Activation of primary and secondary somatosensory regions following tactile stimulation of the face.
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.
Kopietz
Rainer
R
Department of Neuroradiology, University of Munich, Marchioninistrasse 15, Munich, Germany
Sakar
Vehbi
V
Albrecht
Jessica
J
Kleemann
Anna Maria
AM
Schöpf
Veronika
V
Yousry
Indra
I
Linn
Jennifer
J
Fesl
Gunther
G
Wiesmann
Martin
M
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