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Memory Processes (memory + process)
Kinds of Memory Processes Selected AbstractsExchange protein activated by cyclic AMP 2 (Epac2) plays a specific and time-limited role in memory retrieval,HIPPOCAMPUS, Issue 9 2010Anghelus Ostroveanu Abstract Knowledge on the molecular mechanisms involved in memory retrieval is limited due to the lack of tools to study this stage of the memory process. Here we report that exchange proteins activated by cAMP (Epac) play a surprisingly specific role in memory retrieval. Intrahippocampal injection of the Epac activator 8-pCPT-2,O-Me-cAMP was shown to improve fear memory retrieval in contextual fear conditioning whereas acquisition and consolidation were not affected. The retrieval enhancing effect of the Epac activator was even more prominent in the passive avoidance paradigm. Down-regulation of Epac2 expression in the hippocampal CA1 area impaired fear memory retrieval when the memory test was performed 72 h after training, but not when tested after 17 days. Our data thus identify an important time-limited role for hippocampal Epac2 signaling in cognition and opens new avenues to investigate the molecular mechanisms underlying memory retrieval. © 2009 Wiley-Liss, Inc. [source] Forecasting with k -factor Gegenbauer Processes: Theory and ApplicationsJOURNAL OF FORECASTING, Issue 8 2001L. Ferrara Abstract This paper deals with the k -factor extension of the long memory Gegenbauer process proposed by Gray et al. (1989). We give the analytic expression of the prediction function derived from this long memory process and provide the h -step-ahead prediction error when parameters are either known or estimated. We investigate the predictive ability of the k -factor Gegenbauer model on real data of urban transport traffic in the Paris area, in comparison with other short- and long-memory models. Copyright © 2001 John Wiley & Sons, Ltd. [source] Estimation of the location and exponent of the spectral singularity of a long memory processJOURNAL OF TIME SERIES ANALYSIS, Issue 1 2004Javier Hidalgo Abstract., We consider the estimation of the location of the pole and memory parameter ,0 and d of a covariance stationary process with spectral density We investigate optimal rates of convergence for the estimators of ,0 and d, and the consequence that the lack of knowledge of ,0 has on the estimation of the memory parameter d. We present estimators which achieve the optimal rates. A small Monte-Carlo study is included to illustrate the finite sample performance of our estimators. [source] Memory for drawings in locations: Spatial source memory and event-related potentialsPSYCHOPHYSIOLOGY, Issue 4 2000Cyma van Petten Event-related potentials (ERPs) were recorded during recognition tasks for line drawings (items) or for both drawings and their spatial locations (sources). Recognized drawings elicited more positive ERPs than new drawings. Independent of accuracy in the spatial judgment, the old/new effect in the source recognition task was larger over the prefrontal scalp, and of longer temporal duration than in the item recognition task, suggesting that the source memory task engaged a qualitatively distinct memory process. More posterior scalp sites were sensitive to the accuracy of the source judgment, but this effect was delayed relative to the difference between studied and unstudied drawings, suggesting that source memory processes are completed after item recognition. Similarities and differences between spatial source memory and memory for conjunctions of other stimulus attributes are discussed, together with the role of prefrontal cortex in memory. [source] False memory and obsessive,compulsive symptomsDEPRESSION AND ANXIETY, Issue 5 2009Heide Klumpp Ph.D Abstract Background: The memory deficit hypothesis has been used to explain the maintenance of repetitive behavior in individuals with obsessive,compulsive disorder, yet the majority of studies focusing on verbal memory show mixed results. These studies primarily evaluated memory accuracy via the inclusion or omission of previously encountered material, as opposed to false recognition (i.e., the inclusion of erroneous material). We evaluated false memories and memory processes in individuals with obsessive,compulsive washing symptoms (OC), individuals matched on depression and anxiety without OC symptoms (D/A), and in nonanxious individuals (NAC). Methods: Twenty-eight OC, 28 D/A, and 29 NAC individuals read OC-threat relevant, positive, and neutral scenarios and then performed a recognition test. Erroneous recognition of words associated to encoded, but not previously viewed, scenarios were classified as false memories. To evaluate processes underlying memory, participants completed a modified remember/know task to examine whether the OC individuals differed from the other individuals in recollective clarity for false memories of OC-relevant (e.g., germs), positive (e.g., lottery), and neutral (e.g., bread) material. Results: The OC individuals used "know" more than the D/A and NAC individuals for false memories of threat. For veridical memories, the OC individuals used "know" more than the NAC, but not, D/A individuals. Conclusions: The greater reliance on "know" (i.e., feelings of familiarity) in general and false threat memories in particular in individuals with OC symptoms may add to feelings of uncertainty for threat-relevant material, which may contribute to compulsive behavior. Depression and Anxiety, 2009. ©2008 Wiley-Liss, Inc. [source] Exploring dyslexics' phonological deficit I: