The early snail acquires the learning. Comparison of scores for conditioned taste aversion between morning and afternoon

Food deprivation for 1 day in the pond snail Lymnaea stagnalis before aversive classical conditioning results in optimal conditioned taste aversion (CTA) and long-term memory (LTM) formation, whereas 5-day food deprivation before training does not. We hypothesize that snails do in fact learn and form LTM when trained after prolonged food deprivation, but that severe food deprivation blocks their ability to express memory. We trained 5-day food-deprived snails under various conditions, and found that memory was indeed formed but is overpowered by severe food deprivation. Moreover, CTA-LTM was context dependent and was observed only when the snails were in a context similar to that in which the training occurred.

“…3; Wagatsuma et al, 2004;Ito et al, 2012Ito et al, , 2015. Briefly, all snails were first given a pretest in polystyrene Petri dishes (diameter 35 mm).…”

Section: Taste Aversion Training (Cta) Proceduresmentioning

confidence: 99%

Memory block: A consequence of conflict resolution

Ito

Yamagishi

Hatakeyama

et al. 2015

“…Our previously published work tended to focus on group data and on experimental procedures optimized to produce consistent learning and LTM formation (Kojima et al, 1996;Wagatsuma et al, 2004). Thus, individual differences in learning and memory capabilities between subjects were not a major focus.…”

Section: Motivation On Conditioned Taste Aversionmentioning

confidence: 99%

One-trial conditioned taste aversion inLymnaea: good and poor performers in long-term memory acquisition

Sugai

Azami

Shiga

et al. 2007

Self Cite

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 timewindow necessary for the memory consolidation, we found that if we cooled snails to 4°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 onetrial 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.

“…The sea hare (Aplysia californica) and the great pond snail (Lymnaea stagnalis) are now well established as animal models of learning and memory (Kandel, 2001;Lukowiak et al, 2006). Recent studies have demonstrated an influence of the circadian timing system in learning and memory formation in these species (Fernandez et al, 2003;Wagatsuma et al, 2004), but they have not been well studied in the context of sleep. Indeed, it has not yet been determined whether these molluscs do in fact sleep.…”

Section: Introductionmentioning

confidence: 99%

Behavioural evidence for a sleep-like quiescent state in a pulmonate mollusc, Lymnaea stagnalis (Linnaeus)

Stephenson

Lewis

2011

to sleep; resting wakefulness, paralysis, hibernation, torpor, akinesis, diapause, aestivation, anaesthesia and coma all share this characteristic. However, only in sleep and resting wakefulness is the suppression of motor output rapidly and spontaneously reversible. The second criterion, reversible suppression of sensory responsiveness, characterizes a quiescent state as sleep-like, and Accepted 15 November 2010 SUMMARY The objective of this study was to determine whether the great pond snail, Lymnaea stagnalis, expresses a sleep-like behavioural state. We found that snails spontaneously enter a relatively brief (22±1min) quiescent state characterized by postural relaxation of the foot, mantle and tentacles, and cessation of radula rasping. Quiescence was reversed ('aroused') by appetitive (sucrose solution) and aversive (tactile) stimuli. Responsiveness to both stimuli was significantly lower in quiescent snails than in active snails. However, tactile stimuli evoked a more sustained defensive response in quiescent snails. Quiescence bouts were consolidated into 'clusters' over an infradian timescale and were only weakly affected by time of day. Clusters contained 7±0.5 bouts, lasted 13±1h and were separated by long (37±4h) intervals of almost continuous activity. Analysis of Kaplan-Meier survival curves revealed that the quiescent bout duration was described by an exponential probability distribution (time constant 15±1min). Active bout duration was described by a bi-exponential probability distribution (time constants 62±4 and 592±48min). We found no evidence for a 'sleep rebound' mechanism and quiescence expression appeared to be regulated through stochastic processes causing state transitions to resemble a Markovian random walk. We conclude that Lymnaea is a potentially valuable model system for studies of cellular function in sleep.