title: Interictal activity is an important contributor to abnormal intrinsic network connectivity in paediatric focal epilepsy.
abstract: Patients with focal epilepsy have been shown to have reduced functional connectivity in intrinsic connectivity networks (ICNs), which has been related to neurocognitive development and outcome. However, the relationship between interictal epileptiform discharges (IEDs) and changes in ICNs remains unclear, with evidence both for and against their influence. EEG-fMRI data was obtained in 27 children with focal epilepsy (mixed localisation and aetiologies) and 17 controls. A natural stimulus task (cartoon blocks verses blocks where the subject was told "please wait") was used to enhance the connectivity within networks corresponding to ICNs while reducing potential confounds of vigilance and motion. Our primary hypothesis was that the functional connectivity within visual and attention networks would be reduced in patients with epilepsy. We further hypothesized that controlling for the effects of IEDs would increase the connectivity in the patient group. The key findings were: (1) Patients with mixed epileptic foci showed a common connectivity reduction in lateral visual and attentional networks compared with controls. (2) Having controlled for the effects of IEDs there were no connectivity differences between patients and controls. (3) A comparison within patients revealed reduced connectivity between the attentional network and basal ganglia associated with interictal epileptiform discharges. We also found that the task activations were reduced in epilepsy patients but that this was unrelated to IED occurrence. Unexpectedly, connectivity changes in ICNs were strongly associated with the transient effects of interictal epileptiform discharges. Interictal epileptiform discharges were shown to have a pervasive transient influence on the brain's functional organisation. Hum Brain Mapp 38:221-236, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Elhum A
authors.initials: EA
authors.lastname: Shamshiri
authors.affiliation: Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Tim M
authors.initials: TM
authors.lastname: Tierney
authors.affiliation: Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Maria
authors.initials: M
authors.lastname: Centeno
authors.affiliation: Telemetry Unit, Department of Neurophysiology, Great Ormond Street Hospital, London, United Kingdom.
authors.forename: Kelly
authors.initials: K
authors.lastname: St Pier
authors.affiliation: Neuroscience Medicine, Great Ormond Street Hospital, London, United Kingdom.|Clinical Neurosciences, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Ronit M
authors.initials: RM
authors.lastname: Pressler
authors.affiliation: Computational, Cognitive and Clinical Neuroimaging Laboratory, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Sharp
authors.affiliation: Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom.|Department of Basic and Clinical Neurosciences, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, United Kingdom.
authors.forename: Suejen
authors.initials: S
authors.lastname: Perani
authors.affiliation: Neuroscience Medicine, Great Ormond Street Hospital, London, United Kingdom.|Clinical Neurosciences, UCL Institute of Child Health, London, United Kingdom.
authors.forename: J Helen
authors.initials: JH
authors.lastname: Cross
authors.affiliation: Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom.
authors.forename: David W
authors.initials: DW
authors.lastname: Carmichael
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D001921:Brain / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001931:Brain Mapping; D002648:Child; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D015233:Models, Statistical; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation
chemical_list: D010100:Oxygen
keywords: EEG-fMRI; epilepsy; functional connectivity; interictal epileptiform discharges; intrinsic connectivity networks