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Abstract:
Dehaene et al (1999) found that areas of parietal cortex show
greater activation during approximate addition tasks than during
control tasks on letter stimuli. This activation has been explained
in terms of a spatial analog "number line" which is called upon for
tasks involving approximate quantity (Dehaene et al., 1999).
However, another study (Wojciulik & Kanwisher, 1999) found
similar areas to be activated in a very different task that has
little or no spatial component: visual search for
foveally-presented conjunction versus feature target letters in
rapid serial visual presentation. We used fMRI to test whether the
activations observed during these two very different tasks are
merely nearby, or actually overlapping. Preliminary data suggest
that the activations for the nonspatial attentional task and the
approximate arithmetic task do in fact overlap in the region of the
intraparietal sulcus. This finding suggests that the function of
this region may be broader than encompassed by prior
hypotheses.
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