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At least 685 records · Page 38Linked to original sources
PubMed1993

Comparison of GM1 ganglioside, AGF2, and D-amphetamine as treatments for spatial reversal and place learning deficits following lesions of the neostriatum.

These experiments tested the effectiveness of parenterally administered gangliosides and amphetamine as treatments for spatial learning deficits caused by bilateral lesions of the neostriatum. In Expt. 1, rats were tested postsurgically for 30 days on a shock-avoidance, spatial reversal task. Treatments of gangliosides (GM1 at 30 mg/kg, and AGF2 at 20 mg/kg and 30 mg/kg) and D-amphetamine (2 mg/kg) significantly decreased lesion-induced learning deficits on this task, while treatments of 10 mg/kg AGF2 and the combination of GM1 (30 mg/kg) and D-amphetamine (2 mg/kg) were ineffective. In Expt. 2, rats were given bilateral neostriatal lesions and treated with GM1 (30 mg/kg), AGF2 (20 mg/kg) or D-amphetamine (2 mg/kg) and tested postsurgically for 5 days on a place learning task in the Morris water maze. Only the GM1-treated rats showed a reduction in lesion-induced place learning deficits on this task. Since in both experiments, cell counts near the area of the lesion revealed no differences among any of the brain-damaged groups, it was suggested that the treatments exert their behavioral effects by biochemically activating spared neurons, independent of any ultimate effects they may have on neuronal survival.

Adenosine Monophosphate↗
PubMed1976

Effects of neonatal cerebral ventricular injection of ACTH 4-9 and subsequent adult injections on learning in male and female albino rats.

An investigation of permanent developmental effects of a potent, long acting ACTH/MSH 4-10 analogue (Organon 2766) on adult passive avoidance performance and of subsequent peripheral adult injections of the same substance on visual (black and white) discrimination learning and reversal in a Thompson-Bryant box was conducted. A subproblem analysis of visual and position preferences during reversal was performed. No differences in passive avoidance performance or in original discrimination learning were obtained. Both infant and adult treatments enhanced reversal learning and visual orientation (proportion of responese to the previously positive stimulus). Infant treatment suppressed position orientation in males and enhanced position orientation in females. These effects were interpreted as indicating that ACTH-like peptides enhance attention to the relevant stimulus by a direct effect on the brain.

Adrenocorticotropic Hormone↗
PubMed1983

Influence of chlorpromazine administered to rat dams in the peripartum and nursing periods on the learning behavior of the second generation.

Behavioral teratogenicity of chlorpromazine (CPZ) was studied in rats by observing the spontaneous motor activity level and learning behavior of light-dark discrimination in the second generation. The dams were treated with CPZ from day 17 of gestation to postpartum day 21 at doses of 2 mg/kg sc. once daily in one group and 4 mg/kg sc. twice daily in the other. The activity level of F1 was measured at 6 to 7 weeks of age for 68 hrs by a magnetic field counter. The learning experiments were started at 5 weeks of age in one group and 15 weeks of age in the other on the behaviors of the continuous food reinforcement at the beginning, then the light-dark discrimination, and finally the reversal discrimination learning. As the results, no influence of the CPZ treatment was observed in the activity level and learning behaviors of the continuous food reinforcement and light-dark discrimination. But, in the reversal learning of the light-dark discrimination an impairment or delay was observed in some F1 of the CPZ groups. Thus, the significance of observing reversal learning behavior in the assessment of the behavioral teratogenicity of drugs has been shown.

Animals↗
PubMedDate not supplied

TRH analog MK-771 reverses neurochemical and learning deficits in medial septal-lesioned rats.

