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Hatakeyama D, Sunada H, Totani Y, Watanabe T, Felletár I, Fitchett A, Eravci M, Anagnostopoulou A, Miki R, Okada A, Abe N, Kuzuhara T, Kemenes I, Ito E, Kemenes G. Molecular and functional characterization of an evolutionarily conserved CREB-binding protein in the Lymnaea CNS. FASEB J 2022; 36:e22593. [PMID: 36251357 PMCID: PMC9828244 DOI: 10.1096/fj.202101225rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/30/2022] [Accepted: 09/26/2022] [Indexed: 01/12/2023]
Abstract
In eukaryotes, CREB-binding protein (CBP), a coactivator of CREB, functions both as a platform for recruiting other components of the transcriptional machinery and as a histone acetyltransferase (HAT) that alters chromatin structure. We previously showed that the transcriptional activity of cAMP-responsive element binding protein (CREB) plays a crucial role in neuronal plasticity in the pond snail Lymnaea stagnalis. However, there is no information on the molecular structure and HAT activity of CBP in the Lymnaea central nervous system (CNS), hindering an investigation of its postulated role in long-term memory (LTM). Here, we characterize the Lymnaea CBP (LymCBP) gene and identify a conserved domain of LymCBP as a functional HAT. Like CBPs of other species, LymCBP possesses functional domains, such as the KIX domain, which is essential for interaction with CREB and was shown to regulate LTM. In-situ hybridization showed that the staining patterns of LymCBP mRNA in CNS are very similar to those of Lymnaea CREB1. A particularly strong LymCBP mRNA signal was observed in the cerebral giant cell (CGC), an identified extrinsic modulatory interneuron of the feeding circuit, the key to both appetitive and aversive LTM for taste. Biochemical experiments using the recombinant protein of the LymCBP HAT domain showed that its enzymatic activity was blocked by classical HAT inhibitors. Preincubation of the CNS with such inhibitors blocked cAMP-induced synaptic facilitation between the CGC and an identified follower motoneuron of the feeding system. Taken together, our findings suggest a role for the HAT activity of LymCBP in synaptic plasticity in the feeding circuitry.
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Affiliation(s)
- Dai Hatakeyama
- Sussex NeuroscienceSchool of Life Sciences, University of SussexBrightonUK,Faculty of Pharmaceutical SciencesTokushima Bunri UniversityTokushimaJapan
| | - Hiroshi Sunada
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri UniversitySanukiJapan,Present address:
Advanced Medicine, Innovation and Clinical Research CentreTottori University HospitalYonagoJapan
| | - Yuki Totani
- Department of BiologyWaseda UniversityTokyoJapan
| | | | - Ildikó Felletár
- Sussex NeuroscienceSchool of Life Sciences, University of SussexBrightonUK
| | - Adam Fitchett
- Sussex NeuroscienceSchool of Life Sciences, University of SussexBrightonUK
| | - Murat Eravci
- Sussex NeuroscienceSchool of Life Sciences, University of SussexBrightonUK
| | - Aikaterini Anagnostopoulou
- Sussex NeuroscienceSchool of Life Sciences, University of SussexBrightonUK,Present address:
School of Life SciencesUniversity of WestminsterLondonUK
| | - Ryosuke Miki
- Faculty of Pharmaceutical SciencesTokushima Bunri UniversityTokushimaJapan
| | - Ayano Okada
- Faculty of Pharmaceutical SciencesTokushima Bunri UniversityTokushimaJapan
| | - Naoya Abe
- Faculty of Pharmaceutical SciencesTokushima Bunri UniversityTokushimaJapan
| | - Takashi Kuzuhara
- Faculty of Pharmaceutical SciencesTokushima Bunri UniversityTokushimaJapan
| | - Ildikó Kemenes
- Sussex NeuroscienceSchool of Life Sciences, University of SussexBrightonUK
| | - Etsuro Ito
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri UniversitySanukiJapan,Department of BiologyWaseda UniversityTokyoJapan
| | - György Kemenes
- Sussex NeuroscienceSchool of Life Sciences, University of SussexBrightonUK
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Itoh A, Komatsuzaki Y, Lukowiak K, Saito M. Epicatechin increases the persistence of long-term memory formed by conditioned taste aversion in Lymnaea. J Exp Biol 2021; 224:jeb238055. [PMID: 33443041 DOI: 10.1242/jeb.238055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 12/15/2020] [Indexed: 12/15/2022]
Abstract
We examined the effects of epicatechin (Epi), a flavonoid abundant in green tea and cocoa, on long-term memory (LTM) formed following conditioned taste aversion (CTA) training in Lymnaeastagnalis In CTA training, the snails learnt to avoid a food that initially they liked (i.e. sucrose). Twenty-four hours after CTA training, 67% of the trained snails showed a significant decrease in the feeding behaviour elicited by sucrose. Placing snails in the Epi solution in CTA training did not alter the percentage of snails exhibiting LTM, but it significantly increased LTM persistence. We also examined changes following Epi exposure in spontaneous activity of the cerebral giant cells (CGCs) that modulate feeding behaviour and are necessary for CTA-LTM. Our data suggest that Epi causes a decrease in CGC activity and increases LTM persistence, possibly via a GABAergic mechanism.
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Affiliation(s)
- Ayaka Itoh
- Department of Correlative Study in Physics and Chemistry, Graduate School of Integrated Basic Sciences, Nihon University, 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
| | - Yoshimasa Komatsuzaki
- Department of Physics, College of Science and Technology, Nihon University, 1-8-14 Kandasurugadai, Chiyoda-ku, Tokyo 101-8308, Japan
| | - Ken Lukowiak
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1
| | - Minoru Saito
- Department of Correlative Study in Physics and Chemistry, Graduate School of Integrated Basic Sciences, Nihon University, 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
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Totani Y, Aonuma H, Oike A, Watanabe T, Hatakeyama D, Sakakibara M, Lukowiak K, Ito E. Monoamines, Insulin and the Roles They Play in Associative Learning in Pond Snails. Front Behav Neurosci 2019; 13:65. [PMID: 31001093 PMCID: PMC6454038 DOI: 10.3389/fnbeh.2019.00065] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 03/14/2019] [Indexed: 12/28/2022] Open
Abstract
Molluscan gastropods have long been used for studying the cellular and molecular mechanisms underlying learning and memory. One such gastropod, the pond snail Lymnaea stagnalis, exhibits long-term memory (LTM) following both classical and operant conditioning. Using Lymnaea, we have successfully elucidated cellular mechanisms of learning and memory utilizing an aversive classical conditioning procedure, conditioned taste aversion (CTA). Here, we present the behavioral changes following CTA training and show that the memory score depends on the duration of food deprivation. Then, we describe the relationship between the memory scores and the monoamine contents of the central nervous system (CNS). A comparison of learning capability in two different strains of Lymnaea, as well as the filial 1 (F1) cross from the two strains, presents how the memory scores are correlated in these populations with monoamine contents. Overall, when the memory scores are better, the monoamine contents of the CNS are lower. We also found that as the insulin content of the CNS decreases so does the monoamine contents which are correlated with higher memory scores. The present review deepens the relationship between monoamine and insulin contents with the memory score.
