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This Article Full Text Full Text (PDF) All Versions of this Article: 101/6/3246    most recent 91264.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Jung, P. Articles by Treede, R.-D. PubMed PubMed Citation Articles by Jung, P. Articles by Treede, R.-D.

Structural and Functional Asymmetry in the Human Parietal Opercular Cortex

¹Department of Neurology, Johann Wolfgang Goethe University, Frankfurt am Main; ²Chair of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim, Ruprecht Karl University of Heidelberg, Mannheim; and ³Institute of Neuroradiology, Johannes Gutenberg University, Mainz, Germany

Submitted 27 November 2008; accepted in final form 1 January 2009

In this combined electroencephalographic and magnetic resonance imaging (MRI) study, the asymmetry of functional and structural measures in the human parietal operculum (PO) were investigated. Median nerve somatosensory evoked potential recordings showed maximum scalp potentials over contralateral (N80, N110) and ipsilateral (N100, N130) temporal electrode positions. In accordance, MRI-coregistered source analysis revealed two electrical sources in the contralateral (N80, N110) and two in the ipsilateral (N100, N130) PO. The dipole orientations of the contra- and ipsilateral sources with earlier peak activation, N80 and N100, were more tangential than those of the later peaking N110 and N130 sources. The most prominent contralateral N110 source exhibited pronounced left lateralized dipole strengths in the 80- to 120-ms latency range, in contrast to symmetrical N80 and ipsilateral source responses. The asymmetry of the N110 source activity explained both the asymmetry of N110 and N100 scalp potentials. Morphometric analysis demonstrated no interhemispheric differences in the sizes of the anterior PO (aPO), containing the cytoarchitectonic areas OP3 and OP4, but left lateralized sizes of the posterior PO (pPO), which encompasses the anatomically defined areas OP1 and OP2. The N110 source was located in the pPO and its asymmetry was significantly correlated with the structural pPO asymmetry but not with handedness and auditory lateralization. Thus both structural and functional asymmetries exist in the human PO and they are closely related to each other but not to measures of brain asymmetry in other functional systems, i.e., auditory lateralization and handedness.