51
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Mosbah A, Tramoni E, Guedj E, Aubert S, Daquin G, Ceccaldi M, Félician O, Bartolomei F. Clinical, neuropsychological, and metabolic characteristics of transient epileptic amnesia syndrome. Epilepsia 2014; 55:699-706. [DOI: 10.1111/epi.12565] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2014] [Indexed: 02/03/2023]
Affiliation(s)
| | - Eve Tramoni
- Neurology and Neuropsychology Department; Timone Hospital; Marseille France
| | - Eric Guedj
- Biophysics and Nuclear Medicine Department; Timone Hospital; Marseille France
- School of Medicine; Aix Marseille University; Marseille France
| | | | | | - Mathieu Ceccaldi
- Neurology and Neuropsychology Department; Timone Hospital; Marseille France
- School of Medicine; Aix Marseille University; Marseille France
- INSERM; U1106; Brain Dynamic Institute; Marseille France
| | - Olivier Félician
- Neurology and Neuropsychology Department; Timone Hospital; Marseille France
- School of Medicine; Aix Marseille University; Marseille France
- INSERM; U1106; Brain Dynamic Institute; Marseille France
| | - Fabrice Bartolomei
- Henri Gastaut/ Hospital; Marseille France
- School of Medicine; Aix Marseille University; Marseille France
- INSERM; U1106; Brain Dynamic Institute; Marseille France
- Clinical Neurophysiology Department; Timone Hospital; Marseille France
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52
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Atherton KE, Nobre AC, Zeman AZ, Butler CR. Sleep-dependent memory consolidation and accelerated forgetting. Cortex 2014; 54:92-105. [PMID: 24657478 PMCID: PMC4007033 DOI: 10.1016/j.cortex.2014.02.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 01/28/2014] [Accepted: 02/10/2014] [Indexed: 11/26/2022]
Abstract
Accelerated long-term forgetting (ALF) is a form of memory impairment in which learning and initial retention of information appear normal but subsequent forgetting is excessively rapid. ALF is most commonly associated with epilepsy and, in particular, a form of late-onset epilepsy called transient epileptic amnesia (TEA). ALF provides a novel opportunity to investigate post-encoding memory processes, such as consolidation. Sleep is implicated in the consolidation of memory in healthy people and a deficit in sleep-dependent memory consolidation has been proposed as an explanation for ALF. If this proposal were correct, then sleep would not benefit memory retention in people with ALF as much as in healthy people, and ALF might only be apparent when the retention interval contains sleep. To test this theory, we compared performance on a sleep-sensitive memory task over a night of sleep and a day of wakefulness. We found, contrary to the hypothesis, that sleep benefits memory retention in TEA patients with ALF and that this benefit is no smaller in magnitude than that seen in healthy controls. Indeed, the patients performed significantly more poorly than the controls only in the wake condition and not the sleep condition. Patients were matched to controls on learning rate, initial retention, and the effect of time of day on cognitive performance. These results indicate that ALF is not caused by a disruption of sleep-dependent memory consolidation. Instead, ALF may be due to an encoding abnormality that goes undetected on behavioural assessments of learning, or by a deficit in memory consolidation processes that are not sleep-dependent.
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Affiliation(s)
- Kathryn E Atherton
- Department of Experimental Psychology, University of Oxford, Oxford, UK; Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
| | - Anna C Nobre
- Department of Experimental Psychology, University of Oxford, Oxford, UK; Oxford Centre for Human Brain Activity, University of Oxford, Oxford, UK
| | - Adam Z Zeman
- Cognitive and Behavioural Neurology Research Group, University of Exeter Medical School, UK
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53
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Elliott G, Isaac CL, Muhlert N. Measuring forgetting: a critical review of accelerated long-term forgetting studies. Cortex 2014; 54:16-32. [PMID: 24631847 PMCID: PMC4007031 DOI: 10.1016/j.cortex.2014.02.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/09/2013] [Accepted: 02/03/2014] [Indexed: 12/31/2022]
Abstract
Accelerated long-term forgetting (ALF) refers to abnormal forgetting over hours to weeks despite normal acquisition or initial consolidation. Since standardised assessments of memory typically only test at delays of up to 40-minutes, ALF may go undetected in clinical practice. The memory difficulties associated with ALF can however cause considerable distress to patients. It is important therefore that clinicians are aware that ALF may represent a distinct phenomenon that will require additional and careful assessment to aid patients' understanding of the condition and assist in developing strategies to address its effects. At the same time, ALF may also provide insight into long-term memory processes. Studies of ALF in patients with epilepsy have so far demonstrated mixed results, which may reflect differences in methodology. This review explores the methodological issues that can affect forgetting, such as the effects of age, general cognitive function, test sensitivity and initial learning. It then evaluates the extent to which existing studies have considered these key issues. We outline the points to consider when designing ALF studies that can be used to help improve their validity. These issues can also help to explain some of the mixed findings in studies of ALF and inform the design of standardised tests for assessing ALF in clinical practice.
