Distributed and overlapping cerebral representations of number, size, and luminance during comparative judgments.
How are comparative judgments performed in the human brain? We scanned subjects with fMRI while they compared stimuli for size, luminance, or number. Regions involved in comparative judgments were identified using three criteria: task-related activation, presence of a distance effect, and interference of one dimension onto the other. We observed considerable overlap in the neural substrates of the three comparison tasks. Interestingly, the amount of overlap predicted the amount of cross-dimensional interference: in both behavior and fMRI, number interfered with size, and size with luminance, but number did not interfere with luminance. The results suggest that during comparative judgments, the relevant continuous quantities are represented in distributed and overlapping neural populations, with number and size engaging a common parietal spatial code, while size and luminance engage shared occipito-temporal perceptual representations.
Pinel
Philippe
P
INSERM Unit 562, Service Hospitalier Frédéric Joliot, CEA/DRM/DSV, 4 Place du Général Leclerc, 91401 Orsay Cedex, France. pinel@shfj.cea.fr
Piazza
Manuela
M
Le Bihan
Denis
D
Dehaene
Stanislas
S
D000328:Adult; D001931:Brain Mapping; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008029:Lighting; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology*; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000502:physiology; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology