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Relationship of enhanced norepinephrine activity during memory consolidation to enhanced long-term memory in humans.

OBJECTIVE: The purpose of this study was to investigate the effect of enhanced noradrenergic activity on memory consolidation in humans. METHOD: Thirty healthy subjects (21 men and nine women) viewed a series of 12 slides that depicted an emotionally arousing story. Five minutes after viewing the slides, subjects received either intravenous yohimbine or intravenous placebo in a double-blind randomized fashion. Multiple blood samples were drawn for determining plasma free 3-methoxy-4-hydroxyphenylglycol (MHPG). One week later subjects took a surprise memory test for the slides. RESULTS: There was no significant difference in memory score between yohimbine and placebo groups. Linear regression revealed a significant effect of MHPG on memory score for the group as a whole (subjects who had received yohimbine and those who had received placebo) and for the placebo group alone. CONCLUSIONS: These findings strengthen support for the hypothesis that enhanced memory for emotionally arousing events in humans depends critically on postlearning adrenergic modulation.

Adult↗

Face recognition memory deficits and visual object memory performance in patients with schizophrenia and their relatives.

OBJECTIVE: Face recognition memory deficits in schizophrenia are attributed to frontotemporal dysfunction. Biological relatives of patients have similar deficits, suggesting genetic susceptibility. Because the impairment may reflect generalized object memory deficits, the authors evaluated both face and visual object recognition. METHOD: The Penn Face Memory Test and Visual Object Learning Test were given to 102 patients with schizophrenia, 60 of their biological relatives, and 135 healthy comparison subjects. RESULTS: Significant immediate and delayed face recognition deficits were observed in patients and their relatives. Although patients were more impaired in visual object memory than comparison subjects, relatives were not. CONCLUSIONS: Face recognition deficits in patients with schizophrenia and their families are not secondary to generalized object memory deficits and may be an endophenotype reflecting frontotemporal impairment.

Adult↗

Individual differences in emotional memory: adult attachment and long-term memory for child sexual abuse.

In the present study, attachment-related differences in long-term memory for a highly emotional life event, child sexual abuse (CSA), were investigated. Participants were 102 documented CSA victims whose cases were referred for prosecution approximately 14 years earlier. Consistent with the proposal that avoidant individuals defensively regulate the processing of potentially distressing information (Bowlby, 1980), attachment avoidance was negatively associated with memory for particularly severe CSA incidents. This finding was not mediated by the extent to which participants reported talking about the abuse after it occurred, although post abuse discussion did enhance long-term memory. In addition, accuracy was positively associated with maternal support following the abuse and extent of CSA-related legal involvement. Attachment anxiety was unrelated to memory accuracy, regardless of abuse severity. Implications of the findings for theories of avoidant defensive strategies and emotional memory are discussed.

Adolescent↗

On the waxing and waning of working memory: action orientation moderates the impact of demanding relationship primes on working memory capacity.

The present research examined how action- versus state-oriented individuals (Kuhl & Beckmann, 1994) utilize their working memory capacity under varying situational demands. Participants visualized either a demanding or an accepting person, after which their working memory capacity was assessed. Among action-oriented participants, visualizing a demanding person led to greater operation spans (Study 1) and superior memory for intention-related information (Study 2) than visualizing an accepting person. State-oriented participants displayed the opposite pattern, such that visualizing an accepting person led to greater operation spans (Study 1) and superior memory for intentions (Study 2) than visualizing a demanding person. These findings indicate that action versus state orientation moderates the impact of situational demands on working memory capacity.

Adult↗

Volumetric MRI analysis of the amygdala and the hippocampus in subjects with age-associated memory impairment: correlation to visual and verbal memory.

