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In JoVE (1)
Other Publications (7)
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
- Cell
- Neurobiology of Learning and Memory
- Neurobiology of Learning and Memory
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
- Learning & Memory (Cold Spring Harbor, N.Y.)
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Articles by Dorothea Eisenhardt in JoVE
JoVE Neuroscience
פרמקולוגיה ההתנהגות של התניה קלאסית תגובת הרחבה חוטם ב דבורי דבש ( אפיס מליפרה)
Fachbereich Bio/Chem/Pharm, Institut für Biologie – Neurobiologie, Freie Universität Berlin
אנו מדגימים כיצד ליישם שיטה פרמקולוגיה התנהגותיים לפרדיגמה מיזוג תיאבון הריח של דבורים (אפיס מליפרה) על ידי יישום מערכתי של תרופות. שיטה זו מאפשרת חקירה של מנגנוני הלמידה הבסיסית היווצרות הזיכרון בצורה פשוטה ואמינה.
Other articles by Dorothea Eisenhardt on PubMed
Spontaneous Recovery from Extinction Depends on the Reconsolidation of the Acquisition Memory in an Appetitive Learning Paradigm in the Honeybee (Apis Mellifera)
Memory retrieval initiates two consolidation processes: consolidation of an extinction memory and reconsolidation of the acquisition memory. The strength of the consolidation processes depends on both the strength of the acquisition memory and the strength of retrieval trials and is correlated with its sensitivity to inhibition. We demonstrate that in the honeybee (Apis mellifera), memory retrieval of a consolidated appetitive olfactory memory leads to both consolidation processes, depending on the number of retrieval trials. Spontaneous recovery from extinction is induced by many (five), but not by few (one and two), retrieval trials. Spontaneous recovery is blocked by emetine, an inhibitor of protein synthesis. We conclude that reconsolidation of the acquisition memory underlies spontaneous recovery.
Small Brains, Bright Minds
Learning, memory, and social behavior are innate properties of the honeybee that are essential for the survival of each individual as well as for the survival of the hive. The small, accessible brain of the honeybee and the availability of the complete sequence of its genome make this social insect an ideal model for studying the connection between learning, memory, and social behavior.
Extinction Learning, Reconsolidation and the Internal Reinforcement Hypothesis
Retrieving a consolidated memory--by exposing an animal to the learned stimulus but not to the associated reinforcement--leads to two opposing processes: one that weakens the old memory as a result of extinction learning, and another that strengthens the old, already-consolidated memory as a result of some less well-understood form of learning. This latter process of memory strengthening is often referred to as "reconsolidation", since protein synthesis can inhibit this form of memory formation. Although the behavioral phenomena of the two antagonizing forms of learning are well documented, the mechanisms behind the corresponding processes of memory formation are still quite controversial. Referring to results of extinction/reconsolidation experiments in honeybees, we argue that two opposing learning processes--with their respective consolidation phases and memories--are initiated by retrieval trials: extinction learning and reminder learning, the latter leading to the phenomenon of spontaneous recovery from extinction, a process that can be blocked with protein synthesis inhibition.
One Retrieval Trial Induces Reconsolidation in an Appetitive Learning Paradigm in Honeybees (Apis Mellifera)
Combining memory retrieval with the application of a protein synthesis-inhibitor leads to an amnestic effect that is referred to as the reconsolidation phenomenon. Several behavioural studies demonstrate that only a few or weak retrieval trials (that do not result in significant extinction) lead to this phenomenon. In contrast, many trials (that result in significant extinction) combined with a protein synthesis inhibitor result in an inhibition of the extinction memory. Based on these findings it was suggested that extinction is the boundary condition for reconsolidation: when extinction is induced the consolidation of the extinction memory is the dominant process. Recently we were not able to confirm this hypothesis in the honeybee (Apis mellifera): we did not find the reconsolidation phenomenon after one retrieval trial, but demonstrated reconsolidation after five retrieval trials that led to extinction. To exclude that this observation resembles a special case in insects we here wanted to know if one retrieval trial induces reconsolidation as it has been demonstrated before in many other species. To do so we used experimental parameters that had been used before to demonstrate consolidation in the honeybee with the exception that this time the protein synthesis-inhibitor was applied 1 h after one memory retrieval instead after acquisition. We thereby demonstrate the reconsolidation phenomenon after one retrieval trial but only when using the doubled dose of protein synthesis-inhibitor that has been used to inhibit consolidation.
Consolidation of an Extinction Memory Depends on the Unconditioned Stimulus Magnitude Previously Experienced During Training
Here, we examine the role of the magnitude of the unconditioned stimulus (US) during classical conditioning in consolidation processes after memory retrieval. We varied the US durations during training and we test the impact of these variations on consolidation after memory retrieval with one or two conditioned stimulus-only trials. We found that the consolidation of an extinction memory depends on US duration during training and ruled out the possibility that this effect is attributable to differences in satiation after conditioning. We conclude that consolidation of an extinction memory is triggered only when the duration of the US reaches a critical threshold. This demonstrates that memory consolidation cannot be regarded as an isolated process depending solely on training conditions. Instead, it depends on the animal's previous experience as well.
Acute Disruption of the NMDA Receptor Subunit NR1 in the Honeybee Brain Selectively Impairs Memory Formation
Memory formation is a continuous process composed of multiple phases that can develop independently from each other. These phases depend on signaling pathways initiated after the activation of receptors in different brain regions. The NMDA receptor acts as a sensor of coincident activity between neural inputs, and, as such, its activation during learning is thought to be crucial for various forms of memory. In this study, we inhibited the expression of the NR1 subunit of the NMDA receptor in the honeybee brain using RNA interference. We show that the disruption of the subunit expression in the mushroom body region of the honeybee brain during and shortly after appetitive learning selectively impaired memory. Although the formation of mid-term memory and early long-term memory was impaired, late long-term memory was left intact. This indicates that late long-term memory formation differs in its dependence on NMDA receptor activity from earlier memory phases.
Average Group Behavior Does Not Represent Individual Behavior in Classical Conditioning of the Honeybee
Conditioned behavior as observed during classical conditioning in a group of identically treated animals provides insights into the physiological process of learning and memory formation. However, several studies in vertebrates found a remarkable difference between the group-average behavioral performance and the behavioral characteristics of individual animals. Here, we analyzed a large number of data (1640 animals) on olfactory conditioning in the honeybee (Apis mellifera). The data acquired during absolute and differential classical conditioning differed with respect to the number of conditioning trials, the conditioned odors, the intertrial intervals, and the time of retention tests. We further investigated data in which animals were tested for spontaneous recovery from extinction. In all data sets we found that the gradually increasing group-average learning curve did not adequately represent the behavior of individual animals. Individual behavior was characterized by a rapid and stable acquisition of the conditioned response (CR), as well as by a rapid and stable cessation of the CR following unrewarded stimuli. In addition, we present and evaluate different model hypotheses on how honeybees form associations during classical conditioning by implementing a gradual learning process on the one hand and an all-or-none learning process on the other hand. In summary, our findings advise that individual behavior should be recognized as a meaningful predictor for the internal state of a honeybee--irrespective of the group-average behavioral performance.
