Abstract
We investigated the activation of posterior parietal cortex (PPC) to somatosensory stimulation in humans to determine its fundamental role as a somatosensory associated area using magnetoencephalography (MEG). We studied somatosensory evoked magnetic fields (SEF) after stimulation of median nerve, posterior tibial nerve and lip, and analyzed them by the single dipole model and also by the multidipole model using brain electric source analysis (BESA) system. In single source model analysis, the dipole at the peak latency of short-latency components following each site stimulation were located in the corresponding receptive fields in the primary somatosensory cortex (SI) contralateral to the stimulation. The dipole at the peak latency of the middle latency components were located in bilateral upper bank of Sylvian fissure (SII). By contrast, in the five-dipole model of BESA, the equivalent current dipoles (ECDs) of the middle-latency SEF after stimulation of median nerve and posterior tibial nerve were identified in the contralateral SI and in the bilateral SII and PPC, while all activities of middle-latency SEF after lip stimulation appeared to be restricted in the contralateral SI and bilateral SII. Around 80 msec in latency, the ECD location in PPC after median nerve stimulation was, on the average, 2.4 cm posterior, 2.9 cm medial and 2.6 cm superior to the hand area in SI. The ECD in PPC after posterior tibial nerve stimulation was also located posterior to the foot area in SI, but it was close to the SI area of foot, their distance being approximately 1.3 cm. ECD in PPC was almost equally demonstrated in each hemisphere. These findings suggested that the somatosensory associated cortex in PPC represented somatotopic organization in parallel with ‘homunculus’ in SI, but the hand area was much wider than the foot area. It was not clear whether the lip area in PPC was absent or was too close to be separated from the SI.
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References
Akhtari, M., McNay, D., Mandelkern, M., Teeter, B., Cline, H. E. Mallick, J., Clark, G., Tatar, R., Lufkin, R. and Chan, K. Somatosensory evoked response source localization using actual cortical surface as the spatial constraint. Brain Topography 1994, 7: 63–69.
Burton, H. Second somatosensory cortex and related areas. In E.G. Jones and A. Peters (Eds.), Cerebral cortex, Plenum, New York, 1986, 31–98.
Forss, N., Hari, R., Salmelin, R., Ahonen, A., Hämäläinen, M., Kajola, M., Knuutila, J and Simola, J. Activation of the human posterior parietal cortex by median nerve stimulation. Exp. Brain Res., 1994, 99: 309–315.
Henderson, C.J., Butler, S. R. and Glass, A. The localization of equivalent dipoles of EEG sources by the application of electrical field theory. Electroencepharogr. Clin. Neurophysiol., 1975, 39: 117–130.
Hoshiyama, M., Kakigi, R., Kitamura, S., Koyama, S., Shimojo, M. and Watanabe, S. Somatosensory magnetic evoked fields following stimulation of the lip in humans. Electroencepharogr. Clin. Neurophysiol., 1996, 100: 96–104.
Hoshiyama, M., Kakigi, R., Koyama, S., Kitamura, S. Shimojo, M. and Watanabe, S. Somatosensory evoked magnetic fields after mechanical stimulation of the scalp in humans. Neurosci. Lett., 1955, 95: 29–32.
Hyvärinen, J. Regional distribution of functions in parietal association area 7 of the monkey. Brain Res., 1981, 206: 287–303.
Hyvärinen, J. and Poranen, A. Movement-sensitive and direction and orientation-selective cutaneous receptive fields in the hand area of the post-central gyrus in monkeys. J. Physiol., 1978, 283: 523–537.
Iwamura, Y., Iriki, A. and Tanaka, M. Bilateral hand representation in the postcentral cortex. Nature, 1994, 369: 554–556.
Kaas, J. H. Somatosensory system. In G. Paxious (Ed.), The human nervous system, Academic, San Diego, 1990, 813–844.
Kakigi, R. Somatosensory evoked magnetic fields following median nerve stimulation. Neurosci. Res., 1994, 20: 165–174.
