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Nakajima S, Umemoto S, Nagaishi T. Food avoidance learning based on swimming in laboratory mice (Mus musculus). Behav Processes 2023:104910. [PMID: 37406868 DOI: 10.1016/j.beproc.2023.104910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 04/22/2023] [Accepted: 07/01/2023] [Indexed: 07/07/2023]
Abstract
Although it is now well documented that laboratory rats learn to avoid the flavored substance consumed immediately before running in activity wheels or swimming in water buckets, research on this activity-based flavor avoidance learning in other species is limited. Recently, running-based flavor avoidance learning has been demonstrated in laboratory mice by employing a method of resistance-to-habituation of neophobic reaction to novel food; mice that repeatedly experience running after encountering a novel food have a prolonged tendency to reject that food compared to control mice without paired running. The present article reports a series of attempts to obtain evidence of flavor avoidance learning based on swimming rather than running using this resistance-to-habituation method. Swimming-based flavor avoidance was clearly demonstrated in a differential conditioning paradigm; however, its demonstration in a simple conditioning paradigm requires a post-training choice test of the target food and another type of food. These results are likely due to the short swimming time (20min) and the formation of weak flavor aversion.
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Nakajima S. Kaolin clay intake motivated by lactose ingestion in rats. LEARNING AND MOTIVATION 2021. [DOI: 10.1016/j.lmot.2021.101724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Nakajima S. Taste Aversion Learning Based on Swimming and Lithium Chloride Injection in Rats: Implications From Cross‐familiarization Tests and Stimulus Selectivity
1. JAPANESE PSYCHOLOGICAL RESEARCH 2020. [DOI: 10.1111/jpr.12281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Nakajima S. Food aversion learning based on voluntary running in non-deprived rats: a technique for establishing aversive conditioning with minimized discomfort. Exp Anim 2019; 68:71-79. [PMID: 30282846 PMCID: PMC6389511 DOI: 10.1538/expanim.18-0075] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 08/27/2018] [Indexed: 11/12/2022] Open
Abstract
This article presents an experimental preparation for establishing conditioned food aversion (CFA) by voluntary wheel running in rats with laboratory chow and water freely available. In Experiment 1, unfamiliar food (raisins) was avoided by rats when they first encountered it. This neophobic food avoidance was habituated by repeated tests; the rats gradually increased their raisin consumption. However, the consumption remained suppressed in rats that accessed the raisins after wheel running. This finding implies that running yielded CFA, which suppressed consumption of the unfamiliar food rather than increasing it. Because running generated kaolin clay ingestion, which is a behavioral marker of nausea, it is suggested that the running-based CFA was mediated by weak gastrointestinal discomfort. Experiment 2 supported the claim that the suppressed consumption is due to running-based CFA by showing the specificity of food suppression. Demonstration of CFA based on voluntary activity in non-deprived rats will contribute to basic research on learning and memory as an alternative technique for studying aversive conditioning with minimized discomfort in animals.
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Affiliation(s)
- Sadahiko Nakajima
- Department of Psychological Science, Kwansei Gakuin University, 1-1-155 Uegahara, Nishinomiya, Hyogo 662-8501, Japan
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Nakajima S. Food avoidance learning based on voluntary wheel running in laboratory mice (Mus musculus). Behav Processes 2018; 159:31-36. [PMID: 30557602 DOI: 10.1016/j.beproc.2018.12.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/20/2018] [Accepted: 12/13/2018] [Indexed: 12/16/2022]
Abstract
Mice show a reluctance to eat unfamiliar food, when they first encounter it. This neophobic reaction is conventionally habituated by repeated trials: the mice gradually increase their consumption of the novel food. The new finding reported here is that the consumption remains low in mice that voluntarily run in activity wheels after the novel food access. This effect implies that running yields Pavlovian conditioned flavor aversion, which suppresses, otherwise increasing, consumption of the novel food. In the present research, the effect was demonstrated with a between-group design by pitting experimental mice receiving cheese-running paired treatment against cheese/running unpaired control mice (Experiment 1). The running-based food avoidance in mice was also shown in a differential conditioning paradigm, where one of two novel snacks (chocolate and marshmallow) was paired with running while the other was not, in non-deprived animals (Experiment 2 A) and food-deprived animals (Experiment 2B). These results concord with those previously reported in rats, indicating the generality of the phenomenon.
