title: Spatially invariant coding of numerical information in functionally defined subregions of human parietal cortex.
abstract: Macaque electrophysiology has revealed neurons responsive to number in lateral (LIP) and ventral (VIP) intraparietal areas. Recently, fMRI pattern recognition revealed information discriminative of individual numbers in human parietal cortex but without precisely localizing the relevant sites or testing for subregions with different response profiles. Here, we defined the human functional equivalents of LIP (feLIP) and VIP (feVIP) using neurophysiologically motivated localizers. We applied multivariate pattern recognition to investigate whether both regions represent numerical information and whether number codes are position specific or invariant. In a delayed number comparison paradigm with laterally presented numerosities, parietal cortex discriminated between numerosities better than early visual cortex, and discrimination generalized across hemifields in parietal, but not early visual cortex. Activation patterns in the 2 parietal regions of interest did not differ in the coding of position-specific or position-independent number information, but in the expression of a numerical distance effect which was more pronounced in feLIP. Thus, the representation of number in parietal cortex is at least partially position invariant. Both feLIP and feVIP contain information about individual numerosities in humans, but feLIP hosts a coarser representation of numerosity than feVIP, compatible with either broader tuning or a summation code.
authors.affiliation: INSERM U992, Gif/Yvette, France CEA, DSV, I2BM, NeuroSpin, Gif/Yvette, France University Paris-Sud, Orsay, France and.
authors.forename: E
authors.initials: E
authors.lastname: Eger
authors.affiliation: INSERM U992, Gif/Yvette, France CEA, DSV, I2BM, NeuroSpin, Gif/Yvette, France University Paris-Sud, Orsay, France and.
authors.forename: P
authors.initials: P
authors.lastname: Pinel
authors.affiliation: INSERM U992, Gif/Yvette, France CEA, DSV, I2BM, NeuroSpin, Gif/Yvette, France University Paris-Sud, Orsay, France and.
authors.forename: S
authors.initials: S
authors.lastname: Dehaene
authors.affiliation: INSERM U992, Gif/Yvette, France CEA, DSV, I2BM, NeuroSpin, Gif/Yvette, France University Paris-Sud, Orsay, France and Department of Clinical Neurosciences, University Hospital (HUG) and University of Geneva, CH-1211 Geneva, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Kleinschmidt
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008433:Mathematics; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: fMRI; multivariate decoding; number processing; parietal cortex