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Mayor C, Moser C, Korff C. Long-term memory consolidation of new words in children with self-limited epilepsy with centro-temporal spikes. Epilepsy Behav 2024; 153:109720. [PMID: 38428174 DOI: 10.1016/j.yebeh.2024.109720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 03/03/2024]
Abstract
Accelerated long-term forgetting has been studied and demonstrated in adults with epilepsy. In contrast, the question of long-term consolidation (delays > 1 day) in children with epilepsy shows conflicting results. However, childhood is a period of life in which the encoding and long-term storage of new words is essential for the development of knowledge and learning. The aim of this study was therefore to investigate long-term memory consolidation skills in children with self-limited epilepsy with centro-temporal spikes (SeLECTS), using a paradigm exploring new words encoding skills and their long-term consolidation over one-week delay. As lexical knowledge, working memory skills and executive/attentional skills has been shown to contribute to long-term memory/new word learning, we added standardized measures of oral language and executive/attentional functions to explore the involvement of these cognitive skills in new word encoding and consolidation. The results showed that children with SeLECTS needed more repetitions to encode new words, struggled to encode the phonological forms of words, and when they finally reached the level of the typically developing children, they retained what they had learned, but didn't show improved recall skills after a one-week delay, unlike the control participants. Lexical knowledge, verbal working memory skills and phonological skills contributed to encoding and/or recall abilities, and interference sensitivity appeared to be associated with the number of phonological errors during the pseudoword encoding phase. These results are consistent with the functional model linking working memory, phonology and vocabulary in a fronto-temporo-parietal network. As SeLECTS involves perisylvian dysfunction, the associations between impaired sequence storage (phonological working memory), phonological representation storage and new word learning are not surprising. This dual impairment in both encoding and long-term consolidation may result in large learning gap between children with and without epilepsy. Whether these results indicate differences in the sleep-induced benefits required for long-term consolidation or differences in the benefits of retrieval practice between the epilepsy group and healthy children remains open. As lexical development is associated with academic achievement and comprehension, the impact of such deficits in learning new words is certainly detrimental.
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Affiliation(s)
- C Mayor
- Child Neuropsychology Unit, Faculty of Psychology and Educational Sciences, University of Geneva, Switzerland.
| | - C Moser
- Child Neuropsychology Unit, Faculty of Psychology and Educational Sciences, University of Geneva, Switzerland
| | - C Korff
- Pediatric Neurology Unit, University Hospitals of Geneva, Geneva, Switzerland
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Latreille V, Schiller K, Peter-Derex L, Frauscher B. Does epileptic activity impair sleep-related memory consolidation in epilepsy? A critical and systematic review. J Clin Sleep Med 2022; 18:2481-2495. [PMID: 35866226 PMCID: PMC9516593 DOI: 10.5664/jcsm.10166] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 06/21/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022]
Abstract
STUDY OBJECTIVES People with epilepsy often complain about disturbed sleep and cognitive impairment. Beyond seizures, the occurrence of interictal epileptic activity during sleep is also increasingly recognized to negatively impact cognitive functioning, including memory processes. The aim of this study was to critically review the effect of interictal epileptic activity on sleep-related memory consolidation. METHODS PubMed and PsychINFO databases were systematically searched to identify experimental studies that investigated sleep-related memory consolidation and the relationships between sleep-related epileptic activity and memory in adults and children with epilepsy. This review also highlights hypotheses regarding the potential pathophysiological mechanisms. RESULTS A total of 261 studies were identified; 27 of these met selection criteria. Only 13 studies prospectively assessed the effect of sleep on memory in epilepsy. Most studies reported no alteration of sleep-related memory consolidation in patients, with either similar retention levels following a period containing sleep (n = 5) or improved memory performance postsleep (n = 4). Two studies in children with epilepsy found impaired sleep-related memory consolidation. Ten studies, of which 6 were in childhood epilepsy syndromes, reported a debilitating effect of sleep-related epileptic activity on memory functioning. CONCLUSIONS Conclusions from existing studies were hampered by small sample sizes, heterogeneous patient groups, and variations in memory assessment techniques. Overall, results to date preclude any definitive conclusions on the alteration of sleep-related memory consolidation in epilepsy. We discuss methodological considerations specific to people with epilepsy and provide suggestions on how to best investigate the relationship between epileptic activity, sleep, and memory consolidation in future studies. CITATION Latreille V, Schiller K, Peter-Derex L, Frauscher B. Does epilepticimpair sleep-related memory consolidation in epilepsy? A critical and systematic review. J Clin Sleep Med. 2022;18(10):2481-2495.
