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PubMed2006

Noradrenergic modulation of working memory and emotional memory in humans.

RATIONALE: Noradrenaline (NA) is implicated in arousal. Working memory is dependent upon prefrontal cortex, and moderate levels of NA are thought to facilitate working memory whereas higher levels during extreme stress may impair working memory and engage more posterior cortical and sub-cortical circuitry. The NA system also influences emotional memory via modulation of the amygdalae and related mediotemporal structures. NA dysfunction and abnormalities in arousal-dependent memory functions are evident in a variety of neuropsychiatric illnesses. OBJECTIVES: The authors provide a concise overview of pharmacological studies that have investigated effects of selective NA manipulations on working memory and emotional memory functions in healthy human volunteers. MATERIALS AND METHODS: Selection of relevant peer-reviewed publications was based on a PubMed search. RESULTS: Studies to date indicate that: (1) the beta-blocker propranolol impaired working and emotional memory, (2) clonidine frequently impaired working memory, and (3) reboxetine, a selective noradrenaline reuptake inhibitor, enhanced emotional memory for positive material. CONCLUSIONS: Improved understanding of coupling between NA, cortico-subcortical circuitry and human mnemonic functions will suggest novel therapeutic directions for the treatment of neuropsychiatric conditions, such as attention deficit hyperactivity disorder and post-traumatic stress disorder. Future research directions are discussed in relation to neuroimaging techniques, functional central nervous system polymorphisms and study designs.

Adrenergic Agonists↗

PubMed1989

Remote and autobiographical memory, temporal context memory and frontal atrophy in Korsakoff and Alzheimer patients.

Korsakoff and Alzheimer patients were assessed on tests of remote, autobiographical, and temporal context memory. On the remote memory tests, both groups showed a temporal gradient across all the measures used, although the gradient was significantly steeper in the Korsakoff group. Both groups also showed a marked improvement in performance on recognition testing. Correlations with an anterograde "memory quotient" were relatively low, and in the Korsakoff group, there was evidence of partial independence between memory for personal events/facts and memory for public events/facts. Better performance within the Korsakoff group in the recall of early memories was correlated with higher intelligence, whereas worse performance for recent memories was associated with a longer duration of the disorder. Both patient groups were impaired at tests of retrospective and anterograde temporal context memory, but there was no association with a neuroradiological measure of frontal atrophy and only a very weak correlation with tests of frontal function. It is concluded that both patient groups show a retrieval deficit in remote memory, that a superimposed anterograde impairment produces the steeper temporal gradient in Korsakoff patients, and that the deficit in temporal context memory is unlikely to be related to frontal atrophy or frontal dysfunction.

Adult↗

PubMed2004

Medial prefrontal cortex is involved in spatial temporal order memory but not spatial recognition memory in tests relying on spontaneous exploration in rats.

The present study describes two novel tasks relying on spontaneous patterns of exploration in a radial-arm maze that can be used to assess spatial recognition memory and spatial temporal order memory (i.e. memory for the order in which places have been visited) in the rat. In the recognition memory task, rats were permitted to freely explore two arms in the maze on a first trial and one 'familiar' arm and one novelly located arm on a second trial 105 min later. In the temporal order memory task, rats were permitted to explore two arms in the maze on a first trial, two novel arms on a second trial 60 min later, and one 'older familiar' arm and one 'more recent familiar' arm on a third trial 45 min later. Using these tasks, we found that rats direct greater exploration at a novel than a familiar arm location, thus showing long-term spatial recognition memory, and at an older familiar arm than a more recent familiar arm, thus showing long-term spatial temporal order memory. Lidocaine inactivation of the mPFC prior to the final trial in each task disrupted performance on the temporal order but not the recognition memory task, thereby demonstrating a role for the mPFC in the retrieval and/or use of temporal order information but not in spatial memory per se. These findings highlight the specific involvement of the rat mPFC in temporal order memory and have important implications for a broader understanding of mPFC function.

Analysis of Variance↗

PubMed2004

The development of young children's memory strategies: First findings from the Würzburg Longitudinal Memory Study.

