Canadian Association of Neurosciences Review: Learning at a Snail's Pace

Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques (Impact Factor: 1.53). 12/2006; 33(4):347-56. DOI: 10.1017/S0317167100005291
Source: PubMed


While learning and memory are related, they are distinct processes each with different forms of expression and underlying molecular mechanisms. An invertebrate model system, Lymnaea stagnalis, is used to study memory formation of a non-declarative memory. We have done so because: (1) We have discovered the neural circuit that mediates an interesting and tractable behaviour; (2) This behaviour can be operantly conditioned and intermediate-term and long-term memory can be demonstrated; and (3) It is possible to demonstrate that a single neuron in the model system is a necessary site of memory formation. This article reviews how Lymnaea has been used in the study of behavioural and molecular mechanisms underlying consolidation, reconsolidation, extinction and forgetting.

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Available from: Ken Lukowiak, Dec 26, 2013
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    • "The great pond snail, Lymnaea stagnalis, has been used extensively as a model organism to study the mechanisms of learning and memory [20], [21], [22], [23]. Much of this work has been carried out using individuals that have been reared in the laboratory over many generations, derived from a population originally collected in the 1950s from canals in a polder in Utrecht province in the Netherlands (i.e. the Dutch laboratory strain). "
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    ABSTRACT: Cognitive ability varies within species, but whether this variation alters the manner in which memory formation is affected by environmental stress is unclear. The great pond snail, Lymnaea stagnalis, is commonly used as model species in studies of learning and memory. The majority of those studies used a single laboratory strain (i.e. the Dutch strain) originating from a wild population in the Netherlands. However, our recent work has identified natural populations that demonstrate significantly enhanced long-term memory (LTM) formation relative to the Dutch strain following operant conditioning of aerial respiratory behaviour. Here we assess how two populations with enhanced memory formation (i.e. 'smart' snails), one from Canada (Trans Canada 1: TC1) and one from the U.K. (Chilton Moor: CM) respond to ecologically relevant stressors. In control conditions the Dutch strain forms memory lasting 1-3 h following a single 0.5 h training session in our standard calcium pond water (80 mg/l [Ca(2+)]), whereas the TC1 and CM populations formed LTM lasting 5+ days following this training regime. Exposure to low environmental calcium pond water (20 mg/l [Ca(2+)]), which blocks LTM in the Dutch strain, reduced LTM retention to 24 h in the TC1 and CM populations. Crowding (20 snails in 100 ml) immediately prior to training blocks LTM in the Dutch strain, and also did so in TC1 and CM populations. Therefore, snails with enhanced cognitive ability respond to these ecologically relevant stressors in a similar manner to the Dutch strain, but are more robust at forming LTM in a low calcium environment. Despite the two populations (CM and TC1) originating from different continents, LTM formation was indistinguishable in both control and stressed conditions. This indicates that the underlying mechanisms controlling cognitive differences among populations may be highly conserved in L. stagnalis.
    PLoS ONE 02/2012; 7(2):e32334. DOI:10.1371/journal.pone.0032334 · 3.23 Impact Factor
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    • "Therefore, it is important to consider changes in multiple behavioural traits if we are to accurately assess whether an animal has responded to a particular stimulus. The great pond snail L. stagnalis is frequently used as a model species to study learning and memory, due to a simple set of behaviours that are easily observable and altered through experience, and a relatively simple nervous system that allows the neural correlates for these behavioural changes to be determined (Parvez et al. 2006; Benjamin and Kemenes 2008; Lukowiak et al. 2003). "
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    ABSTRACT: Frequently studies of learning and memory measure a single focal behaviour; however it is likely that any learning paradigm will alter multiple behavioural traits in the same animal. We used video footage of the great pond snail (Lymnaea stagnalis), collected immediately prior to both training and testing for memory in response to operant conditioning to reduce aerial respiration, to measure two additional alternate behavioural traits: reducing the size of the pneumostome (breathing orifice) opening and shell tilt to cover the pneumostome. Typically, the training regime used here results in memory to reduce the number of breathing attempts lasting 24 h but not 72 h. However, memory duration when measured using the two additional behavioural traits differed significantly; shell tilt was short-lived lasting less than 1 h following training, whereas the reduction in pneumostome size was still apparent 72 h following training. Therefore, conclusions about the ability of L. stagnalis to retain memory in response to a single type of training regime will differ significantly depending on the focal behavioural trait measured. A significant correlation between the reduction in opening attempts and visible pneumostome area indicated that these behavioural traits are co-specialised, whereas pneumostome opening and shell tilt behaviour varied independently.
    Animal Cognition 02/2012; 15(4):483-94. DOI:10.1007/s10071-012-0472-3 · 2.58 Impact Factor
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    • "In addition there is also some evidence that aquatic gastropods may be able to sense and avoid low levels of heavy metals in their environment as Physella columbiana from heavy metal sites demonstrates avoidance of these pollutants in a Y-maze (Lefcort et al. 2004). The great pond snail, Lymnaea stagnalis, is commonly used as a model species to study learning and memory in neurobiology (Benjamin and Kemenes 2008; Lukowiak et al. 2003; Parvez et al. 2006). Ecologically relevant stressors can alter the ability of this species to learn and remember. "
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    ABSTRACT: The effect of heavy metals on species survival is well documented; however, sublethal effects on behaviour and physiology are receiving growing attention. Measurements of changes in activity and respiration are more sensitive to pollutants, and therefore a better early indicator of potentially harmful ecological impacts. We assessed the effect of acute exposure (48 h) to two heavy metals at concentrations below those allowable in municipal drinking water (Zn: 1,100 μg/l; Cd: 3 μg/l) on locomotion and respiration using the freshwater snail, Lymnaea stagnalis. In addition we used a novel assessment method, testing the ability of the snail to form memory in the presence of heavy metals in both intact snails, and also snails that had the osphradial nerve severed which connects a chemosensory organ, the osphradium, to the central nervous system. Aerial respiration and locomotion remained unchanged by acute exposure to heavy metals. There was also no effect on memory formation of these metals when administered alone. However, when snails were exposed to these metals in combination memory formation was blocked. Severing the osphradial nerve prevented the memory blocking effect of Zn and Cd, indicating that the snails are sensing these metals in their environment via the osphradium and responding to them as a stressor. Therefore, assessing the ability of this species to form memory is a more sensitive measure of heavy metal pollution than measures of activity, and indicates that the snails' ability to demonstrate behavioural plasticity may be compromised by the presence of these pollutants.
    Ecotoxicology 01/2012; 21(3):860-8. DOI:10.1007/s10646-011-0847-2 · 2.71 Impact Factor
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