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Affiliation(s)
- Sadahiko Nakajima
- Department of Psychological Science, Kwansei Gakuin University, Nishinomiya, 662-8501, Japan.
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Abstract
Running in an activity wheel generates pica behavior (kaolin clay intake) in rats. Wheel running also results in Pavlovian conditioned avoidance of the taste solution consumed immediately before the running. Since pica has been considered a behavioral marker of nausea in rats, these findings suggest that wheel running induces nausea, which is the underlying physiological state for establishing taste avoidance. This article reports a replication of running-based pica in rats (Experiment 1) and concurrent demonstrations of running-based pica and taste avoidance in the same animals (Experiments 2 and 3). Also shown is that pica does not alleviate running-based taste avoidance (Experiment 3). Another finding is that pica is generated by a nausea-inducing lithium chloride injection but not by a pain-inducing hypertonic saline injection (Experiment 4). These results, when taken together, support the hypothesis that pica behavior generated by wheel running reflects nausea in rats.
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Nakajima S. Running induces nausea in rats: Kaolin intake generated by voluntary and forced wheel running. Appetite 2016; 105:85-94. [DOI: 10.1016/j.appet.2016.05.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 05/07/2016] [Accepted: 05/10/2016] [Indexed: 12/31/2022]
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Nakajima S. Swimming-based pica in rats. Behav Processes 2016; 130:1-3. [PMID: 27370361 DOI: 10.1016/j.beproc.2016.06.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 06/23/2016] [Accepted: 06/27/2016] [Indexed: 12/16/2022]
Abstract
We have recently demonstrated that voluntary or forced running in activity wheels yields pica behavior (kaolin clay intake) in rats (Nakajima, 2016; Nakajima and Katayama, 2014). The present study provides experimental evidence that a single 40-min session of swimming in water also generates pica in rats, while showering rats with water does not produce such behavior. Because kaolin intake has been regarded as a measure of nausea in rats, this finding suggests that swimming activity, as well as voluntary or forced running, induces nausea in rats.
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Affiliation(s)
- Sadahiko Nakajima
- Department of Psychological Science, Kwansei Gakuin University, Nishinomiya, 662-8501, Japan.
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Prior running, but not swimming, hinders running-based taste aversion learning in rats. LEARNING AND MOTIVATION 2015. [DOI: 10.1016/j.lmot.2015.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Moody L, Liang J, Choi PP, Moran TH, Liang NC. Wheel running decreases palatable diet preference in Sprague-Dawley rats. Physiol Behav 2015; 150:53-63. [PMID: 25791204 DOI: 10.1016/j.physbeh.2015.03.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 02/14/2015] [Accepted: 03/13/2015] [Indexed: 12/13/2022]
Abstract
Physical activity has beneficial effects on not only improving some disease conditions but also by preventing the development of multiple disorders. Experiments in this study examined the effects of wheel running on intakes of chow and palatable diet e.g. high fat (HF) or high sucrose (HS) diet in male and female Sprague-Dawley rats. Experiment 1 demonstrated that acute wheel running results in robust HF or HS diet avoidance in male rats. Although female rats with running wheel access initially showed complete avoidance of the two palatable diets, the avoidance of the HS diet was transient. Experiment 2 demonstrated that male rats developed decreased HF diet preferences regardless of the order of diet and wheel running access presentation. Running associated changes in HF diet preference in females, on the other hand, depended on the testing schedule. In female rats, simultaneous presentation of the HF diet and running access resulted in transient complete HF diet avoidance whereas running experience prior to HF diet access did not affect the high preference for the HF diet. Ovariectomy in females resulted in HF diet preference patterns that were similar to those in male rats during simultaneous exposure of HF and wheel running access but similar to intact females when running occurred before HF exposure. Overall, the results demonstrated wheel running associated changes in palatable diet preferences that were in part sex dependent. Furthermore, ovarian hormones play a role in some of the sex differences. These data reveal complexity in the mechanisms underlying exercise associated changes in palatable diet preference.
