Neural Mechanisms for Response Selection: Representation Specific or Modality Independent?
Journal of Cognitive Neuroscience
Common Neural Substrates for Response Selection across Modalities and Mapping Paradigms
Journal of Cognitive Neuroscience
Parietal Representation of Symbolic and Nonsymbolic Magnitude
Journal of Cognitive Neuroscience
Journal of Cognitive Neuroscience
Journal of Cognitive Neuroscience
Motor Area Activity During Mental Rotation Studied by Time-Resolved Single-Trial fMRI
Journal of Cognitive Neuroscience
Imaging Cognition II: An Empirical Review of 275 PET and fMRI Studies
Journal of Cognitive Neuroscience
Differential Contributions of the Left and Right Inferior Parietal Lobules to Number Processing
Journal of Cognitive Neuroscience
Graded Functional Activation in the Visuospatial System with the Amount of Task Demand
Journal of Cognitive Neuroscience
Order and magnitude share a common representation in parietal cortex
Journal of Cognitive Neuroscience
The neural development of an abstract concept of number
Journal of Cognitive Neuroscience
The role of right and left parietal lobes in the conceptual processing of numbers
Journal of Cognitive Neuroscience
Neural correlates of symbolic number comparison in developmental dyscalculia
Journal of Cognitive Neuroscience
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Neuroimaging studies of number comparison have consistently found activation in the intraparietal sulcus (IPS). Recently, it has been suggested that activations in the IPS vary with the distance between the numbers being compared. In number comparison, the smaller the distance between a number and the reference the longer the reaction time (RT ). Activations in the right or left IPS, however, have also been related to attentional and intentional selection. It is possible, therefore, that activity in this region is a reflection of the more basic stimulus and response-selection processes associated with changes in RT. This fMRI experiment investigated the effect of numerical distance independently from RT. In addition, activations during number comparison of single-digit and double-digit stimuli were compared. During number comparison blocks, subjects had to indicate whether digits were greater or smaller than a reference (5 or 65). In control blocks, they were asked to perform a perceptual task (vertical line present/absent) on either numerical or nonnumerical stimuli. Number comparison versus rest yielded a large bilateral parietal-posterior frontal network. However, no areas showed more activation during number comparison than during the control tasks. Furthermore, no areas were more active during comparison of numbers separated by a small distance than comparisons of those separated by a large distance or vice versa. A left-lateralized parietal-posterior frontal network varied significantly with RT. Our findings suggest that magnitude and numerical-distance-related IPS activations might be difficult to separate from fundamental stimulus and response-selection processes associated with RT changes. As is the case with other parameters, such as space, magnitude may be represented in the context of response selection in the parietal cortex. In this respect, the representation of magnitude in the human IPS may be similar to the representation of magnitude in other nonhuman primates.