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Affiliation(s)
- Yuki Totani
- Department of Biology, Waseda University, Tokyo, Japan
| | - Hitoshi Aonuma
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
- CREST, Japan Science and Technology Agency, Kawaguchi, Japan
| | - Akira Oike
- Department of Biology, Waseda University, Tokyo, Japan
| | - Takayuki Watanabe
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Dai Hatakeyama
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Manabu Sakakibara
- Research Organization for Nano and Life Innovation, Waseda University, Tokyo, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Etsuro Ito
- Department of Biology, Waseda University, Tokyo, Japan
- Research Organization for Nano and Life Innovation, Waseda University, Tokyo, Japan
- Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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Aonuma H, Totani Y, Sakakibara M, Lukowiak K, Ito E. Comparison of brain monoamine content in three populations of Lymnaea that correlates with taste-aversive learning ability. Biophys Physicobiol 2018; 15:129-135. [PMID: 29955564 PMCID: PMC6018436 DOI: 10.2142/biophysico.15.0_129] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 04/20/2018] [Indexed: 12/01/2022] Open
Abstract
To find a causal mechanism of learning and memory is a heuristically important topic in neuroscience. In the pond snail Lymnaea stagnalis, the following experimental facts have accrued regarding a classical conditioning procedure known as conditioned taste aversion (CTA): (1) one-day food-deprived Dutch snails have superior CTA memory formation; (2) the one-day food-deprived snails have a low monoamine content (e.g., serotonin, dopamine, octopamine) in their central nervous system (CNS); (3) fed or five-day food-deprived snails have poorer CTA memory and a higher monoamine content; (4) the Dutch snails form better CTA memory than the Canadian TC1 strain; and, (5) the F1 cross snails between the Dutch and Canadian TC1 strains also form poor CTA memory. Here, in one-day food-deprived snails, we measured the monoamine content in the CNSs of the 3 populations. In most instances, the monoamine content of the Dutch strain was lower than in the other two populations. The F1 cross snails had the highest monoamine content. A lower monoamine content is correlated with the better CTA memory formation.
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Affiliation(s)
- Hitoshi Aonuma
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 060-0811, Japan.,CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Yuki Totani
- Department of Biology, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Manabu Sakakibara
- Research Organization for Nano and Life Innovation, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Etsuro Ito
- Department of Biology, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan.,Research Organization for Nano and Life Innovation, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan.,WASEDA Bioscience Research Institute in Singapore, 138667, Singapore.,Graduate Institute of Medicine and Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
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Aonuma H, Totani Y, Kaneda M, Nakamura R, Watanabe T, Hatakeyama D, Dyakonova VE, Lukowiak K, Ito E. Effects of 5-HT and insulin on learning and memory formation in food-deprived snails. Neurobiol Learn Mem 2018; 148:20-29. [DOI: 10.1016/j.nlm.2017.12.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 12/08/2017] [Accepted: 12/29/2017] [Indexed: 01/20/2023]
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Affiliation(s)
- E. Ito
- Department of Biology, Waseda University , Tokyo, Japan
| | - Y. Totani
- Department of Biology, Waseda University , Tokyo, Japan
| | - A. Oike
- Department of Biology, Waseda University , Tokyo, Japan
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Aonuma H, Kaneda M, Hatakeyama D, Watanabe T, Lukowiak K, Ito E. Weak involvement of octopamine in aversive taste learning in a snail. Neurobiol Learn Mem 2017; 141:189-198. [DOI: 10.1016/j.nlm.2017.04.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 04/20/2017] [Accepted: 04/23/2017] [Indexed: 01/06/2023]
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8
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Sunada H, Lukowiak K, Ito E. Cerebral Giant Cells are Necessary for the Formation and Recall of Memory of Conditioned Taste Aversion inLymnaea. Zoolog Sci 2017; 34:72-80. [DOI: 10.2108/zs160152] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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9
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Aonuma H, Kaneda M, Hatakeyama D, Watanabe T, Lukowiak K, Ito E. Relationship between the grades of a learned aversive-feeding response and the dopamine contents in Lymnaea. Biol Open 2016; 5:1869-1873. [PMID: 27815244 PMCID: PMC5200912 DOI: 10.1242/bio.021634] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pond snail Lymnaea learns conditioned taste aversion (CTA) and remembers not to respond to food substances that initially cause a feeding response. The possible relationship between how well snails learn to follow taste-aversion training and brain dopamine contents is not known. We examined this relationship and found the following: first, snails in the act of eating just before the commencement of CTA training were poor learners and had the highest dopamine contents in the brain; second, snails which had an ad libitum access to food, but were not eating just before training, were average learners and had lower dopamine contents; third, snails food-deprived for one day before training were the best learners and had significantly lower contents of dopamine compared to the previous two cohorts. There was a negative correlation between the CTA grades and the brain dopamine contents in these three cohorts. Fourth, snails food-deprived for five days before training were poor learners and had higher dopamine contents. Thus, severe hunger increased the dopamine content in the brain. Because dopamine functions as a reward transmitter, CTA in the severely deprived snails (i.e. the fourth cohort) was thought to be mitigated by a high dopamine content.
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Affiliation(s)
- Hitoshi Aonuma
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo 060-0811, Japan.,CREST, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Mugiho Kaneda
- Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan
| | - Dai Hatakeyama
- Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan
| | - Takayuki Watanabe
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo 060-0811, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Etsuro Ito
- Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki 769-2193, Japan .,Department of Biology, Waseda University, Shinjuku, Tokyo 162-8480, Japan
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10
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Function of insulin in snail brain in associative learning. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2015; 201:969-81. [PMID: 26233474 DOI: 10.1007/s00359-015-1032-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 07/23/2015] [Accepted: 07/24/2015] [Indexed: 12/23/2022]
Abstract
Insulin is well known as a hormone regulating glucose homeostasis across phyla. Although there are insulin-independent mechanisms for glucose uptake in the mammalian brain, which had contributed to a perception of the brain as an insulin-insensitive organ for decades, the finding of insulin and its receptors in the brain revolutionized the concept of insulin signaling in the brain. However, insulin's role in brain functions, such as cognition, attention, and memory, remains unknown. Studies using invertebrates with their open blood-vascular system have the promise of promoting a better understanding of the role played by insulin in mediating/modulating cognitive functions. In this review, the relationship between insulin and its impact on long-term memory (LTM) is discussed particularly in snails. The pond snail Lymnaea stagnalis has the ability to undergo conditioned taste aversion (CTA), that is, it associatively learns and forms LTM not to respond with a feeding response to a food that normally elicits a robust feeding response. We show that molluscan insulin-related peptides are up-regulated in snails exhibiting CTA-LTM and play a key role in the causal neural basis of CTA-LTM. We also survey the relevant literature of the roles played by insulin in learning and memory in other phyla.
