title: The Cortical Hyperexcitability Index (CHi): a new measure for quantifying correlates of visually driven cortical hyperexcitability.
abstract: BACKGROUND
  Aberrations of visual experience, including visual hallucinations and visual distortions, are known to be associated with increased cortical hyperexcitability. As a consequence, the presence, intensity and frequency of certain experiences may well be indicative of an underlying increase in cortical hyperexcitability.
  
  
  METHODS
  The current study presents a new proxy measure of cortical hyperexcitability, the Cortical Hyperexcitability Index (CHi). Two hundred and fifty healthy participants completed the CHi with the results subjected to exploratory factor analysis (EFA).
  
  
  RESULTS
  The EFA revealed a three-factor model as the most parsimonious solution. The three factors were defined as: (1) heightened visual sensitivity and discomfort; (2) negative aura-type visual aberrations; and (3) positive aura-type visual aberrations. The identification of three factors suggests that multiple mechanisms underlie the notion of cortical hyperexcitability, providing researchers with new and greater precision in delineating these underlying features.
  
  
  CONCLUSIONS
  The factorial structure of the CHi and the increased precision could aid the interpretation of findings from neuroscientific (i.e., brain imaging/stimulation) examinations of cortical processes underlying aberrant perceptions across a host of clinical, neurological and pathological conditions. As a consequence, the CHi is a useful and comprehensive proxy measure of cortical hyperexcitability with considerable scientific and clinical utility.
authors.affiliation: a Behavioural Brain Sciences Centre, School of Psychology , University of Birmingham , Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Braithwaite
authors.forename: Rachel
authors.initials: R
authors.lastname: Marchant
authors.forename: Chie
authors.initials: C
authors.lastname: Takahashi
authors.forename: Hayley
authors.initials: H
authors.lastname: Dewe
authors.forename: Derrick G
authors.initials: DG
authors.lastname: Watson
mesh_terms: D000293:Adolescent; D000328:Adult; D001426:Bacterial Proteins; D002540:Cerebral Cortex / Q000503:physiopathology*; D003243:Consciousness / Q000502:physiology*; D055724:Electrophysiological Phenomena / Q000502:physiology*; D005260:Female; D006212:Hallucinations / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D001426:Bacterial Proteins; C015875:excitability-inducing molecule
keywords: aberrant experience; consciousness; cortical hyperexcitability; hallucinations