lexical vs sub-lexical and input vs output processesDYSLEXIA, Issue 4 2005Gayaneh Szenkovits Abstract We report a series of experiments designed to explore the locus of the phonological deficit in dyslexia. Phonological processing of dyslexic adults is compared to that of age- and IQ-matched controls. Dyslexics' impaired performance on tasks involving nonwords suggests that sub-lexical phonological representations are deficient. Contrasting nonword repetition vs auditory nonword discrimination suggests that dyslexics are specifically impaired in input phonological processing. These data are compatible with the hypothesis that the deficit initially affects input sub-lexical processes, and further spreads to output and lexical processes in the course of language acquisition. Further longitudinal research is required to confirm this scenario as well as to tease apart the role of the quality of phonological representations from that of verbal short-term memory processes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Extracellular signal-regulated kinase activation is required for consolidation and reconsolidation of memory at an early stage of ontogenesisEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2009Solène Languille Abstract The ability to form long-term memories exists very early during ontogeny; however, the properties of early memory processes, brain structures involved and underlying cellular mechanisms are poorly defined. Here, we examine the role of extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase/ERK signaling cascade, which is crucial for adult memory, in the consolidation and reconsolidation of an early memory using a conditioned taste aversion paradigm in 3-day-old rat pups. We show that intraperitoneal injection of SL327, the upstream mitogen-activated protein kinase kinase inhibitor, impairs both consolidation and reconsolidation of early memory, leaving short-term memory after acquisition and after reactivation intact. The amnesic effect of SL327 diminishes with increasing delays after acquisition and reactivation. Biochemical analyses revealed ERK hyperphosphorylation in the amygdala but not the hippocampus following acquisition, suggesting functional activation of the amygdala as early as post-natal day 3, although there was no clear evidence for amygdalar ERK activation after reactivation. These results indicate that, despite an immature brain, the basic properties of memory and at least some of the molecular mechanisms and brain structures implicated in aversion memory share a number of similarities with the adult and emerge very early during ontogeny. [source] Repetition suppression of induced gamma band responses is eliminated by task switchingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2006Thomas Gruber Abstract The formation of cortical object representations requires the activation of cell assemblies, correlated by induced oscillatory bursts of activity >,20 Hz (induced gamma band responses; iGBRs). One marker of the functional dynamics within such cell assemblies is the suppression of iGBRs elicited by repeated stimuli. This effect is commonly interpreted as a signature of ,sharpening' processes within cell-assemblies, which are behaviourally mirrored in repetition priming effects. The present study investigates whether the sharpening of primed objects is an automatic consequence of repeated stimulus processing, or whether it depends on task demands. Participants performed either a ,living/non-living' or a ,bigger/smaller than a shoebox' classification on repeated pictures of everyday objects. We contrasted repetition-related iGBR effects after the same task was used for initial and repeated presentations (no-switch condition) with repetitions after a task-switch occurred (switch condition). Furthermore, we complemented iGBR analysis by examining other brain responses known to be modulated by repetition-related memory processes (evoked gamma oscillations and event-related potentials; ERPs). The results obtained for the ,no-switch' condition replicated previous findings of repetition suppression of iGBRs at 200,300 ms after stimulus onset. Source modelling showed that this effect was distributed over widespread cortical areas. By contrast, after a task-switch no iGBR suppression was found. We concluded that iGBRs reflect the sharpening of a cell assembly only within the same task. After a task switch the complete object representation is reactivated. The ERP (220,380 ms) revealed suppression effects independent of task demands in bilateral posterior areas and might indicate correlates of repetition priming in perceptual structures. [source] Ascending visceral regulation of cortical affective information processingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003Gary G. Berntson Abstract Over a century ago, William James proposed that strong emotions represent the perceptual consequences of somato-visceral feedback. Although the strong form of this conception is no longer viable, considerable evidence has accumulated indicating a range of visceral influences on higher neurobehavioural processes. This literature has only recently begun to consolidate, because earlier reports generally remained at the demonstration level, and pathways and mechanisms for such influences were uncertain. Recently, specific effects of visceral feedback have become apparent on cortical activity, cerebral auditory-evoked responses, anxiety, memory and behavioural aspects of immunological sickness. Moreover, considerable progress has been made recently in determining the specific