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PubMed2005

Memory for performed actions in dementia of Alzheimer type: further evidence for a global semantic memory deficit.

Findings in patients with dementia of the Alzheimer type (AD patients) concerning the enactment effect, i.e. reaching a better memory performance after encoding actions by performing them in contrast to encoding them by reading, are ambiguous. In order to get more insight into memory deterioration in patients suffering from AD, an experimental study was run. Patients with mild-to-moderate AD (n = 23) and healthy elderly control persons (n = 20) took part. They had to encode actions verbally as well as enactively. Memory performance was tested by using recognition judgments instead of the predominating free recall. The AD patients showed no enactment effect and a rate of false alarm judgments that was more than twice as high as found in healthy elderly controls. This enactive encoding failure may be indicative of memory deficits underlying the conceptual system of action representations.

Aged↗

PubMed2006

Beyond spatial memory: the anterior thalamus and memory for the temporal order of a sequence of odor cues.

Influential recent proposals state that the anterior thalamic (AT) nuclei constitute key components of an "extended hippocampal system." This idea is, however, based on lesion studies that used spatial memory tasks and there has been no evidence that AT lesions cause deficits in any hippocampal-dependent nonspatial tasks. The present study investigated the role of the AT nuclei in nonspatial memory for a sequence of events based on the temporal order of a list of odors, because this task has recently been shown to depend on the integrity of the hippocampal formation. After preoperative training, rats with excitotoxic lesions of the AT nuclei showed a severe and selective postoperative impairment when required to remember the order of pseudorandom sequences of six odors. The rats with AT lesions were able instead to learn two new tasks that required recognition memory and the identification of the prior occurrence of events independent of their order. These results strongly matched those described after hippocampal lesions and provide the first unequivocal evidence of a detrimental effect of an AT lesion on a nonspatial hippocampal-dependent memory task.

Animals↗

PubMed1999

Everyday memory deficits in children and adolescents with PTSD: performance on the Rivermead Behavioural Memory Test.

Adult post-traumatic stress disorder (PTSD) patients often report a wide range of cognitive problems in memory, concentration, attention, planning, and judgement. Evaluation of these cognitive aspects of PTSD in adults has helped to define the nature of the disorder. However, there is a paucity of such work in younger subjects. This study has employed the Rivermead Behavioural Memory Test (RBMT) to examine cognitive factors in children and adolescents with PTSD. Eighteen child and adolescent patients with PTSD and 22 control subjects completed the test. PTSD subjects showed poorer overall memory performance compared with controls. Specifically, they were worse on the prospective and orientation items of the RBMT. The results are discussed in the light of research on everyday memory in adults with PTSD.

Adolescent↗

PubMed1996

The East Boston Memory Test: a clinical screening measure for memory impairment in the elderly.

Comparisons between the East Boston Memory Test (EBMT), a brief verbal memory measure used in epidemiological studies with dementia, selected Wechsler Memory Scale-Revised (WMS-R) subtests, and the Mini-Mental State Examination (MMSE) were investigated with 23 geriatric patients diagnosed with dementia. Significant correlations between the EBMT and WMS-R verbal subtests were predicted and occurred (r = .42 to .64). A five minute EBMT recall correlated most highly with the WMS-R Logical Memory subtests. The sensitivity of the EBMT in detecting cognitive impairment was investigated and compared with the sensitivity of the MMSE. The EBMT correctly classified 78% of subjects, compared to a 70% correct classification rate with the MMSE. Implications of these findings and suggestions for future research directions are discussed.

Aged↗

PubMed1990

Luria Memory Words Test and Wechsler Memory Scale: comparison of utility in discriminating neurologically impaired from controls.

Memory deficits are among the most common initial complaints of patients who are suffering from neurological disorders. The present study compared the relative clinical utility of the Wechsler Memory Scale and the Luria Memory Words Test in differentiating brain-damaged (N = 60) from non-brain-damaged patients (N = 60). Separate stepwise regression analyses selected five variables from each test that accounted for the greatest between-group variance. Separate discriminant functions then were computed that used the WMS and the Luria Words variables selected through the regression analyses. The WMS correctly classified 72% of the subjects, whereas the Luria Words correctly classified 76% of the subjects. A final discriminant function was computed that used all 10 variables and resulted in a classification accuracy of 86%, with 6% false positives and 6% false negatives. Results are discussed relative to the use of each instrument in both a general psychological assessment situation and when specific memory functioning is in question.

Brain Damage, Chronic↗

PubMed2005

Virus-induced polyclonal B cell activation improves protective CTL memory via retained CD27 expression on memory CTL.

