Reduced gray matter volume of pars opercularis is associated with impaired social communication in high-functioning autism spectrum disorders.
BACKGROUND
Recent literature suggests that the inferior frontal gyrus, especially its posterior portion, has an important role in imitation and social reciprocity and in the pathophysiology of their disturbance in autism spectrum disorders (ASD). However, the structural abnormality of this region has not fully been clarified in subjects with ASD.


METHODS
Here we obtained magnetic resonance images from 13 right-handed men with high-functioning ASD (Asperger disorder [n = 10] or autism [n = 3]) and from 11 age-, parental socioeconomic background-, and intelligence quotient-matched right-handed typical men. A reliable manual tracing methodology was employed to measure the gray matter volume of the pars opercularis, corresponding to Brodmann area 44, and the pars triangularis, corresponding to Brodmann area 45.


RESULTS
A significant gray matter volume reduction of both the pars opercularis and triangularis was found bilaterally in the subjects with ASD compared with the typical control subjects. The effect size seemed to be larger for pars opercularis (1.25) than for pars triangularis (.90). The reduced volume of right as well as total pars opercularis showed a significant association with the increased severity of social communication problems in the ASD group.


CONCLUSIONS
The current findings support an important role of pars opercularis, a center of the mirror neuron system, in the pathophysiology of ASD.
Yamasaki
Syudo
S
Department of Neuropsychiatry, University of Tokyo, Japan.
Yamasue
Hidenori
H
Abe
Osamu
O
Suga
Motomu
M
Yamada
Haruyasu
H
Inoue
Hideyuki
H
Kuwabara
Hitoshi
H
Kawakubo
Yuki
Y
Yahata
Noriaki
N
Aoki
Shigeki
S
Kano
Yukiko
Y
Kato
Nobumasa
N
Kasai
Kiyoto
K
D000293:Adolescent; D000328:Adult; D001284:Atrophy / Q000523:psychology; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000150:complications / Q000473:pathology* / Q000523:psychology*; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D036421:Nerve Fibers, Unmyelinated / Q000473:pathology*; D011859:Radiography; D012920:Social Behavior Disorders / Q000150:complications / Q000473:pathology*