title: Activation of primary and secondary somatosensory regions following tactile stimulation of the face.
abstract: BACKGROUND
  Since the work of Penfield & Rasmussen it is well established that the human primary somatosensory cortex is organized somatotopically. However, the order of the representation of the face is still a matter of discussion, i.e., it is yet unclear whether the face is represented upside-down or vice versa in the somatosensory cortex.
  
  
  METHODS
  In a functional magnetic resonance imaging study (n = 30), tactile stimuli to three different locations on each side of the face were applied using a pneumatic device. Locations of stimulation corresponded to the three branches of the trigeminal nerve (forehead, cheek, chin). To determine the representation of the face on primary and secondary somatosensory cortices, peak coordinates within these regions were analyzed subjectwise.
  
  
  RESULTS
  Contralateral activation of the primary somatosensory cortex following tactile stimulation of the face was found, whereas the secondary somatosensory cortices were activated bilaterally. However, differences between activation coordinates of different tactile stimuli applied to one side of the face were not statistically significant.
  
  
  CONCLUSIONS
  Tactile stimulation of the face leads to contralateral activation of primary and bilateral activation of secondary somatosensory cortices. Using the authors' methodological approach it was not possible to detect a somatotopic organization related to different facial areas.
authors.affiliation: Department of Neuroradiology, University of Munich, Marchioninistrasse 15, Munich, Germany
authors.forename: Rainer
authors.initials: R
authors.lastname: Kopietz
authors.forename: Vehbi
authors.initials: V
authors.lastname: Sakar
authors.forename: Jessica
authors.initials: J
authors.lastname: Albrecht
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Kleemann
authors.forename: Veronika
authors.initials: V
authors.lastname: Schöpf
authors.forename: Indra
authors.initials: I
authors.lastname: Yousry
authors.forename: Jennifer
authors.initials: J
authors.lastname: Linn
authors.forename: Gunther
authors.initials: G
authors.lastname: Fesl
authors.forename: Martin
authors.initials: M
authors.lastname: Wiesmann
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002680:Chin / Q000294:innervation; D005145:Face / Q000294:innervation* / Q000502:physiology*; D005260:Female; D005546:Forehead / Q000294:innervation; D007839:Functional Laterality; D006801:Humans; D008297:Male; D010812:Physical Stimulation; D012016:Reference Values; D013003:Somatosensory Cortex / Q000502:physiology*; D014110:Touch; D014276:Trigeminal Nerve / Q000502:physiology*; D055815:Young Adult