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At least 721 records · Page 40Linked to original sources
PubMed1993

Glutamate and imprinting memory: the role of glutamate receptors in the encoding of imprinting memory.

Glutamate-sensitive receptors have been implicated in many forms of neural plasticity and learning, including imprinting of chicks. Previous studies have indicated that glutamate binding levels in the left intermediate medial hyperstriatum ventrale (IMHV) region of the chick forebrain increase as a correlate of the acquisition of an imprinting memory; however, it has not been determined whether this is due to an increase in the number of glutamate receptors or to increased receptor affinity. The area specificity of these changes, within the left and right hemisphere, was also unexplored. We have performed Scatchard displacement binding analyses to examine changes in both the number and affinity of glutamate receptors in the left and right hyperstriatum ventrale (HV) and also the left and right archistriatal/lobus parolfactorius (AS/LPO) areas from imprinted and non-imprinted chicks. The results of this study demonstrate lateralised increases in both the number and affinity of glutamate receptors in the left HV area at 7-8 h after imprinting. Significant increases in the affinity, but not the number, of glutamate receptors were found in the left AS/LPO. This suggests that the left AS/LPO, which has previously been shown to be involved in the acquisition of a passive avoidance memory, may also be involved in the formation of an imprinting memory.

Animals↗
PubMed2004

Potential for enlarging DNA memory: the validity of experimental operations of scaled-up nested primer molecular memory.

DNA is an attractive memory unit because of its immense information density. Here, we describe a memory model made of DNA, called Nested Primer Molecular Memory (NPMM). NPMM consists of many DNA strands, and each DNA strand consists of two areas: a data area and a data address area. When the address of target data is specified, only the target data can be extracted from NPMM. In this paper, we evaluate the validity of the basic operations of NPMM and then discuss the feasibility of scaled-up NPMM through some laboratory experiments. In the latter, we deal with scaled-up NPMM simulated by the Concentration Scaling method.

Algorithms↗
PubMed2004

Memory traces of trace memories: neurogenesis, synaptogenesis and awareness.

To associate events that are disparate in time, the brain must record, retain and perhaps even reflect on the individual events themselves. Aspects of such learning can be probed with trace conditioning, during which an animal learns to associate events that are temporally distant from one another. For decades, we have known that the formation of so-called trace memories (in which one stimulus is associated with a second stimulus that is discontinuous and later in time) depends on the hippocampal formation. Recent findings indicate that the hippocampus is crucial for the initial acquisition of trace memories but not for their expression or long-term storage. More recent findings implicate neurogenesis, synaptogenesis and awareness in the formation of trace memories.

Animals↗
PubMed1997

Dissociation of spatial reference memory, spatial working memory, and hippocampal mossy fiber distribution in two rat strains differing in emotionality.

Rats of the inbred strains DA/Han and BDE/Han were compared on two complex spatial learning tasks, a spatial reference memory task in a 16-unit multiple T-maze and a spatial working memory task in an eight-arm radial-maze. In addition, sizes of hippocampal mossy fiber terminal fields were measured. BDE rats showed marked superiority in multiple T-maze learning whereas DA rats outperformed BDE rats on the radial-maze task. DA rats had significantly larger intra- and infrapyramidal mossy fiber terminal fields (IIP-MF). This is consistent with findings from other studies suggesting that large IIP-MF are related to excellent spatial radial-maze learning, but it also indicates that size of IIP-MF is correlated with processing of a specific type of spatial information rather than with overall spatial abilities. BDE rats had more extended suprapyramidal mossy fiber projections (SP-MF) and a larger hilus. Rats of both strains differed in exploratory behaviour and emotionality: DA rats revealed little freezing and had a high rearing activity, whereas BDE rats showed frequent freezing and reared rarely. Results suggest that IIP-MF are involved with flexible expression of memory, updating environmental information and parallel processing whereas SP-MF might be linked to processing of familiar information. Presumably, emotional factors contribute to performance differences.

Animals↗
PubMed1998

Implicit memory, explicit memory and the picture bizarreness effect.