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11
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Frost W, Brandon C, Bruno A, Humphries M, Moore-Kochlacs C, Sejnowski T, Wang J, Hill E. Monitoring Spiking Activity of Many Individual Neurons in Invertebrate Ganglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:127-45. [PMID: 26238051 PMCID: PMC4560204 DOI: 10.1007/978-3-319-17641-3_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Optical recording with fast voltage sensitive dyes makes it possible, in suitable preparations, to simultaneously monitor the action potentials of large numbers of individual neurons. Here we describe methods for doing this, including considerations of different dyes and imaging systems, methods for correlating the optical signals with their source neurons, procedures for getting good signals, and the use of Independent Component Analysis for spike-sorting raw optical data into single neuron traces. These combined tools represent a powerful approach for large-scale recording of neural networks with high temporal and spatial resolution.
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Affiliation(s)
- W.N. Frost
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - C.J. Brandon
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - A.M. Bruno
- Department of Neuroscience, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - M.D. Humphries
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - C. Moore-Kochlacs
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA,McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - T.J. Sejnowski
- Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA,Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - J. Wang
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - E.S. Hill
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA
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Sunada H, Takigami S, Lukowiak K, Sakakibara M. Electrophysiological characteristics of feeding-related neurons after taste avoidance Pavlovian conditioning in Lymnaea stagnalis. Biophysics (Nagoya-shi) 2014; 10:121-33. [PMID: 27493506 PMCID: PMC4629664 DOI: 10.2142/biophysics.10.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 11/20/2014] [Indexed: 01/14/2023] Open
Abstract
Taste avoidance conditioning (TAC) was carried out on the pond snail, Lymnaea stagnalis. The conditional stimulus (CS) was sucrose which elicits feeding behavior; while the unconditional stimulus (US) was a tactile stimulus to the head which causes feeding to be suppressed. The neuronal circuit that drives feeding behavior in Lymnaea is well worked out. We therefore compared the physiological characteristics on 3 classes of neurons involved with feeding behavior especially in response to the CS in conditioned vs. control snails. The cerebral giant cell (CGC) modulates feeding behavior, N1 medial neuron (N1M) is one of the central pattern generator neurons that organizes feeding behavior, while B3 is a motor neuron active during the rasp phase of feeding. We found the resting membrane potential in CGC was hyperpolarized significantly in conditioned snails but impulse activity remained the same between conditioned vs. control snails. There was, however, a significant increase in spontaneous activity and a significant depolarization of N1M’s resting membrane potential in conditioned snails. These changes in N1M activity as a result of training are thought to be due to withdrawal interneuron RPeD11 altering the activity of the CGCs. Finally, in B3 there was: 1) a significant decrease in the amplitude and the frequency of the post-synaptic potentials; 2) a significant hyperpolarization of resting membrane potential in conditioned snails; and 3) a disappearance of bursting activity typically initiated by the CS. These neuronal modifications are consistent with the behavioral phenotype elicited by the CS following conditioning.
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Affiliation(s)
- Hiroshi Sunada
- Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Satoshi Takigami
- Course of Bioscience, Graduate School of Bioscience, Tokai University, Graduate School, 317 Nishino, Numazu 410-0321, Shizuoka, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Manabu Sakakibara
- Course of Bioscience, Graduate School of Bioscience, Tokai University, Graduate School, 317 Nishino, Numazu 410-0321, Shizuoka, Japan; Department of Biological Science and Technology, School of High-Technology for Human Welfare, Tokai University, 317 Nishino, Numazu 410-0321, Shizuoka, Japan
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Ito E, Kojima S, Lukowiak K, Sakakibara M. From likes to dislikes: conditioned taste aversion in the great pond snail (Lymnaea stagnalis). CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0292] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The neural circuitry comprising the central pattern generator (CPG) that drives feeding behavior in the great pond snail (Lymnaea stagnalis (L., 1758)) has been worked out. Because the feeding behavior undergoes associative learning and long-term memory (LTM) formation, it provides an excellent opportunity to study the causal neuronal mechanisms of these two processes. In this review, we explore some of the possible causal neuronal mechanisms of associative learning of conditioned taste aversion (CTA) and its subsequent consolidation processes into LTM in L. stagnalis. In the CTA training procedure, a sucrose solution, which evokes a feeding response, is used as the conditioned stimulus (CS) and a potassium chloride solution, which causes a withdrawal response, is used as the unconditioned stimulus (US). The pairing of the CS–US alters both the feeding response of the snail and the function of a pair of higher order interneurons in the cerebral ganglia. Following the acquisition of CTA, the polysynaptic inhibitory synaptic input from the higher order interneurons onto the feeding CPG neurons is enhanced, resulting in suppression of the feeding response. These changes in synaptic efficacy are thought to constitute a “memory trace” for CTA in L. stagnalis.
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Affiliation(s)
- E. Ito
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki 769-2193, Japan
| | - S. Kojima
- Sandler Neurosciences Center, University of California, San Francisco, 675 Nelson Rising Lane 518, San Francisco, CA 94143-0444, USA
| | - K. Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - M. Sakakibara
- School of High-Technology for Human Welfare, Tokai University, 317 Nishino, Numazu 410-0321, Japan
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Involvement of insulin-like peptide in long-term synaptic plasticity and long-term memory of the pond snail Lymnaea stagnalis. J Neurosci 2013; 33:371-83. [PMID: 23283349 DOI: 10.1523/jneurosci.0679-12.2013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The pond snail Lymnaea stagnalis is capable of learning taste aversion and consolidating this learning into long-term memory (LTM) that is called conditioned taste aversion (CTA). Previous studies showed that some molluscan insulin-related peptides (MIPs) were upregulated in snails exhibiting CTA. We thus hypothesized that MIPs play an important role in neurons underlying the CTA-LTM consolidation process. To examine this hypothesis, we first observed the distribution of MIP II, a major peptide of MIPs, and MIP receptor and determined the amounts of their mRNAs in the CNS. MIP II was only observed in the light green cells in the cerebral ganglia, but the MIP receptor was distributed throughout the entire CNS, including the buccal ganglia. Next, when we applied exogenous mammalian insulin, secretions from MIP-containing cells or partially purified MIPs, to the isolated CNS, we observed a long-term change in synaptic efficacy (i.e., enhancement) of the synaptic connection between the cerebral giant cell (a key interneuron for CTA) and the B1 motor neuron (a buccal motor neuron). This synaptic enhancement was blocked by application of an insulin receptor antibody to the isolated CNS. Finally, injection of the insulin receptor antibody into the snail before CTA training, while not blocking the acquisition of taste aversion learning, blocked the memory consolidation process; thus, LTM was not observed. These data suggest that MIPs trigger changes in synaptic connectivity that may be correlated with the consolidation of taste aversion learning into CTA-LTM in the Lymnaea CNS.
