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Semantic Memory (semantic + memory)
Selected AbstractsConfabulation, but not executive dysfunction discriminate AD from frontotemporal dementiaEUROPEAN JOURNAL OF NEUROLOGY, Issue 11 2004Z. Nedjam We examined confabulation and performance on frontal/executive tasks in Alzheimer's disease (AD) patients and patients with a diagnosis of probable frontotemporal dementia (FTD). Twenty-two patients with probable AD, 10 patients with probable FTD and 32 normal control subjects entered the study. Executive functions were assessed with the Modified Card Sorting test; a verbal fluency test; the Cognitive Estimation test; and the Stroop test. Confabulations were assessed with a modified version of the Confabulation Battery. The Confabulation Battery included 10 questions tapping each of the following domains: Episodic Memory (memories of personal past episodes), Semantic Memory (knowledge of famous facts and famous people), and Personal Future (personal plans). The results revealed that both AD patients and FTD patients were clearly and equally impaired on tests of executive functions. Both patients' groups confabulated across the three tasks of the Confabulation Battery, but FTD patients confabulated significantly more than AD patients on Episodic Memory and Personal Future. The results failed to provide any evidence of a correlation between the performance on frontal/executive tasks and the tendency to produce confabulatory reports. According to our results, confabulation, more than a deficit of frontal/executive functions, discriminate between AD and FTD. Therefore, screening for confabulation and, possibly, for other types of memory distortions may constitute a useful additional clinical tool in order to discriminate AD from FTD. [source] The role of the medial temporal lobe in autistic spectrum disordersEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2005C. H. Salmond Abstract The neural basis of autistic spectrum disorders (ASDs) is poorly understood. Studies of mnemonic function in ASD suggest a profile of impaired episodic memory with relative preservation of semantic memory (at least in high-functioning individuals). Such a pattern is consistent with developmental hippocampal abnormality. However, imaging evidence for abnormality of the hippocampal formation in ASD is inconsistent. These inconsistencies led us to examine the memory profile of children with ASD and the relationship to structural abnormalities. A cohort of high-functioning individuals with ASD and matched controls completed a comprehensive neuropsychological memory battery and underwent magnetic resonance imaging for the purpose of voxel-based morphometric analyses. Correlations between cognitive/behavioural test scores and quantified results of brain scans were also carried out to further examine the role of the medial temporal lobe in ASD. A selective deficit in episodic memory with relative preservation of semantic memory was found. Voxel-based morphometry revealed bilateral abnormalities in several areas implicated in ASD including the hippocampal formation. A significant correlation was found between parental ratings reflecting autistic symptomatology and the measure of grey matter density in the junction area involving the amygdala, hippocampus and entorhinal cortex. The data reveal a pattern of impaired and relatively preserved mnemonic function that is consistent with a hippocampal abnormality of developmental origin. The structural imaging data highlight abnormalities in several brain regions previously implicated in ASD, including the medial temporal lobes. [source] The role of medial temporal lobe in retrieving spatial and nonspatial relations from episodic and semantic memoryHIPPOCAMPUS, Issue 1 2010Lee Ryan Abstract This study examined the involvement of medial temporal lobe, especially the hippocampus, in processing spatial and nonspatial relations using episodic and semantic versions of a relational judgment task. Participants studied object arrays and were tested on different types of relations between pairs of objects. Three prevalent views of hippocampal function were considered. Cognitive map theory (O'Keefe and Nadel (1978) The Hippocampus as a Cognitive Map. USA: Oxford University Press) emphasizes hippocampal involvement in spatial relational tasks. Multiple trace theory (Nadel and Moscovitch (1997) Memory consolidation, retrograde amnesia and the hippocampal complex Curr Opin Neurobiol 7:217,227) emphasizes hippocampal involvement in episodic tasks. Eichenbaum and Cohen's ((2001) From Conditioning to Conscious Recollection: Memory Systems of the Brain. USA: Oxford University Press) relational theory predicts equivalent hippocampal involvement in all relational tasks within both semantic and episodic memory. The fMRI results provided partial support for all three theories, though none of them fit the data perfectly. We observed hippocampal activation during all relational tasks, with increased activation for spatial compared to nonspatial relations, and for episodic compared to semantic relations. The placement of activation along the anterior-posterior axis of the