neural pathways and systems underlying these actions, especially the role of noradrenergic projections from the nucleus of the tractus solitarius and the locus coeruleus to the amygdala in memory processes, and to the basal forebrain in the processing of anxiety-related information. The present paper highlights selected recent findings in this area, and outlines relevant structures and pathways involved in the ascending visceral influence on higher neurobehavioural processes. [source] Strain differences in ,1 receptor-mediated behaviours are related to neurosteroid levelsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2002Vân-Ly Phan Abstract The sigma1 (,1) receptor exerts a potent neuromodulatory role in the brain with relevant consequences in memory processes, response to stress, depression and pharmacodependence. Its precise endogenous ligand is not yet identified but the ,1 receptor appears to be one target for the nongenomic rapid effects of neuroactive steroids in the brain. The aim of the present study was to establish whether differences in ,1 receptor-mediated behaviours could be observed among mouse strains, in relation with differences in either ,1 receptor expression or steroid levels. The ,1 -receptor immunohistochemical distribution appeared similar between Swiss and C57BL/6 strains in all the brain structures examined. The levels of in vivo[3H](+)-SKF-10 047 binding to ,1 receptors were lower in Swiss than in C57BL/6. Adrenalectomy/castration significantly increased [3H](+)-SKF-10 047 binding only in Swiss. The behavioural efficacy of the selective ,1 agonists igmesine and PRE-084 , reversion of the scopolamine-induced amnesia in the passive avoidance test; diminution of the immobility duration in the forced swimming test , were significantly higher in C57BL/6 than in Swiss. Steroid levels were measured in the brain in basal conditions and after stress. C57BL/6 mice presented in both conditions, the lowest progesterone levels, this steroid acting as an endogenous ,1 antagonist. Collectively, the results suggested that strain differences in neuroactive steroid and particularly, progesterone, biosynthesis and sensitivity may contribute to the differential behavioural efficacy of ,1 -receptor ligands. Noteworthy, these observations are coherent with strain differences observed in the intensity of cocaine-induced reward properties, known to critically involve the ,1 receptor. [source] Behavioral characterization of P311 knockout miceGENES, BRAIN AND BEHAVIOR, Issue 7 2008Gregory A. Taylor P311 is an 8-kDa protein that is expressed in many brain regions, particularly the hippocampus, cerebellum and olfactory lobes, and is under stringent regulation by developmental, mitogenic and other physiological stimuli. P311 is thought to be involved in the transformation and motility of neural cells; however, its role in normal brain physiology is undefined. To address this point, P311-deficient mice were developed through gene targeting and their behaviors were characterized. Mutants displayed no overt abnormalities, bred normally and had normal survival rates. Additionally, no deficiencies were noted in motor co-ordination, balance, hearing or olfactory discrimination. Nevertheless, P311-deficient mice showed altered behavioral responses in learning and memory. These included impaired responses in social transmission of food preference, Morris water maze and contextual fear conditioning. Additionally, mutants displayed altered emotional responses as indicated by decreased freezing in contextual and cued fear conditioning and reduced fear-potentiated startle. Together, these data establish P311 as playing an important role in learning and memory processes and emotional responses. [source] Contributions of the hippocampus and medial prefrontal cortex to energy and body weight regulationHIPPOCAMPUS, Issue 3 2009Terry L. Davidson Abstract The effects of selective ibotenate lesions of the complete hippocampus (CHip), the hippocampal ventral pole (VP), or the medial prefrontal cortex (mPFC) in male rats were assessed on several measures related to energy regulation (i.e., body weight gain, food intake, body adiposity, metabolic activity, general behavioral activity, conditioned appetitive responding). The testing conditions were designed to minimize the nonspecific debilitating effects of these surgeries on intake and body weight. Rats with CHip and VP lesions exhibited significantly greater weight gain and food intake compared with controls. Furthermore, CHip-lesioned rats, but not rats with VP lesions, showed elevated metabolic activity, general activity in the dark phase of the light-dark cycle, and greater conditioned appetitive behavior, compared with control rats without these brain lesions. In contrast, rats with mPFC lesions were not different from controls on any of these measures. These results indicate that hippocampal damage interferes with energy and body weight regulation, perhaps by disrupting higher-order learning and memory processes that contribute to the control of appetitive and consummatory behavior. © 2008 Wiley-Liss, Inc. [source] Subicular and CA1 hippocampal projections to the accessory olfactory bulbHIPPOCAMPUS, Issue 2 2009C. de la Rosa-Prieto Abstract The hippocampal formation is anatomically and functionally related to the olfactory structures especially in rodents. The entorhinal cortex (EC) receives afferent projections from the main olfactory bulb; this constitutes an olfactory pathway to the hippocampus. In addition to the olfactory system, most mammals possess an accessory