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Kemenes G. Molecular and Cellular Mechanisms of Classical Conditioning in the Feeding System of Lymnaea. INVERTEBRATE LEARNING AND MEMORY 2013. [DOI: 10.1016/b978-0-12-415823-8.00020-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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16
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Otsuka E, Matsunaga M, Okada R, Yamagishi M, Okuta A, Lukowiak K, Ito E. Increase in cyclic AMP concentration in a cerebral giant interneuron mimics part of a memory trace for conditioned taste aversion of the pond snail. Biophysics (Nagoya-shi) 2013; 9:161-6. [PMID: 27493554 PMCID: PMC4629678 DOI: 10.2142/biophysics.9.161] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 10/18/2013] [Indexed: 12/02/2022] Open
Abstract
Conditioned taste aversion (CTA) can be classically conditioned in the pond snail Lymnaea stagnalis and subsequently be consolidated into long-term memory (LTM). The neural trace that subserves CTA-LTM can be summarized as follows: A polysynaptic inhibitory postsynaptic potential recorded in the neuron 1 medial (N1M) cell in the conditioned snails as a result of activation of the cerebral giant cell (CGC) is larger and lasts longer than that in control snails. The N1M cell is ultimately activated by the CGC via the neuron 3 tonic (N3t) cell. That is, the inhibitory monosynaptic inputs from the N3t cell to the N1M cell are facilitated. The N1M and N3t cells are the members of feeding central pattern generator, whereas the CGC is a multimodal interneuron thought to play a key role in feeding behavior. Here we examined the involvement of a second messenger, cAMP, in the establishment of the memory trace. We injected cAMP into the CGC and monitored the potentials of the B3 motor neuron activated by the CGC. B3 activity is used as an index for the synaptic inputs from the N3t cell to the N1M cell. We found that the B3 potentials were transiently enlarged. Thus, when the cAMP concentration is increased in the CGC by taste aversion training, cAMP-induced changes may play a key role in the establishment of a memory trace in the N3t cell.
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Affiliation(s)
- Emi Otsuka
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Miho Matsunaga
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Ryuichi Okada
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Miki Yamagishi
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
| | - Akiko Okuta
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Etsuro Ito
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan
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Ito E, Otsuka E, Hama N, Aonuma H, Okada R, Hatakeyama D, Fujito Y, Kobayashi S. Memory trace in feeding neural circuitry underlying conditioned taste aversion in Lymnaea. PLoS One 2012; 7:e43151. [PMID: 22900097 PMCID: PMC3416747 DOI: 10.1371/journal.pone.0043151] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 07/17/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The pond snail Lymnaea stagnalis can maintain a conditioned taste aversion (CTA) as a long-term memory. Previous studies have shown that the inhibitory postsynaptic potential (IPSP) evoked in the neuron 1 medial (N1M) cell by activation of the cerebral giant cell (CGC) in taste aversion-trained snails was larger and lasted longer than that in control snails. The N1M cell is one of the interneurons in the feeding central pattern generator (CPG), and the CGC is a key regulatory neuron for the feeding CPG. METHODOLOGY/PRINCIPLE FINDINGS Previous studies have suggested that the neural circuit between the CGC and the N1M cell consists of two synaptic connections: (1) the excitatory connection from the CGC to the neuron 3 tonic (N3t) cell and (2) the inhibitory connection from the N3t cell to the N1M cell. However, because the N3t cell is too small to access consistently by electrophysiological methods, in the present study the synaptic inputs from the CGC to the N3t cell and those from the N3t cell to the N1M cell were monitored as the monosynaptic excitatory postsynaptic potential (EPSP) recorded in the large B1 and B3 motor neurons, respectively. The evoked monosynaptic EPSPs of the B1 motor neurons in the brains isolated from the taste aversion-trained snails were identical to those in the control snails, whereas the spontaneous monosynaptic EPSPs of the B3 motor neurons were significantly enlarged. CONCLUSION/SIGNIFICANCE These results suggest that, after taste aversion training, the monosynaptic inputs from the N3t cell to the following neurons including the N1M cell are specifically facilitated. That is, one of the memory traces for taste aversion remains as an increase in neurotransmitter released from the N3t cell. We thus conclude that the N3t cell suppresses the N1M cell in the feeding CPG, in response to the conditioned stimulus in Lymnaea CTA.
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Affiliation(s)
- Etsuro Ito
- Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan.
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18
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Harris CA, Buckley CL, Nowotny T, Passaro PA, Seth AK, Kemenes G, O'Shea M. Multi-neuronal refractory period adapts centrally generated behaviour to reward. PLoS One 2012; 7:e42493. [PMID: 22860134 PMCID: PMC3409166 DOI: 10.1371/journal.pone.0042493] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/06/2012] [Indexed: 11/18/2022] Open
Abstract
Oscillating neuronal circuits, known as central pattern generators (CPGs), are responsible for generating rhythmic behaviours such as walking, breathing and chewing. The CPG model alone however does not account for the ability of animals to adapt their future behaviour to changes in the sensory environment that signal reward. Here, using multi-electrode array (MEA) recording in an established experimental model of centrally generated rhythmic behaviour we show that the feeding CPG of Lymnaea stagnalis is itself associated with another, and hitherto unidentified, oscillating neuronal population. This extra-CPG oscillator is characterised by high population-wide activity alternating with population-wide quiescence. During the quiescent periods the CPG is refractory to activation by food-associated stimuli. Furthermore, the duration of the refractory period predicts the timing of the next activation of the CPG, which may be minutes into the future. Rewarding food stimuli and dopamine accelerate the frequency of the extra-CPG oscillator and reduce the duration of its quiescent periods. These findings indicate that dopamine adapts future feeding behaviour to the availability of food by significantly reducing the refractory period of the brain's feeding circuitry.