Age-associated memory impairment (AAMI) is a common but disputed entity. It is unclear whether AAMI is a phenomenon of normal aging or an early sign of Alzheimer's disease. The present study aimed to identify possible structural abnormalities in the medial temporal lobe of AAMI subjects. We measured volumes of the hippocampus and amygdala by MRI in 16 AAMI subjects and in 16 age- and sex-matched controls and correlated the volumes with subjects' performance on two visual memory tasks (the Benton and the Heaton visual retention tests) and on a verbal memory task (the Buschke-Fuld Selective Reminding Test). The mean hippocampal and amygdaloid volumes normalized for brain size per se did not differ between the two study groups. In controls, but not in AAMI subjects, the right hippocampus was larger than the left. Accordingly, the volumetric asymmetry between the right and left hippocampi was smaller in AAMI subjects than in controls (Student's t test, p < 0.05). The volume of the right hippocampus (r = 0.37, n = 32, p < 0.05) and the magnitude of the asymmetry between the right and left hippocampi (r = 0.38, n = 32, p < 0.05) correlated with total score on the Benton test. We also found significant correlations between the amygdaloid volumes and the performance on visual memory tests but not with score on the verbal memory test.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Higher order memories for objects encountered in different spatio-temporal contexts in mice: evidence for episodic memory.

The ability to build higher order multi-modal memories comprising information about the spatio-temporal context of events has been termed 'episodic memory'. Deficits in episodic memory are apparent in a number of neuropsychiatric diseases. Unfortunately, the development of animal models of episodic memory has made little progress. Towards the goal of such a model we devised an object exploration task for mice, providing evidence that rodents can associate object, spatial and temporal information. In our task the mice learned the temporal sequence by which identical objects were introduced into two different contexts. The 'what' component of an episodic memory was operationalized via physically distinct objects; the 'where' component through physically different contexts, and, most importantly, the 'when' component via the context-specific inverted sequence in which four objects were presented. Our results suggest that mice are able to recollect the inverted temporal sequence in which identical objects were introduced into two distinct environments. During two consecutive test trials mice showed an inverse context-specific exploration pattern regarding identical objects that were previously encountered with even frequencies. It seems that the contexts served as discriminative stimuli signaling which of the two sequences are decisive during the two test trials.

Analysis of Variance↗

A method of assessing the efficacy of memory rehabilitation techniques using a "real-world" memory task: learning a computer language.

A software program developed to assess the effectiveness of memory rehabilitation techniques is described. This project addresses current weaknesses in the research literature on memory rehabilitation: 1) remediation strategies are evaluated in terms of performance on a practical, real-world memory task, rather than a laboratory learning task; 2) the program allows maximum flexibility in assessing a wide variety of remediation strategies and training schedules; and, 3) the software, which provides sensitive outcome measures and detailed feedback about performance, is adaptable to the needs of patients with widely varying degrees of memory impairment. The results of a demonstration project are included to illustrate the use of this technology in determining the usefulness of different mnemonic strategies for patients with specific patterns of memory deficit. The importance of assessing maintenance of rehabilitation training over time is stressed.

Computer Graphics↗

Episodic memory for object location versus episodic memory for object identity: do they rely on distinct encoding processes?

Three experiments were conducted to determine whether encoding processes that support episodic memory for object location are distinct from those that support memory for object identity. Guided by transfer-appropriate processing notions, we examined with an incidental learning paradigm whether an attentional focus on object location at encoding promotes subsequent recovery of object location, whereas a focus on object identity promotes recovery of object identity. We found that judging spatial relationships at encoding selectively supports recovery of object location, provided the test assesses memory for these relationships (rather than absolute location); our results also showed that judging physical and semantic object attributes promotes recovery of object identity preferentially. Contrasting with these domain-specific effects was evidence that identification processes involved in object naming boost memory for object identity as well as for absolute object location. Object identification at encoding may support memory performance in both domains by triggering the binding of identity and location information through a mechanism of object-based attentional selection.

Adult↗

Autobiographical memories for the September 11th attacks: reconstructive errors and emotional impairment of memory.

College students were asked about their personal memories from September 11, 2001. Consistency in reported features over a 2-month period increased as the delay between the initial test and 9/11 increased. Central features (e.g., Where were you?) were reported with greater consistency than were peripheral features (What were you wearing?) but also contained a larger proportion of reconstructive errors. In addition, highly emotional participants demonstrated poor prospective memory and relatively inconsistent memory for peripheral details, when compared with less emotional participants. Highly emotional participants were also more likely to increase the specificity of their responses over time but did not exhibit greater consistency for central details than did less emotional participants. The results demonstrated reconstructive processes in the memory for a highly consequential and emotional event and emotional impairment of memory processing of incidental details.

Adult↗

Memory for memory.

