title: High frequency spectral changes induced by single-pulse electric stimulation: Comparison between physiologic and pathologic networks.
abstract: To investigate functional coupling between brain networks using spectral changes induced by single-pulse electric stimulation (SPES).
  
  
  
  We analyzed 20 patients with focal epilepsy, implanted with depth electrodes. SPES was applied to each pair of adjacent contacts, and responses were recorded from all other contacts. The mean response amplitude value was quantified in three time-periods after stimulation (10-60, 60-255, 255-500ms) for three frequency-ranges (Gamma, Ripples, Fast-Ripples), and compared to baseline. A total of 30,755 responses were analyzed, taking into consideration three dichotomous pairs: stimulating in primary sensory areas (S1-V1) vs. outside them, to test the interaction in physiologic networks; stimulating in seizure onset zone (SOZ) vs. non-SOZ, to test pathologic interactions; recording in default mode network (DMN) vs. non-DMN.
  
  
  
  Overall, we observed an early excitation (10-60ms) and a delayed inhibition (60-500ms). More specifically, in the delayed period, stimulation in S1-V1 produced a higher gamma-inhibition in the DMN, while stimulation in the SOZ induced a higher inhibition in the epilepsy-related higher frequencies (Ripples and Fast-Ripples).
  
  
  
  Physiologic and pathologic interactions can be assessed using spectral changes induced by SPES.
  
  
  
  This is a promising method for connectivity studies in patients with drug-resistant focal epilepsy.
authors.affiliation: University Emergency Hospital, Department of Neurology, Bucharest, Romania; Danish Epilepsy Centre, Department of Clinical Neurophysiology, Dianalund, Denmark.
authors.forename: Mihai Dragos
authors.initials: MD
authors.lastname: Mălîia
authors.affiliation: University of Bucharest, Physics Department, Bucharest, Romania; University of Texas Health Science Center at Houston, Houston, TX, United States.
authors.forename: Cristian
authors.initials: C
authors.lastname: Donos
authors.affiliation: University of Bucharest, Physics Department, Bucharest, Romania; FHC Inc., Bowdoin, ME, United States.
authors.forename: Andrei
authors.initials: A
authors.lastname: Barborica
authors.affiliation: University Emergency Hospital, Department of Neurology, Bucharest, Romania; University of Medicine and Pharmacy 'Carol Davila', Department of Neurology, Bucharest, Romania.
authors.forename: Ioana
authors.initials: I
authors.lastname: Mindruta
authors.affiliation: University Emergency Hospital, Department of Neurology, Bucharest, Romania.
authors.forename: Irina
authors.initials: I
authors.lastname: Popa
authors.affiliation: University of Bucharest, Physics Department, Bucharest, Romania.
authors.forename: Mirela
authors.initials: M
authors.lastname: Ene
authors.affiliation: Danish Epilepsy Centre, Department of Clinical Neurophysiology, Dianalund, Denmark; Aarhus University Hospital, Department of Clinical Neurophysiology, Aarhus, Denmark. Electronic address: sbz@filadelfia.dk.
authors.forename: Sándor
authors.initials: S
authors.lastname: Beniczky
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D046690:Deep Brain Stimulation; D004828:Epilepsies, Partial / Q000503:physiopathology*; D005071:Evoked Potentials; D005260:Female; D065818:Gamma Rhythm; D006801:Humans; D008297:Male; D008875:Middle Aged; D013003:Somatosensory Cortex / Q000502:physiology / Q000503:physiopathology*
keywords: Cortico-cortical connectivity; Default mode network; Epileptic networks; Single-pulse electric stimulation; Spectral changes