Navegando por Palavras-chave "consolidation"
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- ItemSomente MetadadadosDeficits in avoidance responding after paradoxical sleep deprivation are not associated with altered [H-3]pirenzepine binding to M1 muscarinic receptors in rat brain(Elsevier B.V., 2003-07-04) Moreira, K. M.; Hipolide, D. C.; Nobrega, J. N.; Bueno, OFA; Tufik, S.; Oliveira, MGM; Universidade Federal de São Paulo (UNIFESP); Ctr Addict & Mental HlthPrevious work had indicated that animals that were sleep-deprived and then trained on a passive avoidance task show poor retention of the task 24 h later after being allowed to sleep freely again. Cholinergic involvement is suggested by the fact that this effect is prevented by treatment with the muscarinic agonist pilocarpine during sleep deprivation. the observation that similar deficits are observed in non-deprived rats after treatment with M1-selective antagonist compounds such as dicyclomine or pirenzepine cause similar impairments, and gave rise to the hypothesis that sleep deprivation might induce significant reductions in M1 binding in brain areas involved in learning and memory processes. Rats were deprived of sleep for 96 It and then either immediately killed, or allowed to recover sleep for 24 h before being killed. [H-3]pirenzepine binding to M1 sites was examined by quantitative autoradiography in 39 different brain areas in cage controls, sleep-deprived and sleep-recovered animals (N=8 per group). No significant differences among groups were found in any brain region. A separate group of animals was subjected to the sleep deprivation procedure and then trained in a simple avoidance task. Animals were then allowed to sleep and retested 24 h later. This group showed a significant impairment in the avoidance task compared to cage controls, in agreement with previous observations. These data suggest that proactive learning/memory deficits induced by sleep deprivation cannot be attributed to altered M1 binding either immediately after deprivation (when avoidance training occurs) or after sleep has recovered (when acquisition/retention are tested). the possibility remains that alterations in M1 function occur at post-membrane second messenger systems. (C) 2003 Elsevier Science B.V. All rights reserved.
- ItemSomente MetadadadosEffects of pre- or post-training entorhinal cortex AP5 injection on fear conditioning(Elsevier B.V., 2005-11-15) Schenberg, E. E.; Soares, JCK; Oliveira, MGM; Universidade Federal de São Paulo (UNIFESP)Fear conditioning is one of the most studied paradigms to assess the neural basis of emotional memory. the circuitry involves NNMA receptor activation in the amygdala and, in the case of contextual conditioning, in the hippocampus. Entorhinal cortex is one of the major input/output structures to the hippocampus and also projects to the amygdala, both through glutamatergic transmission. Other learning tasks involving hippocampus and amygdala, such as inhibitory avoidance, require entorhinal cortex during acquisition and consolidation. However, the involvement of NMDA receptors mediated transmission in entorhinal cortex in fear conditioning acquisition and consolidation is not clear. To investigate that issue, rats were trained in fear conditioning to both contextual and tone conditioned stimulus. Immediately before, immediately, 30 or 90 min after training they received NMDA antagonist AP5 or saline injections bilaterally in the entorhinal cortex (AP-6.8 mm, L +/- 5.0 mm DV-6.8 mm). Contextual fear conditioning was measured 24 h after training, and tone fear conditioning 48 h after training. AP5 injections selectively impaired contextual fear conditioning only when injected pre-training. Post-training injections had no effect. These findings suggest that entorhinal cortex NMDA receptors are necessary for acquisition, but not for consolidation, of contextual fear conditioning. On the other hand, both acquisition and consolidation of tone fear conditioning seem to be independent of NMDA receptors in the entorhinal cortex. (c) 2005 Elsevier Inc. All fights reserved.
- ItemAcesso aberto (Open Access)Effects of sleep deprivation on different phases of memory in the rat: dissociation between contextual and tone fear conditioning tasks(Frontiers Research Foundation, 2014-11-07) Rossi, Vanessa Contatto [UNIFESP]; Tiba, Paula Ayako; Monreira, Karin Di Monteiro; Ferreira, Tatiana Lima; Oliveira, Maria Gabriela Menezes de [UNIFESP]; Suchecki, Deborah [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Federal do ABC (UFABC)Numerous studies show that sleep deprivation (SD) impacts negatively on cognitive processes, including learning and memory. Memory formation encompasses distinct phases of which acquisition, consolidation and retrieval are better known. Previous studies with pre-training SD induced by the platform method have shown impairment in fear conditioning tasks. Nonetheless, pre-training manipulations do not allow the distinction between effects on acquisition and/or consolidation, interfering, ultimately, on recall of/performance in the task. in the present study, animals were first trained in contextual and tone fear conditioning (TFC) tasks and then submitted to SD with the purpose to evaluate the effect of this manipulation on different stages of the learning process, e.g., in the uptake of (new) information during learning, its encoding and stabilization, and the recall of stored memories. Besides, we also investigated the effect of SD in the extinction of fear memory and a possible state dependent learning induced by this manipulation. for each task (contextual or TFC), animals were trained and then distributed into control, not sleep-deprived (CTL) and SD groups, the latter being submitted to the modified multiple platform paradigm for 96 h. Subsets of eight rats in each group/experiment were submitted to the test of the tasks, either immediately or at different time intervals after SD. the results indicated that (a) pre- but not post-training SD impaired recall in the contextual and TFC; (b) this impairment was not state-dependent; and (c) in the contextual fear conditioning (CFC), pre-test SD prevented extinction of the learned task. Overall, these results suggest that SD interferes with acquisition, recall and extinction, but not necessarily with consolidation of emotional memory.