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Affiliation(s)
- Véronique Latreille
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Katharina Schiller
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
- Department of Pediatrics, Hospital Group Ostallgaeu-Kaufbeuren, Kaufbeuren, Germany
| | - Laure Peter-Derex
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
- Center for Sleep Medicine and Respiratory Diseases, Croix-Rousse Hospital, University Hospital of Lyon, Lyon 1 University, France
- Lyon Neuroscience Research Center, INSERM 1028/CNRS 5292, Lyon, France
| | - Birgit Frauscher
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
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Smith ML. "Is this normal after such a major surgery?" Memory complaint after right temporal lobe excision in an adolescent. Epilepsy Behav Rep 2022; 18:100515. [PMID: 35243287 PMCID: PMC8857461 DOI: 10.1016/j.ebr.2021.100515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/17/2021] [Accepted: 12/02/2021] [Indexed: 12/01/2022] Open
Abstract
Memory deficits are commonly associated with temporal-lobe epilepsy. Memory may worsen after surgical resection of the temporal lobe. Risk factors for decline are structural integrity of the mesial temporal lobe structures and intact pre-operative memory. Subjective memory complaints are influenced by depression or other psychological disorders. A 16-year-old girl underwent resection from the right lateral and medial temporal lobe and after surgery she complained of a significant memory impairment, which was unexpected given her baseline assessment. Before undertaking a neuropsychological assessment, she was referred for a psychiatric consultation which revealed depression, leading to treatment with anditdepressant medication. Over time she also admitted to severe headaches and inadequate sleep. With these issues addressed, assessment indicated memory performance had not changed relative to her preoperative baseline with stability or improvement in memory across longitudinal assessments. This case illustrates the contribution of mood state and other potential factors in contributing to subjective memory complaints.
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Affiliation(s)
- Mary Lou Smith
- University of Toronto, The Hospital for Sick Children, Toronto ON M5G 1X8, Canada
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Georgopoulou V, Spruyt K, Garganis K, Kosmidis MH. Altered Sleep-Related Consolidation and Neurocognitive Comorbidity in CECTS. Front Hum Neurosci 2021; 15:563807. [PMID: 34163335 PMCID: PMC8215163 DOI: 10.3389/fnhum.2021.563807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 04/21/2021] [Indexed: 12/03/2022] Open
Abstract
Our aim is to use neurophysiological sleep-related consolidation (SRC) phenomena to identify putative pathophysiological mechanisms in CECTS linked to diffuse neurocognitive deficits. We argue that there are numerous studies on the association between seizure aspects and neurocognitive functioning but not as many on interictal variables and neurocognitive deficits. We suggest two additional foci. First, the interictal presentation in CECTS and second, neuronal oscillations involved in SRC processes. Existing data on mechanisms through which interictal epileptiform spikes (IES) impact upon SRC indicate that they have the potential to: (a) perturb cross-regional coupling of neuronal oscillations, (b) mimic consolidation processes, (c) alter the precision of the spatiotemporal coupling of oscillations, and (d) variably impact upon SRC performance. Sleep spindles merit systematic study in CECTS in order to clarify: (a) the state of the slow oscillations (SOs) with which they coordinate, (b) the precision of slow oscillation-spindle coupling, and (c) whether their developmental trajectories differ from those of healthy children. We subsequently review studies on the associations between IES load during NREM sleep and SRC performance in childhood epilepsy. We then use sleep consolidation neurophysiological processes and their interplay with IES to help clarify the diffuse neurocognitive deficits that have been empirically documented in CECTS. We claim that studying SRC in CECTS will help to clarify pathophysiological mechanisms toward diverse neurocognitive deficits. Future developments could include close links between the fields of epilepsy and sleep, as well as new therapeutic neurostimulation targets. At the clinical level, children diagnosed with CECTS could benefit from close monitoring with respect to epilepsy, sleep and neurocognitive functions.
