Direct intracranial, FMRI, and lesion evidence for the causal role of left inferotemporal cortex in reading.
Models of the "visual word form system" postulate that a left occipitotemporal region implements the automatic visual word recognition required for efficient reading. This theory was assessed in a patient in whom reading was explored with behavioral measures, fMRI, and intracranial local field potentials. Prior to surgery, when reading was normal, fMRI revealed a normal mosaic of ventral visual selectivity for words, faces, houses, and tools. Intracranial recordings demonstrated that the left occipitotemporal cortex responded with a short latency to conscious but also to subliminal words. Surgery removed a small portion of word-responsive occipitotemporal cortex overlapping with the word-specific fMRI activation. The patient developed a marked reading deficit, while recognition of other visual categories remained intact. Furthermore, in the post-surgery fMRI map of visual cortex, only word-specific activations disappeared. Altogether, these results provide direct evidence for the causal role of the left occipitotemporal cortex in the recognition of visual words.
Gaillard
Raphaël
R
INSERM, U562, CEA/DSV, IFR 49, Orsay, France.
Naccache
Lionel
L
Pinel
Philippe
P
Clémenceau
Stéphane
S
Volle
Emmanuelle
E
Hasboun
Dominique
D
Dupont
Sophie
S
Baulac
Michel
M
Dehaene
Stanislas
S
Adam
Claude
C
Cohen
Laurent
L
D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology* / Q000601:surgery; D004411:Dyslexia, Acquired / Q000209:etiology / Q000503:physiopathology*; D004827:Epilepsy / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011932:Reading