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Abstract:
In this paper we analyze the EEG changes observed during
figure and word categorization tasks. If the EEG changes were
similar for pictures or words we will consider that they
corresponded with similar processes, whereas differences between
the EEG changes for words and pictures, may indicate independent
systems. EEG was recorded during word and figure categorization in
a group of 28 children between 8-10 years old. Computation of EEG
sources in the frequency domain using Variable Resolution
Electromagnetic Tomography and their statistical evaluation by
multivariate nonparametric permutational tests were carried out.
Our results point towards: a) A common attentional system
represented by frequencies within the beta band that change in
anterior cingulate, premotor and superior parietal areas; b) A
common amodal extense semantic system observed in frontal, temporal
and parietal lobes represented by frequencies at 3.12 and 7.02 Hz;
c) An independent system for figure categorization signaled by
1.56, 2.34 and 7.80 Hz at left and right temporal and prefrontal
areas, and by 13.26 and 14.04 Hz at ventral prefrontal regions, and
d) An independent system for word categorization represented by
3.90, 4.68 and 5.46 Hz at temporal and ventro occipitotemporal
areas, and frequencies from 8.58 to 17.14 Hz that change at
parieto-occipital regions. Partial support was given by
CONACYT.
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