hippocampus also differentiated the conditions. We suggest a view of hippocampal function in memory that incorporates aspects of all three theories. © 2009 Wiley-Liss, Inc. [source] Dissociating the past from the present in the activity of place cellsHIPPOCAMPUS, Issue 9 2006Livia de Hoz Abstract It has been proposed that declarative memories can be dependent on both an episodic and a semantic memory system. While the semantic system deals with factual information devoid of reference to its acquisition, the episodic system, characterized by mental time travel, deals with the unique past experience in which an event took place. Episodic memory is characteristically hippocampus-dependent. Place cells are recorded from the hippocampus of rodents and their firing reflects many of the key characteristics of episodic memory. For example, they encode information about "what" happens "where," as well as temporal information. However, when these features are expressed during an animal's behavior, the neuronal activity could merely be categorizing the present situation and could therefore reflect semantic memory rather than episodic memory. We propose that mental time travel is the key feature of episodic memory and that it should take a form, in the awake animal, similar to the replay of behavioral patterns of activity that has been observed in hippocampus during sleep. Using tasks designed to evoke episodic memory, one should be able to see memory reactivation of behaviorally relevant sequences of activity in the awake animal while recording from hippocampus and other cortical structures. © 2006 Wiley-Liss, Inc. [source] Theta rhythm of navigation: Link between path integration and landmark navigation, episodic and semantic memoryHIPPOCAMPUS, Issue 7 2005György Buzsáki Abstract Five key topics have been reverberating in hippocampal-entorhinal cortex (EC) research over the past five decades: episodic and semantic memory, path integration ("dead reckoning") and landmark ("map") navigation, and theta oscillation. We suggest that the systematic relations between single cell discharge and the activity of neuronal ensembles reflected in local field theta oscillations provide a useful insight into the relationship among these terms. In rats trained to run in direction-guided (1-dimensional) tasks, hippocampal cell assemblies discharge sequentially, with different assemblies active on opposite runs, i.e., place cells are unidirectional. Such tasks do not require map representation and are formally identical with learning sequentially occurring items in an episode. Hebbian plasticity, acting within the temporal window of the theta cycle, converts the travel distances into synaptic strengths between the sequentially activated and unidirectionally connected assemblies. In contrast, place representations by hippocampal neurons in 2-dimensional environments are typically omnidirectional, characteristic of a map. Generation of a map requires exploration, essentially a dead reckoning behavior. We suggest that omnidirectional navigation through the same places (junctions) during exploration gives rise to omnidirectional place cells and, consequently, maps free of temporal context. Analogously, multiple crossings of common junction(s) of episodes convert the common junction(s) into context-free or semantic memory. Theta oscillation can hence be conceived as the navigation rhythm through both physical and mnemonic space, facilitating the formation of maps and episodic/semantic memories. © 2005 Wiley-Liss, Inc. [source] Neuropsychological correlates of hippocampal and rhinal cortex volumes in patients with mesial temporal sclerosisHIPPOCAMPUS, Issue 8 2003Catherine E. O'Brien Abstract Considerable progress has been made toward understanding the function of the primate rhinal cortex, comprising the entorhinal (ErC) and perirhinal (PrC) cortices. However, translating animal models to human memory has been limited by the technological problems associated with characterizing neural structures in vivo. Functional correlates of hippocampal and rhinal cortex volume changes were examined in a sample of 61 temporal lobe epilepsy patients with mesial temporal sclerosis (MTS; 33 left, 28 right). Patients were administered the Wechsler Adult Intelligence Scale (revised or third edition), the Wechsler Memory Scale (revised or third edition), and a spatial maze task. Neuropsychological data, together with rhinal cortex and hippocampal volumes, collected in our earlier study (O'Brien CE, Bowden SC, Whelan G, Cook MJ, unpublished observations), were analyzed using multiple regression. The only significant predictor of verbal memory function was the difference score between the volume of left hippocampus and the left PrC. Spatial maze scores were predicted by the bilateral sum of ErC volume. The difference score between the left hippocampus and left PrC volumes was the most powerful predictor of verbal episodic memory. Right hippocampal volume was not a significant predictor of nonverbal episodic memory. Verbal and nonverbal semantic memory were not significantly predicted by any combination of rhinal cortex structures. This quantitative study suggests