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Affiliation(s)
- Gemma Elliott
- Clinical Neuropsychology Services, Royal Hallamshire Hospital, Sheffield, UK; Department of Psychology, University of Sheffield, Sheffield, UK
| | - Claire L Isaac
- Clinical Neuropsychology Services, Royal Hallamshire Hospital, Sheffield, UK; Neuropsychology Department, Lincolnshire Partnership NHS Foundation Trust, Lincoln, UK
| | - Nils Muhlert
- Neuropsychology Department, Lincolnshire Partnership NHS Foundation Trust, Lincoln, UK; Cognitive Neuroscience, School of Psychology, Cardiff University, Cardiff, UK.
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54
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Grewe P, Lahr D, Kohsik A, Dyck E, Markowitsch HJ, Bien CG, Botsch M, Piefke M. Real-life memory and spatial navigation in patients with focal epilepsy: ecological validity of a virtual reality supermarket task. Epilepsy Behav 2014; 31:57-66. [PMID: 24361763 DOI: 10.1016/j.yebeh.2013.11.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 11/06/2013] [Accepted: 11/12/2013] [Indexed: 11/16/2022]
Abstract
Ecological assessment and training of real-life cognitive functions such as visual-spatial abilities in patients with epilepsy remain challenging. Some studies have applied virtual reality (VR) paradigms, but external validity of VR programs has not sufficiently been proven. Patients with focal epilepsy (EG, n=14) accomplished an 8-day program in a VR supermarket, which consisted of learning and buying items on a shopping list. Performance of the EG was compared with that of healthy controls (HCG, n=19). A comprehensive neuropsychological examination was administered. Real-life performance was investigated in a real supermarket. Learning in the VR supermarket was significantly impaired in the EG on different VR measures. Delayed free recall of products did not differ between the EG and the HCG. Virtual reality scores were correlated with neuropsychological measures of visual-spatial cognition, subjective estimates of memory, and performance in the real supermarket. The data indicate that our VR approach allows for the assessment of real-life visual-spatial memory and cognition in patients with focal epilepsy. The multimodal, active, and complex VR paradigm may particularly enhance visual-spatial cognitive resources.
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Affiliation(s)
- P Grewe
- Physiological Psychology, Faculty of Psychology and Sports Science, Bielefeld University, Bielefeld, Germany; Center of Excellence Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany; Bethel Epilepsy Centre, Mara Hospital, Bielefeld, Germany.
| | - D Lahr
- Bethel Epilepsy Centre, Mara Hospital, Bielefeld, Germany
| | - A Kohsik
- Center of Excellence Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany
| | - E Dyck
- Center of Excellence Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany; Computer Graphics and Geometry Processing, Faculty of Technology, Bielefeld University, Bielefeld, Germany
| | - H J Markowitsch
- Physiological Psychology, Faculty of Psychology and Sports Science, Bielefeld University, Bielefeld, Germany; Center of Excellence Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany
| | - C G Bien
- Bethel Epilepsy Centre, Mara Hospital, Bielefeld, Germany
| | - M Botsch
- Center of Excellence Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany; Computer Graphics and Geometry Processing, Faculty of Technology, Bielefeld University, Bielefeld, Germany
| | - M Piefke
- Physiological Psychology, Faculty of Psychology and Sports Science, Bielefeld University, Bielefeld, Germany; Center of Excellence Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany; Neurobiology and Genetics of Behavior, Department of Psychology and Psychotherapy, Witten/Herdecke University, Witten, Germany
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55
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Lah S, Mohamed A, Thayer Z, Miller L, Diamond K. Accelerated long-term forgetting of verbal information in unilateral temporal lobe epilepsy: Is it related to structural hippocampal abnormalities and/or incomplete learning? J Clin Exp Neuropsychol 2014; 36:158-69. [DOI: 10.1080/13803395.2013.874405] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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56
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Fitzgerald Z, Mohamed A, Ricci M, Thayer Z, Miller L. Accelerated long-term forgetting: A newly identified memory impairment in epilepsy. J Clin Neurosci 2013; 20:1486-91. [DOI: 10.1016/j.jocn.2013.04.037] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/18/2013] [Accepted: 04/21/2013] [Indexed: 10/26/2022]
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57
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Butler C, van Erp W, Bhaduri A, Hammers A, Heckemann R, Zeman A. Magnetic resonance volumetry reveals focal brain atrophy in transient epileptic amnesia. Epilepsy Behav 2013; 28:363-9. [PMID: 23832133 DOI: 10.1016/j.yebeh.2013.05.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 05/20/2013] [Indexed: 12/19/2022]
