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Sleep-dependent memory consolidation in children with self-limited focal epilepsies


Storz, Sarah. Sleep-dependent memory consolidation in children with self-limited focal epilepsies. 2021, University of Zurich, Faculty of Medicine.

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.

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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Additional indexing

Item Type:Dissertation (monographical)
Referees:Bölsterli Bigna K, Huber Reto
Communities & Collections:04 Faculty of Medicine > University Children's Hospital Zurich > Medical Clinic
04 Faculty of Medicine > Psychiatric University Hospital Zurich > Department of Child and Adolescent Psychiatry
UZH Dissertations
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2021
Deposited On:02 Feb 2022 13:57
Last Modified:03 Feb 2022 04:27
OA Status:Green
Free access at:Related URL. An embargo period may apply.
Related URLs:https://www.zora.uzh.ch/id/eprint/194121/
https://www.epilepsybehavior.com/article/S1525-5050(20)30693-4/fulltext
https://pubmed.ncbi.nlm.nih.gov/33129045/
  • Content: Published Version
  • Licence: Creative Commons: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)