Participants read short passages and 1 day later they answered questions via telephone about the passages (text facts) and about the experimental session (event facts). They were telephoned again 6 weeks later and answered the same questions about text and event facts. They also answered new questions about whether they remembered the answers they had given in the initial telephone interview (recall for prior memory performance). Although participants accurately remembered the majority of past memory successes, they were poor at remembering past memory failures. After being provided with the correct answer and tested again, the participants' performance improved somewhat, especially for memory failures. This suggests that some errors in recalling past forgetting might have been due to correctly remembering the answer previously given, but failing to realize that it had been wrong. These findings have implications for a variety of situations in which people are queried about past memory performance.

Adolescent↗

When visual and verbal memories compete: evidence of cross-domain limits in working memory.

Recently, investigators have suggested that visual working memory operates in a manner unaffected by the retention of verbal material. We question that conclusion on the basis of a simple dual-task experiment designed to rule out phonological memory and to identify a more central faculty as the source of a shared limitation. With a visual working memory task in which two arrays of color squares were to be compared, performance was unaffected by concurrent recitation of a two-digit list or a known seven-digit sequence. However, visual working memory performance decreased markedly when paired with a load of seven random digits. This was not a simple tradeoff, inasmuch as errors on the visual array and high digit load tasks tended to co-occur. Working memory for digits and visual information thus are both subject to at least one type of shared limit, not just domain-specific limitations. The nature of the shared limit is discussed.

Adolescent↗

Evaluating characteristics of false memories: remember/know judgments and memory characteristics questionnaire compared.

Subjects hearing a list of associates to a nonpresented lure word later often claim to have heard the lure (Deese, 1959; Roediger & McDermott, 1995). To examine the characteristics of such false memories, subjects completed a memory characteristics questionnaire (MCQ; Johnson, Foley, Suengas, & Raye, 1988) or made remember/know (RK; Gardiner & Java, 1993) judgments for previously heard theme associates and nonpresented lures. MCQ ratings indicated that false memories for lures had less auditory detail and less remembered feelings and reactions than memories for presented words. In addition, rates of false recognition for lures were significantly lower than rates of correct recognition when items from various themes were intermixed instead of blocked at acquisition and subjects made MCQ ratings instead of RK judgments. This demonstrates that false memories can be affected both by how they are acquired and by how extensively they are examined at retrieval.

Adult↗

[Some differences between the visual and auditory memories in the short-term memory].

In order to clarify the differences between the visual and the auditory memories and the interference effect between them, a paired presentation method was developed. In this method, the subject under the experimental condition memorized two independent sequences of random digits, which were presented simultaneously digit by digit, the digits of the one sequence being presented visually and the digits of the other auditorily. After the presentation, subjects were asked to recall first either the visual or the auditory digit sequence, and then the other sequence. The subject under the control condition, on the other hand, memorized one sequence of random digits which were presented either visually or auditorily, and after recalling them memorized another sequence of random digits presented in the other modality. The results can be summarized as follows. (1) Under the experimental as well as under the control conditions, the recency effect appeared in the auditory memory task, but it did not in the visual memory task. (2) The performance for visual by presented digits under the experimental condition was lower than that under the control condition, whereas the performance for auditorily presented digits under the former was equal to that under the latter. The results presented might suggest that: (1) there are independent visual and auditory memories in the short-term memory; and (2) the memorizing of the auditory materials interferes with the memorizing of the visual one, but the latter does not interfere with the former.

Adult↗

Parsimonious prediction of Wechsler Memory Scale--III memory indices.

Equations for prorating the Wechsler Memory Scale--III (WMS-III) Index scores were derived and validated on a sample of 252 mixed clinical cases. Regression equations were performed using age-scaled scores as predictors and the sum of age-scaled scores for Immediate Memory (IM) and General Memory (GM) as the criteria. Including Logical Memory and Verbal Paired Associates with either Faces or Family Pictures resulted in estimated scores that accounted for 95% to 97% of the variance for IM and GM. Over 80% of these cases had estimated sum of scaled scores that fell within 3 points of actual sum of scaled scores, within 1 standard error of measurement. When only Logical Memory and Verbal Paired Associates were included, estimations accounted for only 87% of the variance, and only 60% of the estimated scores fell within 3 points of actual sum of scaled scores. The regression equations are presented, as are the confidence intervals derived from a bootstrapping procedure that created 15,000 different samples.

