Browsing by Subject "Forgetting"

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    The flavonoid apigenin delays forgetting of passive avoidance conditioning in rats
    (SAGE Publications, 2013-11-27) Popovic, Miroljub; Caballero Bleda, María; Benavente-García, Obdulio; Castillo, Julián; Research Institute of Aging, University of Murcia,; Research & Development Department of Nutrafur S.A., Alcantarilla (Murcia),
    The present experiments were performed to study the effect of the flavonoid apigenin (20 mg/kg intraperitoneally (i.p.), 1 h before acquisition), on 24 h retention performance and forgetting of a step-through passive avoidance task, in young male Wistar rats. There were no differences between saline- and apigenin-treated groups in the 24 h retention trial. Furthermore, apigenin did not prevent the amnesia induced by scopolamine (1mg/kg, i.p., 30 min before the acquisition). The saline- and apigenin-treated rats that did not step through into the dark compartment during the cut-off time (540 s) were retested weekly for up to eight weeks. In the saline treated group, the first significant decline in passive avoidance response was observed at four weeks, and complete memory loss was found five weeks after the acquisition of the passive avoidance task. At the end of the experimental period, 60% of the animals treated with apigenin still did not step through. These data suggest that 1) apigenin delays the long-term forgetting but did not modulate the 24 h retention of fear memory and 2) the obtained beneficial effect of apigenin on the passive avoidance conditioning is mediated by mechanisms that do not implicate its action on the muscarinic cholinergic system.
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    Time course of scopolamine effect on memory consolidation and forgetting in rats
    (Elsevier, 2014-11-18) Popovic, Miroljub; Giménez de Béjar, Verónica; Popovic, Natalija; Caballero Bleda, María; Anatomía Humana y Psicobiología
    The effect of scopolamine on the consolidation and forgetting of emotional memory has not been completely elucidated yet. The aim of the present study was to investigate the time course of scopolamine effect on consolidation and forgetting of passive avoidance response. In a first experiment of the present study, we tested the effect of scopolamine (1mg/kg, i.p., immediately after acquisition), on 24h and 48h retention performance of the step-through passive avoidance task, in adult male Wistar rats. On the 24h retested trial, the latency of the passive avoidance response was significantly lower, while on the 48h retested trial it was significantly higher in scopolamine than in the saline-treated group. In a second experiment, we assessed the 24h time course of scopolamine (1mg/kg) effect on memory consolidation in passive avoidance task. We found that scopolamine administration only within the first six and half hours after acquisition improved memory consolidation in 48h retention performance. Finally, a third experiment was performed on the saline- and scopolamine-treated rats (given immediately after acquisition) that on the 48h retention test did not step through into the dark compartment during the cut-off time. These animals were retested weekly for up to first three months, and after that, every three months until the end of experiment (i.e., 15 months after acquisition). The passive avoidance response in the saline treated group lasted up to 6 weeks after acquisition, while in the scopolamine treated group 50% of animals conserved the initial level of passive avoidance response until the experiment end point. In conclusion, the present data suggest that (1) improving or impairment effect of scopolamine given in post-training periods depends on delay of retention trial, (2) memory consolidation process could be modify by scopolamine within first six and half hours after training and (3) scopolamine could delay forgetting of emotional memory.