title: Effects of number magnitude and notation at 7T: separating the neural response to small and large, symbolic and nonsymbolic number.
abstract: We examined the effects of number magnitude (within vs. outside the subitizable range) and notation (symbolic vs. nonsymbolic number) on neural responses to visual displays in the human brain using fMRI at 7T. We found that the right temporoparietal junction (rTPJ) responded more strongly to small than to larger numbers (2, 4 > 6, 8), while there was greater activity bilaterally within and around the intraparietal sulcus (IPS) as number magnitude increased (6, 8 > 2, 4). The effects of number magnitude were greatest for nonsymbolic stimuli. In addition, there was striking overlap between rTPJ regions responding to small numbers and those most strongly activated by symbolic stimuli, and between IPS regions responding to large numbers and those most activated by nonsymbolic stimuli. The results are consistent with distinct neural processes recruited for the processing of small- and large-number magnitudes. Contributions due to differences in representing exact number (small nonsymbolic arrays and all symbolic numbers, in rTPJ) and overall magnitude (particularly with large nonsymbolic arrays, in IPS), and the associated theoretical implications of the findings, are discussed.
authors.affiliation: State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China and lixiahe82@gmail.com.
authors.forename: Lixia
authors.initials: L
authors.lastname: He
authors.affiliation: State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China and.
authors.forename: Zhentao
authors.initials: Z
authors.lastname: Zuo
authors.affiliation: State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China and.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: Departmentof Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK.
authors.forename: Glyn
authors.initials: G
authors.lastname: Humphreys
mesh_terms: D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D055641:Mathematical Concepts; D008606:Mental Processes / Q000502:physiology*; D010775:Photic Stimulation; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: fMRI at 7T; intraparietal sulcus; numerical cognition; right TPJ