title: Dynamic mediolateral activation of the pyramidal cell population in human somatosensory 3b area can be visualized by magnetic recordings.
abstract: Dynamic mediolateral activation in the pyramidal cell population of the human somatosensory 3b area was studied non-invasively. Somatosensory evoked fields (SEFs) were recorded over the hand area contralateral to the right median nerve stimulation at the wrist. Localization of an equivalent current dipole (ECD) for N20m primary cortical response was successively calculated for periods of 2.4 ms around N20m peak where the signal-to-noise ratio exceeded 100 and the spatial resolution was approximately 0.3 mm. The ECD moved toward the anterior, lateral and inferior direction for a distance of 8.7 mm at a propagation velocity of 3.6 m/s. This direction was orthogonal to the orientation of apical dendrites of the pyramidal neurons in area 3b and parallel to the surface of the posterior bank of the central sulcus. These findings suggest that the sequential mediolateral activation of the pyramidal cells in the somatosensory cortex is mediated by horizontal connections running parallel to the cortical surface.
authors.affiliation: Department of Psychophysiology, Tokyo Institute of Psychiatry, Tokyo Metropolitan Organization for Medical Research, Japan. ihashi@prit.go.jp
authors.forename: I
authors.initials: I
authors.lastname: Hashimoto
authors.forename: T
authors.initials: T
authors.lastname: Kimura
authors.forename: K
authors.initials: K
authors.lastname: Sakuma
authors.forename: Y
authors.initials: Y
authors.lastname: Iguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Saito
authors.forename: O
authors.initials: O
authors.lastname: Terasaki
authors.forename: T
authors.initials: T
authors.lastname: Fukushima
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D017966:Pyramidal Cells / Q000166:cytology / Q000502:physiology*; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology*