WORD RECOGNITION IN THE HUMAN INFERIOR TEMPORAL-LOBE

STUDIES of primates(1) and of patients with brain lesions(2) have shown that the visual system represents the external world in regions and pathways specialized to compute visual features and attributes. For example, object recognition is performed by a ventral pathway located in the inferior portion of the temporal lobe(3). We studied visual processing of words and word-like stimuli (letter-strings) by recording held potentials directly from the human inferior temporal lobe. Our results showed that two discrete portions of the fusiform gyrus responded preferentially to letter-strings. A region of the posterior fusiform gyrus responded equally to words and nonwords, and was unaffected by the semantic context in which words were presented. In contrast, a region of the anterior fusiform gyrus was sensitive to these stimulus dimensions. These regions were distinct from areas that responded to other types of complex visual stimuli, including faces and coloured patterns, and thus form a functionally specialized stream within the ventral visual pathway.