Koten, Jan Willem;
Micro and macro pattern analyses of FMRI data support both early and late interaction of numerical and spatial information
In: Frontiers in Human Neuroscience,
URL des Volltextes:
3a. Beiträge in begutachteten Zeitschriften; Aufsatz (keine besondere Kategorie)
Numbers and space are two semantic primitives that interact with each other. Both recruit brain regions along the dorsal pathway, notably parietal cortex. This makes parietal cor- tex a candidate for the origin of numerical spatial interaction. The underlying cognitive architecture of the interaction is still under scrutiny. Two classes of explanations can be dis- tinguished. The early interaction approach assumes that numerical and spatial information are integrated into a single representation at a semantic level. A second approach pos- tulates independent semantic representations. Only at the stage of response selection and preparation these two streams interact. In this study we used a numerical landmark task to identify the locus of the interaction between numbers and space. While lying in an MR scanner participants decided on the smaller of two numerical intervals in a visually presented number triplet. The spatial position of the middle number was varied; hence spatial intervals were congruent or incongruent with the numerical intervals. Responses in incongruent trials were slower and less accurate than in congruent trials. By combining across-vertex correlations (micro pattern) with a cluster analysis (macro pattern) we identi- fied large-scale networks that were devoted to number processing, eye movements, and sensory motor functions. Using support vector classification in different regions of inter- est along the intraparietal sulcus, the frontal eye fields, and supplementary motor area we were able to distinguish between congruent and incongruent trials in each of the networks. We suggest that the identified networks participate in the integration of numerical and spa- tial information and that the exclusive assumption of either an early or a late interaction between numerical and spatial information does not do justice to the complex interaction between both dimensions.
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