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Affiliation(s)
- Laura Moody
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Joy Liang
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Pique P Choi
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Timothy H Moran
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Nu-Chu Liang
- Neuroscience Program, Department of Psychology, University of Illinois-Urbana Champaign, 725 Psychology Bldg., 603 E. Daniel Street, M/C 716, Champaign, IL 61820, USA.
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Nakajima S, Katayama T. Running-based pica in rats. Evidence for the gastrointestinal discomfort hypothesis of running-based taste aversion. Appetite 2014; 83:178-184. [DOI: 10.1016/j.appet.2014.08.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 08/18/2014] [Accepted: 08/23/2014] [Indexed: 12/31/2022]
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Nakajima S. Calorie supply does not alleviate running-based taste aversion learning in rats. Appetite 2011; 57:605-14. [DOI: 10.1016/j.appet.2011.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 07/25/2011] [Accepted: 08/01/2011] [Indexed: 11/25/2022]
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The effect of swimming experience on acquisition and retention of swimming-based taste aversion learning in rats. LEARNING AND MOTIVATION 2010. [DOI: 10.1016/j.lmot.2009.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Havermans RC, Salvy SJ, Jansen A. Single-trial exercise-induced taste and odor aversion learning in humans. Appetite 2009; 53:442-5. [DOI: 10.1016/j.appet.2009.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 11/24/2022]
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Masaki T, Nakajima S. Forward conditioning with wheel running causes place aversion in rats. Behav Processes 2008; 79:43-7. [PMID: 18538954 DOI: 10.1016/j.beproc.2008.04.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 04/08/2008] [Accepted: 04/23/2008] [Indexed: 11/26/2022]
Abstract
Backward pairings of a distinctive chamber as a conditioned stimulus and wheel running as an unconditioned stimulus (i.e., running-then-chamber) can produce a conditioned place preference in rats. The present study explored whether a forward conditioning procedure with these stimuli (i.e., chamber-then-running) would yield place preference or aversion. Confinement of a rat in one of two distinctive chambers was followed by a 20- or 60-min running opportunity, but confinement in the other was not. After four repetitions of this treatment (i.e., differential conditioning), a choice preference test was given in which the rat had free access to both chambers. This choice test showed that the rats given 60-min running opportunities spent less time in the running-paired chamber than in the unpaired chamber. Namely, a 60-min running opportunity after confinement in a distinctive chamber caused conditioned aversion to that chamber after four paired trials. This result was discussed with regard to the opponent-process theory of motivation.
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Affiliation(s)
- Takahisa Masaki
- Psychology Section, Department of Integrated Psychological Science, Kwansei Gakuin University, Nishinomiya, Hyogo, Japan
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Brand L, Groenewald I, Stein DJ, Wegener G, Harvey BH. Stress and re-stress increases conditioned taste aversion learning in rats: possible frontal cortical and hippocampal muscarinic receptor involvement. Eur J Pharmacol 2008; 586:205-11. [PMID: 18439577 DOI: 10.1016/j.ejphar.2008.03.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 02/15/2008] [Accepted: 03/04/2008] [Indexed: 11/25/2022]
Abstract
Symptoms of posttraumatic stress disorder are often precipitated by sensory cues in the form of visual, auditory, olfactory and gustatory "flashbacks" resulting in enhanced fear-memory consolidation and the characteristic symptoms of re-experiencing, avoidance and hyper-arousal. Single prolonged stress with and without re-stress have been used to explore the neurobiology of this disorder, particularly with respect to contextual conditioning and spatial memory impairment. However, less work has been done regarding associative sensory-related memories linked to aversive events. Although growing evidence supports a role for cholinergic pathways in stress, this has not been studied in the above animal models. We studied the effects of single prolonged stress with and without re-stress on conditioned taste aversion learning in rats, together with differential analysis of frontal cortical and hippocampal [3H]-quinuclidinyl benzylate ([3H]-QNB) muscarinic receptor binding. Single prolonged stress with and without re-stress both enhanced associative sensory aversion learning 7 days after stressor-taste pairing, although re-stress did not strengthen this response. Increased cortical and hippocampal muscarinic receptor density (Bmax) was found 7 days after single prolonged stress with re-stress, although receptor affinity remained unaltered. Frontal cortical and hippocampal muscarinic receptor changes may thus underlie conditioned taste aversion learning in rats exposed to stress and re-stress. These data suggest that it may be useful to study the role of cholinergic pathways in mediating associative memory in psychiatric disorders such as posttraumatic stress disorder.