This article reports the first findings of the Würzburg Longitudinal Memory Study, which focuses on children's verbal memory development, particularly the acquisition of memory strategies. At the beginning of the study, 100 kindergarten children (mean age 6 1/2 years) were tested on various memory measures, including sort-recall, text recall, short-term memory capacity, and metamemory. Assessments were repeated twice, with adjacent measurement points separated by 6-month time intervals. One major goal of the initial phase of the study concerned the exploration of the utilization deficiency phenomenon, which refers to the fact that young children who spontaneously use a memory strategy for the first time do not experience immediate memory benefits. Results obtained for the sort-recall task showed that, among those children who acquired a sorting strategy between Times 1 and 2, only a small proportion experienced the utilization deficiency problem. Additional analyses demonstrated that these few children also performed more poorly on the short-term memory tasks and the text recall measure when compared with the groups of efficient strategy users, suggesting that utilization deficiency is accompanied by a more general memory capacity problem. Overall, the findings revealed enormous variability in the early acquisition of memory strategies, indicating that the utilization deficiency phenomenon might not be as frequent as is assumed in the relevant literature.

Child↗

PubMed2000

Auditory working memory and verbal recall memory in schizotypy.

Deficits on verbal memory tasks, as well as on spatial and auditory working memory tasks, have been observed in schizophrenia patients. A useful strategy in the determination of the premorbid indicator status of specific cognitive and memory deficits observed in patients is to examine those persons at increased biological risk for schizophrenia (e.g. first-degree relatives), schizotypal personality disorder patients, and/or psychometrically identified schizotypes for comparable deficits, though perhaps less profound than those seen in actual patients. We examined verbal memory and auditory working memory functioning in 31 schizotypic and 26 normal control subjects from a large randomly ascertained non-clinical university population. Schizotypy status was determined psychometrically using the well-known Perceptual Aberration Scale. Contrary to our theory-guided expectations, noteworthy deficits in verbal memory and auditory working memory were not observed in the schizotypic subjects and the two experimental groups did not differ significantly on any of the memory measures. These results were discussed in light of prior results obtained using the spatial delayed response task (i.e. spatial working memory) and Wisconsin Card Sorting Test performance on these same subjects. The theoretical implications of these findings are discussed in relation to the putative processes involved in the working memory system, as well as in relation to the schizotypy construct.

Adult↗

PubMed2003

Event-related brain potentials in memory: correlates of episodic, semantic and implicit memory.

OBJECTIVE: To study cognitive evoked potentials, recorded from scalp EEG and foramen ovale electrodes, during activation of explicit and implicit memory. The subgroups of explicit memory, episodic and semantic memory, are looked at separately. METHODS: A word-learning task was used, which has been shown to activate hippocampus in H(2)(15)O positron emission tomography studies. Subjects had to study and remember word pairs using different learning strategies: (i) associative word learning (AWL), which activates the episodic memory, (ii) deep single word encoding (DSWE), which activates the semantic memory, and (iii) shallow single word encoding (SSWE), which activates the implicit memory and serves as a baseline. The test included the 'remember/know' paradigm as a behavioural learning control. During the task condition, a 10-20 scalp EEG with additional electrodes in both temporal lobes regions was recorded from 11 healthy volunteers. In one patient with mesiotemporal lobe epilepsy, the EEG was recorded from bilateral foramen ovale electrodes directly from mesial temporal lobe structures. Event-related potentials (ERPs) were calculated off-line and visual and statistical analyses were made. RESULTS: Associative learning strategy produced the best memory performance and the best noetic awareness experience, whereas shallow single word encoding produced the worst performance and the smallest noetic awareness. Deep single word encoding performance was in between. ERPs differed according to the test condition, during both encoding and retrieval, from both the scalp EEG and the foramen ovale electrode recordings. Encoding showed significant differences between the shallow single word encoding (SSWE), which is mainly a function of graphical characteristics, and the other two strategies, deep single word (DSWE) and associative learning (AWL), in which there is a semantic processing of the meaning. ERPs generated by these two categories, which are both functions of explicit memory, differed as well, indicating the presence or the absence of associative binding. Retrieval showed a significant test effect between the word pairs learned by association (AWL) and the ones learned by encoding the words in isolation of each other (DSWE and SSWE). The comparison of the ERPs generated by autonoetic awareness ('remember') and noetic awareness ('know') exhibited a significant test effect as well. CONCLUSIONS: The results of behavioural data, in particular that of the 'remember/know' procedure, are evidence that the task paradigm was efficient in activating different kinds of memory. Associative word learning generated a high degree of autonoetic awareness, which is a result of the episodic memory, whereas both kinds of single word learning generated less. AWL, DSWE and SSWE resulted in different electrophysiological correlates, both for encoding as well as retrieval, indicating that different brain structures were activated in different temporal sequence.

