Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “learning and memory”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,477 records · Page 82Linked to original sources
PubMed1998

Interaction of a subanaesthetic concentration of isoflurane with midazolam: effects on responsiveness, learning and memory.

There are situations in which "light" anaesthesia combined with neuromuscular block is the only anaesthetic regimen that can be tolerated safely by the patient. Benzodiazepines have hypnotic and specific amnesic effects. Therefore, we have examined the interaction of midazolam with a subanaesthetic dose of isoflurane (0.2% end-expired concentration) in 28 healthy volunteers. Thereafter, 15 subjects received midazolam 0.03 mg kg-1 i.v. and 13 subjects received midazolam 0.06 mg kg-1 in a random, double-blind manner. Word lists were administered and response to commands was tested before and after administration of midazolam. After 1 h of recovery, memory for word lists was tested by word completion, free recall and forced choice recognition tasks. After administration of midazolam, recall and, to a lesser degree, implicit memory were absent. Recognition was also absent after administration of midazolam 0.06 mg kg-1 and at the 3-min and 15-min assessments after administration of midazolam 0.03 mg kg-1. Responsiveness was more frequent with midazolam 0.03 mg kg-1 than with 0.06 mg kg-1 and increased over time. We conclude that a larger dose of midazolam or isoflurane, or both, may be necessary to abolish responsiveness.

Adult↗
PubMed2000

Alcoholics' initial organizational and problem-solving skills predict learning and memory performance on the Rey-Osterrieth Complex Figure.

This study was undertaken to investigate whether alcoholics differ qualitatively from controls in their organizational approach to the Rey-Osterrieth Complex Figure (ROCF) and to examine the effects of problem-solving and organizational ability on learning and retention. Data were collected on 3 groups of neuromedically healthy, middle-aged men: 29 recently detoxified alcoholics (RDA) abstinent at least 2 weeks, 29 long-term abstinent alcoholics (LTA) abstinent at least 18 months, and 29 nonalcoholic controls (NAC). Groups were comparable in age, education, WAIS-R Vocabulary score, and ANART IQ. Three indices of problem-solving approach were used to score how participants produce the ROCF during the copy condition: perceptual clustering, organization, and constructional accuracy. Learning and retention were measured by immediate recall, 20-min delayed recall, and recognition performance. RDAs had significantly impaired immediate recall, delayed recall, and recognition scores compared to NACs. RDAs also had significantly lower perceptual clustering, organization, and constructional accuracy scores than their long-term abstinent and nonalcoholic counterparts. Multiple regression analyses revealed that problem-solving ability at copy accounted for a significant proportion of the variance in immediate recall, delayed recall, and recognition. Further investigation of memory performance using a repeated measures design revealed that across the 3 groups, little forgetting occurred between immediate and delayed recall, while performance improved significantly on the recognition trial. Use of less efficient problem-solving strategies appears to affect RDAs' ability to learn and retrieve complex figural information.

Adult↗
PubMed2006

Effect of selective cholinergic denervation on the serotonergic system: implications for learning and memory.

The cholinergic system has been widely implicated in cognitive processes and cholinergic loss is a classical hallmark in Alzheimer disease. Increasing evidence supports a role of the serotonergic system in cognition, possibly through a modulation of cholinergic activity. We compared selective cholinergic denervation by administration of the immunotoxin 192 IgG-saporin in the nucleus basalis of Meynert (NBM) with intracerebroventricular (ICV) lesions of the basal forebrain in male rats 7 days after lesioning. NBM lesions induced significant changes in cholinergic markers in the frontal cortex, whereas ICV lesions produced significant decreases in cholinergic markers both in the frontal cortex and hippocampus. Only ICV lesions lead to memory impairments in passive avoidance and Morris water maze tasks. Both models lead to reductions of serotonin levels in the frontal cortex. Similar changes in 5-hydroxytriptophan levels were observed, suggesting a downregulation of the rate-limiting enzyme for the synthesis of serotonin along with the cholinergic deficit. Neither 5-HT1A nor 5-HT1B receptors seem to mediate this process. These data imply that the serotonergic system in the frontal cortex can compensate for diminished cholinergic function and support the investigation of the serotonergic system as a therapeutic target to treat Alzheimer disease.

Acetylcholine↗
PubMed1991

Aged-related changes in learning and memory, choline acetyltransferase activity and number of neuronal cells in rats.