a lateralized or material-specific memory function for the left hippocampus and left PrC, in contrast to the bilateral role of the ErC. The left hippocampus and left PrC appear to act on verbal memory function through an opposing relationship. Finally, differentiation between hippocampal and subhippocampal components in terms of episodic and semantic memory, respectively, could not be supported by the current data. © 2003 Wiley-Liss, Inc. [source] SSRIs and cognitive performance in a working sampleHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 8 2005Emma J. K. Wadsworth Abstract Background Studies of the impact of antidepressant use on cognitive performance have frequently been carried out among the elderly or on healthy volunteers. Comparatively little research has considered their impact on a relatively young, working population, particularly within the context of everyday life. Aims To examine any association between SSRI use and cognitive performance, mood and human error at work. Methods SSRI users and controls completed a battery of laboratory based computer tasks measuring mood and cognitive function pre- and post-work at the start and end of a working week. They also completed daily diaries reporting their work performance. Results SSRI use was associated with memory impairment: specifically poorer episodic, though not working or semantic memory. Effects of SSRI use on recognition memory seemed to vary according to the underlying psychopathology, while effects on delayed recall were most pronounced among those whose symptoms had not (yet) resolved. There were no detrimental effects on psychomotor speed, attention, mood or perceived human error at work. Conclusions The findings lend support to the SSRIs comparative safety, even among workers, particularly as the symptoms of the underlying psychopathology are successfully addressed. Possible memory impairments may, however, be found in those taking SSRIs. Copyright © 2005 John Wiley & Sons, Ltd. [source] Long-Term Episodic Memory in Children with Attention-Deficit/Hyperactivity DisorderLEARNING DISABILITIES RESEARCH & PRACTICE, Issue 1 2008Jeffrey S. Skowronek Twenty-nine grade-matched 4th,8th-grade males, 12 with attention-deficit/hyperactivity disorder (ADHD) (age M= 12.2 years, SD= 1.48), and 17 without (age M= 11.5, SD= 1.59), completed two working memory tasks (digit span and the Simon game) and three long-term episodic memory tasks (a personal event memory task, story memory task, and picture recognition task). In line with clinical observations, children with ADHD performed worse than peers on all working memory tasks, but performed as well as or better than peers on long-term episodic tasks, demonstrating particularly detailed memory for personally experienced past events. Participants' parents also completed questionnaires about their children's memories in daily life. Parents rated children with ADHD lower than children without ADHD on working and semantic memory (e.g., remembering names, spelling, and math), but rated them as high or higher on memory for events. Implications for theory and educational practice are discussed. [source] Language in Schizophrenia Part 2: What Can Psycholinguistics Bring to the Study of Schizophrenia,and Vice Versa?LINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 8 2010Gina R. Kuperberg This is the second of two articles that discuss higher-order language and semantic processing in schizophrenia. The companion article (Part 1) gives an introduction to language dysfunction in patients with schizophrenia. This article reviews a selection of psycholinguistic studies which suggest that sentence-level abnormalities in schizophrenia may stem from a relative overdependence on semantic associative relationships at the expense of building higher-order meaning. Language disturbances in schizophrenia may be best conceptualized as arising from an imbalance of activity across two streams of processing, one directly drawing upon relationships stored within semantic memory and the other involving the use of combinatorial mechanisms to build propositional meaning. This article also discusses some of the ways in which the study of schizophrenia may offer new insights into the cognitive and neural architecture of the normal language system. [source] Evaluating the efficacy of tele-cognitive rehabilitation for functional performance in three case studiesOCCUPATIONAL THERAPY INTERNATIONAL, Issue 1 2003Dr Sing-Fai Tam PhD Associate Professor Abstract Traumatic brain injury (TBI) is one of the main causes of long-term disability, and its rehabilitation is a challenge to the healthcare team. Tele-rehabilitation, through using advancements in networking and tailor-made software, has been developed and applied to the cognitive rehabilitation of persons with brain injury in the present study. Tele-cognitive rehabilitation uses customized online computer software as a treatment mode. The online treatment software is operated on an interactive tele-communication platform , for example, video conferencing with screen sharing. Through implementing the tele-cognitive rehabilitation activities, therapists can help clients to