Abstract
Transient epileptic amnesia (TEA) is a recently described epilepsy syndrome characterized by recurrent episodes of isolated memory loss. It is associated with two unusual forms of interictal memory impairment: accelerated long-term forgetting (ALF) and autobiographical amnesia. We investigated the neural basis of TEA using manual volumetry and automated multi-atlas-based segmentation of whole-brain magnetic resonance imaging data from 40 patients with TEA and 20 healthy controls. Both methods confirmed the presence of subtle, bilateral hippocampal atrophy. Additional atrophy was revealed in perirhinal and orbitofrontal cortices. The volumes of these regions correlated with anterograde memory performance. No structural correlates were found for ALF or autobiographical amnesia. The results support the hypothesis that TEA is a focal medial temporal lobe epilepsy syndrome but reveal additional pathology in connected brain regions. The unusual interictal memory deficits of TEA remain unexplained by structural pathology and may reflect physiological disruption of memory networks by subclinical epileptiform activity.
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Affiliation(s)
- Christopher Butler
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
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58
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Hoefeijzers S, Dewar M, Della Sala S, Zeman A, Butler C. Accelerated long-term forgetting in transient epileptic amnesia: An acquisition or consolidation deficit? Neuropsychologia 2013; 51:1549-55. [DOI: 10.1016/j.neuropsychologia.2013.04.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 03/28/2013] [Accepted: 04/28/2013] [Indexed: 11/26/2022]
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59
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Zeman A, Butler C, Muhlert N, Milton F. Novel forms of forgetting in temporal lobe epilepsy. Epilepsy Behav 2013; 26:335-42. [PMID: 23146363 DOI: 10.1016/j.yebeh.2012.09.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 09/17/2012] [Indexed: 01/29/2023]
Abstract
Transient Epileptic Amnesia (TEA) is a recently defined subtype of temporal lobe epilepsy, principally affecting people in middle age with a male predominance. Its key manifestation is the occurrence of recurring episodes of transient amnesia, usually lasting less than an hour and often occurring on waking. One-third of patients have exclusively amnestic attacks, while in two-thirds, at least some attacks are accompanied by other manifestations of epilepsy, especially olfactory hallucinations. Several lines of evidence point to a seizure focus in the medial temporal lobes. Transient Epileptic Amnesia is accompanied by a striking loss of autobiographical memories in two-thirds of sufferers, accelerated loss of memories which had been acquired successfully in around one half, and topographical amnesia in around one-third. This paper reviews the findings of the TIME project (The Impairment of Memory in Epilepsy - http://sites.pcmd.ac.uk/time/tea.php) in relation to TEA, accelerated long-term forgetting, and remote memory impairment.
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Affiliation(s)
- Adam Zeman
- Cognitive Neurology Research Group, Peninsula Medical School, University of Exeter, Exeter, UK.
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60
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Abstract
Transient amnesic syndromes are striking clinical phenomena that are commonly encountered by physicians in acute medical settings. Diagnosis of such syndromes can be challenging, and their causes have been debated for over 50 years. Critical clinical distinctions, such as between transient global amnesia (TGA) and transient epileptic amnesia (TEA), as well as important clues to the underlying pathophysiology, have recently been revealed. TGA is characterized by the sudden onset of a profound anterograde and retrograde amnesia that lasts for up to 24 h, with neuroimaging after an acute TGA event showing transient perturbation of specific hippocampal circuits that are involved in memory processing. Some cases of transient amnesia are attributable to focal seizure activity and are termed TEA, which has a clinical presentation similar to that of TGA, but can be distinguished from the latter by the brevity and frequency of amnesic attacks. Moreover, TEA carries a risk of persistent memory impairment that can be mistaken for dementia. Here, we summarize clinically relevant aspects of transient amnesic syndromes, giving practical recommendations for diagnosis and patient management. We describe results from imaging and epidemiological studies that have shed light on the functional anatomy and pathophysiological mechanisms underlying these conditions.