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Affiliation(s)
- Linda Brand
- Unit for Drug Research and Development, School of Pharmacy (Pharmacology), North-West University (Potchefstroom Campus), Potchefstroom, 2520, South Africa
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Forristall JR, Hookey BL, Grant VL. Conditioned taste avoidance induced by forced and voluntary wheel running in rats. Behav Processes 2007; 74:326-33. [PMID: 17229530 DOI: 10.1016/j.beproc.2006.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 11/13/2006] [Accepted: 12/06/2006] [Indexed: 11/17/2022]
Abstract
Voluntary exercise by rats running in a freely rotating wheel (free wheel) produces conditioned taste avoidance (CTA) of a flavored solution consumed before running [e.g., Lett, B.T., Grant, V.L., 1996. Wheel running induces conditioned taste aversion in rats trained while hungry and thirsty. Physiol. Behav. 59, 699-702]. Forced exercise, swimming or running, also produces CTA in rats [e.g., Masaki, T., Nakajima, S., 2006. Taste aversion induced by forced swimming, voluntary running, forced running, and lithium chloride injection treatments. Physiol. Behav. 88, 411-416]. Energy expenditure may be the critical factor in producing such CTA. If so, forced running in a motorized running wheel should produce CTA equivalent to that produced by a similar amount of voluntary running. In two experiments, we compared forced running in a motorized wheel with voluntary running in a free wheel. Mean distance run over 30 min was equated as closely as possible in the two apparatuses. Both types of exercise produced CTA relative to sedentary, locked-wheel controls. However, voluntary running produced greater CTA than forced running. We consider differences between running in the free and motorized wheels that may account for the differences in strength of CTA.
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Affiliation(s)
- J R Forristall
- Memorial University of Newfoundland, St. John's, NL, Canada A1B 3X9
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Heth CD, Pierce WD. The role of pre-exposure to novel food tastes in activity-based conditioned taste avoidance. LEARNING AND MOTIVATION 2007. [DOI: 10.1016/j.lmot.2006.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Masaki T, Nakajima S. Taste aversion in rats induced by forced swimming, voluntary running, forced running, and lithium chloride injection treatments. Physiol Behav 2006; 88:411-6. [PMID: 16777150 DOI: 10.1016/j.physbeh.2006.04.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 03/30/2006] [Accepted: 04/18/2006] [Indexed: 11/22/2022]
Abstract
The present experiment compared the strengths of taste aversion learning in rats induced by forced swimming in a water pool (5, 15, 30, or 60 min), voluntary running in an activity wheel (15, 30, 60, or 120 min), forced running in a motorized wheel (60 min at the speed of 8 m/min), optional running in the apparatus consisting of an activity wheel and a side room (120 min), and a lithium chloride (LiCl, 0.15 M LiCl at 2% of body weight) injection. The rats were given an access to saccharin solution immediately followed by one of the above treatments or simply returned back to the home cages for the control group. On the next 2 days, aversion to the saccharin solution was assessed by two-bottle choice testing between it and tap water. The following results were obtained. (1) The saccharin aversion was a positive function of exercise durations in the forced swimming and voluntary running rats, and the exercise of more than 30 min induced statistically significant saccharin aversion, compared with the control rats. (2) The forced running caused relatively strong saccharin aversion. The group of forced running rats acquired the numerically strongest saccharin aversion on average among all exercised rats. (3) The optional running treatment had little effect. (4) The LiCl injection resulted in the strongest aversion among the all treatments explored here.
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Affiliation(s)
- Takahisa Masaki
- Psychology Section, Department of Integrated Psychological Science, Kwansei Gakuin University, Nishinomiya, Hyogo 662-8501, Japan.