olfactory (or vomeronasal) system. The relationships between the hippocampal formation and the vomeronasal system are virtually unexplored. Recently, a centrifugal projection from CA1 to the accessory olfactory bulb has been identified using anterograde tracers. In the study reported herein, experiments using anterograde tracers confirm this projection, and injections of retrograde tracers show the distribution and morphology of a population of CA1 and ventral subicular neurons projecting to the accessory olfactory bulb of rats. These results extend previous descriptions of hippocampal projections to the accessory olfactory bulb by including the ventral subiculum and characterizing the morphology, neurochemistry (double labeling with somatostatin), and distribution of such neurons. These data suggest feedback hippocampal control of chemosensory stimuli in the accessory olfactory bulb. Whether this projection processes spatial information on conspecifics or is involved in learning and memory processes associated with chemical stimuli remains to be elucidated. © 2008 Wiley-Liss, Inc. [source] Spatial learning results in elevated agmatine levels in the rat brainHIPPOCAMPUS, Issue 11 2008Ping Liu Abstract Accumulating evidence suggests that agmatine, a metabolite of L -arginine by arginine decarboxylase, is a novel neurotransmitter, and exogenous agmatine can modulate behavior functions including learning and memory. However, direct evidence of its involvement in learning and memory processes is currently lacking. This study measured agmatine levels in the hippocampus, parahippocampal region, cerebellum, and vestibular nucleus in rats that were trained to find a hidden escape platform in the water-maze task, or forced to swim in the pool with no platform presented, or kept in the holding-box, using liquid chromatography/mass spectrometry. Compared with the swimming only group and holding-box group, agmatine levels were significantly increased in the CA1 and dentate gyrus subregions of the hippocampus, the entorhinal cortex and the vestibular nucleus in the water-maze training group. These results, for the first time, demonstrate spatial learning-induced region-specific elevation in agmatine, and raise a novel issue of the involvement of agmatine in the processes of learning and memory. © 2008 Wiley-Liss, Inc. [source] Evidence for episodic memory in a pavlovian conditioning procedure in ratsHIPPOCAMPUS, Issue 12 2007Jamus O'Brien Abstract In an effort to evaluate episodic memory processes in the rat, we developed a novel Pavlovian conditioning procedure. Rats explored two distinctive contexts, one in the morning and the other in the evening. Subsequently, either in the morning or the evening, they received a foot shock immediately upon entry into a third context that equally resembled the two explored contexts. When conditioned freezing was measured at an intermediate time of day, rats showed significantly more fear of the context congruent with the time of day of the foot shock. Thus, rats automatically form an integrated time,place memory that can be flexibly updated by future events, essential characteristics of episodic memory. © 2007 Wiley-Liss, Inc. [source] Space and context in the temporal cortexHIPPOCAMPUS, Issue 9 2007David K. Bilkey Abstract The hippocampus has a critical role in certain kinds of spatial memory processes. Hippocampal "place" cells, fire selectively when an animal is in a particular location within the environment. It is thought that this activity underlies a representation of the environment that can be used for memory-based spatial navigation. But how is this representation constructed and how is it "read"? A simple mechanism, based on place field density across an environment, is described that could allow hippocampal representations to be "read" by other brain regions for the purpose of navigation. The possible influence of activity in neighboring brain regions such as the perirhinal cortex, and pre- and para-subiculum on the construction of the hippocampal spatial representation is then discussed. © 2007 Wiley-Liss, Inc. [source] Contrasting roles of neural firing rate and local field potentials in human memoryHIPPOCAMPUS, Issue 8 2007Arne Ekstrom Abstract Recording the activity of neurons is a mainstay of animal memory research, while human recordings are generally limited to the activity of large ensembles of cells. The relationship between ensemble activity and neural firing rate during declarative memory processes, however, remains unclear. We recorded neurons and local field potentials (LFPs) simultaneously from the same sites in the human hippocampus and entorhinal cortex (ERC) in patients with implanted intracranial electrodes during a virtual taxi-driver task that also included a memory retrieval component. Neurons increased their firing rate in response to specific passengers or landmarks both during navigation and retrieval. Although we did not find item specificity in the broadband LFP, both ,- and ,-band LFPs increased power to specific items on a small but significant percent of channels. These responses, however, did not correlate with item-specific neural responses. To contrast item-specific responses with process-specific responses during memory, we compared neural and LFP responses during encoding (navigation) and retrieval (associative and item-specific recognition). A subset of neurons also altered firing rates nonspecifically while subjects viewed items during encoding. Interestingly, LFPs in the hippocampus and ERC increased in power nonspecifically while subjects viewed