Neuroscience 2005 Abstract
| Presentation Number: | 53.11 |
|---|---|
| Abstract Title: | Differential activation in the secondary somatosensory cortex by electrically evoked itch and pain: a human functional MRI study. |
| Authors: |
Ikoma, A.*1
; Hosogi, M.1
; Schmelz, M.3
; Miyachi, Y.1
; Fukuyama, H.2
; Hanakawa, T.2
1Dept Dermatol, Kyoto Univ., Kyoto, Japan 2Human Brain Research Center, Kyoto Univ., Kyoto, Japan 3Germany, Shogoin-Kawahara-cho 54, 606-8507, |
| Primary Theme and Topics |
Sensory and Motor Systems - Pain -- Pain imaging and perception |
| Secondary Theme and Topics | Homeostatic and Neuroendocrine Systems<br />- Brain Blood Flow, Metabolism and Homeostasis<br />-- Functional imaging |
| Session: |
53. Pain imaging Poster |
| Presentation Time: | Saturday, November 12, 2005 3:00 PM-4:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # V29 |
| Keywords: | ELECTRICAL STIMULATION, NEUROIMAGING, BRAIN IMAGING, PSYCHOPHYSICS |
Objective: Different from traditional histamine application, the length and intensity of itch sensation can be controlled with our newly developed electrical stimulation on human skin. fMRI was applied to investigate the neural underpinnings of itch sensation evoked with this new method.
Methods: Fourteen healthy human subjects (6 females and 8 males, aged 29.4±3.0yr, mean±SD) participated in this study. Transcutaneous electrical stimulation of 50Hz frequency and 2-ms pulse length was applied through a thin electrode (0.1 x 7mm) to evoke itch, while stimulation of 100Hz and 0.2-ms through a round plate electrode (diameter 15mm) to evoke pain. Both electrodes were put on the volar surface of the wrist skin. The stimulus intensity was individually adjusted and fixed before starting fMRI imaging to provoke itch or pain with rating of 30% on a VAS-scale (0.13±0.06mA for itch, 2.43±0.27mA for pain, mean±SEM). On a 3-T MRI scanner, functional images were obtained with a gradient-echo, echo planar imaging sequence with prospective motion correction. During an experimental run, 30-s task periods with electrical stimulation were repeated four times and alternated with 30-s rest periods. Itch and pain stimuli were administered in separate runs. Image analysis was performed using statistical parametric mapping (SPM2) implemented on MATLAB.
Results: Itch and pain induced activity in a similar set of brain regions. Although both led to activation in the second somatosensory cortex (S2), the activation by pain was significantly more intense than that by itch.
Conclusion: The result is compatible with previous neuroimaging studies of histamine-induced itch in which, however, no activation in S2 was observed. This study is the first trial to apply electrical evoked itch to functional neuroimaging and certifies the availability of this method to investigate brain mechanisms for itch perception.
Methods: Fourteen healthy human subjects (6 females and 8 males, aged 29.4±3.0yr, mean±SD) participated in this study. Transcutaneous electrical stimulation of 50Hz frequency and 2-ms pulse length was applied through a thin electrode (0.1 x 7mm) to evoke itch, while stimulation of 100Hz and 0.2-ms through a round plate electrode (diameter 15mm) to evoke pain. Both electrodes were put on the volar surface of the wrist skin. The stimulus intensity was individually adjusted and fixed before starting fMRI imaging to provoke itch or pain with rating of 30% on a VAS-scale (0.13±0.06mA for itch, 2.43±0.27mA for pain, mean±SEM). On a 3-T MRI scanner, functional images were obtained with a gradient-echo, echo planar imaging sequence with prospective motion correction. During an experimental run, 30-s task periods with electrical stimulation were repeated four times and alternated with 30-s rest periods. Itch and pain stimuli were administered in separate runs. Image analysis was performed using statistical parametric mapping (SPM2) implemented on MATLAB.
Results: Itch and pain induced activity in a similar set of brain regions. Although both led to activation in the second somatosensory cortex (S2), the activation by pain was significantly more intense than that by itch.
Conclusion: The result is compatible with previous neuroimaging studies of histamine-induced itch in which, however, no activation in S2 was observed. This study is the first trial to apply electrical evoked itch to functional neuroimaging and certifies the availability of this method to investigate brain mechanisms for itch perception.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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