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Affiliation(s)
- Christopher A. Harris
- Sussex Centre for Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- * E-mail: (CAH); (MOS)
| | | | - Thomas Nowotny
- School of Engineering and Informatics, University of Sussex, Brighton, United Kingdom
| | - Peter A. Passaro
- School of Engineering and Informatics, University of Sussex, Brighton, United Kingdom
| | - Anil K. Seth
- School of Engineering and Informatics, University of Sussex, Brighton, United Kingdom
- Sackler Centre for Consciousness Science, University of Sussex, Brighton, United Kingdom
| | - György Kemenes
- Sussex Centre for Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Michael O'Shea
- Sussex Centre for Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- * E-mail: (CAH); (MOS)
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19
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Kawai R, Kobayashi S, Fujito Y, Ito E. Multiple Subtypes of Serotonin Receptors in the Feeding Circuit of a Pond Snail. Zoolog Sci 2011; 28:517-25. [DOI: 10.2108/zsj.28.517] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Kita S, Hashiba R, Ueki S, Kimoto Y, Abe Y, Gotoda Y, Suzuki R, Uraki E, Nara N, Kanazawa A, Hatakeyama D, Kawai R, Fujito Y, Lukowiak K, Ito E. Does conditioned taste aversion learning in the pond snail Lymnaea stagnalis produce conditioned fear? THE BIOLOGICAL BULLETIN 2011; 220:71-81. [PMID: 21385959 DOI: 10.1086/bblv220n1p71] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In conditioned taste aversion (CTA) training performed on the pond snail Lymnaea stagnalis, a stimulus (the conditional stimulus, CS; e.g., sucrose) that elicits a feeding response is paired with an aversive stimulus (the unconditional stimulus, US) that elicits the whole-body withdrawal response and inhibits feeding. After CTA training and memory formation, the CS no longer elicits feeding. We hypothesize that one reason for this result is that after CTA training the CS now elicits a fear response. Consistent with this hypothesis, we predict the CS will cause (1) the heart to skip a beat and (2) a significant change in the heart rate. Such changes are seen in mammalian preparations exposed to fearful stimuli. We found that in snails exhibiting long-term memory for one-trial CTA (i.e., good learners) the CS significantly increased the probability of a skipped heartbeat, but did not significantly change the heart rate. The probability of a skipped heartbeat was unaltered in control snails given backward conditioning (US followed by CS) or in snails that did not acquire associative learning (i.e., poor learners) after the one-trial CTA training. These results suggest that as a consequence of acquiring CTA, the CS evokes conditioned fear in the conditioned snails, as evidenced by a change in the nervous system control of cardiac activity.
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Affiliation(s)
- Serina Kita
- Science Club, Hokkaido Shiraoihigashi High School, 5-17-3 Hinodemachi, Shiraoi-Cho, Japan
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21
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Hill ES, Moore-Kochlacs C, Vasireddi SK, Sejnowski TJ, Frost WN. Validation of independent component analysis for rapid spike sorting of optical recording data. J Neurophysiol 2010; 104:3721-31. [PMID: 20861441 PMCID: PMC3007652 DOI: 10.1152/jn.00691.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Independent component analysis (ICA) is a technique that can be used to extract the source signals from sets of signal mixtures where the sources themselves are unknown. The analysis of optical recordings of invertebrate neuronal networks with fast voltage-sensitive dyes could benefit greatly from ICA. These experiments can generate hundreds of voltage traces containing both redundant and mixed recordings of action potentials originating from unknown numbers of neurons. ICA can be used as a method for converting such complex data sets into single-neuron traces, but its accuracy for doing so has never been empirically evaluated. Here, we tested the accuracy of ICA for such blind source separation by simultaneously performing sharp electrode intracellular recording and fast voltage-sensitive dye imaging of neurons located in the central ganglia of Tritonia diomedea and Aplysia californica, using a 464-element photodiode array. After running ICA on the optical data sets, we found that in 34 of 34 cases the intracellularly recorded action potentials corresponded 100% to the spiking activity of one of the independent components returned by ICA. We also show that ICA can accurately sort action potentials into single neuron traces from a series of optical data files obtained at different times from the same preparation, allowing one to monitor the network participation of large numbers of individually identifiable neurons over several recording episodes. Our validation of the accuracy of ICA for extracting the neural activity of many individual neurons from noisy, mixed, and redundant optical recording data sets should enable the use of this powerful large-scale imaging approach for studies of invertebrate and suitable vertebrate neuronal networks.
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Affiliation(s)
- Evan S Hill
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA.
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22
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Cabanac M, Cabanac AJ, Parent A. The emergence of consciousness in phylogeny. Behav Brain Res 2008; 198:267-72. [PMID: 19095011 DOI: 10.1016/j.bbr.2008.11.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 11/19/2008] [Accepted: 11/20/2008] [Indexed: 11/17/2022]
Abstract
The brains of animals show chemical, anatomical, and functional differences, such as dopamine production and structure of sleep, between Amniota and older groups. In addition, play behavior, capacity to acquire taste aversion, sensory pleasure in decision making, and expression of emotional tachycardia and fever started also to be displayed by Amniota, suggesting that the brain may have began to work differently in early Amniota than in Lissamphibia and earlier vertebrates. Thus we propose that emotion, and more broadly speaking consciousness, emerged in the evolutionary line among the early Amniota. We also propose that consciousness is characterized by a common mental pathway that uses pleasure, or its counterpart displeasure, as a means to optimize behavior.
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Affiliation(s)
- Michel Cabanac
- Faculty of Medicine, Department of Physiology, Laval University, Quebec, Canada G1K 7P4.
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23
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Sugai R, Azami S, Shiga H, Watanabe T, Sadamoto H, Kobayashi S, Hatakeyama D, Fujito Y, Lukowiak K, Ito E. One-trial conditioned taste aversion in Lymnaea: good and poor performers in long-term memory acquisition. ACTA ACUST UNITED AC 2007; 210:1225-37. [PMID: 17371921 DOI: 10.1242/jeb.02735] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the majority of studies designed to elucidate the causal mechanisms of memory formation, certain members of the experimental cohort, even though subjected to exactly the same conditioning procedures, remember significantly better than others, whereas others show little or no long-term memory (LTM) formation. To begin to address the question of why this phenomenon occurs and thereby help clarify the causal mechanism of LTM formation, we used a conditioned taste aversion (CTA) procedure on individuals of the pond snail Lymnaea stagnalis and analyzed their subsequent behavior. Using sucrose as an appetitive stimulus and KCl as an aversive stimulus, we obtained a constant ratio of ;poor' to ;good' performers for CTA-LTM. We found that approximately 40% of trained snails possessed LTM following a one-trial conditioning procedure. When we examined the time-window necessary for the memory consolidation, we found that if we cooled snails to 4 degrees C for 30 min within 10 min after the one-trial conditioning, LTM was blocked. However, with delayed cooling (i.e. longer than 10 min), LTM was present. We could further interfere with LTM formation by inducing inhibitory learning (i.e. backward conditioning) after the one-trial conditioning. Finally, we examined whether we could motivate snails to acquire LTM by depriving them of food for 5 days before the one-trial conditioning. Food-deprived snails, however, failed to exhibit LTM following the one-trial conditioning. These results will help us begin to clarify why some individuals are better at learning and forming memory for specific tasks at the neuronal level.