In a water maze task, the goal latency and distance of swimming onto the platform of aged rats (24 months old) were slowly shortened by repeated training compared with those of young rats (8 weeks old). A significant decrease in choline acetyltransferase activity in the frontal cortex, parietal cortex and striatum was observed in aged rats. Moreover, the number of neuronal cells in the hippocampal CA1 subfield and dentate gyrus of aged rats was smaller than that of young rats. The atrophy of striatal cells was observed. These results suggest that age-related delay of acquisition is due to the above-mentioned biochemical and histological changes, and that rates of aging in biochemical and morphological parameters are different in the discrete brain areas.

Aging↗
PubMedDate not supplied

The effect of chronic vs. acute injection of vasopressin on animal learning and memory.

The effect of chronic and acute treatment with DDAVP, a vasopressin analog, was studied in 2 month old male rats, using an active avoidance test in a shuttle box. The experiment lasted 6 weeks: an acquisition period of 4 weeks and an extinction period of 2 weeks. Rats were treated one hour before behavioral testing 3 times a week for 6 weeks with either DDAVP 20 micrograms/rat/day for the whole period (chronic group) or with DDAVP for the first week and again once only on the first day of the extinction period (acute group) or with saline. Chronic treatment with DDAVP resulted in better acquisition and in a marked retardation of extinction compared with the acute treatment group. These results were obtained both in normal rats and in rats pretreated at age 5 days of life with intracisternal 6-OH dopamine.

Animals↗
PubMedDate not supplied

2-amino-3-phosphonopropionic acid (AP3) and its N-methyl analog improve learning and memory in rats.

The influence of 2-amino-3-phosphonopropionic acid (AP3), an antagonist of metabotropic glutamate receptors and its N-methyl analog (N-methyl AP3) on acquisition, consolidation and recall of information in a passive avoidance situation was tested. Both compounds improved three examined parameters. The significant effect of AP3 appeared at the icv dose of 12.5 micrograms per rat when its influence on acquisition and consolidation was tested, and at the icv dose of 100 micrograms when its influence on retrieval process was evaluated. The significant improvement of acquisition of information was observed at the icv dose of 50 micrograms per rat of N-methyl AP3, but significant facilitation of consolidation and retrieval processes appeared at the higher dose of 100 micrograms per rat. Significant improvement of performance in a passive avoidance situation persisted in all experiments to the highest used dose of both compounds, 250 micrograms.

Alanine↗
PubMed1997

Consciousness in a Self-Learning, Memory-Controlled, Compound Machine.

A memory-controlled, sensor/actuator machine senses conditions in its environment at given moments, and attempts to produce an action based upon its memory. However, a sensor/actuator machine will stop producing new behavior if its environment is removed. A sensor/sensor unit can be added to the sensor/actuator machine, forming a compound machine. The sensor/sensor unit produces a stream of internally created sensed conditions, which can replace the sensed conditions from the environment. This illusion of an environment is similar to consciousness. In addition, actuator/sensor and actuator/actuator units can be added to this compound machine to further enhance its ability to function without an environment. Predetermined and empirical memory cells can be distributed throughout the control units of this compound machine to provide instinctive and learned behavior. The internal and exterior behavior of this compound machine can be modified greatly by changing the cycle start and ramp signals that activate these different kinds of memory cells. These signals are similar in form to brain waves.

Journal Article↗
PubMed1999

The effect of caffeine in animal models of learning and memory.

In the present investigation we studied the effect of caffeine on memory task inhibitory avoidance and habituation to a new environment. Caffeine impaired retention scores in mice submitted to inhibitory avoidance and habituation when administered 30 min before training at the doses of 10-30 mg/kg. These effects cannot be explained by state-dependency since the administration of caffeine 30 min before the test session did not reverse the effect of pre-training caffeine administration, but can more probably be explained by an impairment in the acquisition or by interference with attentional processes. On the other hand, caffeine improved the inhibitory avoidance (but not habituation) retention scores when administered immediately after the training or 30 min before the test session at the doses of 1-30 mg/kg or 3-10 mg/kg, respectively. These results suggest that caffeine differentially affects the different stages of memory processing and that this effect depends on particularities of the memory task under study.

Analysis of Variance↗
PubMed1997

Effects of the kappa-opioid dynorphin A(1-13) on learning and memory in mice.

