title: Early haemodynamic changes observed in patients with epilepsy, in a visual experiment and in simulations.
abstract: OBJECTIVE
  The objective of this study was to investigate whether previously reported early blood oxygen level dependent (BOLD) changes in epilepsy could occur as a result of the modelling techniques rather than physiological changes.
  
  
  METHODS
  EEG-fMRI data were analysed from seven patients with focal epilepsy, six control subjects undergoing a visual experiment, in addition to simulations. In six separate analyses the event timing was shifted by either -9,-6,-3,+3,+6 or +9 s relative to the onset of the interictal epileptiform discharge (IED) or stimulus.
  
  
  RESULTS
  The visual dataset and simulations demonstrated an overlap between modelled haemodynamic response function (HRF) at event onset and at ± 3 s relative to onset, which diminished at ± 6s. Pre-spike analysis at -6s improved concordance with the assumed IED generating lobe relative to the standard HRF in 43% of patients.
  
  
  CONCLUSIONS
  The visual and simulated dataset findings indicate a form of "temporal bleeding", an overlap between the modelled HRF at time 0 and at ± 3s which attenuated at ± 6s. Pre-spike analysis at -6s may improve concordance.
  
  
  CONCLUSIONS
  This form of analysis should be performed at 6s prior to onset of IED to minimise temporal bleeding effect. The results support the presence of relevant BOLD responses occurring prior to IEDs.
authors.affiliation: School of Psychology, University of Birmingham, Birmingham, UK; Birmingham University Imaging Centre (BUIC), University of Birmingham, Birmingham, UK; Department of Neuroscience, Queen Elizabeth Hospital Birmingham, Edgbaston, Birmingham, UK. Electronic address: David.Rollings@uhb.nhs.uk.
authors.forename: David T
authors.initials: DT
authors.lastname: Rollings
authors.affiliation: School of Psychology, University of Birmingham, Birmingham, UK; Birmingham University Imaging Centre (BUIC), University of Birmingham, Birmingham, UK.
authors.forename: Sara
authors.initials: S
authors.lastname: Assecondi
authors.affiliation: Center for Cognitive Neuroscience Berlin, Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany; Center for Adaptive Rationality, Max-Planck-Institute for Human Development, Berlin, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Ostwald
authors.affiliation: Laboratory of Electrophysiology for Translational Neuroscience (LET'S) - ISTC - CNR, Department of Neuroscience, Fatebenefratelli Hospital, Isola Tiberina, Rome, Italy; Institute of Neuroscience, Newcastle University, Medical School, Newcastle upon Tyne, UK.
authors.forename: Camillo
authors.initials: C
authors.lastname: Porcaro
authors.affiliation: Department of Neuroscience, Queen Elizabeth Hospital Birmingham, Edgbaston, Birmingham, UK.
authors.forename: Dougall
authors.initials: D
authors.lastname: McCorry
authors.affiliation: Department of Neuropsychiatry, The Barberry, Birmingham, UK.
authors.forename: Manny
authors.initials: M
authors.lastname: Bagary
authors.affiliation: Department of Neuroscience, Queen Elizabeth Hospital Birmingham, Edgbaston, Birmingham, UK.
authors.forename: Imad
authors.initials: I
authors.lastname: Soryal
authors.affiliation: School of Psychology, University of Birmingham, Birmingham, UK; Birmingham University Imaging Centre (BUIC), University of Birmingham, Birmingham, UK.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Bagshaw
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D014793:Visual Cortex / Q000503:physiopathology*; D055815:Young Adult
keywords: EEG-fMRI; Epilepsy; Haemodynamic response function; Pre-spike response; Simulations; Visual stimulation