Different viruses elicit distinct phenotypes of memory cytotoxic T lymphocytes (CTL). This is reflected in differential expression of homing receptors and costimulatory molecules like CD27. Memory CTL retained CD27 following lymphocytic choriomeningitis virus (LCMV) infection, but not after immunization with recombinant vaccinia virus or tumor cells expressing LCMV glycoprotein. Stable CD27 expression on memory CTL required ligation by CD70 expressed on polyclonally activated B cells during the contraction phase. The functional consequence of CD27 expressed on virus-specific CTL was analyzed in CD27-deficient mice. LCMV infection of CD27(-/-) mice revealed that primary CTL activation and expansion as well as elimination of the virus were independent of CD27 expression. In contrast, ligation of CD27 on memory CTL upon secondary antigen encounter increased clonal expansion and improved protection against re-infection. This points to novel B cell-CTL interactions during viral infection and to a beneficial role of polyclonal B cell activation that represents a characteristic of murine LCMV, human immunodeficiency virus and human hepatitis B and C virus infection.

Animals↗

PubMed1996

Bergson's "Matter and Memory" and modern selectionist theories of memory.

Bergson's reflections (in Matter and Memory, 1896) on memory anticipated development of modern selectionist theories of memory. Selectionist models offer new and potentially useful approaches to a theory of remembering. On the model of natural selection, these selectionist theories require at least two processing components: a device which generates a range of memory representations and a selection process which preserves a subset of those representations. Bergson shows how the subjective experience of remembering might be understood within a selectionist framework.

Brain↗

PubMed1999

The amygdala is involved in the modulation of long-term memory, but not in working or short-term memory.

Rats with cannulae implanted in the junction between the central and the basolateral nuclei of the amygdala were trained in one-trial step-down inhibitory avoidance and tested at 3 s for working memory (WM) or 1.5 or 24 h later for short-term memory (STM) and long-term memory (LTM), respectively. Several drugs were infused 6 min prior to training in the animals in which WM was measured or 0 min posttraining in those in which STM and LTM were measured: the glutamate receptor antagonists CNQX (0.5 microg) and AP5 (5.0 microg), the indirect GABA A receptor antagonist picrotoxin (0.08 microg), the cholinergic muscarinic receptor blocker scopolamine (2. 0 microg), norepinephrine (0.3 microg), the protein kinase C inhibitor staurosporin (1.0 microg), or the calcium/calmodulin dependent protein kinase II inhibitor Kn-62 (3.5 ng). None of the drugs had any effect on either WM or STM. All had, as previously shown, strong effects on LTM: picrotoxin and norepinephrine enhanced it, and CNQX, AP5, scopolamine, Kn-62, and staurosporin inhibited it. The results do not support the idea that memory of this task is formed in the amygdala; they indicate that the amygdala is not involved in WM or STM processing and support the idea that the amygdala modulates LTM storage processes carried out elsewhere.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1995

Effects of post-trial administration of nicotine on human memory: evaluating the conditions for improving memory.

In the studies reported here, we investigated the effects of nicotine on memory for unrelated word lists. Nicotine was delivered through cigarette smoking, and memory performance was assessed using both intentional and incidental recall tasks, and employing an additional, indirect measure of memory. We report the results of four experiments in which we manipulated 1) the intake of nicotine using nicotine-containing and nicotine-free cigarettes, 2) the associative aspects of the word-sets, by unrelated words and category words and by instructing subjects to use an associative mnemonic strategy, 3) the opportunity for rehearsal between the presentation and recall, and 4) the time of nicotine administration, post- or pre-trial. We found a positive effect of post-trial nicotine on memory in the incidental recall task, as indicated by enhanced repetition priming, but no effect of nicotine on either immediate recall or pronunciation times (experiments 1 and 2). In experiment 3 we examined the effects of post-trial nicotine using associative and unrelated word-lists, when volunteers were instructed to use an associative mnemonic strategy. We found no main effect of nicotine, but when volunteers were distracted from rehearsal, related words were recalled better than unrelated words. Experiment 4 was a positive control for the timing of nicotine administration within our experimental design, and this showed that pre-trial nicotine not only improved free recall but differentially enhanced the recall of category words over unrelated words.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1998

Fuels for memory: the role of oxygen and glucose in memory enhancement.

Recent studies indicate that some aspects of memory can be enhanced by the administration of oxygen or glucose. Considering the dependency of glucose metabolism upon oxygen supply, the present study predicted that administering a combination of 100% oxygen with glucose would have greater memory-enhancing effects than when either substance was administered alone. In a placebo-controlled study, 104 healthy adults were given a glucose or placebo drink, and inhaled 100% oxygen or air for 1 min, before carrying out a number of everyday memory tasks designed to measure short-term and long-term memory. Results showed support for the enhancing effects of oxygen (but not for glucose) on delayed recall. These findings are discussed in relation to the possible cholinergic properties of oxygen and glucose and the implications for their clinical use.

