Age-dependent plasticity in the superior temporal sulcus in deaf humans: a functional MRI study.
BACKGROUND
Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language.


RESULTS
The sign-comprehension tasks activated the planum temporale of both early- and late-deaf subjects, but not that of hearing signers. In early-deaf subjects, the middle superior temporal sulcus was more prominently activated than in late-deaf subjects.


CONCLUSIONS
As the middle superior temporal sulcus is known to respond selectively to human voices, our findings suggest that this subregion of the auditory-association cortex, when deprived of its proper input, might make a functional shift from human voice processing to visual processing in an age-dependent manner.
Sadato
Norihiro
N
National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan. sadato@nips.ac.jp
Yamada
Hiroki
H
Okada
Tomohisa
T
Yoshida
Masaki
M
Hasegawa
Takehiro
T
Matsuki
Ken-Ichi
K
Yonekura
Yoshiharu
Y
Itoh
Harumi
H
D000328:Adult; D000367:Age Factors; D001303:Auditory Cortex / Q000033:anatomy & histology / Q000503:physiopathology*; D003638:Deafness / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity; D012813:Sign Language