title: Evoked magnetic fields following noxious laser stimulation of the thigh in humans.
abstract: Primary somatosensory cortex (SI) and posterior parietal cortex (PPC) are activated by noxious stimulation. In neurophysiological studies using magnetoencephalography (MEG), however, it has been difficult to separate the activity in SI from that in PPC following stimulation of the upper limb, since the hand area of SI is very close to PPC. Therefore, we investigated human pain processing using MEG following the application of a thulium-YAG laser to the left thigh to separate the activation of SI and PPC, and to clarify the time course of the activities involved. The results indicated that cortical activities were recorded around SI, contralateral secondary somatosensory cortex (cSII), ipsilateral secondary somatosensory cortex (iSII), and PPC between 150-185 ms. The precise location of PPC was indicated to be the inferior parietal lobule (IPL), corresponding to Brodmann's area 40. The mean peak latencies of SI, cSII, iSII and IPL were 152, 170, 181, and 183 ms, respectively. This is the first study to clarify the time course of the activities of SI, SII, and PPC in human pain processing using MEG.
authors.affiliation: Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, 444-8585, Japan. nakata@nips.ac.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nakata
authors.forename: Yohei
authors.initials: Y
authors.lastname: Tamura
authors.forename: Kiwako
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Kosuke
authors.initials: K
authors.lastname: Akatsuka
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hirai
authors.forename: Koji
authors.initials: K
authors.lastname: Inui
authors.forename: Minoru
authors.initials: M
authors.lastname: Hoshiyama
authors.forename: Youichi
authors.initials: Y
authors.lastname: Saitoh
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Katayama
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Kakigi
mesh_terms: D000328:Adult; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D007834:Lasers; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010812:Physical Stimulation / Q000379:methods*; D013003:Somatosensory Cortex / Q000503:physiopathology*; D013848:Thigh / Q000294:innervation / Q000503:physiopathology*