The effects of intracerebroventricular administration of dynorphin A(1-13) on scopolamine- and pirenzepine-induced amnesia were investigated in mice by observing the step-down-type passive avoidance response and spontaneous alternation performance. The pre- or post-training, or preretention administration of dynorphin A(1-13) (0.3-10 micrograms) alone failed to affect the passive avoidance response, while scopolamine (1 mg/kg) significantly inhibited it. Dynorphin A(1-13) (1 microgram) given 15 min before training and retention tests, but not immediately after training, significantly improved the scopolamine (1 mg/kg)-induced impairment of passive avoidance response, indicating the anti-amnesic effects of dynorphin A(1-13). A lower dose (1 mg/kg) of the kappa-opioid receptor antagonist (-)-(1R,5R,9R)-5,9-diethyl-2-(3-furyl-methyl)-2'-hydroxy-6,7-benzomorpha n reversed the anti-amnesic effects of dynorphin A(1-13) (1 microgram). In contrast, although dynorphin A(1-13) (1, 3 and 10 micrograms) did not influence spontaneous alternation performance, scopolamine (1 mg/kg) and the muscarinic M1 receptor antagonist pirenzepine (3 micrograms) markedly decreased spontaneous alternation performance. Dynorphin A(1-13) (3, 5.6 and/or 10 micrograms) significantly improved the scopolamine (1 mg/kg)- and pirenzepine (3 micrograms)-induced impairment of spontaneous alternation performance. The improving effects of dynorphin A(1-13) (3 micrograms) were almost completely reversed by pretreatment with nor-binaltorphimine (4 micrograms), a kappa-selective opioid receptor antagonist. These results suggest that the stimulation of kappa-opioid receptors improves memory dysfunctions resulting from the blockade of muscarinic M1 receptors.

Analgesics, Opioid↗
PubMed1987

Effect of combined or separate administration of piracetam and choline on learning and memory in the rat.

Different groups of rats received combined or separate administration of different doses of piracetam (P1:100, P2:200, and P4:400 mg/kg) and choline (C1:100 and C2:200 mg/kg). Compared to control treatment, C1 significantly improved performance in a delayed alternation (DA) task, while P1, P2, P4 or P1C1 had no effect. Moreover, rats receiving P2C1 and P4C1 were significantly inferior in acquiring DA to rats receiving the vehicle or separate administration of P1, P2 or C1. The different treatments with combined or separate administration of P and C had no effect on spontaneous locomotor activity and two-way avoidance conditioning. In a recognition-task only groups C1 and P4 were able to discriminate between familiar and new objects. The combined or separate administration of P1 and C1 on NA, DA, DOPAC, 5-HT, 5-HIAA levels, CAT activity and choline uptake were measured in frontal cortex and hippocampus: the only significant effect was a 5-HT increase in the hippocampus of rats treated with C1.

Animals↗
PubMed1993

Indices of verbal learning and memory deficits after right hemisphere stroke.

The deleterious effects of left hemisphere brain damage on language and verbal memory functions are well documented. However, limited attention has been paid to the effects of right hemisphere cerebrovascular accident (CVA) on these critical functions. Twenty-five right-handed, right hemisphere, stroke patients (RHS) were administered the California Verbal Learning Test (CVLT) and selected verbal, nonverbal, and orientation memory subtests of the Wechsler Memory Scale-Revised (WMS-R). An aphasia screening was also performed. The RHS patients performed significantly below the norm on all CVLT indices, whereas no differences were found between the RHS group and the WMS-R normative population for the story memory subtests. Study findings indicate that right hemisphere damage does affect performance of certain verbal memory tasks. Implications for inpatient treatment, post-acute care, and research with survivors of right hemisphere CVA are discussed.

Aged↗
PubMed1998

Ca2+/calcineurin-inhibited adenylyl cyclase, highly abundant in forebrain regions, is important for learning and memory.

Activation of cAMP synthesis by intracellular Ca2+ is thought to be the main mode of cAMP generation in the brain. Accordingly, the Ca2+-activated adenylyl cyclases I and VIII are expressed prominently in forebrain neurons. The present study shows that the novel adenylyl cyclase type IX is inhibited by Ca2+ and that this effect is blocked selectively by inhibitors of calcineurin such as FK506 and cyclosporin A. Moreover, adenylyl cyclase IX is inhibited by the same range of intracellular free Ca2+ concentrations that stimulate adenylyl cyclase I. Adenylyl cyclase IX is expressed prominently in the forebrain. Substantial arrays of neurons positive for AC9 mRNA were found in the olfactory lobe, in limbic and neocortical areas, in the striatum, and in the cerebellar system. These data show that the initiation of the cAMP signal by adenylyl cyclase may be controlled by Ca2+/calcineurin and thus provide evidence for a novel mode of tuning the cAMP signal by protein phosphorylation/dephosphorylation cascades.

Adenylyl Cyclase Inhibitors↗