3911 INTRODUCTION Differences in cognitive ability have been noted previously between strains of the same species of rodent (i.e. within-species variation) (Nguyen et al., 2006). In fact, differences in cognitive ability within the same strain of a species have also been observed that are dependent on both the laboratory performing the experiment and the personnel within each laboratory (Crabbe et al., 1999; Whalsten et al., 2006). There is also a long history of attempting to create specific stable within-strain differences in cognitive ability by the selective mating of ‘smart’ (e.g. maze bright) vs ‘not so smart’ (e.g. maze dull) individuals of the species (Tolman, 1924; Tyron, 1931). Finally, it is believed that outbred members of the same species, e.g. Rattus norvegicus, or strains that are more closely related to the non-domesticated rat (i.e. more wild-like such as the Long–Evans variety) have fewer cognitive deficits compared with inbred rats, more distantly related to the wild-type (Harker and Whishaw, 2002). It is unclear at present what the causes of these within and between strain differences are or whether in fact they actually exist, as some of the apparent differences are not observed in different learning and memory tasks (Brush, 2003). The lack of understanding of why on specific tasks some rodent strains perform better than others is due to the complexities of the behavioural task and the complexity of the mammalian brain. In our model system, the pond snail Lymnaea stagnalis (L.) where a single neuron is known to be a necessary site for long-term memory (LTM) formation (Scheibenstock et al., 2002; Lukowiak et al., 2008), we have also found within-species variation in the ability to form LTM following operant conditioning of aerial respiratory behaviour (Orr et al., 2008; Orr et al., 2009). In L. stagnalis geographically separate strains (The Netherlands vs Alberta Belly River snails) have different cognitive abilities (Orr et al., 2008). That is, laboratory-reared snails (over 250 generations; originally derived from snails collected in the Province of Utrecht in The Netherlands) had a reduced ability to form LTM compared with snails collected from the Belly River drainage (i.e. Belly snails) in Southern Alberta. Initially the differences in LTM-forming ability between the lab-reared and the Belly snails were hypothesized to be due to the ‘wild’ snails having an enriched environment compared with the lab-reared snails. However, that hypothesis was rejected because: (1) Belly snails hatched in the lab from eggs collected in the wild still exhibited enhanced LTM formation compared with the lab-reared snails; and (2) snails freshly collected in the same area of The Netherlands where the founding members of the lab colony were originally collected exhibited comparable LTM-forming abilities to their lab-reared descendants (i.e. not as good as Belly snails). Thus, we concluded that the Belly snails had an enhanced ability compared with the Dutch snails to form LTM following operant conditioning of aerial respiration [i.e. an inherent strain difference (Orr et al., 2008)]. Because the Belly River ponds are located over 200 km from our Calgary laboratory, we sought a closer collection site (in order to in part reduce our ‘carbon footprint’) that had an abundance of L. stagnalis. We found such a site (only a few kilometres from the Lukowiak residence) and collected wild L. stagnalis from this new location, the Jackson pond (referred to as Jackson snails). However, we found in our initial experiments that the Jackson snails did not possess the enhanced memory-forming capabilities seen in the Belly snails but rather exhibited LTM-forming abilities more akin to the Dutch wild and lab-reared snails. More recently, we showed that we could enhance the memory-forming capabilities of the Jackson snails when trained in the lab by exposing them to the scent of a sympatric predator, the Tiger salamander [salamander effluent, SE (Orr et al., 2009; Orr and Lukowiak, 2010)]. We wondered, however, whether the differences in cognitive ability between the two strains of Alberta The Journal of Experimental Biology 212, 3911-3918 Published by The Company of Biologists 2009 doi:10.1242/jeb.024281 Differences in LTM-forming capability between geographically different strains of Alberta Lymnaea stagnalis are maintained whether they are trained in the lab or in the wild M. Orr, K. Hittel, K. S. Lukowiak, J. Han and K. Lukowiak Hotchkiss Brain Institute, Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, 3330 Hospital Drive North West, Calgary, Alberta, Canada T2N 4N1 Author for correspondence (lukowiak@ucalgary.ca) Accepted 3 September 2009 SUMMARY We found strain differences in the ability of wild Alberta Lymnaea stagnalis to form long-term memory (LTM) following operant conditioning when L. stagnalis were collected from the wild and trained in the laboratory. Lymnaea stagnalis obtained from the Belly River watershed had an enhanced ability to form LTM compared with those from an isolated pond (referred to as Jackson snails). We therefore asked whether the differences in cognitive ability were an epiphenomenon as a result of training in the laboratory. To answer this question we trained each specific strain (Belly and Jackson) in both the laboratory and the field (i.e. in their home pond and in the pond where the other strain resided – referred to as the visitor pond). We found that within each strain there was no difference in the LTM phenotype whether they were trained in the lab or in either their home or visitor pond. That is, the strain differences in the ability to form LTM were still present. Interestingly, we found no strain differences in the ability to learn or the ability to form intermediate-term memory (ITM). Key words: Lymnaea, operant conditioning, long-term memory, strain differences, laboratory vs wild conditions. 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