PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Memory Disorders”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 901 records · Page 50Linked to original sources
PubMed1992

Acquisition and transfer of declarative and procedural knowledge by memory-impaired patients: a computer data-entry task.

Previous research demonstrated that a single amnesic patient could acquire complex knowledge and processes required for the performance of a computer data-entry task. The present study extends the earlier work to a larger group of brain-damaged patients with memory disorders of varying severity and of various etiologies and with other accompanying cognitive deficits. All patients were able to learn both the data-entry procedures and the factual information associated with the task. Declarative knowledge was acquired by patients at a much slower rate than normal whereas procedural learning proceeded at approximately the same rate in patients and control subjects. Patients also showed evidence of transfer of declarative knowledge to the procedural task, as well as transfer of the data-entry procedures across changes in materials.

Amnesia↗
PubMed1993

Short-term memory impairments in Alzheimer-type dementia: evidence for separable impairments of articulatory rehearsal and long-term memory.

Two experiments are described which investigate the short-term memory deficits found in Alzheimer-type dementia. In the first experiment memory span for words of differing spoken duration is related to speech rate. Memory span was lower in subjects suffering from Alzheimer-type dementia than for normal elderly controls but in both cases a linear function related recall to speech rate for items of differing spoken durations. The function for Alzheimer subjects had an equivalent slope (interpreted as reflecting a contribution from a sub-vocal rehearsal process) but a lower intercept (interpreted as reflecting a contribution from a long-term memory component). The second experiment investigated the effects of repeating supra-span lists of items in a serial recall task. As predicted the control subjects showed substantial increases in recall across trials associated with elevations of the speech rate/recall functions while the Alzheimer subjects showed very little benefit from repetition of the lists. We conclude that the verbal short-term memory deficit found in Alzheimer-type dementia has two components: a deficit in the rate of rehearsal and an impairment in the long-term memory component of short-term recall.

Aged↗
PubMed1993

The possible contribution of the septal region to memory.

A particularly well-documented, intelligent patient (H.I.) with very selective, minute, but most likely bilateral damage of the basal forebrain including the septal region is presented. Though behavioral progress was found for a number of areas, she remained deficient, especially in long-term memory. The severest and largely modality-nonspecific deficits were observed in recall (as opposed to recognition) situations. As a peculiar finding which we would attribute to septal damage, H.I. was mainly affected in tests containing emotional (especially emotionally negative) stimuli, or certain flavours. While this involvement might have helped her in memorizing material judged as positive, it was of negative influence under other circumstances. The septal area may serve as an interface contributing a specific combination of emotional flavour and evaluating (feedback) judgement to a larger (septo-hippocampal-amygdalar) memory and learning processing network.

Affective Symptoms↗
PubMed1994

Capacity of visual short-term memory after unilateral frontal or anterior temporal-lobe resection.

The effect of unilateral temporal- or frontal-lobe lesions on the capacity of short-term memory for a single pattern was explored; this measure has been designated pattern span. Pattern span was assessed under different delays and with and without distraction. Both the passage of time and presence of distraction decreased pattern span for all subject groups. Right anterior temporal lobectomy did not result in an impairment in pattern span in any condition, whereas right frontal-lobe excisions were associated with impaired span in all conditions. It is suggested that this deficit represents a decreased ability to encode the more complex patterns under a time constraint.

Adolescent↗
PubMed1996

Systemic NMDA antagonist CGP-37849 produces non-specific impairment in a working memory task: the effect does not resemble those of AP5 and of lesions of the hippocampus or fornix.

The N-methyl-D-aspartate (NMDA) receptor antagonist CGP-37849 (D,L-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid), administered i.p. (2.0 and 4.0 mg/kg), impaired rats' performance in a delayed matching-to-sample working memory task. This task is sensitive to hippocampal/fornix lesions or intracerebroventricular (i.c.v.) administration of another NMDA antagonist, AP5 (2-amino-5-phosphono-pentanoic acid) in a stimulus-specific manner: the highest impairment when simple stimuli are used repeatedly; moderate impairment when complex stimuli are used repeatedly; and no impairment when complex stimuli are used in a pseudo-trial-unique fashion. The effect of CGP-37849, unlike those of surgical lesions and of AP5, was not stimulus-specific and therefore cannot be solely attributed to blockade of NMDA-dependent long-term potentiation (LTP) in the hippocampus. We infer that systemic administration of NMDA antagonists may affect a broad range of anatomical structures thereby interfering with other neural mechanisms of memory and motor performance.

2-Amino-5-phosphonovalerate↗
PubMed1996

The relevance of continuous blood pressure monitoring in examining the relationship of memory efficiency with blood pressure characteristics.