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61
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McGibbon T, Jansari AS. Detecting the onset of accelerated long-term forgetting: Evidence from temporal lobe epilepsy. Neuropsychologia 2013; 51:114-22. [DOI: 10.1016/j.neuropsychologia.2012.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 09/01/2012] [Accepted: 11/02/2012] [Indexed: 10/27/2022]
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62
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Abstract
Patients with temporal lobe epilepsy (TLE) often present with memory complaints despite performing within normal limits on standard memory tests. One possible explanation for this phenomenon is accelerated long-term forgetting (ALF). The present study investigated material-specific ALF in patients with unilateral TLE and also examined whether ALF could be demonstrated on a novel, standardized anterograde autobiographical memory (ABM) task. Fourteen patients with TLE and 17 controls were administered verbal, nonverbal and ABM event memory tasks. The participants were tested for immediate recall, recall and recognition at 30-minute delay, and recall and recognition after four weeks. The extent of ALF was calculated based on the percentage decay of memory from the 30-minute delay trial to the four-week delay trial. Patients with left TLE showed significantly greater ALF for verbal material and a trend towards greater forgetting of ABM. Patients with right TLE showed a non-significant trend towards greater ALF for nonverbal material. Patients with unilateral hippocampal abnormalities showed greater ALF compared to patients without hippocampal abnormalities. Patients with seizures that generalize had more global memory deficits and greater ALF. We conclude that patients with unilateral TLE show material-specific ALF, which appears to be more pronounced with an abnormal hippocampus or seizures that secondarily generalize.
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63
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Barkas L, Redhead E, Taylor M, Shtaya A, Hamilton DA, Gray WP. Fluoxetine restores spatial learning but not accelerated forgetting in mesial temporal lobe epilepsy. ACTA ACUST UNITED AC 2012; 135:2358-74. [PMID: 22843410 DOI: 10.1093/brain/aws176] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Learning and memory dysfunction is the most common neuropsychological effect of mesial temporal lobe epilepsy, and because the underlying neurobiology is poorly understood, there are no pharmacological strategies to help restore memory function in these patients. We have demonstrated impairments in the acquisition of an allocentric spatial task, in patients with unilateral hippocampal sclerosis. We also show that patients have accelerated forgetting of the learned spatial task and that this is associated with damage to the non-dominant hippocampal formation. We go on to show a very similar pattern of chronic allocentric learning and accelerated forgetting in a status epilepticus model of mesial temporal lobe epilepsy in rats, which is associated with reduced and abnormal hippocampal neurogenesis. Finally, we show that reversal of the neurogenic deficit using fluoxetine is associated with reversal of the learning deficit but not the accelerated forgetting, pointing to a possible dissociation in the underlying mechanisms, as well as a potential therapeutic strategy for improving hippocampal-dependent learning in patients with mesial temporal lobe epilepsy.
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Affiliation(s)
- Lisa Barkas
- Division of Clinical Neurosciences, University of Southampton; LD70, South Academic Block, Southampton General Hospital, Southampton SO166YD, UK
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64
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Milton F, Butler CR, Benattayallah A, Zeman AZJ. The neural basis of autobiographical memory deficits in transient epileptic amnesia. Neuropsychologia 2012; 50:3528-41. [PMID: 23036282 DOI: 10.1016/j.neuropsychologia.2012.09.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 09/13/2012] [Accepted: 09/15/2012] [Indexed: 12/11/2022]
Abstract
Transient epileptic amnesia (TEA) is a recently recognized form of temporal lobe epilepsy which is often associated with persistent interictal impairment of autobiographical memory. We used fMRI to investigate the neural basis of this deficit. Eleven patients with TEA, who had no significant deficits on standard tests of anterograde memory, and 17 age and IQ matched healthy controls retrieved memories from across the lifespan. Both groups engaged the autobiographical memory network, but activation in patients was less extensive than in controls. Direct comparison revealed hypoactivation of regions in the right hemisphere. Specifically, patients showed reduced activation of the posterior parahippocampal gyrus (pPHG), especially for mid-life and recent memories, with decreased engagement of the right temporoparietal junction and the cerebellum. In addition, we found reduced effective connectivity in patients between the right pPHG and the right middle temporal gyrus. Our results are consistent with other evidence that TEA is a syndrome of medial temporal lobe epilepsy and indicate that it affects the function and connectivity of regions within the autobiographical memory network.