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Affiliation(s)
- Rio Sugai
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
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24
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Martens KR, De Caigny P, Parvez K, Amarell M, Wong C, Lukowiak K. Stressful stimuli modulate memory formation in Lymnaea stagnalis. Neurobiol Learn Mem 2007; 87:391-403. [PMID: 17126571 DOI: 10.1016/j.nlm.2006.10.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Revised: 10/17/2006] [Accepted: 10/18/2006] [Indexed: 11/21/2022]
Abstract
Stress has been shown to be a strong modulator of learning and memory in animals. We employ operant training of aerial respiratory behaviour in our model system, the pond snail Lymnaea stagnalis, to show that application of an acute consistent physical stressor enhances memory formation. A single 30 min operant conditioning training session, which normally results in intermediate-term memory (ITM) persisting 3h, results in long-term memory (LTM) persisting 24h if immediately preceded or followed by a stressor, for example a 30s exposure to 25 mM KCl. Other physical stressors (0.3% quinine-HCl or quick cooling and warming) similarly enhance memory formation. The memory is context specific and is not seen after the application of too much or too little stress. The memory can be extinguished by exposing snails to the hypoxic training environment and withholding reinforcing stimuli. The LTM that results from 30 min of training and stressor exposure is dependent on de novo protein synthesis and gene transcription in a single neuron, RPeD1. Because the soma of RPeD1 must be present for memory augmentation by the application of a stressor we are well placed for future investigations to directly determine the specific molecular alterations by which stress primes the formation of LTM.
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Affiliation(s)
- Kara R Martens
- Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr NW, Calgary AB, Canada T2P 1N3
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25
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Baxter DA, Byrne JH. Feeding behavior of Aplysia: a model system for comparing cellular mechanisms of classical and operant conditioning. Learn Mem 2007; 13:669-80. [PMID: 17142299 DOI: 10.1101/lm.339206] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Feeding behavior of Aplysia provides an excellent model system for analyzing and comparing mechanisms underlying appetitive classical conditioning and reward operant conditioning. Behavioral protocols have been developed for both forms of associative learning, both of which increase the occurrence of biting following training. Because the neural circuitry that mediates the behavior is well characterized and amenable to detailed cellular analyses, substantial progress has been made toward a comparative analysis of the cellular mechanisms underlying these two forms of associative learning. Both forms of associative learning use the same reinforcement pathway (the esophageal nerve, En) and the same reinforcement transmitter (dopamine, DA). In addition, at least one cellular locus of plasticity (cell B51) is modified by both forms of associative learning. However, the two forms of associative learning have opposite effects on B51. Classical conditioning decreases the excitability of B51, whereas operant conditioning increases the excitability of B51. Thus, the approach of using two forms of associative learning to modify a single behavior, which is mediated by an analytically tractable neural circuit, is revealing similarities and differences in the mechanisms that underlie classical and operant conditioning.
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Affiliation(s)
- Douglas A Baxter
- Department of Neurobiology and Anatomy, W.M. Keck Center for the Neurobiology of Learning and Memory, The University of Texas Medical School at Houston, Houston, Texas 77030, USA.
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26
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Frost WN, Wang J, Brandon CJ. A stereo-compound hybrid microscope for combined intracellular and optical recording of invertebrate neural network activity. J Neurosci Methods 2007; 162:148-54. [PMID: 17306887 PMCID: PMC1906850 DOI: 10.1016/j.jneumeth.2007.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 12/22/2006] [Accepted: 01/04/2007] [Indexed: 10/23/2022]
Abstract
Optical recording studies of invertebrate neural networks with voltage-sensitive dyes seldom employ conventional intracellular electrodes. This may in part be due to the traditional reliance on compound microscopes for such work. While such microscopes have high light-gathering power, they do not provide depth of field, making working with sharp electrodes difficult. Here we describe a hybrid microscope design, with switchable compound and stereo objectives, that eases the use of conventional intracellular electrodes in optical recording experiments. We use it, in combination with a voltage-sensitive dye and photodiode array, to identify neurons participating in the swim motor program of the marine mollusk Tritonia. This microscope design should be applicable to optical recording studies in many preparations.
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Affiliation(s)
- William N Frost
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA.
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27
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Azami S, Wagatsuma A, Sadamoto H, Hatakeyama D, Usami T, Fujie M, Koyanagi R, Azumi K, Fujito Y, Lukowiak K, Ito E. Altered gene activity correlated with long-term memory formation of conditioned taste aversion in Lymnaea. J Neurosci Res 2007; 84:1610-20. [PMID: 16941636 DOI: 10.1002/jnr.21045] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pond snail Lymnaea stagnalis is capable of learning conditioned taste aversion (CTA) and then consolidating that learning into long-term memory (LTM) that persists for at least 1 month. LTM requires de novo protein synthesis and altered gene activity. Changes in gene activity in Lymnaea that are correlated with, much less causative, memory formation have not yet been identified. As a first step toward rectifying this situation, we constructed a cDNA microarray with mRNAs extracted from the central nervous system (CNS) of Lymnaea. We then, using this microarray assay, identified genes whose activity either increased or decreased following CTA memory consolidation. We also identified genes whose expression levels were altered after inhibition of the cyclic AMP response element-binding protein (CREB) that is hypothesized to be a key transcription factor for CTA memory. We found that the molluscan insulin-related peptide II (MIP II) was up-regulated during CTA-LTM, whereas the gene encoding pedal peptide preprohormone (Pep) was down-regulated by CREB2 RNA interference. We next examined mRNAs of MIP II and Pep using real-time RT-PCR with SYBR Green. The MIP II mRNA level in the CNS of snails exhibiting "good" memory for CTA was confirmed to be significantly higher than that from the CNS of snails exhibiting "poor" memory. In contrast, there was no significant difference in expression levels of the Pep mRNA between "good" and "poor" performers. These data suggest that in Lymnaea MIP II may play a role in the consolidation process that forms LTM following CTA training.
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Affiliation(s)
- Sachiyo Azami
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
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28
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Sugai R, Shiga H, Azami S, Watanabe T, Sadamoto H, Fujito Y, Lukowiak K, Ito E. Taste discrimination in conditioned taste aversion of the pond snail Lymnaea stagnalis. J Exp Biol 2006; 209:826-33. [PMID: 16481572 DOI: 10.1242/jeb.02069] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Conditioned taste aversion (CTA) in the pond snail Lymnaea stagnalis has been widely used as a model for gaining an understanding of the molecular and behavioral mechanisms underlying learning and memory. At the behavioral level, however, it is still unclear how taste discrimination and CTA interact. We thus examined how CTA to one taste affected the feeding response induced by another appetitive food stimulus. We first demonstrated that snails have the capacity to recognize sucrose and carrot juice as distinct appetitive stimuli. We then found that snails can become conditioned(i.e. CTA) to avoid one of the stimuli and not the other. These results show that snails can distinguish between appetitive stimuli during CTA, suggesting that taste discrimination is processed upstream of the site where memory consolidation in the snail brain occurs. Moreover, we examined second-order conditioning with two appetitive stimuli and one aversive stimulus. Snails acquired second-order conditioning and were still able to distinguish between the different stimuli. Finally, we repeatedly presented the conditional stimulus alone to the conditioned snails, but this procedure did not extinguish the long-term memory of CTA in the snails. Taken together, our data suggest that CTA causes specific, irreversible and rigid changes from appetitive stimuli to aversive ones in the conditioning procedure.