items during retrieval, more often during associative than item-recognition. Furthermore, we found no correlation between neural firing rate and broadband, ,-band, and ,-band LFPs during process-specific responses. Our findings suggest that neuronal firing and ensemble activity can be dissociated during encoding, item-maintenance, and retrieval in the human hippocampal area, likely relating to functional properties unique to this region. © 2007 Wiley-Liss, Inc. [source] Enhancement of temporal and spatial synchronization of entorhinal gamma activity by phase resetHIPPOCAMPUS, Issue 4 2002Clayton T. Dickson Abstract The synchronization of cortical gamma oscillatory activity (25,80 Hz) is thought to coordinate neuronal assemblies in the processing and storage of information. The mechanism by which independently oscillating and distantly located cortical zones become synchronized is presumed to involve activity in corticocortical connections, although evidence supporting this conjecture has only been indirect. In the present study, we show that activation of synaptic inputs within and to the medial entorhinal cortex (mEC) of the in vitro isolated guinea pig brain preparation resets the phase of ongoing gamma activity induced by muscarinic receptor agonism with carbachol (frequency: 24 ± 2 Hz at 32°C). Phase reset was associated with a transient enhancement of the synchronization of gamma activity recorded at distant (>1 mm) mEC sites, across which low coherence (>0.75) was observed before stimulation. This increase in synchronization, as measured by cross-correlation analysis, was restricted to a maximal period of 200 ms after either local mEC or CA1 afferent stimulation. The results provide direct evidence that synaptic activation can enhance the rhythmic synchronization of spatially remote, independently oscillating neuronal assemblies in the mEC through a mechanism of synaptically evoked phase reset. Dynamic functional grouping of oscillatory discharges across long distances in the mEC may underlie coding processes involved in the integration and storage of incoming information and thus may be important for the role of this region in memory processes. Hippocampus 2002;12:447,456. © 2002 Wiley-Liss, Inc. [source] Finding Meaning in Memory: A Methodological Critique of Collective Memory StudiesHISTORY AND THEORY, Issue 2 2002Wolf Kansteiner The memory wave in the humanities has contributed to the impressive revival of cultural history, but the success of memory studies has not been accompanied by significant conceptual and methodological advances in the research of collective memory processes. Most studies on memory focus on the representation of specific events within particular chronological, geographical, and media settings without reflecting on the audiences of the representations in question. As a result, the wealth of new insights into past and present historical cultures cannot be linked conclusively to specific social collectives and their historical consciousness. This methodological problem is even enhanced by the metaphorical use of psychological and neurological terminology, which misrepresents the social dynamics of collective memory as an effect and extension of individual, autobiographical memory. Some of these shortcomings can be addressed through the extensive contextualization of specific strategies of representation, which links facts of representation with facts of reception. As a result, the history of collective memory would be recast as a complex process of cultural production and consumption that acknowledges the persistence of cultural traditions as well as the ingenuity of memory makers and the subversive interests of memory consumers. The negotiations among these three different historical agents create the rules of engagement in the competitive arena of memory politics, and the reconstruction of these negotiations helps us distinguish among the abundance of failed collective memory initiatives on the one hand and the few cases of successful collective memory construction on the other. For this purpose, collective memory studies should adopt the methods of communication and media studies, especially with regard to media reception, and continue to use a wide range of interpretive tools from traditional historiography to poststructural approaches. From the perspective of collective memory studies, these two traditions are closely related and mutually beneficial, rather than mutually exclusive, ways of analyzing historical cultures. [source] Accessing the mental space,Spatial working memory processes for language and vision overlap in precuneusHUMAN BRAIN MAPPING, Issue 5 2008Mikkel Wallentin Abstract The "overlapping systems" theory of language function argues that linguistic meaning construction crucially relies on contextual information provided by "nonlinguistic" cognitive systems, such as perception and memory. This study examines whether linguistic processing of spatial relations established by reading sentences call on the same posterior parietal neural system involved in processing spatial relations set up through visual input. Subjects read simple sentences, which presented two agents in relation to each other, and were subsequently asked to evaluate spatial (e.g., "Was he turned towards her?") and equally concrete nonspatial content (e.g., "Was he older than her?"). We found that recall of the spatial content relative to the nonspatial content resulted in higher BOLD response in a dorsoposterior network of brain regions, most significantly in precuneus, strikingly overlapping a