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Affiliation(s)
- Fraser Milton
- Discipline of Psychology, University of Exeter, Exeter, UK.
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65
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Bell BD. Route learning impairment in temporal lobe epilepsy. Epilepsy Behav 2012; 25:256-62. [PMID: 23041173 PMCID: PMC3481014 DOI: 10.1016/j.yebeh.2012.07.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 07/21/2012] [Accepted: 07/25/2012] [Indexed: 10/27/2022]
Abstract
Memory impairment on neuropsychological tests is relatively common in temporal lobe epilepsy (TLE) patients. However, memory has been rarely evaluated in more naturalistic settings. This study assessed TLE (n=19) and control (n=32) groups on a real-world route learning (RL) test. Compared to the controls, the TLE group committed significantly more total errors across the three RL test trials. Route learning errors correlated significantly with standardized auditory and visual memory and visual-perceptual test scores in the TLE group. In the TLE subset for whom hippocampal data were available (n=14), RL errors also correlated significantly with left hippocampal volume. This is one of the first studies to demonstrate real-world memory impairment in TLE patients and its association with both mesial temporal lobe integrity and standardized memory test performance. The results support the ecological validity of clinical neuropsychological assessment.
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Affiliation(s)
- Brian D. Bell
- Department of Neurology/Neuropsychology section, University of Wisconsin School of Medicine and Public Health, Madison, WI,Mental Health Service, W.S. Middleton Memorial VA Hospital, Madison, WI
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66
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Kopelman MD, Bright P. On remembering and forgetting our autobiographical pasts: retrograde amnesia and Andrew Mayes's contribution to neuropsychological method. Neuropsychologia 2012; 50:2961-72. [PMID: 22884958 DOI: 10.1016/j.neuropsychologia.2012.07.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 06/06/2012] [Accepted: 07/18/2012] [Indexed: 10/28/2022]
Abstract
Andrew Mayes's contribution to the neuropsychology of memory has consisted in steadily teasing out the nature of the memory deficit in the amnesic syndrome. This has been done with careful attention to matters of method at all stages. This particularly applies to his investigations of forgetting rates in amnesia and to his studies of retrograde amnesia. Following a brief outline of his work, the main current theories of retrograde amnesia are considered: consolidation theory, episodic-to-semantic shift theory, and multiple trace theory. Findings across the main studies in Alzheimer dementia are reviewed to illustrate what appears to be consistently found, and what is much more inconsistent. A number of problems and issues in current theories are then highlighted--including the nature of the temporal gradient, correlations with the extent of temporal lobe damage, what we would expect 'normal' remote memory curves to look like, how they would appear in focal retrograde amnesia, and whether we can pinpoint retrograde amnesia to hippocampal/medial temporal damage on the basis of existing studies. A recent study of retrograde amnesia is re-analysed to demonstrate temporal gradients on recollected episodic memories in hippocampal/medial temporal patients. It is concluded that there are two requirements for better understanding of the nature of retrograde amnesia: (i) a tighter, Mayesian attention to method in terms of both the neuropsychology and neuroimaging in investigations of retrograde amnesia; and (ii) acknowledging that there may be multiple factors underlying a temporal gradient, and that episodic and semantic memory show important interdependencies at both encoding and retrieval. Such factors may be critical to understanding what is remembered and what is forgotten from our autobiographical pasts.
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Affiliation(s)
- M D Kopelman
- King's College London, Institute of Psychiatry, University Department of Neuropsychiatry, Adamson Centre, South Wing, St Thomas' Hospital, Lambeth Palace Road, London, SE1 7EH, UK.
