鼠鬚刺激系統之開發與眶下神經重合之術後功能性回復評估

Stimulation system for rat whisker and functional recovery after infraorbital nerve transection

陳吉麟(Ji-Lin Chen)

指導教授 ： 趙福杉

共同指導教授 ： 裴育晟(Yu-Cheng Pei)

國立臺灣大學/工學院/醫學工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201610144

摘要

臨床上許多狀況會造成周邊感覺神經的截斷，如刀傷、車禍碰撞、撕裂傷、移植手術等。少數神經重建術接合斷裂神經的患者在經過長時間復原後可達到部分的感覺回復，究竟這些重拾感覺輸入的患者其大腦發生了哪些轉變是我們所好奇的課題。本研究以大鼠的觸鬚-桶狀皮質系統作為模型，截斷與重新接合支配觸鬚感受器的眶下神經模擬臨床情況，建立出刺激參數與神經反應的調性方程式以評估手術前後感覺皮質發生的變化。
本研究開發了定量化且精確的觸鬚刺激系統以應用於動物實驗。兩組軟體產生的訊號經類比轉換及電壓放大後控制雙軸向壓電致動元件，利用黏附其上的夾具帶動鼠鬚產生雙自由度的撓動。藉由夾具的設計以及軟體的校正，本系統達到高精度的振幅刺激，此外，系統加入了應變量測裝置對輸出振幅作即時監測以減低實驗誤差。
於感受域分析結果，超過半數的樣本在術後可以重新獲得周邊觸鬚受器與皮質感受域的對應關係。其中約三成樣本的感受域分布在手術前後具有相似性。針對感受域回復的樣本，刺激速度辨識能力在手術之後立即降低，但會隨著復原時間增長而回升。另外，皮質神經的刺激後反應時間在手術後增加，但會隨著復原之過程而逐漸減少。本研究呈現了大鼠觸鬚系統在受損的感覺神經功能性回復期間所伴隨的生理變化。

關鍵字

鼠鬚刺激器 ； 功能性回復 ； 神經調性 ； 感受域

並列摘要

Functional loss of peripheral nerve, such as cutting injury, blunt injury, laceration injury and nerve transplantation, is a common clinical condition. For example, the sensation of the finger will take a long time to recover following a nerve reconstruction surgery for some patients with nerve injury. Therefore, the neuroplasticity mechanisms in the primary somatosensory cortex by a nerve reconstruction surgery were investigated. The whisker-to-barrel model was used to evaluate the change of neuronal tuning following neurotomy and neurorrhaphy surgery, an approach that simulates a clinical nerve reconstruction surgery.
We first developed a whisker stimulator that can present precise whisker bending at various directions and speeds. The whiskers were bended by the piezoelectric actuator that has two degrees of freedom, each of which was driven by amplified voltage signals controlled by the software. We designed the whisker holder and completed the software calibration to provide whisker movement with precise amplitude and phase control. Furthermore, we developed a measuring device to monitor the amplitude movement of stimulator in real time.
Multi-unit neuronal activities were recorded before and after the neurotomy and neurorrhaphy surgery, and the follow-up period reached 4-6 weeks post-surgery. The results showed that all units lost their sensory responses immediately after the surgery. Surprisingly, the sensory responses could recover as early as 7 days. In the long-term follow-up, one third of the unit regained whisker tuning that was analogous to that before the surgery. Also, their tuning strength to stimulus speed was weakened in the early recovery period and then gradually increased in the late recovery period. Similarly, the onset latency of a cortical response to whisker stimulation also prolonged in the early recovery period and gradually decreased in the late recovery period. In conclusion, the present study reveals the neuronal mechanisms that account for the functional recovery following nerve reconstruction in the whisker-to-barrel model.

並列關鍵字

whisker stimulator ； functional recovery ； tuning function ； receptive field

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