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Affiliation(s)
- Victoria Georgopoulou
- 2nd Centre for Educational and Counseling Support of Eastern Thessaloniki, Ministry of Education, Thessaloniki, Greece.,Department of Educational and Social Policy, University of Macedonia, Thessaloniki, Greece
| | - Karen Spruyt
- INSERM, Claude Bernard University, School of Medicine, Lyon, France
| | | | - Mary H Kosmidis
- Lab of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Storz S, Wilhelm I, Critelli H, Feldmann M, Ramirez A, Ramantani G, Huber R, Bölsterli BK. Sleep-dependent memory consolidation in children with self-limited focal epilepsies. Epilepsy Behav 2020; 113:107513. [PMID: 33129045 DOI: 10.1016/j.yebeh.2020.107513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 09/17/2020] [Accepted: 09/20/2020] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Children with self-limited focal epilepsies of childhood (SLFE) are known to show impaired memory functions, particularly in the verbal domain. Interictal epileptiform discharges (IED) in these epilepsies are more pronounced in nonrapid eye movement (NREM) sleep. Nonrapid eye movement sleep is crucial for consolidation of newly-encoded memories. Therefore, we hypothesize that sleep-dependent memory consolidation is altered in relation to IED in children with SLFE. METHODS We conducted a prospective case-control study. We applied a verbal (word pair) and a visuospatial (two-dimensional [2D] object location) learning task, both previously shown to benefit from sleep in terms of memory consolidation. Learning took place in the evening, and retrieval was tested in the morning after a night of sleep. Electroencephalogram (EEG) was recorded across night. After sleep-stage scoring, the spike-wave index (SWI) was assessed at the beginning and the end of sleep. Fourteen patients with SLFE (age: 5.5 to 11.6 years) were compared with 15 healthy controls (age: 6.8 to 9.1 years) examined in a previous study. RESULTS In contrast to healthy controls (mean: +12.9% recalled word pairs, p = .003, standard deviation (SD) = 12.4%), patients did not show overnight performance gains in the verbal memory task (mean: +6.4% recalled word pairs, p > .05, SD = 17.3) Neither patients nor controls showed significant overnight changes in visuospatial task performance. Spike-wave index was negatively correlated with recall performance in the verbal but not in the visuospatial task. SIGNIFICANCE We found evidence for impaired overnight improvement of performance in children with SLFE in a verbal learning task, with high SWI rates predicting low recall performance. We speculate that spike-waves hamper long-term memory consolidation by interfering with NREM sleep.
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Affiliation(s)
- Sarah Storz
- Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Child Development Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland.
| | - Ines Wilhelm
- Department of Psychiatry and Psychotherapy, Translational Psychiatry Unit (TPU), University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany
| | - Hanne Critelli
- Department of Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Maria Feldmann
- Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Child Development Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Ana Ramirez
- Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Child Development Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Georgia Ramantani
- Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Department of Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Reto Huber
- Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Child Development Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital University of Zurich, Lenggstrasse 31, 8032 Zurich, Switzerland
| | - Bigna K Bölsterli
- Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Department of Neurology, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
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Chan S, Pressler R, Boyd SG, Baldeweg T, Cross JH. Does sleep benefit memory consolidation in children with focal epilepsy? Epilepsia 2017; 58:456-466. [DOI: 10.1111/epi.13668] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2016] [Indexed: 02/05/2023]
Affiliation(s)
- Samantha Chan
- Developmental Neurosciences Programme; UCL Great Ormond Street Institute of Child Health; London United Kingdom
- Great Ormond Street Hospital NHS Trust; London United Kingdom
| | - Ronit Pressler
- Developmental Neurosciences Programme; UCL Great Ormond Street Institute of Child Health; London United Kingdom
- Great Ormond Street Hospital NHS Trust; London United Kingdom
| | - Stewart G. Boyd
- Great Ormond Street Hospital NHS Trust; London United Kingdom
| | - Torsten Baldeweg
- Developmental Neurosciences Programme; UCL Great Ormond Street Institute of Child Health; London United Kingdom
| | - J. Helen Cross
- Developmental Neurosciences Programme; UCL Great Ormond Street Institute of Child Health; London United Kingdom
- Great Ormond Street Hospital NHS Trust; London United Kingdom
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Atherton KE, Nobre AC, Lazar AS, Wulff K, Whittaker RG, Dhawan V, Lazar ZI, Zeman AZ, Butler CR. Slow wave sleep and accelerated forgetting. Cortex 2016; 84:80-89. [PMID: 27710778 PMCID: PMC5084685 DOI: 10.1016/j.cortex.2016.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 07/04/2016] [Accepted: 08/29/2016] [Indexed: 12/12/2022]
Abstract
We investigated whether the benefit of slow wave sleep (SWS) for memory consolidation typically observed in healthy individuals is disrupted in people with accelerated long-term forgetting (ALF) due to epilepsy. SWS is thought to play an active role in declarative memory in healthy individuals and, furthermore, electrographic epileptiform activity is often more prevalent during SWS than during wakefulness or other sleep stages. We studied the relationship between SWS and the benefit of sleep for memory retention using a word-pair associates task. In both the ALF and the healthy control groups, sleep conferred a memory benefit. However, the relationship between the amount of SWS and sleep-related memory benefits differed significantly between the groups. In healthy participants, the amount of SWS correlated positively with sleep-related memory benefits. In stark contrast, the more SWS, the smaller the sleep-related memory benefit in the ALF group. Therefore, contrary to its role in healthy people, SWS-associated brain activity appears to be deleterious for memory in patients with ALF.