The experiments reported here were designed to explore the bizarreness effect in implicit and explicit memory by using simple line drawings of common objects (normal vs. bizarre). Each drawing was presented alone under mixed-list encoding conditions. Results showed that performance on explicit conceptual memory tests (cued recall in Experiments 1 and 2) was higher when material was studied in a bizarre format. No such effect was found with implicit conceptual tests (free association in Experiment 1 and category association in Experiment 2). Experiment 3 showed no effect of bizarreness with word-fragments as perceptual implicit or explicit test cues. These dissociative results have important theoretical implications for the comprehension of memory processes.

Adult↗
PubMed2003

Long-term memory in high-functioning autism: controversy on episodic memory in autism reconsidered.

Two studies were conducted to examine the nature of verbal long-term memory (LTM) in people with autism. In Study 1, undergraduate students showed better LTM and more verbal associations for concrete than abstract nouns. Probability of recall of the nouns strongly correlated with the number of associations with those nouns. In Study 2, unlike controls, autistic subjects did not show superior recall of concrete over abstract nouns despite overall comparable performance. A highly significant correlation between probability of recall and associative value was found only in the controls. Furthermore, there was an unusual correlation between LTM performance and a nonverbal measure in the autistic group. The results were discussed in terms of the relation between episodic memory and semantic memory.

Adolescent↗
PubMed1992

N-methyl-D-aspartate receptor antagonist MK-801 and spatial memory representation: working memory is impaired in an unfamiliar environment but not in a familiar environment.

Female Sprague-Dawley rats were injected with the noncompetitive N-methyl-D-aspartate (NMDA) antagonist MK-801 or saline 30 min before daily testing in spatial working memory (WM) and reference memory (RM) procedures in an 8-arm radial maze. MK-801 impaired RM and WM acquisition but not performance when rats were trained to criterion before drug administration. Neither a 2-hr nor a 4-hr delay between the first and last 2 correct WM choices impaired long-term WM. MK-801 impaired WM performance in trained rats only when rats were tested in a new environment. Thus, 2 mechanisms may be required for relational memory: an NMDA-dependent mechanism for acquiring long-term spatial representations and an NMDA-insensitive mechanism for operating on these stored representations.

Animals↗
PubMed2003

Is large-scale community memory screening feasible? Experience from a regional memory-screening day.

OBJECTIVES: To investigate whether a large-scale memory-screening program for community-dwelling elders would be successful in identifying individuals with a high probability of dementia in need of further assessment that would result in the earlier diagnosis of dementia. DESIGN: A descriptive study of experience with a volunteer sample. SETTING: Ten sites (e.g., senior centers, churches, clinics) throughout New England on October 29, 1999. PARTICIPANTS: Trained volunteer clinicians evaluated 497 community-dwelling individuals on the screening day. An additional 162 subjects who could not be accommodated on that day were subsequently screened at local sites by appointment during the following month. MEASUREMENTS: Subjects participated in a standardized format consisting of an educational lecture, followed by individual screenings with the 7-minute screen (7MS) with locally trained staff. Subjects were informed immediately of test results and counseled regarding follow-up options. A survey was conducted with these subjects and their primary care physicians over the following year. RESULTS: Because the groups tested at different times were not statistically different in terms of demographics, they were combined in the analysis. One hundred ten (16.7% of all screened) individuals received high/retest scores on the 7MS. They were advised to seek diagnostic evaluation and encouraged to have results sent to their primary care physicians (PCPs). Of those followed up, 64% reported that they followed up the screening results with their PCP. More than one-third (38%) of participants with a high/retest score on the 7MS had inconclusive findings on follow-up or were awaiting further diagnostic evaluation. Of those for whom follow-up data were available, 10 (9%) were diagnosed with probable Alzheimer's disease (AD), and an additional nine (8%) who had previous diagnoses of AD were correctly identified by the 7MS. Anecdotally, feedback from participants indicated a high level of satisfaction with the process. Participants reported that the educational talk and the possibility of early detection were the most helpful components of the screening program. Moreover, most individuals surveyed in follow-up would recommend the program to a friend or family member. CONCLUSION: A follow-up survey of participants and their physicians supported the conclusion that a community memory-screening program might detect individuals who were previously unknown to have cognitive problems. Furthermore, such a program was highly acceptable to participants. The small number of individuals diagnosed with dementia as a result of the screening program indicates that this form of screening may be inefficient as performed. Multiple obstacles to seeking follow-up care were identified and would need to be addressed in larger-scale programs to make this a worthwhile endeavor. The experience gained in this memory screening program might aid in the planning of better programs, which will be essential if early diagnosis is to keep pace with the growth of treatments for dementia.

