Reorganization of Large-Scale Functional Networks during Low-Frequency Electrical Stimulation of the Cortical Surface

Bálint File, Tibor Nánási, Emília Tóth, Virág Bokodi, Brigitta Tóth, Boglárka Hajnal, Zsófia Kardos, László Entz, Loránd Eross, István Ulbert, Dániel Fabó

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We investigated the functional network reorganization caused by low-frequency electrical stimulation (LFES) of human brain cortical surface. Intracranial EEG data from subdural grid positions were analyzed in 16 pre-surgery epileptic patients. LFES was performed by injecting current pulses (10mA, 0.2ms pulse width, 0.5Hz, 25 trials) into all adjacent electrode contacts. Dynamic functional connectivity analysis was carried out on two frequency bands (low: 1-4Hz; high: 10-40Hz) to investigate the early, high frequency and late, low frequency responses elicited by the stimulation. The centralization increased in early compared to late responses, suggesting a more prominent role of direct neural links between primarily activated areas and distant brain regions. Injecting the current into the seizure onset zone (SOZ) evoked a more integrated functional topology during the early (N1) period of the response, whereas during the late (N2) period - regardless of the stimulation site - the connectedness of the SOZ was elevated compared to the non-SOZ tissue. The abnormal behavior of the epileptic sub-network during both part of the responses supports the idea of the pathogenic role of impaired inhibition and excitation mechanisms in epilepsy.

Original languageEnglish
Article number1950022
JournalInternational journal of neural systems
Issue number3
Publication statusPublished - Mar 1 2020



  • Cortico-cortical evoked potentials
  • dynamic functional connectivity
  • epilepsy
  • graph parameters
  • seizure onset zone

ASJC Scopus subject areas

  • Computer Networks and Communications

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