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Affiliation(s)
- Kathryn E Atherton
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Anna C Nobre
- Oxford Centre for Human Brain Activity, University of Oxford, Oxford, UK
| | - Alpar S Lazar
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, UK
| | - Katharina Wulff
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | - Vandana Dhawan
- Institute of Neuroscience, Newcastle University, Newcastle, UK
| | - Zsolt I Lazar
- Department of Physics, Babes-Bolyai University, Cluj-Napoca, Romania
| | - Adam Z Zeman
- Cognitive and Behavioural Neurology, Peninsular Medical School, University of Exeter, UK
| | - Christopher R Butler
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
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Sarkis RA, Alam J, Pavlova MK, Dworetzky BA, Pennell PB, Stickgold R, Bubrick EJ. Sleep-dependent memory consolidation in the epilepsy monitoring unit: A pilot study. Clin Neurophysiol 2016; 127:2785-2790. [PMID: 27417054 DOI: 10.1016/j.clinph.2016.05.275] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 05/20/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVE We sought to examine whether patients with focal epilepsy exhibit sleep dependent memory consolidation, whether memory retention rates correlated with particular aspects of sleep physiology, and how the process was affected by seizures. METHODS We prospectively recruited patients with focal epilepsy and assessed declarative memory using a task consisting of 15 pairs of colored pictures on a 5×6 grid. Patients were tested 12h after training, once after 12h of wakefulness and once after 12h that included sleep. EMG chin electrodes were placed to enable sleep scoring. The number and density of sleep spindles were assessed using a wavelet-based algorithm. RESULTS Eleven patients were analyzed age 21-56years. The percentage memory retention over 12h of wakefulness was 62.7% and over 12h which included sleep 83.6% (p=0.04). Performance on overnight testing correlated with the duration of slow wave sleep (SWS) (r=+0.63, p<0.05). Three patients had seizures during the day, and 3 had nocturnal seizures. Day-time seizures did not affect retention rates, while those patients who had night time seizures had a drop in retention from an average of 92% to 60.5%. CONCLUSIONS There is evidence of sleep dependent memory consolidation in patients with epilepsy which mostly correlates with the amount of SWS. Our preliminary findings suggest that nocturnal seizures likely disrupt sleep dependent memory consolidation. SIGNIFICANCE Findings highlight the importance of SWS in sleep dependent memory consolidation and the adverse impact of nocturnal seizures on this process.