network previously shown to be involved in recall of spatial aspects of images depicting similar scenarios. This supports a neurocognitive model of language function, where sentences establish meaning by interacting with the perceptual and working memory networks of the brain. Hum Brain Mapp 2008. © 2007 Wiley-Liss, Inc. [source] Bilateral activation of the prefrontal cortex after strategic semantic cognitive trainingHUMAN BRAIN MAPPING, Issue 4 2006Eliane C. Miotto Abstract The prefrontal cortex (PFC) has been implicated in the ability to apply semantic organizational strategies during verbal encoding and episodic learning. However, there has been no direct evidence demonstrating which specific areas in the PFC are engaged after cognitive training using semantic organizational strategies in healthy adult human subjects. In this study, we investigated the effects of semantic strategic training on brain activity and changes in behavioral performance, after cognitive training, using functional MRI (fMRI). There was a significant activation in bilateral dorsolateral prefrontal (DLPF) and orbitofrontal (OFC) areas after cognitive training. These results demonstrate the engagement of bilateral DLPF and OFC cortex during strategic memory processes, particularly when mobilization and effort of effective use of strategies are required. The functional adaptations observed here may also shed light on some of the processes underlying recovery with cognitive rehabilitation in patient populations with brain injury. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc. [source] Self-report of memory and affective dysfunction in association with medication use in a sample of individuals with chronic sleep disturbanceHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 8 2000Mary Pat McAndrews Abstract Benzodiazepines produce memory disturbance after acute administration. It is not clear whether chronic use of benzodiazepines is hazardous to memory processes. Epidemiological data indicate that a large proportion (10,30 per cent) of individuals with sleep dysfunction take hypnotic aids for a year or longer. The purpose of the present study was to evaluate self-reported memory dysfunction in a sample of individuals who considered their sleep disturbance sufficiently severe to seek investigation in sleep clinics. It was hypothesized that individuals taking benzodiazepines for sleep would report greater perceived everyday memory failures than individuals taking other sleep aids or no medication. Questionnaires were given to 368 individuals referred into the study by investigators in six sleep disorders clinics. All respondents completed a lengthy (700-item) questionnaire, which included scales assessing memory difficulties, affective status and sleep disturbance. Respondents also reported any medication use for sleep problems and duration of use of the current drug. Information on medication use was reported by 289 participants. Fifty-six per cent of respondents reported using some form of psychoactive medication (antidepressants, benzodiazepines, Zopiclone). Twenty-two per cent reported using no medication. Analysis of covariance showed that these medications had no detectable effect on subjective memory difficulties during chronic use, F(4,226)=1·34, p=0·25. Copyright © 2000 John Wiley & Sons, Ltd. [source] A NOTE ON CHAMBERS'S "LONG MEMORY AND AGGREGATION IN MACROECONOMIC TIME SERIES",INTERNATIONAL ECONOMIC REVIEW, Issue 3 2005Leonardo Rocha Souza This note reviews some results on aggregating discrete-time long memory processes, providing a formula for the spectrum of the aggregates that considers the aliasing effect. [source] Neural correlates of verbal episodic memory in patients with MCI and Alzheimer's disease,,a VBM studyINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 11 2008Dirk T. Leube Abstract Objective The hippocampus is a key area for episodic memory processes. Hippocampal atrophy is a hallmark feature of Alzheimer's disease (AD). We used a new and automatized morphometric technique to better characterize brain atrophy in subjects with different levels of cognitive deficit. Methods In this study 21 participants with Mild Cognitive Impairment (MCI), 12 patients with early AD and 29 elderly control subjects were subjected to high resolution MRI and a neuropsychological test battery. Brain volume across participants, measured by voxel-based morphometry (VBM), was correlated with verbal memory capacity, measured with a verbal memory test (VLMT). Results Atrophy in the anterior hippocampus, the ento- and perirhinal cortex as well as the parahippocampal gyrus, middle temporal gyrus and anterior cingulate cortex correlated closely with episodic memory performance. Conclusions These brain areas are known to subserve episodic encoding of verbal material. The data contribute to a better understanding of atrophic brain processes in subjects at risk for AD. A combination of neuropsychological testing and voxel-based morphometry may serve as a diagnostic tool in the future. Copyright © 2008 John Wiley & Sons, Ltd. [source] Psychopathology and autobiographical memory in stroke and non-stroke hospitalized patientsINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 1 2003Mark John Sampson Abstract Background Psychopathology and autobiographical memory were investigated in a cohort of stroke and non-stroke hospitalized patients. Both these cohorts have been identified as having high levels of psychopathology (Katon and Sullivan 1990; Burvill et al., 1995). Difficulties recalling specific autobiographical memories (overgeneral