Adolescent↗

PubMed1992

Muscimol infused into the medial septal area impairs long-term memory but not short-term memory in inhibitory avoidance, water maze place learning and rewarded alternation tasks.

These experiments investigated the effects of injections of muscimol (1 or 5 nmol), administered into the medial septal area prior to training, on memory tested at different retention delays after training in 3 tasks: an inhibitory avoidance task, a one-trial place learning task, and a rewarded alternation task. In all 3 tasks, intraseptal injections of muscimol did not impair memory performance at short retention delays, but impaired memory at the longer retention delays. These findings are consistent with the view that GABAergic regulation of the septohippocampal cholinergic system plays a selective role in the establishment of long-term memory.

Animals↗

PubMed1990

Excitatory amino acid antagonists and memory: effect of drugs acting at N-methyl-D-aspartate receptors in learning and memory tasks.

The role of N-methyl-D-aspartate (NMDA) receptors in memory processes was examined using a Y-shaped maze and a step-through passive avoidance task in mice. In the Y-maze, the total number of arm entries, which represents locomotor activity and alternation behaviour, thought to reflect working memory, were measured. Competitive NMDA antagonists, CGS 19755 (cis-4-phosphonomethyl-2-piperidine-carboxylate) and CPP (3-((+)-2-carboxypiperazin-4-yl)-propyl-1-phosphate), impaired spontaneous alternation at doses which reduced locomotion of mice. N-Methyl-D-aspartate prevented the impairment of alternation and decrease of locomotor activity produced by CGS 19755 and CPP. These results suggest that NMDA-dependent processes are involved in the mechanisms of working memory. In contrast, the non-competitive NMDA antagonist, MK 801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cycloheptan-5,10-imine maleate) dramatically enhanced the total number of arm entries, while reducing alternation behaviour, N-Methyl-D-aspartate had no effect on MK 801-induced enhancement of locomotor activity and impairment of alternation. In the passive avoidance task, mice were trained to avoid entry into the dark compartment. At doses which impaired working memory in the alternation task, CPP, CGS 19755 and MK-801 reduced acquisition, when administered before training. N-Methyl-D-aspartate antagonized the effect of CPP, CGS 19755 and MK-801. Neither CPP nor MK-801 affected retention, when administered immediately after training or before testing retention. N-Methyl-D-aspartate had no effect on retention with high-intensity shock, but facilitated retention with low-intensity shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

A vasopressin metabolite produces qualitatively different effects on memory retrieval depending on the accessibility of the memory.

A vasopressin metabolite, AVP4-9, was injected 1 h prior to retention tests at 1, 6, 11, and 16 days after learning to test the hypothesis that the peptide exerts qualitatively different effects on memory retrieval depending on the accessibility of the memory. The findings provided strong support for this hypothesis: At a retention interval associated with excellent recall in control animals, pretest administration of AVP4-9 (3.0 micrograms/kg) significantly impaired memory, while this same treatment significantly improved recall at an interval associated with poor retention in controls. At retention tests associated with intermediate recall in controls, retrieval was not significantly affected by the peptide treatment. This pattern of results indicates that the peptide treatment is interacting with endogenous changes that correspond to the accessibility of the memory.

Animals↗

PubMed2006

Effects of memory load on cortical oscillatory activity during auditory pattern working memory.

The present magnetoencephalography study investigated memory load-dependent changes in cortical oscillatory activity during a modified auditory version of the Sternberg paradigm. Twelve subjects were presented with test stimulus sets of 1-3 syllables spoken in a natural female voice. After an 800-ms delay period, a probe syllable was presented and subjects had to judge whether the probe had been included in the preceding test set. Compared to a non-memory-control task, memory trials elicited an increase of beta activity over right temporal regions and an increase of alpha activity over right middle prefrontal cortex at the end of the delay phase. Monotonic increases in spectral amplitude as a function of memory load were revealed for the beta band over right temporal sensors and the alpha band over right frontal sensors during the delay period. The results demonstrate the relevance of both beta and alpha oscillations for the memorization of multiple stimuli. The former may be associated with the representation of task-relevant stimulus features, while the latter may reflect the top-down control of these representations.

Acoustic Stimulation↗

PubMed2005

New ways of looking at memory function: certain traumatic memories function like viruses, replicating themselves.

