Cue-invariant activation in object-related areas of the human occipital lobe.
The extent to which primary visual cues such as motion or luminance are segregated in different cortical areas is a subject of controversy. To address this issue, we examined cortical activation in the human occipital lobe using functional magnetic resonance imaging (fMRI) while subjects performed a fixed visual task, object recognition, using three different primary visual cues: motion, texture, or luminance contrast. In the first experiment, a region located on the lateral aspect of the occipital lobe (LO complex) was preferentially activated in all 11 subjects both by luminance and motion-defined object silhouettes compared to full-field moving and stationary noise (ratios, 2.00+/-0.19 and 1.86+/-0.65, respectively). In the second experiment, all subjects showed enhanced activation in the LO complex to objects defined both by luminance and texture contrast compared to full-field texture patterns (ratios, 1.43+/-0.08 and 1.32+/-0.08, respectively). An additional smaller dorsal focus that exhibited convergence of object-related cues appeared to correspond to area V3a or a region slightly anterior to it. These results show convergence of visual cues in LO and provide strong evidence for its role in object processing.
Weizmann Institute of Science, Rehovot, Israel.
K
K
Grill-Spector
T
T
Kushnir
S
S
Edelman
Y
Y
Itzchak
R
R
Malach
D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology; D003463:Cues; D005260:Female; D006801:Humans; D008027:Light; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology; D009778:Occipital Lobe / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D014796:Visual Perception / Q000502:physiology*