Are Distal and Proximal Visual Cues Equally Important during Spatial Learning in Mice? A Pilot Study of Overshadowing in the Spatial Domain

Animals use distal and proximal visual cues to accurately navigate in their environment, with the possibility of the occurrence of associative mechanisms such as cue competition as previously reported in honey-bees, rats, birds and humans. In this pilot study, we investigated one of the most common forms of cue competition, namely the overshadowing effect, between visual landmarks during spatial learning in mice. To this end, C57BL/6J × Sv129 mice were given a two-trial place recognition task in a T-maze, based on a novelty free-choice exploration paradigm previously developed to study spatial memory in rodents. As this procedure implies the use of different aspects of the environment to navigate (i.e., mice can perceive from each arm of the maze), we manipulated the distal and proximal visual landmarks during both the acquisition and retrieval phases. Our prospective findings provide a first set of clues in favor of the occurrence of an overshadowing between visual cues during a spatial learning task in mice when both types of cues are of the same modality but at varying distances from the goal. In addition, the observed overshadowing seems to be non-reciprocal, as distal visual cues tend to overshadow the proximal ones when competition occurs, but not vice versa. The results of the present study offer a first insight about the occurrence of associative mechanisms during spatial learning in mice, and may open the way to promising new investigations in this area of research. Furthermore, the methodology used in this study brings a new, useful and easy-to-use tool for the investigation of perceptive, cognitive and/or attentional deficits in rodents

Apprentissage et mémoire chez la seiche (sepia officinalis) (approches comportementale et neurobiologique)

Chez la seiche, l'inhibition du comportement prédateur vis-à-vis de crevettes inaccessibles constitue un excellent modèle permettant l'étude des bases neurobiologiques de l'apprentissage et de la mémoire. Apres avoir vérifié la nature associative de ce conditionnement de type évitement passif, nous avons démontré que les bonnes performances de rétention observées après de courts intervalles de temps correspondaient réellement a l'expression d'un stock de mémoire à court terme et non pas à des facteurs non spécifiques tel que le stress. Par ailleurs, une étude ontogénétique a confirmé la maturation précoce de cette mémoire avec parallèlement la mise en place progressive d'une trace mnésique a plus long terme. Nous avons révèle l'évolution des fenêtres temporelles des différents systèmes mnésiques au cours du développement et démontré l'existence d'un profil poly phasique de la rétention suggérant un stockage des informations en trois étapes : une mémoire à court terme, une mémoire intermédiaire et une mémoire à long terme. Sur le plan neurophysiologique, l'utilisation d'un antibiotique (la cycloheximide) a permis d'établir que la mémoire à long terme était dépendante d'une synthèse protéique de novo essentielle au cours des trois premières heures suivant l'apprentissage. D'autre part, la révélation histochimique de l'activité cytochrome oxydase a permis de mettre en évidence des modifications métaboliques spécifiquement associées à l'intervalle post-apprentissage dans le lobe frontal supérieur, une structure du complexe vertical dont l'implication dans l'apprentissage et la mémoire avait été suggérée par les approches lésionnelles. Ces travaux montrent, pour la première fois chez les céphalopodes, un profil d'activité neuronale corrélé à la formation de la mémoire.PARIS13-BU Sciences (930792102) / SudocBANYULS/MER-Observ.Océanol. (660162201) / SudocSudocFranceF

The “prawn-in-the-tube” procedure in the cuttlefish: Habituation or passive avoidance learning?

This study examines whether or not habituation contributes to the regulation of the inhibition of predatory behavior observed during the “prawn-in-the-tube” training procedure. When presented with prawns that are visible behind glass but untouchable, cuttlefish promptly learn to inhibit their capture attempts. The first three experiments demonstrated that the acquired response in the course of training cannot be dishabituated. The fourth experiment demonstrated that the repeated application of a brief visual prawn stimulus, one that is terminated before the cuttlefish can strike, decreases attack latencies. Taken together, the results of this study establish that habituation does not play a significant role in this learning task. In fact, the present findings strengthen the results of previous studies suggesting that passive avoidance learning contributes to the regulation of the inhibition of predatory behavior

