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Location of Sources of Evoked Scalp Potentials: Corrections for Skull and Scalp Thicknesses

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Check out this Knowledge Base article from StressTherapy Solutions: Location of Sources of Evoked Scalp Potentials: Corrections for Skull and Scalp Thicknesses.

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Study at a glance

Area
QEEG, Methods & Mechanisms
Study type
Observational study
Authors
Ary JP, Klein SA, Fender DH
Journal
IEEE Transactions on Biomedical Engineering
Year
1981
Protocol
mathematical dipole source-localization head models

Key findings

  • The earlier correction by Sidman and colleagues works well for deep sources near the head's center, such as midbrain or brainstem
  • For cortical sources (eccentricity 0.6-0.9) that correction may add as much error as it removes
  • Midrange guesses of skull and scalp thickness can shift localization by about 7% and 3% of the outer scalp radius
  • A poor estimate of skull conductivity adds at most a 2% error

DOI 10.1109/tbme.1981.324817 → PubMed 7287042 →

A mathematical modeling paper on how to pinpoint where evoked potentials recorded on the scalp originate in the brain. The authors show that a source's position in a more realistic head model (a sphere wrapped in two shells standing for skull and scalp, each with different electrical conductivity) can be recovered from calculations done on a simpler uniform sphere. They also test an earlier shortcut correction and find it unreliable for sources in the cortex.