memory) have been identified as important psychological variables in depression and predictors of outcome (Williams and Scott 1988; Brittlebank et al., 1993). Intrusive autobiographical memories have also been found to be associated with depression and overgeneral memory in depressed women (Kuyken and Brewin, 1995) and depressed cancer patients (Brewin et al., 1998a). This study looked at levels of psychopathology and autobiographical memories in stroke and non-stroke hospital patients. Method 417 patients were screened, of the 176 eligible 103 agreed to participate (54 stroke and 49 non-stroke). Participants were assessed for overgenerality using the Autobiographical Memory Test and intrusiveness of memories using the Impact of Events Scale. Also assessed were PTSD-like symptoms (PCL-S), mood (HADS, GHQ-28) and cognitive ability (MMSE, verbal fluency, digit span and estimated pre-morbid IQ). Results No significant differences were found between stroke and non-stroke patients on severity of depression, anxiety, severity of PTSD-like symptoms or autobiographical memories. Backward multivariate regression analyses for combined data (stroke and non-stroke) indicated that overgeneral memory recall, intrusive memories of past events and intrusive memories of illness were significant independent predictors of depression (HADS). Avoidance of intrusive memories and reported childhood distress were not predictors of overgeneral memory recall. Significant predictors of overgeneral memory recall were; Gender, antidepressant medication, and estimated IQ. Conclusion Significant levels of psychopathology were identified in this cohort. However, there were no significant differences in the levels of depression, anxiety, PTSD symptoms and autobiographical memory between stroke and non-stroke hospitalized patients. Of particular interest was the finding that PTSD-like symptoms did not appear to be influenced by the nature of the person's illness. In combined data (stroke and non-stroke) autobiographical memories (intrusive images of their illness, intrusive memories of other events and overgeneral memory recall variables) were significant predictors of depression in this cohort. This suggests that psychological intervention of memory processes may be a worthwhile target in psychological intervention for depression in these cohorts. Gender, cognitive impairment, antidepressant medication, and estimated IQ were significant predictors of overgeneral memory recall and further investigation into the validity of these findings are warranted. Suggestions for further research and limitations of the study are also discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Generalized long memory processes, failure of cointegration tests and exchange rate dynamicsJOURNAL OF APPLIED ECONOMETRICS, Issue 4 2006Aaron D. Smallwood This paper presents evidence that the equilibrium relationship in a system of nominal exchange rates is best described as a stationary GARMA process. The implementation of the GARMA methodology helps explain conflicting and puzzling results from the use of linear cointegration and fractional cointegration methods. Furthermore, we use Monte Carlo analysis to document problems with standard cointegration tests when the attraction process is distributed as a long memory GARMA process. Copyright © 2006 John Wiley & Sons, Ltd. [source] Age and probabilistic reasoning: Biases in conjunctive, disjunctive and Bayesian judgements in early and late adulthoodJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 1 2005John E. Fisk Abstract Probabilistic reasoning plays an essential part in many aspects of our daily routine and it has been argued that as we grow older, the need to make judgements under uncertainty becomes increasingly important. Two studies were conducted to establish whether the propensity to commit probabilistic reasoning errors increased with age. Young (aged 16,24), middle aged (25,54), and older persons (55 years and above) were included. Study 1 revealed systematic biases and errors across a range of judgement tasks. However, no evidence of any age effect in Bayesian inference, the incidence of the conjunction fallacy, or in the number of disjunction errors was found. The results obtained in Study 1 were replicated in Study 2, where the potential mediating role of working memory processes and intellectual capacity were explicitly assessed. While some aspects of probabilistic reasoning performance were correlated with measures of intelligence and working memory functioning among young adults, this was much less evident in older persons. The present findings are discussed in relation to the evolution of the dualistic heuristic,analytical system over the adult lifespan. Copyright © 2005 John Wiley & Sons, Ltd. [source] Neuropsychological components of intellectual disability: the contributions of immediate, working, and associative memoryJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 5 2010Jamie O. Edgin Abstract Background Efficient memory functions are important to the development of cognitive and functional skills, allowing individuals to manipulate and store information. Theories of memory have suggested the presence of domain-specific (i.e. verbal and spatial) and general processing mechanisms across memory domains, including memory functions dependent on the prefrontal cortex (PFC) and the hippocampus. Comparison of individuals who have syndromes associated with striking contrasts in skills on verbal and spatial tasks [e.g. Down syndrome (DS) and Williams syndrome (WS)] allows us to test whether