Structural and Functional Asymmetry in the Human Parietal Opercular Cortex
Journal of Neurophysiology
Jung P, Baumgä rtner U, Stoeter P, Treede R-D. Structural and functional asymmetry in the human parietal opercular cortex. . 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
... cordance, 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 contraand 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. Backes WH, Mess WH, van Kranen-Mastenbroek V, Reulen JP. Somatosensory cortex responses to median nerve stimulation: fMRI effects of current amplitude and selective attention. Clin Neurophysiol 111: 1738 -1744, 2000. Baumgärtner U, Vogel H, Ellrich J, Gawehn J, Stoeter P, Treede RD. Brain electrical source analysis of primary cortical components of the tibial nerve somatosensory evoked potential using regional sources. Electroencephalogr Clin Neurophysiol 108: 588 -599, 1998. Bear D, Schiff D, Saver J, Greenberg M, Freeman R. Quantitative analysis of cerebral asymmetries. Fronto-occipital correlation, sexual dimorphism and association with handedness. Arch Neurol 43: 598 -603, 1986. Brody CD, Hernandez A, Zainos A, Lemus L, Romo R. Analysing neuronal correlates of the comparison of two sequentially presented sensory stimuli. areas within the lateral sulcus connected to cutaneous representations in areas 3b and 1: a revised interpretation of the second somatosensory area in macaque monkeys. J Comp Neurol 355: 539 -562, 1995. Burton H, Videen TO, Raichle ME. Tactile-vibration-activated foci in insular and parietal-opercular cortex studied with positron emission tomography: mapping the second somatosensory area in humans. Somatosens Mot Res 10: 297-308, 1993. Coghill RC, Gilron I, Iadarola MJ. Hemispheric lateralization of somatosensory processing. J Neurophysiol 85: 2602-2612, 2001. Corballis MC. From mouth to hand: gesture, speech, and the evolution of right-handedness. Behav Brain Sci 26: 199 -208; discussion 208 -160, 2003. Dassonville P, Zhu XH, Uurbil K, Kim SG, Ashe J. Functional activation in motor cortex reflects the direction and the degree of handedness. Proc Natl Acad Sci USA 94: 14015-14018, 1997. Dijkerman HC, de Haan EH. Somatosensory processes subserving perception and action. Behav Brain Sci 30: 189 -201; discussion 201-139, 2007. Disbrow E, Litinas E, Recanzone GH, Padberg J, Krubitzer L. Cortical connections of the second somatosensory area and the parietal ventral area in macaque monkeys.