LEVELS OF CATEGORIZATION IN VISUAL RECOGNITION STUDIED USING FUNCTIONAL MAGNETIC-RESONANCE-IMAGING

Background: Recent functional neuroimaging results implicate part of t he ventral temporal lobe of the brain in face recognition, and have, t ogether with neurophysiological findings, been used as evidence for a face-specific neural module in the brain. Experimental designs, howeve r, have often failed to distinguish between the class of the object us ed as the stimulus (face or non-face) and the level of categorization at which the stimulus is recognized (the 'basic' level, such as 'bird' , at which familiar objects are first recognized, or more subordinate levels - 'sparrow', for example - which require additional perceptual processing), We have used echo-planar functional magnetic resonance im aging to compare brain activation for the matching of non-face objects with subordinate-level and basic-level descriptors, Results: The addi tional visual processing required to verify the subordinate level of a picture over its basic level was associated with activation of the fu siform and inferior temporal gyri (FIT) as well as the temporal poles, These areas correspond closely to those previously implicated in the processing of facial images. Conclusions: Our results indicate that ar eas of the ventral visual pathway that have been associated with face recognition are sensitive to manipulations of the categorization level of non-face objects, This idea offers an alternative to the dominant view that FIT may be organized according to conceptual categories, and our results establish the importance oi: manipulating task requiremen ts when evaluating a 'neural module' hypothesis.