Evidence for a specific short-term memory in the cuttlefish, Sepia

International audienceCuttlefish quickly learn to inhibit their predatory motor pattern when shown prawns in a glass tube. The available literature suggests that cuttlefish show an excellent retention between 2 and 8 min, a recovery of the predatory responses around 20 min and good retention after 1 h of the training phase. These results have been considered as the product of two separate short- and long-term memory stores. In this study, we have investigated the fact that the retention seen after a brief delay of the training phase corresponds to a true effect of learning. We compared animals under three experimental conditions. In two, there was a unique training trial of different duration (5 or 20 min), a third group served as controls. Our results demonstrate that the control situation failed to reduce the level of attack; in contrast the short-term retention, obtained after a single learning trial, is related to a specific short-term memory process

Vasopressin/oxytocin-related peptides influence long-term memory of a passive avoidance task in the cuttlefish, Sepia officinalis

International audienceThe vasopressin (VP)/oxytocin (OT)-related peptides constitute a large superfamily found in a wide range of both vertebrate and invertebrate species. While intensive literature reports that these neuropeptides influence behavior, especially learning and memory, in numerous species from diverse vertebrate groups, their roles in behavioral regulation have never been studied in invertebrates. Here, we investigated the role of two VP/OT superfamily peptides, octopressin (OP) and cephalotocin (CT), on long-term memory (LTM) formation of a passive avoidance task in a cephalopod mollusc, the cuttlefish, Sepia officinalis. Subadult cuttlefish were intravenously injected, in a dose range of 3-60 microg/kg, 1h after the training phase (consolidation design); retention performance was tested 24h post-training. We found that administration of OP at low dose (3 microg/kg) enhanced LTM, whereas a dose of 60 microg/kg attenuated it. No effect of OP on LTM was observed for the 15 microg/kg dose. Conversely, an enhancement of retention performance was observed at all doses of CT tested. This study is the first to demonstrate the behavioral effects of VP/OT superfamily peptides in an invertebrate species. The valuable role of VP/OT-like peptides on memory processes offers new evolutionary perspectives on peptidergic transmission and neuromodulation

Developmental study of multiple memory stages in the cuttlefish, Sepia officinalis.

International audienceThe inhibition of predatory behavior observed during the "prawn-in-the-tube" procedure has been extensively used in studies of cuttlefish learning. The present study examines the effect of age on the conditioning of this response in the cuttlefish, Sepia officinalis. Data show that a significant increase in acquisition performance occurs between 15 and 21 days of age. The retention curves in 8- and 15-day-old cuttlefish show a monotonic memory process, presumably reflecting the presence of only short-term memory. In 21-day-old cuttlefish, there are two distinct processes which could be a labile short-term memory, and a subsequent intermediate memory. These mnesic systems seem to become more effective over the course of post-embryonic development. Moreover, the retention curves obtained in the oldest cuttlefish (30- and 90-day-old) bear a close resemblance to that observed in adults. These behavioral findings will allow further work on the cellular and molecular mechanisms of learning and memory in the cuttlefish

Rapid taste aversion learning in adult cuttlefish, Sepia officinalis

International audienceThe common cuttlefish is an opportunistic predator with certain prey preferences. The literature suggests that learning plays a role in the predatory behaviour of cuttlefish. However, nothing is known about taste aversion learning in cephalopods. We developed a learning procedure in which the preferred prey of the experimental cuttlefish was made distasteful by a bitter taste (quinine). In the training session, the modified prey was repeatedly presented until the experimental cuttlefish stopped attacking it. Of 32 experimental cuttlefish, 26 attacked a different prey from the originally preferred one when both were presented in a choice test 24 or 72 h after learning. In contrast, matched control cuttlefish that had not been subjected to negative reinforcement continued to choose the initially preferred prey under identical test conditions. These results are the first demonstration of taste aversion learning in cephalopods. They underline essential adaptive functions in cuttlefish and the flexibility of their feeding behaviour. Cuttlefish were able to learn that a prey is not acceptable food, even if they usually preyed on it, to recognize it and to avoid it for several days and as a result to eat a usually nonpreferred prey

Behavioral and Neural maturation in the cuttlefish

International audienceThis paper briefly describes findings concerning the ontogenesis of behavioural and neural plasticity in cuttlefish. Predatory and defensive behaviours were investigated and learning and memory abilities were assessed during post-embryonic development. In parallel studies, the maturation of brain structures was determined at different ages. Learning abilities were poor and defensive strategies appeared relatively stereotyped in early juveniles. Memory developed and the plasticity of both defensive and predatory behaviour gradually increased during the first 3 months of life. These behavioural changes occurred simultaneously with the maturation of the most associative structures of the brain. Based on these laboratory observations, several hypotheses are proposed for the behaviour of juvenile cuttlefish in the field