Information received by the human cortex is supplied by two main sources: extrinsic stimuli delivered by the external environment and intrinsic information regarding the body and self. We reanalyzed electrophysiological data involving the same external stimuli, but manipulating the degree of ‘self-projection’ to locations inside and outside the body border. Electrical neuroimaging and spatial principal component analysis (PCA) showed a bipartition of the cerebral cortex into two main subsystems: occipital and frontal activity was similar across tasks; activity in temporo-parietal and anterior frontal regions was modulated according to the manipulation of self-projection in a given task. These data suggest that the first system relates to external stimulus processing (‘extrinsic’) and the latter one relates to processing of the ‘internal milieu’ of body and self (‘intrinsic’).
aDepartment of Neurology, Hadassah Hebrew University Hospital
bRacah Institute of Physics, Hebrew University, Jerusalem
cThe School of Education, Bar-Ilan University, Ramat-Gan, Israel
dLaboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
Correspondence to Shahar Arzy, MD, PhD, Department of Neurology, Hadassah Hebrew University Hospital Jerusalem, Israel
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Received 16 February 2010 accepted 15 March 2010