Adult↗

PubMed2002

Excitotoxic lesions of the rhinal cortex in the baboon differentially affect visual recognition memory, habit memory and spatial executive functions.

To specify the functional role of the rhinal cortex, baboons with bilateral excitotoxic lesions of the rhinal cortex (RH group) were tested on a series of computerized memory and learning tasks. Preoperatively, they were trained to and then tested on a delayed nonmatching-to-sample (DNMS) task with trial-unique stimuli. Postoperatively, this visual recognition memory task was given twice. As compared to a sham-operated group, the RH group showed good retention of rule learning and were unimpaired on the Delay memory subtest. Performance on the List Length memory subtest was, however, severely impaired at both postoperative evaluations, with a significant negative correlation between cognitive performance and neuronal loss in rhinal areas. Visual habit memory and spatial working memory were assessed postoperatively only, using a concurrent discrimination learning task and both a delayed-response task (with a two- and four-location choice) and a delayed alternation task, respectively. The RH group was unimpaired on the first two tasks and was even faster than the controls in learning the delayed-response task with four locations. Finally, most RH baboons failed to learn the delayed alternation task within the limits of testing. These results indicate that neuronal loss in the rhinal cortex is sufficient to impair visual recognition memory, and extend the implication of this area to spatial executive functions. Furthermore, the observation of impaired recognition memory and executive processes with preserved procedural memory and retrograde memory suggests that damage to the rhinal cortex probably participates in the cognitive deficits typical of the early stages of Alzheimer's disease.

Animals↗

PubMedDate not supplied

How does the severity of a learning disability affect working memory performance?

Working memory performance was examined in children aged 11-12 years who had borderline, mild, and moderate learning disabilities. Comparisons with children of average abilities were used to determine whether those with more severe learning disabilities had greater impairments in working memory. Seven measures of working memory span were used to assess temporary phonological short-term storage (digit span, word span), temporary visuo-spatial short-term storage (pattern span, spatial span), and temporary short-term storage with additional processing, or central executive, demands (listening span. odd one out span, reverse digit span). Children with mild and moderate learning disabilities were impaired on all measures of working memory compared to children of average abilities. Children with borderline learning disabilities were just as good as children with average abilities on visuo-spatial and complex span tasks, but showed an impairment on phonological span tasks. Children with moderate learning disabilities were indistinguishable from children with mild learning disabilities on simple span tasks, but were significantly poorer than the mild group on the more demanding complex span tasks. For the group as a whole, working memory was strongly related to mental age.

Case-Control Studies↗

PubMedDate not supplied

The phonological loop and memory for rhythms: an individual differences approach.

The purpose of the current study was to examine the relationship between short-term memory for rhythm and the phonological loop in working memory. Results showed that digit span scores significantly correlated with the scores on the rhythmic memory task, and that the correlation between the two scores remained significant even after the common variance with reading speed was partialled out. Partial correlation and regression analyses indicated that the relation between memory for rhythm and digit span scores is mediated by the third component in the phonological loop, the component that is responsible for regulation of timing mechanisms in immediate memory tasks.

Adult↗

PubMed2004

Memory of myself: autobiographical memory and identity in Alzheimer's disease.

A number of theories posit a relationship between autobiographical memory and identity. To test this we assessed the status of autobiographical memory and identity in 20 individuals with Alzheimer's disease (AD) and 20 age-matched controls, and investigated whether degree of autobiographical memory impairment was associated with changes in identity. Two tests of autobiographical memory (Autobiographical Memory Interview, autobiographical fluency) and two measures of identity (Twenty Statements Test, identity items of the Tennessee Self Concept Scale) were administered. AD participants exhibited significant impairments on both memory tests, and changes in the strength, quality, and direction of identity relative to controls. Impairments of some components of autobiographical memory, particularly autobiographical memory for childhood and early adulthood, were related to changes in the strength and quality of identity. These findings support the critical role of early adulthood autobiographical memories (16-25 years) in identity, and suggest autobiographical memory loss affects identity.