The study of the relationship between hypertension and cognitive decline is characterized by various difficulties of realization and, as a consequence, by incongruent results. One of the reasons for these difficulties may be explained by the occasional method of measurement of blood pressure (once a day). This study presents the results obtained in 27 normotensive and mild hypertensive subjects of both sexes (ages between 20 and 77 years) with a continuous blood pressure monitoring for 24 h. A noninvasive sphygmomanometric technique was used employing a portable recorder programmed to take a measure every 30 min. Both objective and subjective measures of memory, measures of attention efficiency, and IQ were correlated to the blood pressure measures. Continuous monitoring data of blood pressure were analyzed according to a model that included a macroscopic descriptive analysis, a microscopic rhythmometric analysis, and a microscopic integrative analyses where the effects of the interaction between level and duration of excess and the time of the day when the excess eventually appeared were considered. Results evidenced no differences in cognitive efficiency between those subjects identified with the traditional occasional measurement of blood pressure as hypertensives of mild severity and the normal subjects. Cognitive efficiency of our subjects was found correlated, independently from the clinical diagnosis, with the time of peak and with the duration of excess of their blood pressure when the results of the analyses on the continuous monitoring of blood pressure were considered.

Adult↗
PubMed1995

Physostigmine, but not 3,4-diaminopyridine, improves radial maze performance in memory-impaired rats.

The results of some studies suggest that 3,4-diaminopyridine (3,4-DAP), a drug that enhances the release of acetylcholine, may improve memory. The present study examined the ability of 3,4-DAP to reverse the memory impairment produced by scopolamine and the ability of 3,4-DAP and physostigmine to reverse the memory impairment produced by quinolinic acid lesions of the nucleus basalis magnocellularis (nbm) in rats. Mnemonic functioning was assessed with the use of a partially baited eight-arm radial maze. Entries into arms that were never baited were defined as reference memory errors; entries into baited arms from which the food already had been eaten were defined as working memory errors. In Experiment 1, 0.1 mg/kg scopolamine produced a significant increase in working and reference memory errors. Various doses of 3,4-DAP had no significant ameliorative effect on the mnemonic deficit. In Experiment 2, cholinergic function was impaired using a unilateral intra-nbm injection of quinolinic acid (120 nmol in 1.0 microliter). These lesions reduced the levels of the cholinergic marker, choline acetyltransferase, in the cortex by more than 40%. Results showed that the nbm lesion animals were significantly more impaired on the working than reference memory component of the task. Physostigmine (0.01, 0.05, 0.10, 0.20, 0.50 mg/kg) dose-dependently decreased the number of working but not reference memory errors. 3,4-DAP (10(-8), 10(-6), 10(-4), 10(-2), 10(0) mg/kg) had no reliable effect. It was concluded that physostigmine, but not 3,4-DAP, ameliorates memory impairments following decreases in cholinergic function.

4-Aminopyridine↗
PubMedDate not supplied

The benzodiazepine receptor inverse agonist RO 15-3505 reverses recent memory deficits in aged mice.

The benzodiazepine receptor partial inverse agonist RO 15-3505 was tested for its ability to improve impaired recent memory of aged mice. All mice successfully acquired a learning set for accurate identification of the correct arm of a T-maze and could perform with nearly 100% accuracy after 1-min delays. However, performance of the aged mice approached chance levels after 2-h delays. When injected just before testing on a series of 2-h retention tests, RO 15-3505 (from 2.5-3505 (from 2.5-10.0 mg/kg) resulted in a marked improvement of response accuracy. These results confirm the role of benzodiazepine receptor mechanisms in the modulation of memory processes, and suggest that the memory-facilitating effects RO 15-3505 or similar benzodiazepine receptor ligands may be generalized to aged rodents with impaired memory function.

Aging↗
PubMed1996

Neurosteroids block the memory-impairing effects of ethanol in mice.

Using a win-shift foraging paradigm to assess working memory in C57BL/6 mice, the memory-enhancing effect of low doses of the neurosteroids 5-pregnen-3 beta-ol-20-one [pregnenolone (PE)], 5-pregnen-3 beta-ol-20-one sulfate [pregnenolone sulfate (PS)], 5-androsten-3 beta-ol-17-one [dehydroepiandrosterone (DHEA)], and 5-androsten-3 beta-ol-17-one sulfate [dehydroepiandrosterone sulfate (DHEAS)] were demonstrated. The neurosteroids 5 beta-pregnan-3 alpha-ol-20-one [pregnanolone (PA)] and 5 beta-pregnan-3 beta-ol-20-one [epipregnanolone (EPI)] disrupted memory in this paradigm. PE, PS, DHEA, DHEAS, and PA were also capable of blocking the memory-impairing effect of 0.5 g/kg ethanol. EPI prevented PA from blocking the effect of ethanol. The influence of these compounds on memory and their interactions on this behavior are consistent with their actions on the GABAA system.

Animals↗
PubMed1994

Neurotransmission in the rat amygdala related to fear and anxiety.

