title: Electrical Stimulation of the Anterior Cingulate Gyrus Induces Responses Similar to K-complexes in Awake Humans.
abstract: BACKGROUND
  The brain region responsible for the initiation of K-complexes has not been identified to date.
  
  
  OBJECTIVE
  To determine the brain region responsible for originating K-complexes.
  
  
  METHODS
  We reviewed all 269 patients assessed for epilepsy surgery with intracranial electrodes and single pulse electrical stimulation (SPES) at King's College Hospital between 1999 and 2013. Intracranial EEG responses to electrical stimulation at orbitofrontal, frontal, cingulate, temporal and parietal loci were compared visually with each patient's K-complexes and the degree of resemblance was quantified.
  
  
  RESULTS
  Among the 269 patients, K-complex-like responses were exclusively observed in all 6 patients who had depth electrodes in the cingulate cortex. In each patient, the stimulation site eliciting the response of greatest similarity to the patient's K-complex was located within the dorso-caudal anterior cingulate. The K-complex like responses were evoked when the patients were awake.
  
  
  CONCLUSIONS
  Our findings provide the first causal evidence that the cingulate gyrus initiates the widespread synchronous activity that constitutes the K-complex. The induction of K-complex-like responses during wakefulness suggests that the mechanisms required for the initiation of K-complexes are separate from those involved in sleep.
authors.affiliation: Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology and Neuroscience, UK.
authors.forename: Zanna
authors.initials: Z
authors.lastname: Voysey
authors.affiliation: Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology and Neuroscience, UK; Department of Clinical Neurophysiology, King's College Hospital NHS Trust, London, UK; West Surrey Clinical Neurophysiology, St Peter's Hospital, Chertsey, UK.
authors.forename: David
authors.initials: D
authors.lastname: Martín-López
authors.affiliation: Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology and Neuroscience, UK; Department of Clinical Neurophysiology, King's College Hospital NHS Trust, London, UK; Universidad San Francisco de Quito, School of Medicine, Quito, Ecuador.
authors.forename: Diego
authors.initials: D
authors.lastname: Jiménez-Jiménez
authors.affiliation: Department of Neurosurgery, King's College Hospital NHS Trust, London, UK.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Selway
authors.affiliation: Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology and Neuroscience, UK; Department of Clinical Neurophysiology, King's College Hospital NHS Trust, London, UK; Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Neurology Section, Medicine Department, Hamad Medical Corporation, Doha, Qatar.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Alarcón
authors.affiliation: Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology and Neuroscience, UK; Department of Clinical Neurophysiology, King's College Hospital NHS Trust, London, UK; Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, Madrid, Spain. Electronic address: avhuete@hotmail.com.
authors.forename: Antonio
authors.initials: A
authors.lastname: Valentín
mesh_terms: D000328:Adult; D058256:Brain Waves; D046690:Deep Brain Stimulation / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006179:Gyrus Cinguli / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014851:Wakefulness
keywords: Cingulate gyrus; K-complex; Single pulse electrical stimulation; Sleep phenomena