title: Human EEG responses to controlled alterations of the Earth's magnetic field.
abstract: OBJECTIVE
  Examine the effects of controlled changes in the Earth's magnetic field on electroencephalogram (EEG) and subjective report.
  
  
  METHODS
  Fifty volunteers were exposed double-blind to changes in field magnitude, angle of inclination, and angle of deviation. Volunteers were also exposed to magnetic field conditions found near the North and South Pole. EEG recorded over temporal and occipital sites was compared across 4s baseline, field exposure, and no-change control trials.
  
  
  RESULTS
  No EEG spectral differences as a function of gender or recording site were found. Geomagnetic field alterations had no effect on total energy (0.5-42 Hz), energy within traditional EEG analysis bands, or on the 95% spectral edge. Most volunteers reported no sensations; others reported non-specific symptoms unrelated to type of field change.
  
  
  CONCLUSIONS
  Three hypothesized field detection mechanisms were not supported: (1) mechanical reception through torque exerted on the ferromagnetic material magnetite; (2) movement-induced induction of an electric field in the body; and (3) enhanced sensitivity due to alterations in the rates of chemical reactions involving electron spin states.
  
  
  CONCLUSIONS
  Humans have little ability to detect brief alterations in the geomagnetic field, even if these alteration are of a large magnitude.
authors.affiliation: Midwest Research Institute, 425 Volker Boulevard, Kansas City, MO 64110, USA. asastre@mriresearch.org
authors.forename: Antonio
authors.initials: A
authors.lastname: Sastre
authors.forename: Charles
authors.initials: C
authors.lastname: Graham
authors.forename: Mary R
authors.initials: MR
authors.lastname: Cook
authors.forename: Mary M
authors.initials: MM
authors.lastname: Gerkovich
authors.forename: Paul
authors.initials: P
authors.lastname: Gailey
mesh_terms: D000328:Adult; D000367:Age Factors; D002138:Calibration; D004311:Double-Blind Method; D018534:Earth, Planet; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008280:Magnetics / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds; D012737:Sex Factors; D013702:Temporal Lobe / Q000502:physiology