Working memory in Parkinson's disease patients: clinical features and response to levodopa / Memória de trabalho em pacientes com doença de Parkinson: características clínicas e resposta a levodopa

OBJECTIVE: To evaluate the clinical features of the working memory (WM) in Parkinson's disease (PD) patients and to test the effect of levodopa on WM. METHOD: The paradigm was based on the 'n-back' tasks, which enables to study the level of executive demand (three levels of difficulty) and the domain of the information being processed (spatial items, faces and letters). The effect of levodopa was studied by testing PD patients in "on" and "off" states. RESULTS: PD patients performed less well in WM tasks than controls. There was no interaction between groups and complexity. Levodopa therapy had a positive effect only on spatial WM tasks but no effect on complexity. CONCLUSION: Our results suggest that impairment observed may result from a maintenance deficit within WM regardless the level of processing and levodopa therapy presents a positive effect on spatial WM.

OBJETIVO: Avaliar as características clínicas da memória de trabalho (MT) em pacientes com doença de Parkinson (DP) e testar o efeito da levodopa na MT. MÉTODO: O paradigma baseou-se nas tarefas 'n-back', que permitem avaliar o nível de demanda executiva (três níveis de dificuldade) e o domínio da informação sendo processado (posições espaciais, faces e letras). O efeito da levodopa foi estudado pela testagem dos pacientes no estado "on" e "off". RESULTADOS: Pacientes com DP apresentam desempenho inferior ao dos controles em tarefas de MT. Não foi observada interação entre grupos e complexidade. A terapia com levodopa mostrou efeito positivo sobre a modalidade espacial, e nenhum efeito sobre a complexidade. CONCLUSÃO: Nossos resultados sugerem que o comprometimento observado pode resultar de défict de manutenção da MT, independente do nível de processamento. A terapia com levodopa apresenta efeito positivo sobre a MT espacial.

Investigation on the effect of eclipta alba on animal models of learning and memory.

Short and long term memory loss may result from deteriorating cerebral mechanisms due to varied causes which could have a tremendous impact on the quality of life. Herbs are being constantly explored to resolve cognitive deficits. Eclipta alba (Ea) commonly called as the trailing Eclipta is being examined for its memory enhancing quality as it is traditionally used for this purpose. The shade dried leaves of Eclipta alba was extracted with distilled water. The suspension of Ea containing 100 and 200 mg/kg was administered to rats to evaluate Transfer Latency (TL) on an elevated plus maze. TL was a measure of acquisition and retrieval learning. Mice were placed at the center of open field apparatus to assess spatial habitual learning, observed for 20 minutes for rearing and time spent during rearing using varied doses for 30 minutes, 24 hours and 96 hours and 144 hrs. The results revealed significant improvement of retrieval memory.

Four-arm radial open maze (FAROM) as a tool for assessing the effect of atropine in spatial memory of the rats.

Place learning behaviour for working (short term) memory and reference (long term) memory is studied with the Four-arm radial open maze (FAROM) in 18 rats divided equally in three groups. In group I, 0.5 mg of atropine was injected intra-peritoneally 30 minutes before the trial. In group II, saline and in group III Glycopyrrolate were injected instead. Twenty three hours hungry animals were tested on each day in the maze to search for food kept in one of the eight cul-de-sacs of maze. The latency i.e. the time to reach the goal cul-de-sacs, as well as the error score i.e. the number of entries in the non-goal cul-de-sacs were counted during six consecutive trials, per day. Each trial duration was 5 minutes or the time taken by the animal to search the goal compartment whichever was less. The inter-trials period was 10 min and the work was carried out for a period of 3 weeks. The results show that atropine does block effectively both the memory faculties i.e. working and reference memory and that level of memory deficit induced by atropine is related to the rate of drug uptake by the central cholinergic receptors.