Aged↗
PubMed1998

Does memory test performance in children become more consistent with age? Cross-sectional comparisons using the WRAML. Wide Range Assessment of Memory and Learning.

This study examined intertask consistency on the Wide Range Assessment of Memory and Learning (WRAML), using two age cohorts of children. Eighty-one neurologically impaired children and 76 matched (i.e., age, gender, race) controls were separated into two age groups, 5- to 9- and 10- to 14-year-olds. Performance on four subtests from the WRAML Memory Screening Index were examined. For the older neurologic sample, all six intertask correlations were significant (mean r = .58) while only three of the six correlation coefficients were significant among the younger neurologic group (mean r = .26). In contrast, only three of the six intertask coefficients were statistically significant in both the younger and older controls. A possible explanation for these divergent findings and clinical implications of intertask variability on memory measures are discussed.

Adolescent↗
PubMed1967

Quantitative studies of the adoptive immunological memory in mice. II. Linear transmission of cellular memory.

A calibrated cell transfer system allows detection of the anamnestic response to albumin without interference from the host's immune machinery; it was used to study the immunological memory of mouse spleen cell populations. The secondary antibody-forming capacity of the transferred cells was measured by challenging them at periods up to 6 months after transfer. The peak levels attained show a declining pattern in two phases: during the first month with a half-life of 15 days; thereafter, with a half-life of 100 days. The corresponding half-lives of the cellular memory are 26 and 190 days. In the light of these and of radioinactivation data, immunological memory is defined as the persistence of a specifically determined stem cell line, along which the information necessary to give rise to an antibody-forming cell population is transmitted from mother to daughter cells.

Animals↗
PubMed1994

Elicitation of "childhood memories" in hypnosis-like settings is associated with complex partial epileptic-like signs for women but not for men: implications for the false memory syndrome.

20 male and 20 female undergraduate students were exposed singly for 20 min. to an exotic setting (partial sensory deprivation and weak, bilateral transtemporal pulsed magnetic fields) that enhances relaxation and exotic experiences. The numerical incidence of subjective experiences described as old memories, dreams, emotions, or vestibular sensations did not differ significantly between the sexes; however, women who reported a greater prevalence of preexperimental complex partial epileptic-like signs were more likely to report experiences of "old memories" (r = 0.61) while men who exhibited these signs were more likely to report dream-like (r = 0.49) experiences. Because complex partial epileptic-like signs are positively associated with suggestibility, the potential contribution of this differential gender effect to the etiology of the False Memory Syndrome requires further investigation.

Adolescent↗
PubMed1992

Extended normative data for the Logical Memory subtests of the Wechsler Memory Scale--Revised: responses from a sample of cognitively intact elderly medical patients.

66 cognitively intact geriatric medical patients (ages 70 to 99; M = 77 yr.) were given the Logical Memory subtests of the Wechsler Memory Scale--Revised to extend normative data. 43 women and 23 men, 35 white and 31 black persons made up this urban geriatric sample. A review of patients' medical histories and Mattis' Dementia Rating scores of 129 or greater were used to ensure a sample of cognitively intact patients. Analyses showed that Logical Memory scores were uncorrelated with education, race, sex, or age.

Aged↗
PubMed1994

Normative problems for the Wechsler Memory Scale-revised logical memory test when used in litigation.

A sample of 100 neuropsychologically normal worker's compensation claimants was evaluated with the Trail Making Test, the Logical Memory Test of the Wechsler Memory Scale-Revised (WMS-R) (immediate and delayed) and the (MMPI) to determine the appropriateness of the Logical Memory norms for individuals in litigation. Results indicate these claimants performed below normal, possibly due to depression or poor motivation while age and education were not important factors. The danger of using such norms uncritically in litigation cases is discussed.

