title: Interictal epileptiform discharges impair word recall in multiple brain areas.
abstract: Interictal epileptiform discharges (IEDs) have been linked to memory impairment, but the spatial and temporal dynamics of this relationship remain elusive. In the present study, we aim to systematically characterize the brain areas and times at which IEDs affect memory.
  
  
  
  Eighty epilepsy patients participated in a delayed free recall task while undergoing intracranial electroencephalography (EEG) monitoring. We analyzed the locations and timing of IEDs relative to the behavioral data in order to measure their effects on memory.
  
  
  
  Overall IED rates did not correlate with task performance across subjects (r = 0.03, p = 0.8). However, at a finer temporal scale, within-subject memory was negatively affected by IEDs during the encoding and recall periods of the task but not during the rest and distractor periods (p < 0.01, p < 0.001, p = 0.3, and p = 0.8, respectively). The effects of IEDs during encoding and recall were stronger in the left hemisphere than in the right (p < 0.05). Of six brain areas analyzed, IEDs in the inferior-temporal, medial-temporal, and parietal areas significantly affected memory (false discovery rate < 0.05).
  
  
  
  These findings reveal a network of brain areas sensitive to IEDs with key nodes in temporal as well as parietal lobes. They also demonstrate the time-dependent effects of IEDs in this network on memory.
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.
authors.forename: Peter C
authors.identifier: 0000-0002-3688-1458
authors.initials: PC
authors.lastname: Horak
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.
authors.forename: Stephen
authors.initials: S
authors.lastname: Meisenhelter
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.|Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A.
authors.forename: Yinchen
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.|Thayer School of Engineering at Dartmouth, Hanover, New Hampshire, U.S.A.
authors.forename: Markus E
authors.initials: ME
authors.lastname: Testorf
authors.affiliation: Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kahana
authors.affiliation: Department of Biomedical Data Science, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.
authors.forename: Weston D
authors.initials: WD
authors.lastname: Viles
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.|Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A.
authors.forename: Krzysztof A
authors.initials: KA
authors.lastname: Bujarski
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Connolly
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.
authors.forename: Ashlee A
authors.initials: AA
authors.lastname: Robbins
authors.affiliation: Department of Neurology, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, U.S.A.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Sperling
authors.affiliation: Department of Neurological Surgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, U.S.A.
authors.forename: Ashwini D
authors.initials: AD
authors.lastname: Sharan
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.|Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, U.S.A.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Worrell
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.|Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, U.S.A.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Miller
authors.affiliation: Department of Neurosurgery, Emory University Hospital, Atlanta, Georgia, U.S.A.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Gross
authors.affiliation: Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Davis
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.|Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A.|Department of Neurosurgery, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.
authors.forename: David W
authors.initials: DW
authors.lastname: Roberts
authors.affiliation: Department of Neurosurgery, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A.
authors.forename: Bradley
authors.initials: B
authors.lastname: Lega
authors.affiliation: Department of Neurosurgery, Columbia University Medical Center, New York, New York, U.S.A.
authors.forename: Sameer A
authors.initials: SA
authors.lastname: Sheth
authors.affiliation: Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, U.S.A.
authors.forename: Kareem A
authors.initials: KA
authors.lastname: Zaghloul
authors.affiliation: Department of Neuroradiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
authors.forename: Joel M
authors.initials: JM
authors.lastname: Stein
authors.affiliation: Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
authors.forename: Sandhitsu R
authors.initials: SR
authors.lastname: Das
authors.affiliation: Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Rizzuto
authors.affiliation: Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.|Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A.
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Jobst
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D001931:Brain Mapping; D004827:Epilepsy / Q000150:complications* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology*; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D012372:ROC Curve; D014706:Verbal Learning / Q000502:physiology; D055815:Young Adult
keywords: Brain mapping; Electrocorticography; Epilepsy; Interictal spikes; Memory