二氧化碳雷射在大鼠尾部進行傷害性刺激之大腦皮質反應的分析及機械式傷害性刺激器之開發

對於探討人類大腦認知之奧秘，一直是本實驗室長期致力研究體感覺神經系統之動力。而各種感覺信號之中尤以痛覺的信號對生物體具有重要意義。對人類而言，如何減輕疼痛，尤其是癌症患者之疼痛一直是臨床上的重要問題，然而受限於疼痛之傳導速度十分緩慢，且在中樞神經系統的分佈不易確定，因此不易有重大突破性之結果。本研究以二氧化碳雷射對大鼠尾巴進行疼痛刺激，然後記錄其大腦皮質之誘發場電位並以電流源密度分析之。由結果得知記錄點越靠近尾部則反應延遲時間越短，而雷射所誘發的場電位分佈與機械式的觸覺反應比較起來在大腦皮質體感覺區的較深層之部位，自表面算起約為900 μm處為最大反應之深度，此反應中心呈現一個電偶極的現象。為了驗証不同型式之傷害性刺激於大腦皮質所引發反應之關連性，因此本文也開發一部可量化施力大小之機械性傷害性刺激器，其具有同步觸發A/D卡及示波器之取樣與波形顯示之弁遄A也提供連續輸出之刺激波形供觀察與記錄之用，相信對疼痛之研究十分有用。

關鍵字

大腦皮質；大鼠；二氧化碳雷射；誘發電位

並列摘要

To probe into the mystery of human brain, we are motivated to study the somatosensory system. Among various sensory modalities, the pain sensation plays an important role in any species. How to release “pain,” especially for a patient with cancer diseases is an important issue in clinical practice. It is however due partially to the show, conduction velocity of pain sensation and the localization in the CNS is not clear; studies on pain have hardly break–through findings. In this investigation, we used CO2 laser as noxious stimulation to induce “pain” in the tail of the rat. The evoked potential was recorded within the rat’s cerebral cortex and analyzed with current-source-density in turn. We found that the closer the recording distance, with respect to the stimulus the shorter the latency of the evoked responses. The maximally evoked responses were at a deeper layer of the cortex, while compared with those obtained from mechanical stimulation. The responsive center located at 0.9 mm in depth from the surface of the cerebral cortex, and a dipole only could be used to model it. To compare the cortical noxious responses evoked from different sources of energy, a noxious mechanical stimulator was developed in this thesis. This device can quantify the force we applied to the body of the experimental animals, and provide an external synchronous output to trigger the data acquisition system. Furthermore, the applied force is also provided as an output connector in analog form for quatilization purpose. This stimulator could be valuable for further studies in our laboratory.

並列關鍵字

cerebral cortex ； rat ； CO2 laser ； evoked potential

參考文獻

9. Y. -Y. Chen, “Current source density of field potential in the brain,” M.S. thesis, National Taiwan Univ., Taipei, 1998.

1. R. A. Meyer and J. N. Campbell,“Myelinated nociceptive afferents account for the hyperalgesia that follows a burn to the hand,” Science, vol.213: 1527-1529, 1981.

2. Robert F. Schmidt, “Fundamentals of Sensory Physiology,” 3th edition, Pring er-Verlay, Berlin, pp. 1-143, 1986

6. J. G. Webster (Ed.), Medical instrumentation application and design, John Wiley and Sons, New York, pp. 183-232, 1998.

7. John G. Nicholls, A. Robert Martin, Bruce G. Wallace, Paul A. Fuchs, “From Neuron to Brain,” pp. 61-476, 2001.

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二氧化碳雷射在大鼠尾部進行傷害性刺激之大腦皮質反應的分析及機械式傷害性刺激器之開發

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