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Epilepsy Behav. 2015 Feb;43:16-23. doi: 10.1016/j.yebeh.2014.11.032. Epub 2014 Dec 26.

Impaired sleep-related consolidation of declarative memories in idiopathic focal epilepsies of childhood.

Author information

1
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. Electronic address: sgaler@ulb.ac.be.
2
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.
3
LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.
4
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.
5
LISA - Laboratories of Image, Signal Processing and Acoustics, Université Libre de Bruxelles (ULB), Brussels, Belgium.

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.

KEYWORDS:

Children; Consolidation; Epilepsy; Idiopathic focal epilepsy; Memory; Sleep

PMID:
25546732
DOI:
10.1016/j.yebeh.2014.11.032
[Indexed for MEDLINE]

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