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Masaki T, Nakajima S. Taste aversion learning induced by delayed swimming activity. Behav Processes 2005; 67:357-62. [PMID: 15518986 DOI: 10.1016/j.beproc.2004.06.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Accepted: 06/22/2004] [Indexed: 11/26/2022]
Abstract
The experiment reported here demonstrated that forced swimming endows rats with aversion to a taste solution consumed 30 min before the swimming. The experimental rats were allowed to drink 0.2% sodium saccharin solution, which was followed by a 30-min empty interval, and then a 20-min swimming opportunity in water. Compared with the control rats, which were returned to their home cages after drinking the saccharin, the experimental rats drank a small amount of saccharin solution both in the later sessions of one-bottle training and in the subsequent two-bottle choice (saccharin versus tap water) testing. The delayed swimming procedure was as effective as an immediate swimming procedure, extending the generality of the swimming-induced taste aversion, which we recently discovered with the immediate swimming procedure.
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Affiliation(s)
- Takahisa Masaki
- Department of Integrated Psychological Science, Kwansei Gakuin University, Nishinomiya 662-8501, Japan
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Masaki T, Nakajima S. Further evidence for conditioned taste aversion induced by forced swimming. Physiol Behav 2004; 84:9-15. [PMID: 15642601 DOI: 10.1016/j.physbeh.2004.09.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Accepted: 09/02/2004] [Indexed: 11/23/2022]
Abstract
A series of experiments with rats reported that aversion to a taste solution can be established by forced swimming in a water pool. Experiment 1 demonstrated that correlation of taste and swimming is a critical factor for this phenomenon, indicating associative (i.e., Pavlovian) nature of this learning. Experiment 2 showed that this learning obeys the Pavlovian law of strength, by displaying a positive relationship between the duration of water immersion in training and the taste aversion observed in subsequent testing. Experiment 3 revealed that swimming rather than being wet is the critical agent, because a water shower did not endow rats with taste aversion. Experiment 4 found that taste aversion was a positive function of water level of the pools in training (0, 12 or 32 cm). These results, taken together, suggest that energy expenditure caused by physical exercise might be involved in the development of taste aversion.
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Affiliation(s)
- Takahisa Masaki
- Psychology Section, Department of Integrated Psychological Science, Kwansei Gakuin University, Nishinomiya, 662-8501, Japan
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Masaki T, Nakajima S. Swimming-induced taste aversion and its prevention by a prior history of swimming. LEARNING AND MOTIVATION 2004. [DOI: 10.1016/j.lmot.2004.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Nakajima S. Conditioned ethanol aversion in rats induced by voluntary wheel running, forced swimming, and electric shock: an implication for aversion therapy of alcoholism. Integr Psychol Behav Sci 2004; 39:95-104. [PMID: 15759597 DOI: 10.1007/bf02734275] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This study was planned to demonstrate rats' acquisition of aversion to ethanol solution consumed before voluntary running, forced swimming, or electric shock delivery. Wistar rats under water deprivation were allotted to four groups of eight rats each, and all rats were allowed to drink 5% ethanol solution for 15 min. Immediately after the ethanol drinking, rats of Group Run were put into the individual running wheels for 15 min, those of Group Swim were put into the individual swimming pools for 15 min, those of Group Shock received electric shocks for 15 min (15 0.45-mA shocks of 0.7s with the intershock interval of 1 min) in the individual small chambers, and those of Group Control were directly returned back to the home cages. This procedure was repeated for six days, followed by a two-day choice test of ethanol aversion where a bottle containing 5% ethanol solution and a bottle of tap water were simultaneously presented for 15 min. In the test, Groups Run, Swim, and Shock drank ethanol solution significantly less than tapwater, while Group Control drank both fluids equally. The effects of running, swimming, and shock were equivalent. The successful demonstration of acquired ethanol aversion induced by exercise (running and swimming) or shock in rats suggests an avenue for clinical application of exercise and shock treatments for human alcoholics, though there are many issues to be resolved before the practical use.
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Affiliation(s)
- Sadahiko Nakajima
- Department of Integrated Psychological Science and Research Center for Applied Psychological Science, Kwansei Gakuin University, Nishinomiya, 662-8501, Japan.
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