practise and thus improve their cognitive skills through using the treatment software successfully. Moreover, hypermedia programming techniques allow the therapist to adjust the software to meet the client's treatment needs, so that the treatment is appropriate to his/her functional levels and living environment. Also the software can customize immediate visual, auditory and personalized feedback to motivate the client and training can be set at the right pace for the client's needs. The present study aimed to evaluate the effectiveness and perceived efficacy of the newly developed customized tele-cognitive rehabilitation programme for three subjects with traumatic brain injury through using single-case and qualitative research design. The cognitive factors investigated in this pilot study were, respectively, Chinese word recognition, prospective memory and semantic memory. The subjects had undergone a recruitment process with stipulated screening criteria. A single case experimental design (ABA reversal/withdrawal design) consisted of a no-intervention baseline phase (A), an intervention phase (B) and a no-intervention withdrawal phase (A). There were six sessions in each phase, making a total of 18 sessions. Tele-cognitive rehabilitation software was tailor-made according to each subject's cognitive functional needs. To monitor the change in cognitive functions, variables were tapped by tailor-made assessment and qualitative questionnaires through interviews, and they were then used to explore subjects' opinions of the programme and to test the treatment efficacy of the tele-cognitive rehabilitation programme. Finally, the relationships among the three phases were analysed through visual analysis and trend line analysis by means of the split-middle method. The three persons with brain injury showed improving trends and levels of specific cognitive performance during the treatment phase. Qualitative findings were analysed and confirmed the efficacy of the treatment module. The tele-cognitive rehabilitation approach was well received by subjects. The authors suggest that further replication studies of this kind should be conducted in the future and that more subjects should be recruited to improve the generalizability of the results. Copyright © 2003 Whurr Publishers Ltd. [source] Visual novel stimuli in an ERP novelty oddball paradigm: Effects of familiarity on repetition and recognition memoryPSYCHOPHYSIOLOGY, Issue 1 2007Yael M. Cycowicz Abstract The orienting response, the brain's reaction to novel and/or out of context familiar events, is reflected by the novelty P3 of the ERP. Contextually novel events also engender high rates of recognition memory. We examined, under incidental and intentional conditions, the effects of visual symbol familiarity on the novelty P3 recorded during an oddball task and on the parietal episodic memory (EM) effect, an index of recollection. Repetition of familiar, but not unfamiliar, symbols elicited a reduction in the novelty P3. Better recognition performance for the familiar symbols was associated with a robust parietal EM effect, which was absent for the unfamiliar symbols in the incidental task. These data demonstrate that processing of novel events depends on expectation and whether stimuli have preexisting representations in long-term semantic memory. [source] Some Correspondences and Similarities of Shamanism and Cognitive Science: Interconnectedness, Extension of Meaning, and Attribution of Mental StatesANTHROPOLOGY OF CONSCIOUSNESS, Issue 2 2002Timothy L. Hubbard Correspondences and similarities between ideas in shamanism and ideas in contemporary cognitive science are considered. The importance of interconnectedness in the web of life worldview characteristic of shamanism and in connectionist models of semantic memory in cognitive science, and the extension of meaning to elements of the natural world in shamanism and indistributed cognition, are considered. Cognitive consequences of such an extension (e.g., use of representativeness and intentional stance heuristics, magical thinking, social attribution errors, and social in-group/out-group differences) are discussed. It is suggested that attributions of mental states, beliefs, and desires to a computer on the basis of behavioral measures (e.g., the Turing test) is consistent with the extension of meaning and intentionality to nonhuman elements of the natural world in shamanism. In general, the existence of such correspondencesand similarities suggests that elements of shamanism may reflect cognitive structures and processes that are also used by nonshamans and in nonshamanic settings. [source] Validating reports of poor childhood memoryAPPLIED COGNITIVE PSYCHOLOGY, Issue 5 2002Chris R. Brewin Recent evidence indicates that judgements about the quality of one's own childhood memory can be influenced experimentally, for example by manipulating ease of retrieval. This has led to the suggestion that judgements of poor memory made by clients in therapy may not be reliable. We therefore investigated whether individuals who judge themselves to have poor memory for their childhood do in fact score worse on a standardized