was as good as with the 1-day food-deprived snails. Injection of the snails with insulin to reduce glucose levels resulted in better learning and memory. Insulin is also known to cause a long-term enhancement of synaptic transmission between the feeding-related neurons. On the other hand, injection of glucose into 5-day food-deprived snails did not alter their inability to learn and remember. However, if these snails were fed on sucrose for 3min, they then exhibited learning and memory formation. Our data suggest that hemolymph glucose concentration is an important factor in motivating acquisition of CTA in Lymnaea and that the action of insulin in the brain and the feeding behavior are also important factors.
authors.affiliation: Department of Nano Material and Bio Engineering, Faculty of Science and Engineering, Tokushima Bunri University, Sanuki 769-2193, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Mita
authors.affiliation: Cellular and Structural Physiology Institute, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Okuta
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okada
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Hatakeyama
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Otsuka
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Yamagishi
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Morikawa
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Naganuma
authors.affiliation: Department of Systems Neuroscience, School of Medicine, Sapporo Medical University, Sapporo 060-8556, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Fujito
authors.affiliation: Laboratory of Comparative Physiology, Institute for Developmental Biology, RAS, Moscow 119909, Russia.
authors.forename: Varvara
authors.initials: V
authors.lastname: Dyakonova
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
authors.forename: Ken
authors.initials: K
authors.lastname: Lukowiak
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan. Electronic address: eito@kph.bunri-u.ac.jp.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Ito
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D001786:Blood Glucose / Q000032:analysis; D003214:Conditioning, Classical / Q000502:physiology*; D005508:Food Deprivation / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology; D006458:Hemolymph / Q000737:chemistry; D008195:Lymnaea; D008568:Memory / Q000187:drug effects / Q000502:physiology; D009042:Motivation / Q000502:physiology*; D013395:Sucrose / Q000494:pharmacology; D013649:Taste / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D013395:Sucrose; D005947:Glucose
keywords: Conditioned taste aversion; Deprivation; Glucose; Hemolymph; Insulin; Lymnaea; Motivation; Sucrose