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Affiliation(s)
- Rani A Sarkis
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
| | - Javad Alam
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Milena K Pavlova
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Barbara A Dworetzky
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Page B Pennell
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Robert Stickgold
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Ellen J Bubrick
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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Höller Y, Trinka E. Is There a Relation between EEG-Slow Waves and Memory Dysfunction in Epilepsy? A Critical Appraisal. Front Hum Neurosci 2015; 9:341. [PMID: 26124717 PMCID: PMC4463866 DOI: 10.3389/fnhum.2015.00341] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 05/28/2015] [Indexed: 12/12/2022] Open
Abstract
Is there a relationship between peri-ictal slow waves, loss of consciousness, memory, and slow-wave sleep, in patients with different forms of epilepsy? We hypothesize that mechanisms, which result in peri-ictal slow-wave activity as detected by the electroencephalogram, could negatively affect memory processes. Slow waves (≤4 Hz) can be found in seizures with impairment of consciousness and also occur in focal seizures without impairment of consciousness but with inhibited access to memory functions. Peri-ictal slow waves are regarded as dysfunctional and are probably caused by mechanisms, which are essential to disturb the consolidation of memory entries in these patients. This is in strong contrast to physiological slow-wave activity during deep sleep, which is thought to group memory-consolidating fast oscillatory activity. In patients with epilepsy, slow waves may not only correlate with the peri-ictal clouding of consciousness, but could be the epiphenomenon of mechanisms, which interfere with normal brain function in a wider range. These mechanisms may have transient impacts on memory, such as temporary inhibition of memory systems, altered patterns of hippocampal-neocortical interactions during slow-wave sleep, or disturbed cross-frequency coupling of slow and fast oscillations. In addition, repeated tonic-clonic seizures over the years in uncontrolled chronic epilepsy may cause a progressive cognitive decline. This hypothesis can only be assessed in long-term prospective studies. These studies could disentangle the reversible short-term impacts of seizures, and the impacts of chronic uncontrolled seizures. Chronic uncontrolled seizures lead to irreversible memory impairment. By contrast, short-term impacts do not necessarily lead to a progressive cognitive decline but result in significantly impaired peri-ictal memory performance.
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Affiliation(s)
- Yvonne Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria
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Galer S, Urbain C, De Tiège X, Emeriau M, Leproult R, Deliens G, Nonclerq A, Peigneux P, Van Bogaert P. Impaired sleep-related consolidation of declarative memories in idiopathic focal epilepsies of childhood. Epilepsy Behav 2015; 43:16-23. [PMID: 25546732 DOI: 10.1016/j.yebeh.2014.11.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/27/2014] [Accepted: 11/29/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Declarative memory is consolidated during sleep in healthy children. We tested the hypothesis that consolidation processes are impaired in idiopathic focal epilepsies (IFE) of childhood in association with frequent interictal epileptiform discharges (IEDs) during sleep. METHODS A verbal (word-pair association) and a nonverbal (2D object location) declarative memory task were administrated to 15 children with IFEs and 8 control children 6-12 years of age. Patients had either centrotemporal (11 patients) or occipital (4 patients) IEDs. All but 3 patients had a history of unprovoked seizures, and 6 of them were treated with valproate (VPA). The learning procedure (location of object pairs presented on a grid; association of word pairs) was executed in the evening. Retrieval was tested immediately after learning and on the next morning after a night of sleep. Participants were tested twice, once in natural home conditions and one month later in the unfamiliar conditions of the sleep unit under EEG monitoring. RESULTS Overnight recall performance was lower in children with IFE than in control children on both tasks (ps<0.05). Performance in home conditions was similar to that in hospital conditions. Higher spike-wave index (SWI) during nonrapid eye movement (NREM) sleep was associated with poorer performance in the nonverbal task (p<0.05). Valproate treatment was not associated with overnight recall performance for both tasks (ps>0.05). CONCLUSION Memory consolidation is impaired in IFE of childhood. The association between higher SWI during NREM sleep and poorer nonverbal declarative memory consolidation supports the hypothesis that interictal epileptic activity could disrupt sleep memory consolidation.
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Affiliation(s)
- Sophie Galer
- LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium; UR2NF - Neuropsychology and Functional Neuroimaging Research Group at CRCN - Center for Research in Cognition and Neurosciences, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.
| | - Charline Urbain
- LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium; UR2NF - Neuropsychology and Functional Neuroimaging Research Group at CRCN - Center for Research in Cognition and Neurosciences, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - Xavier De Tiège
- LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - Mathilde Emeriau
- LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - Rachel Leproult
- UR2NF - Neuropsychology and Functional Neuroimaging Research Group at CRCN - Center for Research in Cognition and Neurosciences, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - Gaetane Deliens
- UR2NF - Neuropsychology and Functional Neuroimaging Research Group at CRCN - Center for Research in Cognition and Neurosciences, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - Antoine Nonclerq
- LISA - Laboratories of Image, Signal Processing and Acoustics, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Philippe Peigneux
- UR2NF - Neuropsychology and Functional Neuroimaging Research Group at CRCN - Center for Research in Cognition and Neurosciences, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - Patrick Van Bogaert
- LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium
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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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