Spatial Learning In Adult Rats Research Articles

Effects of early sensory deprivation on spatial learning in adult rats

Following vibrissae removal in early ontogenesis from P1 (post-natal day 1) to P30, three-month old rats were trained to run for food in an 8-arm radial maze. Training started at the age of three months. Adult rats demonstrated ability to perform the behavioral task; however, their performance was not as good as in the control group. Our findings revealed the differences in the rats exploratory strategy and key behavioral tactics of entering the maze arms at a certain angle. The results show that active vibrissae sensing plays an important role in shaping rat behavioral tactics during spatial learning in the 8-arm radial maze.

Vitamin D deficiency impairs spatial learning in adult rats.

Through its membrane and intracellular receptors, vitamin D regulates many vital functions in the body including its well known actions on musculoskeletal system. Growing body of evidences demonstrate that vitamin D undergoes some of behavioral aspects of neurocognition. The present study was designed to evaluate the effect of food regimens without vitamin D or with a supplement of 1,25(OH)2D3 on spatial performance of adult rats. The animals were trained in the Morris water maze to find a hidden platform. The time spent and the distance traveled to find the platform, speed of navigation and the percentage of unsuccessful trials were considered for assessment of the task learning. Our findings indicated that the vitamin D-deprived rats had a significant lower performance compared to both the controls and the animals receiving 1,25(OH)2D3 supplementation. Concerning the unsuccessful trials, lack of vitamin D resulted in the highest failures in the maze navigation. The regimen with additional 1,25(OH)2D3 did not considerably influence learning of the maze task. We concluded that while vitamin D deficiency deteriorates the spatial task learning, the 1,25(OH)2D3 supplementation did not effectively underlie the maze performance.

P.1.d.007 Selective NMDA-NR2B receptor antagonist with neurogenic properties, Ro 25-6981 facilitates repeated spatial learning in adult rats

P.1.d.007 Selective NMDA-NR2B receptor antagonist with neurogenic properties, Ro 25-6981 facilitates repeated spatial learning in adult rats

Neurogenesis Enhancer RO 25-6981 Facilitates Repeated Spatial Learning in Adult Rats

The effects of Ro 25-6981 (selective NMDA receptor blocker) in a dose stimulating neurogenesis on repeated learning, reversal learning, and memory reconsolidation were studied in adult rats in Morris water maze. Ro 25-6981 facilitated repeated learning 13 days after injection, but did not influence reversal learning. The blocker injected directly before reminder did not disturb repeated learning and reversal learning in Morris water maze. These effects of Ro 25-6981 on the dynamics of repeated learning seemed to be due to its effects on neurogenesis processes in adult brain.

The next generation of cholinesterase inhibitors.

Clinical trials with tacrine (THA) have resulted in elevations of liver enzymes in Alzheimer patients that showed improvement. In an effort to minimize these side effects several THA analogues were synthesized. These analogues were compared to THA in biochemical as well as behavioural studies. The biochemical effects of these drugs on plasma cholinesterase activity and cholinergic receptors as well as the effect of these drugs on spatial learning in adult rats were examined. It is possible that some of these analogues with more potent cholinergic effect than THA might be the next generation of cholinesterase inhibitors which can be useful in the treatment of Alzheimer's disease.

Methamphetamine exposure from postnatal day 11 to 20 causes impairments in both behavioral strategies and spatial learning in adult rats

Spatial learning and memory deficits in a water maze have been observed in adult animals exposed to a regimen of 4 daily doses of d-methamphetamine (MA) at 2 h intervals from postnatal day 11 to 20. An interpretational issue for these long-term effects of MA is whether they are truly spatial deficits or are secondary to alterations in sensorimotor systems. In this experiment, we evaluated the effects of a pretraining procedure shown to minimize the influence of drug-induced sensorimotor deficits. Animals within a litter were treated with MA or saline. Animals were either pretrained for nonspatial task requirements in the water maze (i.e., swimming and platform climbing) or were naı̈ve to the task. Animals that received the pretraining did better than the naı̈ve animals. The naı̈ve MA animals performed worse than the naı̈ve control animals as previously observed. By contrast, no difference in search time was noted between pretrained MA- and SAL-treated animals during the acquisition phase of testing. When the platform was relocated in a novel position, spatial learning was impaired for MA animals, regardless of pretraining. No increase in the number of platform nonrecognition events (swimovers, deflections, or jump-offs) occurred among pretrained or naı̈ve groups compared to controls. These data suggest that sensorimotor deficits do not account for the spatial learning and memory deficits in animals exposed neonatally to MA.

Inhibition of MAO‐A Activity Enhances Behavioural Activity of Rats Assessed Using Water Maze and Open Arena Tasks

To determine if the inhibition of MAO-A and/or MAO-B activities can influence cognitive processes in adult rats, we analysed whether chronic treatment with clorgyline, 1-deprenyl and pargyline could modify the performance of adult rats in a modified version of the water maze task. The effects of these treatments on locomotor activity and enzyme activities were also assessed. Rats were treated for 24 days with clorgyline (0.2 mg/kg), 1-deprenyl (0.25 mg/kg) and pargyline (I or 10 mg/kg). The treatments were started two weeks before the water maze experiment and continued until the end of testing. The rats were trained to find a submerged platform (6 days: I trial/day; 7 th day: probe trial). Over the next three days, locomotor activity was assessed in an open arena. Treatments with clorgyline (MAO-A inhibitor), 1-deprenyl (MAO-B inhibitor) and pargyline (non-selective MAO inhibitor) did not improve the finding of the hidden platform, when compared to treatment with saline, but significantly increased the swimming speed of the rats. The different treatments, when compared to saline, failed to modify the distance covered and the number of groomings performed in the open arena. However, clorgyline and pargyline, 10 mg/kg, increased the number of faecal boli and clorgyline enhanced the number of rearings made when compared to saline, 1-deprenyl and pargyline, 10 mg/kg. These results indicate that near total inhibition of MAO-A by clorgyline and pargyline as assessed by MAO activity measurement induces an increase in locomotor activity but that inhibition of MAO-A or MAO-B, either alone or combined, does not facilitate spatial learning in adult rats.

An increase in dendritic spine density on hippocampal CA1 pyramidal cells following spatial learning in adult rats suggests the formation of new synapses.

The search for cellular correlates of learning is a major challenge in neurobiology. The hippocampal formation is important for learning spatial relations. A possible long-lasting consequence of such spatial learning is alteration of the size, shape, or number of excitatory synapses. The dendritic spine density is a good index for the number of hippocampal excitatory synapses. By using laser-scanning confocal microscopy, we observed a significantly increased spine density in CA1 basal dendrites of spatially trained rats when compared to nontrained controls. With unchanged dendritic length, the higher spine density reflects an increased number of excitatory synapses per neuron associated with spatial learning.

A novel anticholinesterase THB013: biochemical and behavioural studies.

Clinical trials with tacrine (THA) have resulted in elevations of liver enzymes in Alzheimer patients that showed improvement. In an effort to minimize these side effects several THA analogues were synthesized. These analogues were compared to THA in biochemical as well as behavioural studies. In this study, the biochemical effects of THA and one of these analogs, THB 013, on plasma cholinesterase activity, cholinergic receptors as well as the effect of these drugs on spatial learning in adult rats were examined. THB 013 was, at lower concentration, more efficacious in inhibiting plasma cholinesterase as well as blocking the scopolamine induced disruption of spatial learning when administered 10 min before the scopolamine injection. It is possible that THB 013 with more potent cholinergic effects than THA might be useful in the treatment of Alzheimer's disease.