A difference exists in somatosensory processing between the anterior and posterior parts of the tongue.
The somatic sensation of the tongue is necessary for daily life, but it is difficult to know the underlying neural mechanisms. In particular, because of the vomiting reflex and several morphological problems, no neuroimaging studies have examined somatosensory processing by stimulating the posterior part of the tongue, except for two magnetoencephalographic studies (Sakamoto et al., 2008a,b). This is the first study to clarify the human cortical processing for sensory perception by the posterior part of the tongue with a newly developed device and functional magnetic resonance imaging (fMRI). Stimulation of the left and right postero-lateral parts of the tongue induced significant activity in the primary somatosensory cortex (SI) and Brodmann area 40 in the right hemisphere and the anterior cingulate cortex (ACC). In contrast, antero-lateral stimulation produced activity only in the right SI. The activated region in SI was significantly larger following stimulation of the posterior than anterior part. These results indicate that a clear difference exists in somatosensory processing between stimulation of the antero-lateral and postero-lateral parts of the tongue, and a right hemisphere is dominant for the stimulation of both antero-lateral and postero-lateral areas. The activity in BA 40 and ACC may imply that the posterior of the tongue belongs to the visceral system.
Sakamoto
Kiwako
K
ITAB-Institute for Advanced Biomedical Technologies, University of Chieti, Chieti, Italy. kiwakos@nips.ac.jp
Nakata
Hiroki
H
Inui
Koji
K
Perrucci
Mauro Gianni
MG
Del Gratta
Cosimo
C
Kakigi
Ryusuke
R
Romani
Gian Luca
GL
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D001931:Brain Mapping; D004558:Electric Stimulation; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006179:Gyrus Cinguli / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D013003:Somatosensory Cortex / Q000502:physiology*; D013649:Taste / Q000502:physiology; D055697:Taste Perception / Q000502:physiology*; D014059:Tongue / Q000502:physiology*