Kakigi, R., Koyama, S., Hoshiyama, M., Shimojo, M., Kitamura, Y. and Watanabe, S. Topography of somatosensory evoked magnetic fields following posterior tibial nerve stimulation. Electroencepharogr. Clin. Neurophysiol., 1995a, 95: 127–134.
Kakigi, R., Koyama, S., Hoshiyama, M., Watanabe, S., Shimojo, M. and Kitamura, Y. Gating of somatosensory evoked responses during active finger movements: magnetoencephalographic studies. J. Neurol. Sci., 1995b, 128: 195–204.
Leinonen, L. Integration of somatosensory events in the posterior parietal cortex of the monkey. In E. Eccles O. Franzen U. Lindblom and P. Ottoson (Eds.), Somatosensory mechanisms, Macmillan, London, 1984, 113–124.
Leinonen, L. and Nyman, G. II. Functional properties of cells in anterolateral part of area 7 associative face area of awake monkeys. Exp. Brain Res., 1979, 34: 321–333.
Lynch, J. C. The functional organization of posterior parietal association cortex. Behav. Brain Res., 1980, 3: 485–534.
MacKay, W. A., Kwan, M. C., Murphy, J. T. and Wong, Y. C. Responses to active and passive wrist rotation in area 5 of awake monkeys. Neurosci. Lett., 1978, 10: 235–239.
Mountcastle, V. B., Lynch, J. C., Georgopoulos, A., Sakata, H. and Acuna, C. Posterior parietal association cortex of the monkey:O command function for operations within extrapersonal space. J. Neurophysiol., 1975, 38: 871–908.
Penfield, W. and Boldray, E. Somatic motor and sensory representation in the cerebral cortex of man as studied by electrical stimulation. Brain, 1937, 60: 389–443.
Pons, T.P. and Kaas, J. H. Corticocortical connections of area 2 of somatosensory cortex in macaque monkeys: a correlative anatomical and electrophysiological study. J. Comp. Neurol., 1986, 248: 313–335.
Sakata, H. Somatic sensory responses of neurons in the parietal association area 5 of monkeys. In H. H. Kornhuber (Ed.), The somatosensory system, Thiem, Stuttgart, 1975, 250–261.
Sakata, H., Takaoka, Y., Kawarasaki, A. and Shibutani, H. Somatosensory properties of neurons in the superior parietal cortex (area 5) of the rehsus monkey. Brain Res., 1973, 64: 85–102.
Scherg, M. BESA-M (Version 2.1). MEGIS Software Gmbh, Munch, FRG, 1995.
Scherg, M. and Buchner, H. Somatosensory evoked potentials and magnetic fields: separation of multiple source activities. Physiol. Meas., 1993, 14(Suppl.A): A35–A39.
Scherg, M. and Von-Cramon, D. Evoked dipole source potentials of the human auditory cortex. Electorencepharogr. Clin. Neurophysiol., 1986, 65: 344–360.
Toro, C., Matsumoto, J., Deuschel, G., Roth, B.J. and Hallett, M. Source analysis of scalp-recorded movement-related electrical potentials. Electroencepharogr. Clin. Neurophysiol., 1993, 86: 167–175.
Valeriani, M., Restuccia, D., Di-Lazzaro V., Le-Pera, D. and Tonali, P. The pathophysiology of giant SEPs in cortical myoclonus: a scalp topography and dipolar source modeling study. Electroencepharogr. Clin. Neurophysiol., 1997, 104: 122–131.
Yeterian, E. H. and Pandya, D. N. Corticothalamic connections of the posterior parietal cortex in the rhesus monkey. J. Comp. Neurol.; 1985, 237: 408–426.
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Hoshiyama, M., Kakigi, R., Koyama, S. et al. Activity in Posterior Parietal Cortex Following Somatosensory Stimulation in Man: Magnetoencephalographic Study Using Spatio-Temporal Source Analysis. Brain Topogr 10, 23–30 (1997). https://doi.org/10.1023/A:1022206906360
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DOI: https://doi.org/10.1023/A:1022206906360