test of autobiographical memory. Matched groups of individuals reporting poor and normal memory for childhood were administered the Autobiographical Memory Interview. Consistent with a previous study of neurological patients, subjective judgements were associated with performance on both personal semantic memory and autobiographical incident memory. Copyright © 2002 John Wiley & Sons, Ltd. [source] Diaschisis after thalamic stroke: a comparison of metabolic and structural changes in a patient with amnesic syndromeACTA NEUROLOGICA SCANDINAVICA, Issue 2007V. Stenset Introduction,, We present a patient with a left anteromedial thalamic lesion with an amnesic syndrome. The patient underwent neuropsychological testing, cerebrospinal fluid (CSF) analyses, magnetic resonance imaging (MRI) [T2, flair, and diffusion tensor imaging (DTI)] and [18F]-2-fluoro-deoxy- d -glucose positron emission tomography (FDG-PET) to assess indirect effects of thalamic lesions on cortical function. Case report,, A 67-year-old right-handed woman was admitted to a university-based memory unit because of memory and concentration problems. Neuropsychological testing revealed dysfunction of episodic memory, semantic memory and working memory. General intellectual function and attention capacity were preserved. MRI revealed an anteromedial thalamic lesion in the left hemisphere. FDG-PET showed decreased uptake in the frontal, parietal and temporal lobes of the left hemisphere. Regions of interest (ROI) in white matter were selected and left and right hemispheres were compared. Fractional anisotropy (FA) in ROI representing thalamo-cortical connections were decreased in the left hemisphere when compared with the right. Conclusion,, The results show the importance of a network that include the anterior and dorsomedian nuclei, which influence the activity in areas of the cortex responsible for memory processes. The imaging findings suggest that areas of cortical diaschisis after thalamic infarction correspond to areas affected by thalamo-cortical fibre loss as measured with FA. [source] Memory function in normal agingACTA NEUROLOGICA SCANDINAVICA, Issue 2003Lars-Göran Nilsson Basic findings obtained on memory functions in normal aging are presented and discussed with respect to five separate but interacting memory systems. These systems are: episodic memory, semantic memory, short-term memory, perceptual representation system and procedural memory. All available evidence from cross-sectional research shows that there is a linear, decreasing memory performance as a function of age for episodic memory. Longitudinal studies suggest, however, that this age deficit may be an overestimation, by showing a relatively stable performance level up to middle age, followed by a sharp decline. Studies on semantic memory, short-term memory, perceptual representation system, and procedural memory show a relatively constant performance level across the adult life span, although some tasks used to assess short-term memory and procedural memory have revealed an age deficit. Disregarding the mixed results for these latter two memory systems, it can be concluded that episodic memory is unique in showing an age deficit. Episodic memory is also unique in the sense that it is the only memory system showing gender differences in performance throughout the adult life span with a significantly higher performance for women. [source] Anosognosia for memory impairment in Alzheimer's diseaseACTA NEUROPSYCHIATRICA, Issue 4 2010Georgina Stewart Stewart G, McGeown WJ, Shanks MF, Venneri A. Anosognosia for memory impairment in Alzheimer's disease. Objective: To investigate whether patients with Alzheimer's disease (AD) were able to alter their awareness of memory deficits after exposure to a memory task. Methods: Thirty normal older adults and 23 mild AD patients participated in the study. Anosognosia was assessed using discrepancies between self- and informant-evaluations of cognitive and functional performance. Participants estimated their performance on the Verbal Paired Associates task at different points in time (before, immediately after the task and after a 1-h delay). Results: AD patients were generally less able to judge their memory abilities than healthy older adults, and tended to overestimate their task performance beforehand. Their prediction accuracy increased immediately after the task, but after a 1-h delay, they again misjudged their abilities at pretesting accuracy levels. Self-carer discrepancy scores of awareness of deficits in memory and other areas correlated significantly with memory tests but not with other neuropsychological tasks in the assessment, and larger discrepancy scores were associated with poorer performance. Conclusion: AD patients can monitor their task performance online, but are unable to maintain awareness of their deficits over time. Loss of awareness of memory deficits (or of any other deficits) in early stage AD may indicate damage to a system which updates a personal knowledge base with recent information. Failure to retain this information impedes abstraction from episodic to semantic memory. [source] | |||||||||||||||||||||||||||||||