or not these dissociations may extend across cognitive domains, including PFC and hippocampal memory processes. Methods The profile of memory function, including immediate memory (IM), working memory (WM) and associative memory (AM), was examined in a sample of adolescents and young adults with DS (n = 27) or WS (n = 28), from which closely CA- and IQ-matched samples of individuals with DS (n = 18) or WS (n = 18) were generated. Relations between memory functions and IQ and adaptive behaviour were also assessed in the larger sample. Results Comparisons of the two matched groups indicated significant differences in verbal IM (DS < WS), spatial IM (DS > WS) and spatial and verbal AM (DS > WS), but no between-syndrome differences in WM. For individuals with DS, verbal IM was the most related to variation in IQ, and spatial AM related to adaptive behaviour. The pattern was clearly different for individuals with WS. Verbal and spatial AM were the most related to variation in IQ, and verbal WM related to adaptive behaviour. Conclusions These results suggest that individuals with these two syndromes have very different patterns of relative strengths and weaknesses on memory measures, which do not fully mirror verbal and spatial dissociations. Furthermore, different patterns of memory dysfunction relate to outcome in individuals with each syndrome. [source] Implicit memory is independent from IQ and age but not from etiology: evidence from Down and Williams syndromesJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 12 2007S. Vicari Abstract Background In the last few years, experimental data have been reported on differences in implicit memory processes of genetically distinct groups of individuals with Intellectual Disability (ID). These evidences are relevant for the more general debate on supposed asynchrony of cognitive maturation in children with abnormal brain development. This study, comparing implicit memory processes in individuals with Williams syndrome (WS) and Down syndrome (DS), was planned to verify the ,etiological specificity' hypotheses pertaining to the skill learning abilities of individuals with ID. Method A modified version of Nissen and Bullemer's (1987) Serial Reaction Time (SRT) task was used. The performances of three group were evaluated. The first group consisted of thirty-two people with WS (18 males and 14 females). The second group was comprised of twenty-six individuals with DS (14 males and 12 females). The two groups of individuals with ID were selected so that the groups were comparable as for mental age and chronological age. The third group consisted of forty-nine typically developed children with a mental age similar to that of the groups with WS and DS. Results The two groups of individuals with ID demonstrated different patterns of procedural learning. WS individuals revealed poor implicit learning of the temporal sequence of events characterizing the ordered blocks in the SRT task. Indeed, differently from normal controls, WS participants showed no reaction time (RT) speeding through ordered blocks. Most importantly, the rebound effect, which so dramatically affected normal children's RTs passing from the last ordered to the last block, had only a marginal influence on WS children's RTs. Differently from the WS group, the rate of procedural learning of the participants with DS was comparable to that of their controls. Indeed, DS and typically developed individuals showed parallel RT variations in the series of ordered blocks and, more importantly, passing from the last ordered to the last block. Therefore, a substantial preservation of skill learning abilities in this genetic syndrome is confirmed. Conclusions The results of the present study document that procedural learning in individuals with ID depends on the aetiology of the syndrome, thus supporting the etiological specificity account of their cognitive development. These results are relevant for our knowledge about the qualitative aspects and the underlying neurobiological substrate of the anomalous cognitive development in mentally retarded people. [source] Changes in explicit memory associated with early dementia in adults with Down's syndromeJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 3 2002S. J. Krinsky-McHale Abstract Background A modified version of the Selective Reminding Test (SRT) (Buschke 1973) was used to examine the changes in memory that occur with early-stage dementia of the Alzheimer's type (DAT) in adults with intellectual disability (ID) and Down's syndrome (DS), and to compare these changes to those occurring with ,normal' ageing. Method Hierarchical linear modelling analyses showed steep declines in the performance of participants who had met the criteria for the onset of DAT. Non-demented participants also showed declines in performance which were related to their age. However, the absolute magnitude of these declines was consistent with a ,normal' ageing pattern and not with undetected dementia. Results In analysing the specific memory components that are compromised, the present authors found that participants with early-stage DAT showed severely diminished long-term storage and retrieval processing abilities compared to their non-demented peers. Notably, these declines preceded other symptoms of dementia, in most cases by more than a full year and sometimes by as much as 3 years. Conclusions Thus, the present results clearly confirm that memory processes are affected during early dementia in adults with DS, and that the SRT has promise as a clinical tool. [source] | ||||||||||||||||||||||