Functional segregation of cortical language areas by sentence repetition.
The functional organization of the perisylvian language network was examined using a functional MRI (fMRI) adaptation paradigm with spoken sentences. In Experiment 1, a given sentence was presented every 14.4 s and repeated two, three, or four times in a row. The study of the temporal properties of the BOLD response revealed a temporal gradient along the dorsal-ventral and rostral-caudal directions: From Heschl's gyrus, where the fastest responses were recorded, responses became increasingly slower toward the posterior part of the superior temporal gyrus and toward the temporal poles and the left inferior frontal gyrus, where the slowest responses were observed. Repetition induced a decrease in amplitude and a speeding up of the BOLD response in the superior temporal sulcus (STS), while the most superior temporal regions were not affected. In Experiment 2, small blocks of six sentences were presented in which either the speaker voice or the linguistic content of the sentence, or both, were repeated. Data analyses revealed a clear asymmetry: While two clusters in the left superior temporal sulcus showed identical repetition suppression whether the sentences were produced by the same speaker or different speakers, the homologous right regions were sensitive to sentence repetition only when the speaker voice remained constant. Thus, hemispheric left regions encode linguistic content while homologous right regions encode more details about extralinguistic features like speaker voice. The results demonstrate the feasibility of using sentence-level adaptation to probe the functional organization of cortical language areas.
Unité INSERM 562, Service Hospitalier Frédéric Joliot, CEA/DRM/DSV, Orsay, France. gdehaene2shfj.cea.fr
Ghislaine
G
Dehaene-Lambertz
Stanislas
S
Dehaene
Jean-Luc
JL
Anton
Aurelie
A
Campagne
Philippe
P
Ciuciu
Guillaume P
GP
Dehaene
Isabelle
I
Denghien
Antoinette
A
Jobert
Denis
D
Lebihan
Mariano
M
Sigman
Christophe
C
Pallier
Jean-Baptiste
JB
Poline
D000328:Adult; D001288:Attention / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D019260:Expressed Emotion / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000502:physiology; D014705:Verbal Behavior / Q000502:physiology*