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Affiliation(s)
- Rio Sugai
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
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29
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Wagatsuma A, Azami S, Sakura M, Hatakeyama D, Aonuma H, Ito E. De Novo synthesis of CREB in a presynaptic neuron is required for synaptic enhancement involved in memory consolidation. J Neurosci Res 2006; 84:954-60. [PMID: 16886187 DOI: 10.1002/jnr.21012] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Interaction between the activator type of cyclic AMP response element binding protein (CREB1) and the repressor type (CREB2) results in determining the emergence of long-lasting synaptic enhancement involved in memory consolidation. However, we still do not know whether the constitutively expressed forms of CREB are enough or the newly synthesized forms are required for the synaptic enhancement. In addition, if the newly synthesized forms are needed, we must determine the time for translation of CREB from its mRNA. We applied the methods of RNA interference and real-time polymerase chain reaction (PCR) to CREB in the cerebral giant cells of Lymnaea. The cerebral giant cells play an important role in associative learning and employ a CREB cascade for the synaptic enhancement to neurons such as the B1 motoneurons. We injected the small interfering RNA (siRNA) of CREB1 or CREB2 into the cerebral giant cells and examined the changes in amplitude of excitatory postsynaptic potential (EPSP) recorded in the B1 motoneurons. The changes in the amounts of CREB1 and CREB2 mRNAs were also examined in the cerebral giant cells. The EPSP amplitude was suppressed 15 min after injection of CREB1 siRNA, whereas that was augmented 60 min after injection of CREB2 siRNA. In the latter case, the decrease in the amount of CREB2 mRNA was confirmed by real-time PCR. Our results showed that the de novo synthesized forms of CREB are required within tens of minutes for the synaptic enhancement in memory consolidation.
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Affiliation(s)
- Akiko Wagatsuma
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
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30
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Hatakeyama D, Sadamoto H, Watanabe T, Wagatsuma A, Kobayashi S, Fujito Y, Yamashita M, Sakakibara M, Kemenes G, Ito E. Requirement of new protein synthesis of a transcription factor for memory consolidation: paradoxical changes in mRNA and protein levels of C/EBP. J Mol Biol 2005; 356:569-77. [PMID: 16403525 DOI: 10.1016/j.jmb.2005.12.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 11/20/2005] [Accepted: 12/02/2005] [Indexed: 11/17/2022]
Abstract
Some specific transcription factors are essential for memory consolidation across species. However, it is still unclear whether only the activation of constitutively expressed forms of these conserved transcription factors is involved in memory consolidation or their de novo synthesis also occurs after learning. This question has remained unanswered partly because of the lack of an efficient method for the determination of copy numbers of particular mRNAs in single neurons, which allows the detection of new transcription at the cellular level. Here we applied a newly developed protocol of single-cell quantitative real-time polymerase chain reaction (qRT-PCR) to single neurons playing an important role in associative learning. Specifically, we examined the changes in the mRNA and protein expression levels of a highly conserved transcription factor, CCAAT/enhancer binding protein (C/EBP), in the paired B2 motoneurons of the pond snail Lymnaea stagnalis. These buccal neurons are involved in the motor control of feeding behavior, with a potentially important role in conditioned taste aversion (CTA). Single-cell qRT-PCR revealed a significant decrease in LymC/EBP mRNA copy numbers in the B2 motoneurons during memory consolidation after CTA training. By contrast, isoelectric focusing and immunoblotting of extracts of the buccal ganglia showed that translation and phosphorylation levels of LymC/EBP significantly increased during memory consolidation. The C/EBP-like immunoreactivity in the B2 motoneurons, which are the major immunopositive component in the buccal ganglia, also significantly increased during memory consolidation, suggesting that the main source of increase in the level of protein in the buccal ganglia are the B2 motoneurons. Thus, early memory consolidation after CTA learning in L.stagnalis involves both the rapid synthesis and phosphorylation of LymC/EBP as well as the rapid breakdown of LymC/EBP mRNA in the neural network controlling feeding, suggesting that all of these processes play a role in the function of C/EBP in memory consolidation.
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Affiliation(s)
- Dai Hatakeyama
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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Wagatsuma A, Sadamoto H, Kitahashi T, Lukowiak K, Urano A, Ito E. Determination of the exact copy numbers of particular mRNAs in a single cell by quantitative real-time RT-PCR. ACTA ACUST UNITED AC 2005; 208:2389-98. [PMID: 15939778 DOI: 10.1242/jeb.01625] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Gene expression is differently regulated in every cell even though the cells are included in the same tissue. For this reason, we need to measure the amount of mRNAs in a single cell to understand transcription mechanism better. However, there are no accurate, rapid and appropriate methods to determine the exact copy numbers of particular mRNAs in a single cell. We therefore developed a procedure for isolating a single, identifiable cell and determining the exact copy numbers of mRNAs within it. We first isolated the cerebral giant cell of the pond snail Lymnaea stagnalis as this neuron plays a key role in the process of memory consolidation of a learned behavior brought about by associative learning of feeding behavior. We then determined the copy numbers of mRNAs for the cyclic AMP-responsive element binding proteins (CREBs). These transcription factors play an important role in memory formation across animal species. The protocol uses two techniques in concert with each other: a technique for isolating a single neuron with newly developed micromanipulators coupled to an assay of mRNAs by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). The molecular assay determined the mRNA copy numbers, each of which was compared with a standard curve prepared from cDNA solutions corresponding to the serially diluted solutions of Lymnaea CREB mRNA. The standard curves were linear within a range of 10 to 10(5) copies, and the intra-assay variation was within 15%. Each neuron removed from the ganglia was punctured to extract the total RNA directly and was used for the assay without further purification. Using this two-step procedure, we found that the mRNA copy number of CREB repressor (CREB2) was 30-240 in a single cerebral giant cell, whereas that of CREB activator (CREB1) was below the detection limits of the assay (< 25). These results suggest that the CREB cascade is regulated by an excess amount of CREB2 in the cerebral giant cells. Our procedure is the only quantitative analysis for elucidation of the dynamics of gene transcription in a single cell.
