Two causes of forgetting have been promulgated: memory trace decay and retroactive interference. The authors show that forgetting is an active process requiring both new learning and memory. In the present (1)Lymnaea model system, prevention of new learning of a conflicting association, inhibition of memory consolidation, or Right Pedal Dorsal 1 soma ablation, which blocks LTM formation, are all potent means to prevent forgetting.
View Article and Find Full Text PDFA 3-neuron central pattern generator, whose sufficiency and necessity has been directly demonstrated, mediates aerial respiratory behaviour in the pond snail, Lymnaea stagnalis. This behaviour can be operantly conditioned, and this associative learning is consolidated into long-lasting memory. Depending on the operant conditioning training procedure used the learning can be consolidated into intermediate term (ITM) or long-term memory (LTM).
View Article and Find Full Text PDFLymnaea stagnalis were operantly conditioned to not perform aerial respiratory behavior. This learned response was subsequently extinguished. Here, we show that spaced extinction training is more effective than massed extinction training, in addition to the occurrence of spontaneous recovery.
View Article and Find Full Text PDFReconsolidation of a long-term memory (LTM) in the snail Lymnaea stagnalis can be disrupted by cooling, an RNA synthesis blocker (actinomycin D), and by specifically ablating the soma of a cell we know is a site of LTM consolidation (right pedal dorsal 1, RPeD1). Aerial respiratory behavior was conditioned operantly by applying a gentle tactile stimulus to the pneumostome area (the respiratory orifice) every time the snail began to open its pneumostome to perform aerial respiration. This resulted in a reduction of this behavior while leaving cutaneous respiration intact.
View Article and Find Full Text PDFThe search for 'the how and the where' of memory formation in the brain, the engram, is still one of the unattained 'Holy Grails' of neuroscience. Over the years, various paths have been trodden in attempts to attain this goal, and while tantalizing glimpses appear now and then on the scientific horizon, the Grail still has not been grasped. One of the paths that investigators have walked is the invertebrate 'model system' approach.
View Article and Find Full Text PDFAerial respiratory behaviour in the pond snail, Lymnaea stagnalis, can be operantly conditioned. This associative learning then undergoes consolidation into a long-lasting memory which, depending on the training procedure used, causes intermediate-term memory (ITM; lasting 3 h) or long-term memory (LTM; lasting >6 h) to be formed. We determined the differential susceptibility of these two forms of memory to translation and transcription blockers.
View Article and Find Full Text PDFThe cellular basis of long-term memory (LTM) storage is not completely known. We have developed a preparation where we are able to specify that a single identified neuron, Right Pedal Dorsal 1 (RPeD1), is a site of LTM formation of associative learning in the pond snail, Lymnaea stagnalis. We demonstrated this by ablating the soma of the neuron but leaving behind its functional primary neurite, as evidenced by electrophysiological and behavioral analyses.
View Article and Find Full Text PDFAerial respiratory behavior in the pond snail Lymnaea was operantly conditioned so that snails learned not to perform aerial respiration in a hypoxic environment. Snails were trained in either the standard context (no food odorant) or a carrot (food-odorant) context. An operant training procedure of two 45-min training sessions with a 1-h interval between the sessions followed by a third 45-min training session 18 h later was sufficient to produce associative learning and long-term memory (LTM) that persisted for at least 5 days.
View Article and Find Full Text PDFA continuous schedule of reinforcement (CR) in an operant conditioning procedure results in the acquisition of associative learning and the formation of long-term memory. A 50 % partial reinforcement (PR) schedule does not result in learning. The sequence of PR-CR training has different and significant effects on memory retention and resistance to extinction.
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