2005 Fiscal Year Final Research Report Summary
Investigation of mechanisms for human pain perception and its clinical application, mainly on function of signals ascending through C fibers.
| Project/Area Number |
15390480
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Anesthesiology/Resuscitation studies
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| Research Institution | National Institute for Physiological Sciences (2004-2005)
Okazaki National Research Institutes (2003) |
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Principal Investigator |
KAKIGI Ryusuke National Institute for Physiological Sciences, Department of Integrative Physiology, Professor, 統合生理研究系, 教授 (10145196)
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| Co-Investigator(Kenkyū-buntansha) |
INUI Koji National Institute for Physiological Sciences, Department of Integrative Physiology, Assistant Professor, 統合生理研究系, 助手 (70262996)
TOTOKI Tadahide Saga university, Faculty of Medicine, Professor & Director of Hospital, 佐賀大学・医学部, 理事・病院長 (20038722)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Pain / Electroencephalography / Magnetoencephalography / Functional magnetic resonance imaging / First pain / Second pain / A-delta fibers / C fibers |
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| Research Abstract |
OBJECTIVE : We studied electrophysiological studies using electroencephalography (EEG), magnetoencephalography (MEG) and repetitive transcranial magnetic stimulation (rTMS) as well as functional magnetic resonance imaging (fMRI) on human pain perception.
METHODS : For recording activities following A delta fiber stimulation relating to first pain, several kinds of lasers such as CO2, Tm : YAG and argon lasers are now widely used. The activity is frequently termed laser evoked potential (LEP). We also developed new method, epidermal stimulation (ES), which is useful for recording brain activities by the signals ascending through A delta fibers. For recording activities following C fiber stimulation relating to second pain, several methods have been used but weak CO2 laser stimuli applied to tiny areas of the skin were recently used.
RESULTS : EEG and MEG findings following C fiber stimulation were similar to those following A delta fiber stimulation except for a longer latency. We also studied the effect of rTMS on acute pain perception. rTMS alleviated acute pain induced by intracutaneous injection of capsaicin, which activated C fibers, but it enhanced acute pain induced by laser stimulation, which activated A delta fibers. As for fMRI studies, thalamus, secondary somatosensory cortex (SII), insula and cingulate cortex in the bilateral hemispheres were activated following both A delta and C fiber stimulation. However, only a small region, area 6/8/32 and pre supplementally motor area (SMA) were selectively activated following C fiber stimulation.
DISCUSSION : In addition to the above methods, one promising approach in the near future is to analyze the change of a frequency band. This method will probably be used for evaluation of continuous tonic pain such as cancer pain, which evoked response studies cannot evaluate.
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