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Affiliation(s)
- Akiko Wagatsuma
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
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Wagatsuma A, Sugai R, Chono K, Azami S, Hatakeyama D, Sadamoto H, Itoi E. The early snail acquires the learning. Comparison of scores for conditioned taste aversion between morning and afternoon. ACTA BIOLOGICA HUNGARICA 2004; 55:149-55. [PMID: 15270229 DOI: 10.1556/abiol.55.2004.1-4.18] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The pond snail Lymnaea stagnalis acquires conditioned taste aversion (CTA) and maintains its memory for more than a month. Snails in our laboratory were cultured at 20 degrees C on a 12:12 light-dark cycle (light from 7 am to 7 pm). To examine the hours during which snails acquire CTA effectively, we trained some snails in the morning and others in the afternoon, and then compared their scores. CTA developed in both cases, but scores were significantly better in the morning than in the afternoon. To elucidate the cause of this difference in scores, we observed the voluntary activity of snails and found the circadian rhythm reflected in the snails' free-movement distances; distances at the circadian time 0-12 (daytime) were significantly longer than those at the circadian time 12-24 (nighttime). This rhythm was kept up for at least 3 days, even in constant darkness. In conclusion, L. stagnalis should be trained in the morning to acquire associative learning, possibly because of its greater propensity to roam about at that time as opposed to the afternoon.
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Affiliation(s)
- Akiko Wagatsuma
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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Sadamoto H, Sato H, Kobayashi S, Murakami J, Aonuma H, Ando H, Fujito Y, Hamano K, Awaji M, Lukowiak K, Urano A, Ito E. CREB in the pond snail Lymnaea stagnalis: cloning, gene expression, and function in identifiable neurons of the central nervous system. ACTA ACUST UNITED AC 2004; 58:455-66. [PMID: 14978723 DOI: 10.1002/neu.10296] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The pond snail Lymnaea stagnalis is an excellent model system in which to study the neuronal and molecular substrates of associative learning and its consolidation into long-term memory. Until now, the presence of cyclic AMP (cAMP)-responsive element binding protein (CREB), which is believed to be a necessary component in the process of a learned behavior that is consolidated into long-term memory, has only been assumed in Lymnaea neurons. We therefore cloned and analyzed the cDNA sequences of homologues of CREB1 and CREB2 and determined the presence of these mRNAs in identifiable neurons of the central nervous system (CNS) of L. stagnalis. The deduced amino acid sequence of Lymnaea CREB1 is homologous to transcriptional activators, mammalian CREB1 and Aplysia CREB1a, in the C-terminal DNA binding (bZIP) and phosphorylation domains, whereas the deduced amino acid sequence of Lymnaea CREB2 is homologous to transcriptional repressors, human CREB2, mouse activating transcription factor-4, and Aplysia CREB2 in the bZIP domain. In situ hybridization revealed that only a relatively few neurons showed strongly positive signals for Lymnaea CREB1 mRNA, whereas all the neurons in the CNS contained Lymnaea CREB2 mRNA. Using one of the neurons (the cerebral giant cell) containing Lymnaea CREB1 mRNA, we showed that the injection of a CRE oligonucleotide inhibited a cAMP-induced, long-lasting synaptic plasticity. We therefore conclude that CREBs are present in Lymnaea neurons and may function as necessary players in behavioral plasticity.
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Affiliation(s)
- Hisayo Sadamoto
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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Ribeiro MJ, Serfozo Z, Papp A, Kemenes I, O'Shea M, Yin JCP, Benjamin PR, Kemenes G. Cyclic AMP response element-binding (CREB)-like proteins in a molluscan brain: cellular localization and learning-induced phosphorylation. Eur J Neurosci 2003; 18:1223-34. [PMID: 12956721 DOI: 10.1046/j.1460-9568.2003.02856.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The phosphorylation and the binding to DNA of the nuclear transcription factor, cyclic adenosine 3',5'-monophosphate (cAMP) response element-binding protein (CREB) are conserved key steps in the molecular cascade leading to the formation of long-term memory (LTM). Here, we characterize, for the first time, a CREB1-like protein in the central nervous system (CNS) of Lymnaea, a model system used widely for the study of the fundamental mechanisms of learning and memory. We demonstrate cAMP response element (CRE)-binding activity in CNS protein extracts and show that one of the CRE-binding proteins is recognized by a polyclonal antibody raised to mammalian (human) CREB1. The same antibody detects specific CREB1 immunoreactivity in CNS extracts and in the nuclei of most neurons in the brain. Moreover, phospho-CREB1-specific immunoreactivity is increased significantly in protein extracts of the CNS by forskolin, an activator of adenylate cyclase. The forskolin-induced increase in phospho-CREB1 immunoreactivity is localized to the nuclei of CNS neurons, some of which have an important role in the formation of LTM. Significantly, classical food-reward conditioning increases phospho-CREB1 immunoreactivity in Lymnaea CNS protein extracts. This increase in immunoreactivity is specific to the ganglia that contain the feeding circuitry, which undergoes cellular changes after classical conditioning. This work establishes the expression of a highly conserved functional CREB1-like protein in the CNS of Lymnaea and opens the way for a detailed analysis of the role of CREB proteins in LTM formation in this model system.
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Affiliation(s)
- Maria J Ribeiro
- Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Falmer, Brighton, UK
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Kinoshita M, Ueda R, Kojima S, Sato K, Watanabe M, Urano A, Ito E. Multiple-site optical recording for characterization of functional synaptic organization of the optic tectum of rainbow trout. Eur J Neurosci 2002; 16:868-76. [PMID: 12372023 DOI: 10.1046/j.1460-9568.2002.02160.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To map the functional synaptic organization over a wide area in the optic tectum, we directly monitored two-dimensional propagation of postsynaptic depolarization evoked by firing of retinotectal afferents in optic tectum slices prepared from rainbow trout (Oncorhynchus mykiss), using a voltage-sensitive dye and a photodiode array system. The postsynaptic responses to afferent stimulation first propagated in the stratum opticum and stratum fibrosum et griseum superficiale in an anterograde fashion in the afferents and then expanded vertically into the deep layers. This vertical propagation appeared to occur along a bundle-like structure that corresponded well with a cluster of neurons whose somata are located in the stratum periventriculare. Pharmacological studies showed that these postsynaptic responses were mediated by ionotropic glutamate receptors. On the other hand, the optical signals appeared to consist of at least two components (a transient signal and a slow signal). The second transient signal summated with the first slow signal by paired stimulation, suggesting that the transient and slow signals originated from different cell types. Taken together, these results showed that the functional synaptic organization of the teleost optic tectum comprises of two depolarization-signal propagating paths along a horizontal layer structure and a vertical bundle-like structure and that these synaptic responses occur via glutamatergic transmission.
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Affiliation(s)
- Masae Kinoshita
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
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