Journal Article↗
PubMed2004

No effects of a combination of caregivers support group and memory training/music therapy in dementia patients from a memory clinic population.

OBJECTIVES: To evaluate the impact of a combination of caregiver support group and memory training/music therapy in dementia patients on behavioural and psychological symptoms (BPSD) and caregiver burden compared to a control group. METHOD: Eighteen patient-carer-dyads in the treatment group and 18 patient-carer-dyads as controls were studied in the setting of a memory clinic of a psychiatric university hospital over a period of 2 years. Controls were matched for age, gender, diagnosis, dementia severity, living arrangement and medication. The interventions were conducted once per week for 1 hour run by a clinical psychogeriatric team. Outcome measures were patients' cognitive and functional status as well as BPSD and caregivers subjective burden and depression measured by validated scales. Data were obtained 6, 12 and 24 months after baseline. RESULTS: There were no significant differences between the intervention and control group neither after 6, 12 nor after 24 months treatment. CONCLUSIONS: The lack of a positive impact in alleviating caregiver burden or BPSD after intensive psychological interventions may result from extensive care in the routine clinical management including individual counselling for patients and families. The effect of 'treatment as usual' needs to be taken into account when comparing an intervention and control group, as well as the dosage of the intervention.

Aged↗
PubMed2004

Inductive reasoning and implicit memory: evidence from intact and impaired memory systems.

In this study, we modified a classic problem solving task, number series completion, in order to explore the contribution of implicit memory to inductive reasoning. Participants were required to complete number series sharing the same underlying algorithm (e.g., +2), differing in both constituent elements (e.g., 2468 versus 57911) and correct answers (e.g., 10 versus 13). In Experiment 1, reliable priming effects emerged, whether primes and targets were separated by four or ten fillers. Experiment 2 provided direct evidence that the observed facilitation arises at central stages of problem solving, namely the identification of the algorithm and its subsequent extrapolation. The observation of analogous priming effects in a severely amnesic patient strongly supports the hypothesis that the facilitation in number series completion was largely determined by implicit memory processes. These findings demonstrate that the influence of implicit processes extends to higher level cognitive domain such as induction reasoning.

Adult↗
PubMed1998

Reversible inactivation of the medial septum or nucleus basalis impairs working memory in rats: a dissociation of memory and performance.

Lidocaine-induced inactivation of the medial septum immediately after training or prior to testing in a delay radial-arm maze task produced deficits in spatial working memory that reflected impaired acquisition of the task. Injection of lidocaine into the nucleus basalis magnocellularis produced a profile of behavioral changes that indicated that temporary inactivation of this structure impaired the behavioral expression of information already stored in working memory. This appears to reflect an impairment in processes that are required for performance (i.e., attention, motivation, sensorimotor function) of the task but not for retrieval of stored information. Site-specific inactivation of the basal forebrain should help to reveal the involvement of its component structures in different aspects of cognitive function.

Analysis of Variance↗
PubMed2003

Inhibition of hippocampal Jun N-terminal kinase enhances short-term memory but blocks long-term memory formation and retrieval of an inhibitory avoidance task.

Learning initiates a series of plastic events the occurrence of which are required for the storage of information related to the training experience. Several lines of evidence indicate that, in the rat hippocampus, different members of the family of mitogen-activated protein kinases (MAPK) play a key role in the onset of such plastic events. Using SP600125, the newly developed inhibitor of the MAPK c-Jun amino-terminal kinase (JNK), we show a direct involvement of this protein kinase in mnemonic processes. The intra-CA1 infusion of SP600125, at a dose that in naïve animals significantly reduced the phosphorylation levels of c-Jun without affecting the activity of ERK1/2 or p38 MAPK, enhanced short-term memory (STM) but blocked long-term memory (LTM) formation and retrieval of an inhibitory avoidance learning task. No action of this drug on locomotor/exploratory activity or general anxiety state could be detected. The significance of these results is discussed in the context of others describing the independence of LTM from STM.

Animals↗