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67
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Butler C, Kapur N, Zeman A, Weller R, Connelly A. Epilepsy-related long-term amnesia: anatomical perspectives. Neuropsychologia 2012; 50:2973-80. [PMID: 22841993 DOI: 10.1016/j.neuropsychologia.2012.07.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2011] [Revised: 05/27/2012] [Accepted: 07/18/2012] [Indexed: 11/29/2022]
Abstract
There are few clues as to the neural basis of selective long-term amnesia. We report group and single-case data to shed light on this issue. In a group study of patients with transient epileptic amnesia, there were no significant correlations between volumetric measures of the hippocampus and indices of accelerated long-term forgetting or longer-term autobiographical memory loss. Post-mortem investigations in a patient with temporal lobe epilepsy who showed accelerated long-term forgetting, together with a degree of autobiographical memory loss, yielded evidence of neuronal loss and gliosis in regions of both the right and the left hippocampus. Neuronal loss and gliosis were more evident in anterior than posterior hippocampus. These results indicate that the unusual forms of long-term forgetting seen in some patients with temporal lobe epilepsy have no gross anatomical correlate. The findings leave open the possibilities that subtle structural damage or subtle functional disturbance, perhaps in the form of subclinical epileptiform activity, underly epilepsy-related long-term amnesia.
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Affiliation(s)
- Chris Butler
- Department of Clinical Neurosciences, University of Oxford, United Kingdom
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68
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[Syndrome of transient epileptic amnesia and epileptic amnesic syndrome: the same entity?]. Rev Neurol (Paris) 2012; 169:76-83. [PMID: 22763205 DOI: 10.1016/j.neurol.2012.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 01/04/2012] [Accepted: 03/28/2012] [Indexed: 11/22/2022]
Abstract
A chronic subjective cognitive impairment can be symptomatic of temporal lobe epilepsy (TLE); it is thereby frequently reversible with the use of antiepileptic monotherapy. In this field, two distinct syndromes have been described: the Epileptic Amnesic Syndrome (EAS) and the Syndrome of Transient Epileptic Amnesia. Their diagnostic criteria have much in common but identification of STEA is based only on transient amnesic attacks. On the contrary, EAS takes into account subtle temporal lobe seizures. Here, we report a case where chronic cognitive disturbances were combined with very limited temporal lobe seizures while amnesic attacks were lacking. Antiepileptic drug treatment led to normalization of cognitive function. The criteria of STEA were not applicable because of the lack of transient amnesia in the patients' medical history. Considering brief episodes of flashbacks and abdominal pain as possibly seizure-related, the criteria of EAS were more operative: they allowed proper investigation to confirm TLE in our patient.
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69
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Muhlert N, Zeman A. The enigma of long-term forgetting. Seizure 2012; 21:77-8. [DOI: 10.1016/j.seizure.2011.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 12/19/2011] [Indexed: 11/29/2022] Open
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70
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Milton F, Muhlert N, Butler C, Smith A, Benattayallah A, Zeman AZ. An fMRI study of long-term everyday memory using SenseCam. Memory 2011; 19:733-44. [DOI: 10.1080/09658211.2011.552185] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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71
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Milton F, Muhlert N, Butler C, Benattayallah A, Zeman A. The neural correlates of everyday recognition memory. Brain Cogn 2011; 76:369-81. [DOI: 10.1016/j.bandc.2011.04.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 04/11/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
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72
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Muhlert N, Grünewald R, Hunkin N, Reuber M, Howell S, Reynders H, Isaac C. Accelerated long-term forgetting in temporal lobe but not idiopathic generalised epilepsy. Neuropsychologia 2011; 49:2417-26. [DOI: 10.1016/j.neuropsychologia.2011.04.018] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 04/05/2011] [Accepted: 04/14/2011] [Indexed: 11/15/2022]
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73
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Complex transient epileptic amnesia. Epilepsy Behav 2011; 20:410-3. [PMID: 21262589 DOI: 10.1016/j.yebeh.2010.12.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 12/17/2010] [Accepted: 12/17/2010] [Indexed: 11/22/2022]
Abstract
Transient epileptic amnesia is a rare but probably underrecognized form of temporal lobe epilepsy, which typically manifests as episodic isolated memory loss. Consequently, transient epileptic amnesia may be readily misdiagnosed as a nonepileptic memory dysfunction in older individuals. When appropriately recognized, it has been described as a treatment-responsive syndrome amenable to antiepileptic drugs. We describe a patient with drug-resistant transient epileptic amnesia treated with unilateral temporal lobectomy. Prolonged postictal slowing in the mesial temporal structures was evident on invasive electroencephalography 5 hours after the occurrence of a brief focal seizure. These findings support the theory of a Todd phenomenon as the underlying pathophysiological mechanism in transient epileptic amnesia.
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