A sequence of object-processing stages revealed by fMRI in the human occipital lobe

✍ Scribed by Kalanit Grill-Spector; Tammar Kushnir; Talma Hendler; Shimon Edelman; Yacov Itzchak; Rafael Malach

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 1008 KB
• Volume: 6
• Category: Article
• ISSN: 1065-9471
• DOI: 10.1002/(sici)1097-0193(1998)6:4<316::aid-hbm9>3.0.co;2-6

✦ Synopsis

Functional magnetic resonance imaging was used in combined functional selectivity and retinotopic mapping tests to reveal object-related visual areas in the human occpital lobe. Subjects were tested with right, left, up, or down hemivisual field stimuli which were composed of images of natural objects (faces, animals, man-made objects) or highly scrambled (1,024 elements) versions of the same images. In a similar fashion, the horizontal and vertical meridians were mapped to define the borders of these areas. Concurrently, the same cortical sites were tested for their sensitivity to image-scrambling by varying the number of scrambled picture fragments (from 16-1,024) while controlling for the Fourier power spectrum of the pictures and their order of presentation. Our results reveal a stagewise decrease in retinotopy and an increase in sensitivity to image-scrambling. Three main distinct foci were found in the human visual object recognition pathway (Ungerleider and Haxby [1994]: Curr Opin Neurobiol 4:157-165): 1) Retinotopic primary areas V1-3 did not exhibit significant reduction in activation to scrambled images. 2) Areas V4v (