title: The topographic representation of esophageal motor function on the human cerebral cortex.
abstract: OBJECTIVE
  Corticofugal pathways to the human esophagus have been recently identified in humans using transcranial magnetic stimulation. The aim of this study was to determine the topographic representation of the esophagus on the cerebral cortex.
  
  
  METHODS
  Focal magnetic stimulation of 1-cm areas was performed over both hemispheres in 10 healthy subjects. Esophageal electromyographic responses were recorded 2 cm below the upper esophageal sphincter. The studies were repeated to determine reproducibility in 3 subjects; in 2 subjects, esophageal topography was compared with thenar muscle topography.
  
  
  RESULTS
  In all subjects, esophageal electromyographic responses were evoked by stimulation of either the right or left hemisphere. Largest amplitude responses were obtained anterior to those of the thenar muscles, indicating that the esophagus may be represented on either the anterior aspect of the motor cortex or on the premotor cortex. In all subjects, the area of response was asymmetric, being more extensive on the right hemisphere than on the left hemisphere in 8 subjects. In 2 subjects, the area of response on the left hemisphere was more extensive than on the right. Repeat studies showed that this asymmetry was consistent.
  
  
  CONCLUSIONS
  Esophageal motor function shows bilateral cortical representation with consistent interhemispheric asymmetry.
authors.affiliation: Department of Gastroenterology, Hope Hospital, University of Manchester, England.
authors.forename: Q
authors.initials: Q
authors.lastname: Aziz
authors.forename: J C
authors.initials: JC
authors.lastname: Rothwell
authors.forename: S
authors.initials: S
authors.lastname: Hamdy
authors.forename: J
authors.initials: J
authors.lastname: Barlow
authors.forename: D G
authors.initials: DG
authors.lastname: Thompson
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D004576:Electromyography; D004947:Esophagus / Q000502:physiology*; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results