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PET reveals occipitotemporal pathway activation during elementary form perception in humans

Published online by Cambridge University Press:  01 March 1998

LORI L. BEASON-HELD
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
KEITH P. PURPURA
Affiliation:
Department of Neurology and Neuroscience, Cornell University Medical College, New York
JOHN W. VAN METER
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
NINA P. AZARI
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
DAVID J. MANGOT
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
LANCE M. OPTICAN
Affiliation:
Section on Neural Modeling, National Eye Institute, National Institutes of Health, Bethesda
MARC J. MENTIS
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
GENE E. ALEXANDER
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
CHERYL L. GRADY
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
BARRY HORWITZ
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
STANLEY I. RAPOPORT
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda
MARK B. SCHAPIRO
Affiliation:
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda

Abstract

To define brain regions involved in feature extraction or elementary form perception, regional cerebral blood flow (rCBF) was measured using positron emission tomography (PET) in subjects viewing two classes of achromatic textures. Textures composed of local features (e.g. extended contours and rectangular blocks) produced activation or increased rCBF along the occipitotemporal pathway relative to textures with the same mean luminance, contrast, and spatial-frequency content but lacking organized form elements or local features. Significant activation was observed in striate, extrastriate, lingual, and fusiform cortices as well as the hippocampus and brain stem. On a scan-by-scan basis, increases in rCBF shifted from the occipitotemporal visual cortices to medial temporal (hippocampus) and frontal lobes with increased exposure to only those textures containing local features. These results suggest that local feature extraction occurs throughout the occipitotemporal (ventral) pathway during extended exposure to visually salient stimuli, and may indicate the presence of similar receptive-field mechanisms in both occipital and temporal visual areas of the human brain.

Type
Research Article
Copyright
1998 Cambridge University Press

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