Experimental Brain Research

, Volume 189, Issue 3, pp 311–321

Cortical processing of tactile stimuli applied in quick succession across the fingertips: temporal evolution of dipole sources revealed by magnetoencephalography

  • Elissaios Karageorgiou
  • Ioannis G. Koutlas
  • Aurelio A. Alonso
  • Arthur C. Leuthold
  • Scott M. Lewis
  • Apostolos P. Georgopoulos
Research Article

DOI: 10.1007/s00221-008-1425-6

Cite this article as:
Karageorgiou, E., Koutlas, I.G., Alonso, A.A. et al. Exp Brain Res (2008) 189: 311. doi:10.1007/s00221-008-1425-6

Abstract

We used magnetoencephalography (MEG) in 10 healthy human subjects to study cortical responses to tactile stimuli applied to the fingertips of digits 2–5 of the right hand. Each stimulus lasted 50 ms and was produced by air-driven elastic membranes. Four-hundred stimuli were delivered on each finger in three temporal patterns (conditions). In the “Discrete” condition, stimuli were applied to each finger repetitively with an interstimulus interval (ISI) of 1–2 s. In the “Continuous” condition, stimuli were applied to the fingers sequentially as four-stimulus trains with zero ISI and 1–2 s intervening between trains. Finally, in the “Gap” condition, stimuli were applied as in the Continuous condition but with an ISI of 50 ms. A sensation of tactile motion across fingers (digit 2 → digit 5) was reported by all subjects in the Continuous and Gap conditions. Cortical responses were extracted as single equivalent current dipoles over a period of 1 s following stimulus onset. In all three conditions, initial responses in left primary somatosensory cortex (SI) were observed ~20 to 50 ms after stimulus onset and were followed by additional left SI responses and bilateral responses in the secondary somatosensory cortex (SII). In addition, in the Continuous and Gap conditions, there was an activation of the precentral gyrus, the temporal aspects of which depended on the temporal relation of the administered stimuli, as follows. An ISI of 0 ms led to activation of the precentral gyrus shortly after the second stimulation, whereas an ISI of 50 ms led to activation of the precentral gyrus after the third stimulation. The current findings support results from previous studies on temporal activity patterns in SI and SII, verify the participation of the precentral gyrus during tactile motion perception and, in addition, reveal aspects of integration of sequential sensory stimulations over nonadjacent areas as well as temporal activity patterns in the postcentral and precentral gyri.

Keywords

MagnetoencephalographyDipolesSomatosensoryCerebral cortexMotion perception

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Elissaios Karageorgiou
    • 1
    • 2
    • 7
  • Ioannis G. Koutlas
    • 1
    • 3
    • 8
  • Aurelio A. Alonso
    • 1
    • 4
  • Arthur C. Leuthold
    • 1
    • 2
  • Scott M. Lewis
    • 1
    • 5
  • Apostolos P. Georgopoulos
    • 1
    • 2
    • 4
    • 5
    • 6
    • 7
  1. 1.Brain Sciences CenterVeterans Affairs Medical CenterMinneapolisUSA
  2. 2.Department of NeuroscienceUniversity of Minnesota Medical SchoolMinneapolisUSA
  3. 3.Department of Diagnostic and Biological SciencesUniversity of Minnesota School of DentistryMinneapolisUSA
  4. 4.Graduate Program in Oral BiologyUniversity of MinnesotaMinneapolisUSA
  5. 5.Department of NeurologyUniversity of Minnesota Medical SchoolMinneapolisUSA
  6. 6.Department of PsychiatryUniversity of Minnesota Medical SchoolMinneapolisUSA
  7. 7.Center for Cognitive SciencesUniversity of Minnesota Medical SchoolMinneapolisUSA
  8. 8.Diag/Biolo Sci-Oral PathologyMinneapolisUSA