Adolescent↗

PubMed2004

A preliminary study of autobiographical memory in remitted bipolar and unipolar depression and the role of imagery in the specificity of memory.

Autobiographical memory was investigated in a sample of 19 individuals with remitted bipolar affective disorder and a community sample of 16 individuals with remitted unipolar depression who had similar low levels of current symptoms. Each participant was prompted to recall one positive memory and one negative memory, to rate it on several scales, and to describe it in detail. Relative to the remitted unipolar group, the remitted bipolar group reported more general than specific negative memories and more frequent recollections of the negative memory during their everyday life. Across the sample, 95% of all specific memories involved a mental image, whereas only 56% of all general memories involved a mental image, suggesting a role of imagery in the retrieval of a specific memory. Characteristic examples of memories are provided. These results are preliminary yet they suggest that patients with bipolar disorder in remission may show memory characteristics that are often associated with symptomatic unipolar depression.

Adult↗

PubMed2004

Parsing the recognition memory components of the WMS-III face memory subtest: normative data and clinical findings in dementia groups.

The WMS-III face memory subtest was developed as a quick, reliable, measure of non-verbal recognition memory. While the face memory subtest has demonstrated clinical sensitivity, the test has been criticized for low correlation with other WMS-III visual memory subtests and for failing to differentiate performance between clinical groups. One possible reason for these findings may be due to the impact of response bias associated with recognition memory tests. Four studies were conducted to evaluate the utility of applying signal detection measures to the face memory subtests. The first two studies used the WMS-III standardization data set to determine age and education effects and to present normative and reliability data for hits, false positives, discriminability and response bias. The third study tested the hypothesis that using response components and signal detection measures would enhance the correlation between face memory and the other WMS-III visual memory subtests. The fourth study compared performance of patients with Alzheimer's disease, Huntington's disease, Korsakoff's syndrome and demographically matched controls on the new face memory scores. The new measures did not have higher correlation with other WMS-III visual memory measures than the standard scoring of the test. Analysis of the clinical samples indicated that the discriminability index best differentiated patients from controls. The response components, particularly delayed false positives, differentiated performance among the clinical groups. Normative and reliability data are presented.

Adolescent↗

PubMed2006

Discrepancy of performance among working memory-related tasks in autism spectrum disorders was caused by task characteristics, apart from working memory, which could interfere with task execution.

Working memory performance has been inconsistently reported in autism spectrum disorders (ASD). Several studies in ASD have found normal performance in digit span and poor performance in digit symbol task although these are closely related with working memory. It is assumed that poor performance in digit symbol could be explained by confirmatory behavior, which is induced due to the vague memory representation of number-symbol association. Therefore it was hypothesized that the performance of working memory task, in which vagueness did not cause confirmatory behavior, would be normal in ASD. For this purpose, the Advanced Trail Making Test (ATMT) was used. The performance of digit span, digit symbol and ATMT was compared between ASD and normal control. The digit span, digit symbol and ATMT was given to 16 ASD subjects and 28 IQ-, age- and sex-matched control subjects. The scores of these tasks were compared. A significantly lower score for ASD was found only in digit symbol compared with control subjects. There were no significant difference in digit span and working memory estimated by ATMT. Discrepancy of scores among working memory-related tasks was demonstrated in ASD. Poor digit symbol performance, normal digit span and normal working memory in ATMT implied that ASD subjects would be intact in working memory itself, and that superficial working memory dysfunction might be observed due to confirmatory behavior in digit symbol. Therefore, to evaluate working memory in ASD, tasks that could stimulate psychopathology specific to ASD should be avoided.

Adult↗

PubMed1983

Memory symptoms and memory performance of neurological patients.

