title: Impaired sleep-related consolidation of declarative memories in idiopathic focal epilepsies of childhood.
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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: 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.
authors.forename: Sophie
authors.initials: S
authors.lastname: Galer
authors.affiliation: 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.
authors.forename: Charline
authors.initials: C
authors.lastname: Urbain
authors.affiliation: LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: De Tiège
authors.affiliation: LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Emeriau
authors.affiliation: 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.
authors.forename: Rachel
authors.initials: R
authors.lastname: Leproult
authors.affiliation: 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.
authors.forename: Gaetane
authors.initials: G
authors.lastname: Deliens
authors.affiliation: LISA - Laboratories of Image, Signal Processing and Acoustics, Université Libre de Bruxelles (ULB), Brussels, Belgium.
authors.forename: Antoine
authors.initials: A
authors.lastname: Nonclerq
authors.affiliation: 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.
authors.forename: Philippe
authors.initials: P
authors.lastname: Peigneux
authors.affiliation: LCFC - Laboratoire de Cartographie fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Van Bogaert
mesh_terms: D000927:Anticonvulsants / Q000009:adverse effects / Q000627:therapeutic use; D002648:Child; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000150:complications* / Q000523:psychology*; D019305:Epilepsy, Rolandic / Q000150:complications / Q000523:psychology; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000209:etiology / Q000523:psychology; D008297:Male; D008569:Memory Disorders / Q000209:etiology* / Q000523:psychology*; D011939:Mental Recall; D017286:Polysomnography; D011597:Psychomotor Performance; D012640:Seizures / Q000523:psychology; D012890:Sleep; D012893:Sleep Wake Disorders / Q000209:etiology* / Q000523:psychology*; D014635:Valproic Acid / Q000009:adverse effects / Q000627:therapeutic use; D014936:Word Association Tests
chemical_list: D000927:Anticonvulsants; D014635:Valproic Acid
keywords: Children; Consolidation; Epilepsy; Idiopathic focal epilepsy; Memory; Sleep