Adult↗

Laterality of phonological working memory: dependence on type of stimulus, memory load, and sex.

Investigations of the laterality of phonological working memory have not always yielded consistent results. The present experiment investigated working memory for letters and numbers in two memory load conditions. In the low load condition, working memory for letters and numbers was similar. However, in the high load condition, males were more accurate at the recall of letters. This effect was not observed with numbers, in which both sexes performed more poorly. Furthermore, we observed consistent RVF advantages for both tasks, although males were more asymmetrical for the recall of letters and females were more asymmetrical for the recall of numbers. This result indicates that laterality of working memory for letters and numbers differs, and these asymmetries depend upon the sex of the participant.

Adult↗

Involuntary aware memory enhances priming on a conceptual implicit memory task.

This study investigated the role of involuntary aware memory (phenomenological awareness of the study episode) on a conceptual implicit memory task. Subjects studied words under levels of processing conditions (LOP: nonsemantic vs. semantic) and then received a category exemplar generation priming task. Subjects were either aware or unaware of the study test relationship. Subjects who were study test aware showed more priming for semantic study than subjects who were study test unaware, thus producing an LOP dissociation between them. The findings suggest that involuntary aware memory can enhance performance on conceptual implicit memory tasks, thus having theoretical implications for implicit and explicit memory.

Awareness↗

Differential sensitivity of virgin and memory T lymphocytes to calcium ionophores suggests a buoyant density separation method and a model for memory cell hyporesponsiveness to Con A.

Previous work from this laboratory has indicated that murine memory T cells differ from virgin T cells in that the former are more resistant to agents that alter intracellular [Ca]i. We have used this difference to devise a method for separating virgin from memory T cells by centrifugation over an ionomycin-containing Percoll step gradient after brief exposure to 2 microM ionomycin. Under these conditions, those T cells that are most sensitive to ionomycin-induced changes in [Ca]i become more dense and therefore travel further into the Percoll/ionomycin gradient than cells that are more resistant to ionomycin. We show that the ionomycin-resistant cell population is enriched for cells that express high levels of Pgp-1 (CD44), and low levels of CD45RB, and thus appears to consist largely of memory T cells. Both CD4 and CD8 cells can be divided into Pgp-1hi and Pgp-1lo subsets in this way. Cells recovered from such a gradient and washed to remove the ionomycin appear normally functional, i.e., neither more nor less responsive to mitogens and costimuli than untreated cells. Limiting dilution methods show that the ionomycin-sensitive (virgin) subset contains most of the Con A-responsive precursors for cytotoxicity, and most of the cells able to produce IL-2 in responses to Con A or staphylococcal enterotoxin B. Ag-specific helper memory cells are, however, found predominantly in the ionomycin-resistant fraction of the spleen and draining lymph nodes of mice infected with Schistosoma mansoni. Changes in resistance to calcium signal development may represent a fundamental distinction between virgin and memory T cells, and could contribute to differences in activation requirements between these two cell subsets.

Animals↗

Studies on B-cell memory. I. Generation and exhaustion of B-cell memory by thymus-dependent antigen in T-cell depleted mice.

Mice depleted of T cells by adult thymectomy, X-irradiation and reconstitution with syngeneic bone marrow cells, either untreated or treated with anti-Thy-1 serum and complement, were immunized intensively with alum-precipitated bovine serum albumin (AP-BSA) along with or without bacterial lipopolysaccharide (LPS), but no significant anti-BSA antibody response was detected. Priming of the T-cell depleted mice, however, either by a single injection of AP-BSA plus LPS or by multiple injections of AP-BSA without LPS, resulted in the generation of immunological memory. A single injection of AP-BSA without LPS was ineffective. The memory required the aid of syngeneic T cells to be recalled by the challenge with AP-BSA plus LPS. On the other hand, multiple injections of AP-BSA plus LPS did not cause the generation of memory and the response of these mice to the challenge was lower than that of unprimed control mice. These results suggest that (1) the anti-BSA response is highly dependent on the helper function of T cells, (2) the degree of T-cell requirement for the memory generation is very low, and (3) priming with too much strong stimulation in the absence of functional T cells leads to the suppression or abortion of previously generated immunological memory.

Animals↗