Left anterior temporal cortex actively engages in speech perception: A direct cortical stimulation study.
Recent neuroimaging studies proposed the importance of the anterior auditory pathway for speech comprehension. Its clinical significance is implicated by semantic dementia or pure word deafness. Neurodegenerative or cerebrovascular nature, however, precluded precise localization of the cortex responsible for speech perception. Electrical cortical stimulation could delineate such localization by producing transient, functional impairment. We investigated engagement of the left anterior temporal cortex in speech perception by means of direct electrical cortical stimulation. Subjects were two partial epilepsy patients, who underwent direct cortical stimulation as a part of invasive presurgical evaluations. Stimulus sites were coregistered to presurgical 3D-MRI, and then to MNI standard space for anatomical localization. Separate from the posterior temporal language area, electrical cortical stimulation revealed a well-restricted language area in the anterior part of the superior temporal sulcus and gyrus (aSTS/STG) in both patients. Auditory sentence comprehension was impaired upon electrical stimulation of aSTS/STG. In one patient, additional investigation revealed that the functional impairment was restricted to auditory sentence comprehension with preserved visual sentence comprehension and perception of music and environmental sounds. Both patients reported that they could hear the voice but not understand the sentence well (e.g., heard as a series of meaningless utterance). The standard coordinates of this restricted area at left aSTS/STG well corresponded with the coordinates of speech perception reported in neuroimaging activation studies in healthy subjects. The present combined anatomo-functional case study, for the first time, demonstrated that aSTS/STG in the language dominant hemisphere actively engages in speech perception.
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Kyoto, Japan. Electronic address: matsumot@kuhp.kyoto-u.ac.jp.
Riki
R
Matsumoto
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Kyoto, Japan.
Hisaji
H
Imamura
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Kyoto, Japan.
Morito
M
Inouchi
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Kyoto, Japan.
Tomokazu
T
Nakagawa
Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Yohei
Y
Yokoyama
Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Masao
M
Matsuhashi
Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Nobuhiro
N
Mikuni
Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Susumu
S
Miyamoto
Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Hidenao
H
Fukuyama
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Kyoto, Japan.
Ryosuke
R
Takahashi
Department of Neurology, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Kyoto, Japan.
Akio
A
Ikeda
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D032882:Comprehension; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology*; D014825:Vocabulary