Neuroimaging study on brain asymmetries in situs inversus totalis.
Situs inversus totalis (SI) is a rare condition in which all visceral organs are arranged as mirror images of the usual pattern. The objective of this study was to determine whether SI individuals have reversed brain asymmetries. We performed a neuroimaging study on 3 SI subjects and 11 control individuals with normally arranged visceral organs. The language-dominant hemisphere was determined by magnetoencephalography. Left-hemispheric dominance was observed in 1 SI subject and all controls, whereas right-hemispheric dominance was observed in the remaining 2 SI subjects. Statistical analysis revealed that language dominance patterns in SI subjects were different from those in the controls, suggesting that the developmental mechanisms underlying visceral organ asymmetries are related to those underlying functional brain asymmetry. Anatomical brain asymmetries were determined by magnetic resonance imaging. SI subjects had the same planum temporale (PT) asymmetry pattern as the controls, but a reversed petalia asymmetry pattern. The inferior frontal gyrus (IFG) asymmetry pattern varied within both groups, indicating a relationship between the rightward IFG and right-hemispheric language dominance. These results suggest that the developmental mechanisms underlying visceral organ asymmetries are related to those underlying petalia asymmetry but not to those underlying PT and IFG asymmetries, and that brain asymmetries might develop via multiple region-dependent mechanisms.
Ihara
Aya
A
Biological ICT Group, Kobe Advanced ICT Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan. ihara@po.nict.go.jp
Hirata
Masayuki
M
Fujimaki
Norio
N
Goto
Tetsu
T
Umekawa
Yuka
Y
Fujita
Norihiko
N
Terazono
Yasushi
Y
Matani
Ayumu
A
Wei
Qiang
Q
Yoshimine
Toshiki
T
Yorifuji
Shiro
S
Murata
Tsutomu
T
D000328:Adult; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology*; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D017397:Prefrontal Cortex / Q000473:pathology; D012857:Situs Inversus / Q000473:pathology*