Column-Based Model of Electric Field Excitation of Cerebral Cortex

Peter T. Fox, Shalini Narayana, Nitin Tandon, Hugo Sandoval, Sarabeth P. Fox, Peter Kochunov, Jack L. Lancaster

Research output: Contribution to journalArticlepeer-review

184 Scopus citations


A model to explain the orientation selectivity of the neurophysiologic effects of electric-field transients applied to cerebral cortex is proposed and supported with neuroimaging evidence. Although it is well known that transcranial magnetic stimulation (TMS) excites cerebral cortex in an orientation-selective manner, a neurophysiologically compelling explanation of this phenomenon has been lacking. It is generally presumed that TMS-induced excitation is mediated by horizontal fibers in the cortical surfaces nearest to the stimulating coil, i.e., at the gyral crowns. No evidence exists, however, that horizontal fibers are orientation selective either anatomically or physiologically. We used positron emission tomography to demonstrate that TMS-induced cortical activation is selectively sulcal. This observation allows the well-established columnar organization of cerebral cortex to be invoked to explain the observed orientation selectivity. In addition, Rushton's cosine principle can used to model stimulation efficacy for an electrical field applied at any cortical site at any intensity and in any orientation.

Original languageEnglish (US)
Pages (from-to)1-14
Number of pages14
JournalHuman Brain Mapping
Issue number1
StatePublished - May 2004


  • Cerebral cortex
  • PET
  • Positron emission tomography
  • TMS
  • Transcranial magnetic stimulation

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology
  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging
  • Anatomy


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