The spontaneous memory symptoms of 100 brain-damaged patients suffering from a variety of conditions were elicited. The most frequent types of symptom related to memory for people's names, memory for recent events occurring a few days or weeks ago, memory for a spoken message and remembering to do something. The spontaneous symptoms from 50 non-brain-damaged patients were also elicited. There was a considerable degree of overlap between the type and incidence of symptoms in brain-damaged and control patients. Some symptoms (e.g. remembering people's names) were reported by a similar proportion of control as brain-damaged patients. A few symptoms (e.g. spatial disorientation, temporal disorientation) were reported by brain-damaged patients but not by any control patients. One symptom (remembering to do something) occurred more frequently in the control group of patients than in the brain-damaged group. The relationship between memory symptoms and memory performance was examined in a group of head-injured patients. A short questionnaire on memory symptoms was completed by each patient and by a close observer, and the head-injured subjects also performed tests of immediate and delayed recall. Although there was a highly significant correlation between degree of memory impairment as perceived by the patient and as perceived by an observer, there was generally a low correlation between subjective or observed memory impairment and scores on commonly used clinical memory tests.

Adolescent↗

PubMed1997

A comparison of the encoding of content and order in olfactory memory and in memory for visually presented verbal materials.

The claim that there is no olfactory short-term memory store, as olfactory serial position (SP) effects are absent (Engen, 1987, 1989; Lawless & Engen, 1977), raises the issue whether memory for sensory qualities is differently organized from memories for more cognitive materials in vision and hearing. Early memory processing in olfaction is re-examined by comparing the results of similarly designed experiments which examine short-term memory for words and consonants, and for odours. Memory for content and memory for order were separately examined in each case. Serial position functions were obtained both for visually presented verbal materials and for odours. The serial position effects for content and order memory in both modalities are sufficiently similar in pattern to support the conclusion that short-term memory processing of olfactory and verbal stimuli is conducted by analogous memory mechanisms.

Adolescent↗

PubMed2003

Persistent LIP activity in memory antisaccades: working memory for a sensorimotor transformation.

The lateral intraparietal area (LIP) contains neurons that are active during the memory interval of memory saccades. We call these "persistent neurons." Here we study the activity of the persistent neurons in memory antisaccades, "motor" (the saccade is made toward the response field, although the response field is not stimulated visually) and "visual" (the response field is stimulated visually, but the movement is away from the field). Most persistent neurons are active during parts of the memory intervals of both visual and motor memory-antisaccades. Typically, these parts significantly overlap each other and together span the entire memory interval. The amplitude of the activity changes systematically during the memory intervals of visual and motor memory antisaccades. These changes are reflected in an antisaccade differential activity, which turns first to the visual direction and then crosses over to the motor direction. Some persistent neurons appear to show the paradoxical activity previously characterized in visual neurons; paradoxical activity accelerates the transition of the neuron's activity from visual to motor. These observations suggest that the persistent neurons reflect working memory for the computation of the antisaccade sensorimotor transformation. Ensembles of persistent neurons with different response fields may make up modules of working memory.

Animals↗

PubMed2003

Enhancement of declarative memory by emotional arousal and visual memory function in Alzheimer's disease.

The specific effects of visual and verbal memory on the ability of emotional arousal to enhance declarative memory were examined by using multiple linear regression analysis on data from a sample of 56 patients with probable Alzheimer's disease (AD). The enhancing effect of emotion on memory was evaluated by an illustrated story paradigm, and the visual and verbal memory by a standard memory test. In AD, memory enhancement by emotion was significantly correlated with visual memory but not with verbal memory, regardless of age, sex, educational attainment, and severity of dementia, suggesting a close association between memory enhancement by emotion and visual memory.

Aged↗

PubMedDate not supplied

Memory complaints and memory deficits in young and old psychiatric inpatients.

Memory complaints and memory deficits were investigated in 206 consecutively admitted psychiatric inpatients at the University of Iowa Psychiatric Hospital. Forty-five percent of patients over age 60 years and 29% of patients less than 60 years old had severe memory complaints. Patients with complaints of memory loss were no more likely than patients without such complaints to have a memory deficit. In patients over age 60 years, memory complaint was more common in depression than in dementing and amnestic disorders (73% v 43%), while in younger patients memory complaint was slightly more common in dementing and amnestic disorders than in depression (57% v 41%). Increasing age was significantly correlated with increasing likelihood of memory complaint for depressed patients but not for nondepressed patients. As a result of these findings, memory complaint was found to be a statistically significant marker for depression in the elderly (sensitivity = 73%, specificity = 75%) but not in younger patients. Our results confirm the clinical observation that memory complaints are a useful marker for depressed states in the elderly.

Adjustment Disorders↗