An impressive amount of evidence from many different laboratories using a variety of experimental techniques indicates that the amygdala plays a crucial role in the acquisition, consolidation and retention or expression of conditioned fear. Electrophysiological data are beginning to detail the transmitters and inter-amygdala connections that transmit information to, within, and out of the amygdala. In general, treatments that increase the excitability of amygdala output neurons in the basolateral nucleus (for example, by decreasing opiate and GABA transmission, and increasing noradrenergic transmission) improve aversive conditioning, whereas treatments that decrease excitability of these neurons (by increasing opiate and GABA transmission, and decreasing NMDA and noradrenergic transmission) retard aversive conditioning as well as producing anxiolytic effects in appropriate animal tests. A better understanding of brain systems that inhibit the amygdala, as well as the role of its very high levels of peptides, might eventually lead to the development of more effective pharmacological strategies for treating clinical anxiety and memory disorders.

Amino Acids↗
PubMed1993

Wistar-Kyoto rats in the Morris water maze: impaired working memory and hyper-reactivity to stress.

Wistar-Kyoto (WKY) rats were tested as a potential animal model for memory dysfunction. These animals were reported to be highly reactive to stress and this was associated with findings of alterations in their hippocampal cholinergic activity. Since hippocampal cholinergic hypofunction is often associated with deficits in memory processes, untreated WKY rats were tested here in a working memory task in the Morris water maze. Animals were tested for five daily sessions, with two identical trials per day, and their performance was compared to that of Sprague-Dawley (SD) rats. Results show that WKY rats failed to improve their performance both from day to day and within the two trials each day. This suggests impaired memory capabilities of WKY rats and may support their use as an animal model of memory dysfunction. However, because of their increased tendency to float, speed of performance was also reduced in WKY compared to SD rats. This difference may be associated with their increased reactivity to stress. The combination of memory dysfunction and stress hyper-reactivity seen in WKY rats may be used to study the association between these two functions, particularly the possible interaction between memory and depression.

Animals↗
PubMedDate not supplied

Sundowning syndrome in demented patients without neuroleptic therapy.

Characterisation of sundowning syndrome, defined as 'an exacerbation of symptoms indicating increased arousal or impairment in late afternoon, evening or at night, among elderly demented individuals', is complicated by neuroleptic therapy and frequent failure to specify the nature of the associated dementia. Screening by a memory disorders unit of an institutionalized population of 30 neuroleptic-free demented patients revealed 8 sundowners, with diagnoses of probable Alzheimer's disease (n = 5), frontal lobe dementia (n = 1), Lewy body disease (n = 1), and sequelae of herpes encephalitis (n = 1). Sundowners did not differ from non-sundowners in age, Mini Mental State score, degree of temporal and spatial disorientation or perceptual delusion. Sundowning was related to restlessness (P < 0.0001), sleep disorder (P < 0.003) and a history of hypotension lipothymia (P < 0.08). These results provide further evidence for a chronobiological explanation of sundowning syndrome.

Journal Article↗
PubMed1991

Effects of fetal treatment with methylazoxymethanol acetate on radial maze performance in rats.

Pregnant rats (Wistar-Imamichi strain) were treated with 15 mg/kg/d of methylazoxymethanol acetate (MAM) on days 13-15 of gestation. Nine male rats, which were randomly selected from the MAM-treated offspring (MAM rats), were examined for their spatial recognition ability by the radial maze technique and compared with control offspring. Although the performances of MAM rats were inferior to the control, they could reach the predetermined criterion within 15 trials. Subsequent retention tests revealed the drastic impairment of performance in MAM rats when the retention interval was over 15 min. The total activity of choline acetyltransferase showed a significant decrease in the hippocampus and cerebral cortex of MAM rats. These results suggest that working memory disorders of MAM rats on radial maze tasks may be due to the lowering of cholinergic functions in their hippocampus and cerebral cortex.

Animals↗
PubMedDate not supplied

Beneficial effects of nicotine administered prior to a delayed matching-to-sample task in young and aged monkeys.

Our earlier studies have demonstrated that administration of low micrograms/kg doses of nicotine to young adult monkeys prior to a delayed matching-to-sample (DMTS) task resulted in a centrally mediated improvement in performance of the task, particularly when delay intervals which most greatly challenged the animal's capabilities were involved. The present study confirmed these findings using a completely computer driven and automated procedure. In addition, performance on the DMTS was observed to be enhanced when animals were again tested 24 h after the dose of nicotine. Further analysis of the data indicated that the majority of enhancement to nicotine could be accounted for by a greatly increased performance at the least preferred stimulus color. Position preference (left vs. right stimulus) was not a factor in nicotine-induced enhancement. Two aged monkeys (34 years old Macaca mulatta) were significantly more difficult to train in the DMTS task and their longest delay capabilities were significantly shorter than the young animals (Macaca fascicularis). Nevertheless, the aged animals were essentially similar in most respects in their responses to nicotine administration. These data are consistent with a role for central nicotinic systems in memory performance and with the ability of nicotine to produce enhancement of selective features of mnemonic strategy in young and old monkeys. Furthermore, it is possible that either model, the aged animal, or the young animal stressed to his mnemonic capability may provide a good model for learning and memory disorders in humans.

Aging↗