By the process of natural selection, life on earth spreads in all directions, finding niches favorable for survival. Some niches are harmful to another plant or animal (parasitism). This universal survival strategy applies to all living things, and apparently even non-living things such as viruses and prions. The same pattern may occur with immaterial entities such as memories. Traumatic memories mimic virus behavior in many ways such as infecting, spreading, occasionally becoming latent, and even reproducing themselves. Patients with past traumatic experiences are still "infected" with pathogenic memories. The experience remains ever-present in the patient's neural pathways and may even grow via a feedback loop in which each episode of remembering produces a stress hormone response. Under this model, doctors might view and treat patients with a history of trauma as persons infected with latent memories which periodically break out and cause new damage.

Biomimetics↗

PubMed2007

The worth of pictures: using high density event-related potentials to understand the memorial power of pictures and the dynamics of recognition memory.

To understand the neural correlates of the memorial power of pictures, pictures and words were systematically varied at study and test within subjects, and high-density event-related potentials (ERPs) were recorded at retrieval. Using both conventional and novel methods, the results were presented as ERP waveforms, 50 ms scalp topographies, and video clips, and analyzed using t-statistic topographic maps and nonparametric p-value maps. The authors found that a parietally-based ERP component was enhanced when pictures were presented at study or test, compared to when words were presented. An early frontally-based component was enhanced when words were presented at study compared to pictures. From these data the authors speculate that the memorial power of pictures is related to the ability of pictures to enhance recollection. Familiarity, by contrast, was enhanced when words were presented at study compared to pictures. From these results and the dynamic view of memory afforded by viewing the data as video clips, the authors propose an ERP model of recognition memory.

Adolescent↗

PubMed2006

When true memory availability promotes false memory: evidence from confabulating patients.

We explored the extent to which confabulators are susceptible to false recall and false recognition, and whether false recognition is reduced when memory for studied items is experimentally enhanced. Five confabulating patients, nine non-confabulating amnesics--including patients with (F amnesics) and without frontal-lobe dysfunction (NF amnesics)--and 14 control subjects underwent the DRM paradigm [Roediger, H. L., & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory and Cognition, 21, 803-814.] in two experimental conditions. In both conditions participants studied eight lists of semantic associates, and free recall was tested after the presentation of each list. In the Standard condition recognition was tested after the presentation of all the lists, whereas in the Proximal condition patients were administered a six-item recognition task after the presentation of each list. Participants also provided remember or know judgements, and described the content of their recollections. All groups of patients recalled a lower proportion of targets and critical lures than did control subjects, but confabulators recalled more words unrelated to the studied lists than did NF amnesics and controls. All groups of participants improved true recognition across conditions. However, whereas normal controls suppressed false recognition to critical lures in the Proximal compared to the Standard condition, and non-confabulating amnesics showed comparable gist-based false recognition, confabulators showed increased levels of false recognition to critical lures across conditions. Furthermore, NF amnesics significantly reduced false recognition to unrelated lures in the Proximal compared to the Standard condition, whereas confabulators were unable to suppress false recognition to unrelated lures across conditions. Analysis of the phenomenological experience showed that, unlike non-confabulating amnesics, confabulators characterized true and false memories with irrelevant information related to test items. Results are interpreted in light of confabulators' monitoring deficits.

Adult↗

PubMed2006

Selective preservation of memory for people in the context of semantic memory disorder: patterns of association and dissociation.

A number of single cases in the literature demonstrate that person-specific semantic knowledge can be selectively impaired after acquired brain damage compared with that of object categories. However, there has been little unequivocal evidence for the reverse dissociation, selective preservation of person-specific semantic knowledge. Recently, three case studies have been published which provide support for the claim that such knowledge can be selectively preserved [Kay, J., & Hanley, J. R. (2002). Preservation of memory for people in semantic memory disorder: Further category-specific semantic dissociation. Cognitive Neuropsychology, 19, 113-134; Lyons, F., Hanley, J. R., & Kay, J. (2002). Anomia for common names and geographical names with preserved retrieval of names of people: A semantic memory disorder. Cortex, 38, 23-35; Thompson, S. A, Graham, K. S., Williams, G., Patterson, K., Kapur, N., & Hodges, J. R. (2004). Dissociating person-specific from general semantic knowledge: Roles of the left and right temporal lobes. Neuropsychologia, 42, 359-370]. In this paper, we supply further evidence from a series of 18 patients with acquired language disorder. Of this set, a number were observed to be impaired on tests of semantic association and word-picture matching using names of object categories (e.g. objects, animals and foods), but preserved on similar tests using names of famous people. Careful methodology was applied to match object and person-specific categories for item difficulty. The study also examined whether preservation of person-specific semantic knowledge was associated with preservation of knowledge of 'biological categories' such as fruit and vegetables and animals, or with preservation of 'token' knowledge of singular categories such as countries. The findings are discussed in the context of a variety of accounts that examine whether semantic memory has a categorical structure.

Adult↗