Microinjection of ibotenic acid into medial septum of rats decreased choline acetyltransferase (CAT) and high-affinity choline uptake (HACU) activities in hippocampus and retarded the learning of a spatial memory task in the radial-arm maze. Administration of MK-771, a stable TRH analog, to such animals restored HACU activity in hippocampus to normal levels. Daily treatment of rats with MK-771 prior to maze running also restored the animals' learning ability. MK-771 did not enhance hippocampal HACU activity or maze performance in sham-lesioned rats. These results suggest that MK-771 reversed the ibotenic acid-induced memory deficit by restoring septohippocampal cholinergic function. MK-771 and other TRH analogs may represent novel agents for improving memory deficits produced by cholinergic insufficiency in Alzheimer's disease.

Animals↗
PubMed2005

Learning ability in aged beagle dogs is preserved by behavioral enrichment and dietary fortification: a two-year longitudinal study.

The effectiveness of two interventions, dietary fortification with antioxidants and a program of behavioral enrichment, was assessed in a longitudinal study of cognitive aging in beagle dogs. A baseline protocol of cognitive testing was used to select four cognitively equivalent groups: control food-control experience (C-C), control food-enriched experience (C-E), antioxidant fortified food-control experience (A-C), and antioxidant fortified food-enriched experience(A-E). We also included two groups of young behaviorally enriched dogs, one receiving the control food and the other the fortified food. Discrimination learning and reversal was assessed after one year of treatment with a size discrimination task, and again after two years with a black/white discrimination task. The four aged groups were comparable at baseline. At one and two years, the aged combined treatment group showed more accurate learning than the other aged groups. Discrimination learning was significantly improved by behavioral enrichment. Reversal learning was improved by both behavioral enrichment and dietary fortification. By contrast, the fortified food had no effect on the young dogs. These results suggest that behavioral enrichment or dietary fortification with antioxidants over a long-duration can slow age-dependent cognitive decline, and that the two treatments together are more effective than either alone in older dogs.

Age Factors↗
PubMedDate not supplied

[Recovery of memory impaired during learning in chickens: reversal of amnesia induced by blockers of protein synthesis].

Administration of protein synthesis inhibitors (PSI) produced an obvious amnesia in chicks (20-25% of avoidance responses). A "reminder" treatment: giving of environmental clues presented during learning, recovered of the learned avoidance response up to level of the control animals (75-80%). The data obtained suggest a possibility of memory recovery following the "reminder" treatment.

Animals↗
PubMed2001

Inducible and reversible enhancement of learning, memory, and long-term potentiation by genetic inhibition of calcineurin.

The threshold for hippocampal-dependent synaptic plasticity and memory storage is thought to be determined by the balance between protein phosphorylation and dephosphorylation mediated by the kinase PKA and the phosphatase calcineurin. To establish whether endogenous calcineurin acts as an inhibitory constraint in this balance, we examined the effect of genetically inhibiting calcineurin on plasticity and memory. Using the doxycycline-dependent rtTA system to express a calcineurin inhibitor reversibly in the mouse brain, we find that the transient reduction of calcineurin activity facilitates LTP in vitro and in vivo. This facilitation is PKA dependent and persists over several days in vivo. It is accompanied by enhanced learning and strengthened short- and long-term memory in several hippocampal-dependent spatial and nonspatial tasks. The LTP and memory improvements are reversed fully by suppression of transgene expression. These results demonstrate that endogenous calcineurin constrains LTP and memory.

Animals↗
PubMed1983

Probable role of reverse transcription in learning: correlation between hippocampal RNA-dependent DNA synthesis and learning ability in rats.

The activities of RNA-dependent DNA polymerase and DNA-dependent DNA polymerase were measured in hippocampus of fast and slow learning Wistar rats. The RNA-dependent DNA polymerase activity in the hippocampus of fast learning rats exceeds two-fold that in the slow learning ones, while the rates of the DNA-dependent DNA polymerase activities are similar. A significant increase in RNA-dependent DNA polymerase only was found in the hippocampus of rats 20 min after training for the conditioned food response before the trace consolidation registered 40 min after the training session. The data obtained are consistent with the suggestion that reverse transcription plays an important role in memory consolidation.

Animals↗